path: root/contrib/binutils/gas/doc/as.txt

START-INFO-DIR-ENTRY
* As: (as).                     The GNU assembler.
* Gas: (as).                    The GNU assembler.
END-INFO-DIR-ENTRY

Using as
1 Overview
  1.1 Structure of this Manual
  1.2 The GNU Assembler
  1.3 Object File Formats
  1.4 Command Line
  1.5 Input Files
  1.6 Output (Object) File
  1.7 Error and Warning Messages
2 Command-Line Options
  2.1 Enable Listings: '-a[cdhlns]'
  2.2 '--alternate'
  2.3 '-D'
  2.4 Work Faster: '-f'
  2.5 '.include' Search Path: '-I' PATH
  2.6 Difference Tables: '-K'
  2.7 Include Local Symbols: '-L'
  2.8 Configuring listing output: '--listing'
  2.9 Assemble in MRI Compatibility Mode: '-M'
  2.10 Dependency Tracking: '--MD'
  2.11 Name the Object File: '-o'
  2.12 Join Data and Text Sections: '-R'
  2.13 Display Assembly Statistics: '--statistics'
  2.14 Compatible Output: '--traditional-format'
  2.15 Announce Version: '-v'
  2.16 Control Warnings: '-W', '--warn', '--no-warn', '--fatal-warnings'
  2.17 Generate Object File in Spite of Errors: '-Z'
3 Syntax
  3.1 Preprocessing
  3.2 Whitespace
  3.3 Comments
  3.4 Symbols
  3.5 Statements
  3.6 Constants
    3.6.1 Character Constants
      3.6.1.1 Strings
      3.6.1.2 Characters
    3.6.2 Number Constants
      3.6.2.1 Integers
      3.6.2.2 Bignums
      3.6.2.3 Flonums
4 Sections and Relocation
  4.1 Background
  4.2 Linker Sections
  4.3 Assembler Internal Sections
  4.4 Sub-Sections
  4.5 bss Section
5 Symbols
  5.1 Labels
  5.2 Giving Symbols Other Values
  5.3 Symbol Names
  5.4 The Special Dot Symbol
  5.5 Symbol Attributes
    5.5.1 Value
    5.5.2 Type
6 Expressions
  6.1 Empty Expressions
  6.2 Integer Expressions
    6.2.1 Arguments
    6.2.2 Operators
    6.2.3 Prefix Operator
    6.2.4 Infix Operators
7 Assembler Directives
  7.1 '.abort'
  7.2 '.align ABS-EXPR, ABS-EXPR, ABS-EXPR'
  7.3 '.ascii "STRING"'...
  7.4 '.asciz "STRING"'...
  7.5 '.balign[wl] ABS-EXPR, ABS-EXPR, ABS-EXPR'
  7.6 '.byte EXPRESSIONS'
  7.7 '.comm SYMBOL , LENGTH '
  7.8 '.cfi_startproc [simple]'
  7.9 '.cfi_endproc'
  7.10 '.cfi_personality ENCODING [, EXP]'
  7.11 '.cfi_lsda ENCODING [, EXP]'
  7.12 '.cfi_def_cfa REGISTER, OFFSET'
  7.13 '.cfi_def_cfa_register REGISTER'
  7.14 '.cfi_def_cfa_offset OFFSET'
  7.15 '.cfi_adjust_cfa_offset OFFSET'
  7.16 '.cfi_offset REGISTER, OFFSET'
  7.17 '.cfi_rel_offset REGISTER, OFFSET'
  7.18 '.cfi_register REGISTER1, REGISTER2'
  7.19 '.cfi_restore REGISTER'
  7.20 '.cfi_undefined REGISTER'
  7.21 '.cfi_same_value REGISTER'
  7.22 '.cfi_remember_state',
  7.23 '.cfi_return_column REGISTER'
  7.24 '.cfi_signal_frame'
  7.25 '.cfi_window_save'
  7.26 '.cfi_escape' EXPRESSION[, ...]
  7.27 '.file FILENO FILENAME'
  7.28 '.loc FILENO LINENO [COLUMN] [OPTIONS]'
  7.29 '.loc_mark_blocks ENABLE'
  7.30 '.data SUBSECTION'
  7.31 '.double FLONUMS'
  7.32 '.eject'
  7.33 '.else'
  7.34 '.elseif'
  7.35 '.end'
  7.36 '.endfunc'
  7.37 '.endif'
  7.38 '.equ SYMBOL, EXPRESSION'
  7.39 '.equiv SYMBOL, EXPRESSION'
  7.40 '.eqv SYMBOL, EXPRESSION'
  7.41 '.err'
  7.42 '.error "STRING"'
  7.43 '.exitm'
  7.44 '.extern'
  7.45 '.fail EXPRESSION'
  7.46 '.file STRING'
  7.47 '.fill REPEAT , SIZE , VALUE'
  7.48 '.float FLONUMS'
  7.49 '.func NAME[,LABEL]'
  7.50 '.global SYMBOL', '.globl SYMBOL'
  7.51 '.hidden NAMES'
  7.52 '.hword EXPRESSIONS'
  7.53 '.ident'
  7.54 '.if ABSOLUTE EXPRESSION'
  7.55 '.incbin "FILE"[,SKIP[,COUNT]]'
  7.56 '.include "FILE"'
  7.57 '.int EXPRESSIONS'
  7.58 '.internal NAMES'
  7.59 '.irp SYMBOL,VALUES'...
  7.60 '.irpc SYMBOL,VALUES'...
  7.61 '.lcomm SYMBOL , LENGTH'
  7.62 '.lflags'
  7.63 '.line LINE-NUMBER'
  7.64 '.linkonce [TYPE]'
  7.65 '.ln LINE-NUMBER'
  7.66 '.mri VAL'
  7.67 '.list'
  7.68 '.long EXPRESSIONS'
  7.69 '.macro'
  7.70 '.altmacro'
  7.71 '.noaltmacro'
  7.72 '.nolist'
  7.73 '.octa BIGNUMS'
  7.74 '.org NEW-LC , FILL'
  7.75 '.p2align[wl] ABS-EXPR, ABS-EXPR, ABS-EXPR'
  7.76 '.previous'
  7.77 '.popsection'
  7.78 '.print STRING'
  7.79 '.protected NAMES'
  7.80 '.psize LINES , COLUMNS'
  7.81 '.purgem NAME'
  7.82 '.pushsection NAME , SUBSECTION'
  7.83 '.quad BIGNUMS'
  7.84 '.reloc OFFSET, RELOC_NAME[, EXPRESSION]'
  7.85 '.rept COUNT'
  7.86 '.sbttl "SUBHEADING"'
  7.87 '.section NAME'
  7.88 '.set SYMBOL, EXPRESSION'
  7.89 '.short EXPRESSIONS'
  7.90 '.single FLONUMS'
  7.91 '.size'
  7.92 '.sleb128 EXPRESSIONS'
  7.93 '.skip SIZE , FILL'
  7.94 '.space SIZE , FILL'
  7.95 '.stabd, .stabn, .stabs'
  7.96 '.string' "STR"
  7.97 '.struct EXPRESSION'
  7.98 '.subsection NAME'
  7.99 '.symver'
  7.100 '.text SUBSECTION'
  7.101 '.title "HEADING"'
  7.102 '.type'
  7.103 '.uleb128 EXPRESSIONS'
  7.104 '.version "STRING"'
  7.105 '.vtable_entry TABLE, OFFSET'
  7.106 '.vtable_inherit CHILD, PARENT'
  7.107 '.warning "STRING"'
  7.108 '.weak NAMES'
  7.109 '.weakref ALIAS, TARGET'
  7.110 '.word EXPRESSIONS'
  7.111 Deprecated Directives
8 ARM Dependent Features
  8.1 Options
  8.2 Syntax
    8.2.1 Special Characters
    8.2.2 Register Names
    8.2.3 ARM relocation generation
  8.3 Floating Point
  8.4 ARM Machine Directives
  8.5 Opcodes
  8.6 Mapping Symbols
9 80386 Dependent Features
  9.1 Options
  9.2 AT&T Syntax versus Intel Syntax
  9.3 Instruction Naming
  9.4 Register Naming
  9.5 Instruction Prefixes
  9.6 Memory References
  9.7 Handling of Jump Instructions
  9.8 Floating Point
  9.9 Intel's MMX and AMD's 3DNow! SIMD Operations
  9.10 Writing 16-bit Code
  9.11 AT&T Syntax bugs
  9.12 Specifying CPU Architecture
  9.13 Notes
10 IA-64 Dependent Features
  10.1 Options
  10.2 Syntax
    10.2.1 Special Characters
    10.2.2 Register Names
    10.2.3 IA-64 Processor-Status-Register (PSR) Bit Names
  10.3 Opcodes
11 MIPS Dependent Features
  11.1 Assembler options
  11.2 MIPS ECOFF object code
  11.3 Directives for debugging information
  11.4 Directives to override the size of symbols
  11.5 Directives to override the ISA level
  11.6 Directives for extending MIPS 16 bit instructions
  11.7 Directive to mark data as an instruction
  11.8 Directives to save and restore options
  11.9 Directives to control generation of MIPS ASE instructions
12 PowerPC Dependent Features
  12.1 Options
  12.2 PowerPC Assembler Directives
13 SPARC Dependent Features
  13.1 Options
  13.2 Enforcing aligned data
  13.3 Floating Point
  13.4 Sparc Machine Directives
14 Reporting Bugs
  14.1 Have You Found a Bug?
  14.2 How to Report Bugs
15 Acknowledgements
Appendix A GNU Free Documentation License
  ADDENDUM: How to use this License for your documents
AS Index
Using as
********

This file is a user guide to the GNU assembler 'as' version "2.17.50
[FreeBSD] 2007-07-03".  This version of the file describes 'as'
configured to generate code for machine specific architectures.

   This document is distributed under the terms of the GNU Free
Documentation License.  A copy of the license is included in the section
entitled "GNU Free Documentation License".

1 Overview
**********

Here is a brief summary of how to invoke 'as'.  For details, see *note
Command-Line Options: Invoking.

     as [-a[cdhlns][=FILE]] [-alternate] [-D]
      [-defsym SYM=VAL] [-f] [-g] [-gstabs]
      [-gstabs+] [-gdwarf-2] [-help] [-I DIR] [-J]
      [-K] [-L] [-listing-lhs-width=NUM]
      [-listing-lhs-width2=NUM] [-listing-rhs-width=NUM]
      [-listing-cont-lines=NUM] [-keep-locals] [-o
      OBJFILE] [-R] [-reduce-memory-overheads] [-statistics]
      [-v] [-version] [-version] [-W] [-warn]
      [-fatal-warnings] [-w] [-x] [-Z] [@FILE]
      [-target-help] [TARGET-OPTIONS]
      [-|FILES ...]

     _Target ARM options:_
        [-mcpu=PROCESSOR[+EXTENSION...]]
        [-march=ARCHITECTURE[+EXTENSION...]]
        [-mfpu=FLOATING-POINT-FORMAT]
        [-mfloat-abi=ABI]
        [-meabi=VER]
        [-mthumb]
        [-EB|-EL]
        [-mapcs-32|-mapcs-26|-mapcs-float|
         -mapcs-reentrant]
        [-mthumb-interwork] [-k]

     _Target i386 options:_
        [-32|-64] [-n]
        [-march=CPU] [-mtune=CPU]

     _Target IA-64 options:_
        [-mconstant-gp|-mauto-pic]
        [-milp32|-milp64|-mlp64|-mp64]
        [-mle|mbe]
        [-mtune=itanium1|-mtune=itanium2]
        [-munwind-check=warning|-munwind-check=error]
        [-mhint.b=ok|-mhint.b=warning|-mhint.b=error]
        [-x|-xexplicit] [-xauto] [-xdebug]

     _Target MIPS options:_
        [-nocpp] [-EL] [-EB] [-O[OPTIMIZATION LEVEL]]
        [-g[DEBUG LEVEL]] [-G NUM] [-KPIC] [-call_shared]
        [-non_shared] [-xgot [-mvxworks-pic]
        [-mabi=ABI] [-32] [-n32] [-64] [-mfp32] [-mgp32]
        [-march=CPU] [-mtune=CPU] [-mips1] [-mips2]
        [-mips3] [-mips4] [-mips5] [-mips32] [-mips32r2]
        [-mips64] [-mips64r2]
        [-construct-floats] [-no-construct-floats]
        [-trap] [-no-break] [-break] [-no-trap]
        [-mfix7000] [-mno-fix7000]
        [-mips16] [-no-mips16]
        [-msmartmips] [-mno-smartmips]
        [-mips3d] [-no-mips3d]
        [-mdmx] [-no-mdmx]
        [-mdsp] [-mno-dsp]
        [-mdspr2] [-mno-dspr2]
        [-mmt] [-mno-mt]
        [-mdebug] [-no-mdebug]
        [-mpdr] [-mno-pdr]

     _Target PowerPC options:_
        [-mpwrx|-mpwr2|-mpwr|-m601|-mppc|-mppc32|-m603|-m604|
         -m403|-m405|-mppc64|-m620|-mppc64bridge|-mbooke|
         -mbooke32|-mbooke64]
        [-mcom|-many|-maltivec] [-memb]
        [-mregnames|-mno-regnames]
        [-mrelocatable|-mrelocatable-lib]
        [-mlittle|-mlittle-endian|-mbig|-mbig-endian]
        [-msolaris|-mno-solaris]

     _Target SPARC options:_
        [-Av6|-Av7|-Av8|-Asparclet|-Asparclite
         -Av8plus|-Av8plusa|-Av9|-Av9a]
        [-xarch=v8plus|-xarch=v8plusa] [-bump]
        [-32|-64]



'@FILE'
     Read command-line options from FILE.  The options read are inserted
     in place of the original @FILE option.  If FILE does not exist, or
     cannot be read, then the option will be treated literally, and not
     removed.

     Options in FILE are separated by whitespace.  A whitespace
     character may be included in an option by surrounding the entire
     option in either single or double quotes.  Any character (including
     a backslash) may be included by prefixing the character to be
     included with a backslash.  The FILE may itself contain additional
     @FILE options; any such options will be processed recursively.

'-a[cdhlmns]'
     Turn on listings, in any of a variety of ways:

     '-ac'
          omit false conditionals

     '-ad'
          omit debugging directives

     '-ah'
          include high-level source

     '-al'
          include assembly

     '-am'
          include macro expansions

     '-an'
          omit forms processing

     '-as'
          include symbols

     '=file'
          set the name of the listing file

     You may combine these options; for example, use '-aln' for assembly
     listing without forms processing.  The '=file' option, if used,
     must be the last one.  By itself, '-a' defaults to '-ahls'.

'--alternate'
     Begin in alternate macro mode.  *Note '.altmacro': Altmacro.

'-D'
     Ignored.  This option is accepted for script compatibility with
     calls to other assemblers.

'--defsym SYM=VALUE'
     Define the symbol SYM to be VALUE before assembling the input file.
     VALUE must be an integer constant.  As in C, a leading '0x'
     indicates a hexadecimal value, and a leading '0' indicates an octal
     value.  The value of the symbol can be overridden inside a source
     file via the use of a '.set' pseudo-op.

'-f'
     "fast"--skip whitespace and comment preprocessing (assume source is
     compiler output).

'-g'
'--gen-debug'
     Generate debugging information for each assembler source line using
     whichever debug format is preferred by the target.  This currently
     means either STABS, ECOFF or DWARF2.

'--gstabs'
     Generate stabs debugging information for each assembler line.  This
     may help debugging assembler code, if the debugger can handle it.

'--gstabs+'
     Generate stabs debugging information for each assembler line, with
     GNU extensions that probably only gdb can handle, and that could
     make other debuggers crash or refuse to read your program.  This
     may help debugging assembler code.  Currently the only GNU
     extension is the location of the current working directory at
     assembling time.

'--gdwarf-2'
     Generate DWARF2 debugging information for each assembler line.
     This may help debugging assembler code, if the debugger can handle
     it.  Note--this option is only supported by some targets, not all
     of them.

'--help'
     Print a summary of the command line options and exit.

'--target-help'
     Print a summary of all target specific options and exit.

'-I DIR'
     Add directory DIR to the search list for '.include' directives.

'-J'
     Don't warn about signed overflow.

'-K'
     This option is accepted but has no effect on the machine specific
     family.

'-L'
'--keep-locals'
     Keep (in the symbol table) local symbols.  These symbols start with
     system-specific local label prefixes, typically '.L' for ELF
     systems or 'L' for traditional a.out systems.  *Note Symbol
     Names::.

'--listing-lhs-width=NUMBER'
     Set the maximum width, in words, of the output data column for an
     assembler listing to NUMBER.

'--listing-lhs-width2=NUMBER'
     Set the maximum width, in words, of the output data column for
     continuation lines in an assembler listing to NUMBER.

'--listing-rhs-width=NUMBER'
     Set the maximum width of an input source line, as displayed in a
     listing, to NUMBER bytes.

'--listing-cont-lines=NUMBER'
     Set the maximum number of lines printed in a listing for a single
     line of input to NUMBER + 1.

'-o OBJFILE'
     Name the object-file output from 'as' OBJFILE.

'-R'
     Fold the data section into the text section.

     Set the default size of GAS's hash tables to a prime number close
     to NUMBER.  Increasing this value can reduce the length of time it
     takes the assembler to perform its tasks, at the expense of
     increasing the assembler's memory requirements.  Similarly reducing
     this value can reduce the memory requirements at the expense of
     speed.

'--reduce-memory-overheads'
     This option reduces GAS's memory requirements, at the expense of
     making the assembly processes slower.  Currently this switch is a
     synonym for '--hash-size=4051', but in the future it may have other
     effects as well.

'--statistics'
     Print the maximum space (in bytes) and total time (in seconds) used
     by assembly.

'--strip-local-absolute'
     Remove local absolute symbols from the outgoing symbol table.

'-v'
'-version'
     Print the 'as' version.

'--version'
     Print the 'as' version and exit.

'-W'
'--no-warn'
     Suppress warning messages.

'--fatal-warnings'
     Treat warnings as errors.

'--warn'
     Don't suppress warning messages or treat them as errors.

'-w'
     Ignored.

'-x'
     Ignored.

'-Z'
     Generate an object file even after errors.

'-- | FILES ...'
     Standard input, or source files to assemble.

   The following options are available when as is configured for the ARM
processor family.

'-mcpu=PROCESSOR[+EXTENSION...]'
     Specify which ARM processor variant is the target.
'-march=ARCHITECTURE[+EXTENSION...]'
     Specify which ARM architecture variant is used by the target.
'-mfpu=FLOATING-POINT-FORMAT'
     Select which Floating Point architecture is the target.
'-mfloat-abi=ABI'
     Select which floating point ABI is in use.
'-mthumb'
     Enable Thumb only instruction decoding.
'-mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant'
     Select which procedure calling convention is in use.
'-EB | -EL'
     Select either big-endian (-EB) or little-endian (-EL) output.
'-mthumb-interwork'
     Specify that the code has been generated with interworking between
     Thumb and ARM code in mind.
'-k'
     Specify that PIC code has been generated.

   The following options are available when 'as' is configured for the
SPARC architecture:

'-Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite'
'-Av8plus | -Av8plusa | -Av9 | -Av9a'
     Explicitly select a variant of the SPARC architecture.

     '-Av8plus' and '-Av8plusa' select a 32 bit environment.  '-Av9' and
     '-Av9a' select a 64 bit environment.

     '-Av8plusa' and '-Av9a' enable the SPARC V9 instruction set with
     UltraSPARC extensions.

'-xarch=v8plus | -xarch=v8plusa'
     For compatibility with the Solaris v9 assembler.  These options are
     equivalent to -Av8plus and -Av8plusa, respectively.

'-bump'
     Warn when the assembler switches to another architecture.

   The following options are available when as is configured for a MIPS
processor.

'-G NUM'
     This option sets the largest size of an object that can be
     referenced implicitly with the 'gp' register.  It is only accepted
     for targets that use ECOFF format, such as a DECstation running
     Ultrix.  The default value is 8.

'-EB'
     Generate "big endian" format output.

'-EL'
     Generate "little endian" format output.

'-mips1'
'-mips2'
'-mips3'
'-mips4'
'-mips5'
'-mips32'
'-mips32r2'
'-mips64'
'-mips64r2'
     Generate code for a particular MIPS Instruction Set Architecture
     level.  '-mips1' is an alias for '-march=r3000', '-mips2' is an
     alias for '-march=r6000', '-mips3' is an alias for '-march=r4000'
     and '-mips4' is an alias for '-march=r8000'.  '-mips5', '-mips32',
     '-mips32r2', '-mips64', and '-mips64r2' correspond to generic 'MIPS
     V', 'MIPS32', 'MIPS32 Release 2', 'MIPS64', and 'MIPS64 Release 2'
     ISA processors, respectively.

'-march=CPU'
     Generate code for a particular MIPS cpu.

'-mtune=CPU'
     Schedule and tune for a particular MIPS cpu.

'-mfix7000'
'-mno-fix7000'
     Cause nops to be inserted if the read of the destination register
     of an mfhi or mflo instruction occurs in the following two
     instructions.

'-mdebug'
'-no-mdebug'
     Cause stabs-style debugging output to go into an ECOFF-style
     .mdebug section instead of the standard ELF .stabs sections.

'-mpdr'
'-mno-pdr'
     Control generation of '.pdr' sections.

'-mgp32'
'-mfp32'
     The register sizes are normally inferred from the ISA and ABI, but
     these flags force a certain group of registers to be treated as 32
     bits wide at all times.  '-mgp32' controls the size of
     general-purpose registers and '-mfp32' controls the size of
     floating-point registers.

'-mips16'
'-no-mips16'
     Generate code for the MIPS 16 processor.  This is equivalent to
     putting '.set mips16' at the start of the assembly file.
     '-no-mips16' turns off this option.

'-msmartmips'
'-mno-smartmips'
     Enables the SmartMIPS extension to the MIPS32 instruction set.
     This is equivalent to putting '.set smartmips' at the start of the
     assembly file.  '-mno-smartmips' turns off this option.

'-mips3d'
'-no-mips3d'
     Generate code for the MIPS-3D Application Specific Extension.  This
     tells the assembler to accept MIPS-3D instructions.  '-no-mips3d'
     turns off this option.

'-mdmx'
'-no-mdmx'
     Generate code for the MDMX Application Specific Extension.  This
     tells the assembler to accept MDMX instructions.  '-no-mdmx' turns
     off this option.

'-mdsp'
'-mno-dsp'
     Generate code for the DSP Release 1 Application Specific Extension.
     This tells the assembler to accept DSP Release 1 instructions.
     '-mno-dsp' turns off this option.

'-mdspr2'
'-mno-dspr2'
     Generate code for the DSP Release 2 Application Specific Extension.
     This option implies -mdsp.  This tells the assembler to accept DSP
     Release 2 instructions.  '-mno-dspr2' turns off this option.

'-mmt'
'-mno-mt'
     Generate code for the MT Application Specific Extension.  This
     tells the assembler to accept MT instructions.  '-mno-mt' turns off
     this option.

'--construct-floats'
'--no-construct-floats'
     The '--no-construct-floats' option disables the construction of
     double width floating point constants by loading the two halves of
     the value into the two single width floating point registers that
     make up the double width register.  By default '--construct-floats'
     is selected, allowing construction of these floating point
     constants.

'--emulation=NAME'
     This option causes 'as' to emulate 'as' configured for some other
     target, in all respects, including output format (choosing between
     ELF and ECOFF only), handling of pseudo-opcodes which may generate
     debugging information or store symbol table information, and
     default endianness.  The available configuration names are:
     'mipsecoff', 'mipself', 'mipslecoff', 'mipsbecoff', 'mipslelf',
     'mipsbelf'.  The first two do not alter the default endianness from
     that of the primary target for which the assembler was configured;
     the others change the default to little- or big-endian as indicated
     by the 'b' or 'l' in the name.  Using '-EB' or '-EL' will override
     the endianness selection in any case.

     This option is currently supported only when the primary target
     'as' is configured for is a MIPS ELF or ECOFF target.  Furthermore,
     the primary target or others specified with '--enable-targets=...'
     at configuration time must include support for the other format, if
     both are to be available.  For example, the Irix 5 configuration
     includes support for both.

     Eventually, this option will support more configurations, with more
     fine-grained control over the assembler's behavior, and will be
     supported for more processors.

'-nocpp'
     'as' ignores this option.  It is accepted for compatibility with
     the native tools.

'--trap'
'--no-trap'
'--break'
'--no-break'
     Control how to deal with multiplication overflow and division by
     zero.  '--trap' or '--no-break' (which are synonyms) take a trap
     exception (and only work for Instruction Set Architecture level 2
     and higher); '--break' or '--no-trap' (also synonyms, and the
     default) take a break exception.

'-n'
     When this option is used, 'as' will issue a warning every time it
     generates a nop instruction from a macro.

1.1 Structure of this Manual
============================

This manual is intended to describe what you need to know to use GNU
'as'.  We cover the syntax expected in source files, including notation
for symbols, constants, and expressions; the directives that 'as'
understands; and of course how to invoke 'as'.

   We also cover special features in the machine specific configuration
of 'as', including assembler directives.

   On the other hand, this manual is _not_ intended as an introduction
to programming in assembly language--let alone programming in general!
In a similar vein, we make no attempt to introduce the machine
architecture; we do _not_ describe the instruction set, standard
mnemonics, registers or addressing modes that are standard to a
particular architecture.

1.2 The GNU Assembler
=====================

GNU 'as' is really a family of assemblers.  This manual describes 'as',
a member of that family which is configured for the machine specific
architectures.  If you use (or have used) the GNU assembler on one
architecture, you should find a fairly similar environment when you use
it on another architecture.  Each version has much in common with the
others, including object file formats, most assembler directives (often
called "pseudo-ops") and assembler syntax.

   'as' is primarily intended to assemble the output of the GNU C
compiler 'gcc' for use by the linker 'ld'.  Nevertheless, we've tried to
make 'as' assemble correctly everything that other assemblers for the
same machine would assemble.

   Unlike older assemblers, 'as' is designed to assemble a source
program in one pass of the source file.  This has a subtle impact on the
'.org' directive (*note '.org': Org.).

1.3 Object File Formats
=======================

The GNU assembler can be configured to produce several alternative
object file formats.  For the most part, this does not affect how you
write assembly language programs; but directives for debugging symbols
are typically different in different file formats.  *Note Symbol
Attributes: Symbol Attributes.  For the machine specific target, 'as' is
configured to produce ELF format object files.

1.4 Command Line
================

After the program name 'as', the command line may contain options and
file names.  Options may appear in any order, and may be before, after,
or between file names.  The order of file names is significant.

   '--' (two hyphens) by itself names the standard input file
explicitly, as one of the files for 'as' to assemble.

   Except for '--' any command line argument that begins with a hyphen
('-') is an option.  Each option changes the behavior of 'as'.  No
option changes the way another option works.  An option is a '-'
followed by one or more letters; the case of the letter is important.
All options are optional.

   Some options expect exactly one file name to follow them.  The file
name may either immediately follow the option's letter (compatible with
older assemblers) or it may be the next command argument (GNU standard).
These two command lines are equivalent:

     as -o my-object-file.o mumble.s
     as -omy-object-file.o mumble.s

1.5 Input Files
===============

We use the phrase "source program", abbreviated "source", to describe
the program input to one run of 'as'.  The program may be in one or more
files; how the source is partitioned into files doesn't change the
meaning of the source.

   The source program is a concatenation of the text in all the files,
in the order specified.

   Each time you run 'as' it assembles exactly one source program.  The
source program is made up of one or more files.  (The standard input is
also a file.)

   You give 'as' a command line that has zero or more input file names.
The input files are read (from left file name to right).  A command line
argument (in any position) that has no special meaning is taken to be an
input file name.

   If you give 'as' no file names it attempts to read one input file
from the 'as' standard input, which is normally your terminal.  You may
have to type <ctl-D> to tell 'as' there is no more program to assemble.

   Use '--' if you need to explicitly name the standard input file in
your command line.

   If the source is empty, 'as' produces a small, empty object file.

Filenames and Line-numbers
--------------------------

There are two ways of locating a line in the input file (or files) and
either may be used in reporting error messages.  One way refers to a
line number in a physical file; the other refers to a line number in a
"logical" file.  *Note Error and Warning Messages: Errors.

   "Physical files" are those files named in the command line given to
'as'.

   "Logical files" are simply names declared explicitly by assembler
directives; they bear no relation to physical files.  Logical file names
help error messages reflect the original source file, when 'as' source
is itself synthesized from other files.  'as' understands the '#'
directives emitted by the 'gcc' preprocessor.  See also *note '.file':
File.

1.6 Output (Object) File
========================

Every time you run 'as' it produces an output file, which is your
assembly language program translated into numbers.  This file is the
object file.  Its default name is 'a.out'.  You can give it another name
by using the '-o' option.  Conventionally, object file names end with
'.o'.  The default name is used for historical reasons: older assemblers
were capable of assembling self-contained programs directly into a
runnable program.  (For some formats, this isn't currently possible, but
it can be done for the 'a.out' format.)

   The object file is meant for input to the linker 'ld'.  It contains
assembled program code, information to help 'ld' integrate the assembled
program into a runnable file, and (optionally) symbolic information for
the debugger.

1.7 Error and Warning Messages
==============================

'as' may write warnings and error messages to the standard error file
(usually your terminal).  This should not happen when a compiler runs
'as' automatically.  Warnings report an assumption made so that 'as'
could keep assembling a flawed program; errors report a grave problem
that stops the assembly.

   Warning messages have the format

     file_name:NNN:Warning Message Text

(where NNN is a line number).  If a logical file name has been given
(*note '.file': File.) it is used for the filename, otherwise the name
of the current input file is used.  If a logical line number was given
then it is used to calculate the number printed, otherwise the actual
line in the current source file is printed.  The message text is
intended to be self explanatory (in the grand Unix tradition).

   Error messages have the format
     file_name:NNN:FATAL:Error Message Text
   The file name and line number are derived as for warning messages.
The actual message text may be rather less explanatory because many of
them aren't supposed to happen.

2 Command-Line Options
**********************

This chapter describes command-line options available in _all_ versions
of the GNU assembler; see *note Machine Dependencies::, for options
specific to the machine specific target.

   If you are invoking 'as' via the GNU C compiler, you can use the
'-Wa' option to pass arguments through to the assembler.  The assembler
arguments must be separated from each other (and the '-Wa') by commas.
For example:

     gcc -c -g -O -Wa,-alh,-L file.c

This passes two options to the assembler: '-alh' (emit a listing to
standard output with high-level and assembly source) and '-L' (retain
local symbols in the symbol table).

   Usually you do not need to use this '-Wa' mechanism, since many
compiler command-line options are automatically passed to the assembler
by the compiler.  (You can call the GNU compiler driver with the '-v'
option to see precisely what options it passes to each compilation pass,
including the assembler.)

2.1 Enable Listings: '-a[cdhlns]'
=================================

These options enable listing output from the assembler.  By itself, '-a'
requests high-level, assembly, and symbols listing.  You can use other
letters to select specific options for the list: '-ah' requests a
high-level language listing, '-al' requests an output-program assembly
listing, and '-as' requests a symbol table listing.  High-level listings
require that a compiler debugging option like '-g' be used, and that
assembly listings ('-al') be requested also.

   Use the '-ac' option to omit false conditionals from a listing.  Any
lines which are not assembled because of a false '.if' (or '.ifdef', or
any other conditional), or a true '.if' followed by an '.else', will be
omitted from the listing.

   Use the '-ad' option to omit debugging directives from the listing.

   Once you have specified one of these options, you can further control
listing output and its appearance using the directives '.list',
'.nolist', '.psize', '.eject', '.title', and '.sbttl'.  The '-an' option
turns off all forms processing.  If you do not request listing output
with one of the '-a' options, the listing-control directives have no
effect.

   The letters after '-a' may be combined into one option, _e.g._,
'-aln'.

   Note if the assembler source is coming from the standard input (e.g.,
because it is being created by 'gcc' and the '-pipe' command line switch
is being used) then the listing will not contain any comments or
preprocessor directives.  This is because the listing code buffers input
source lines from stdin only after they have been preprocessed by the
assembler.  This reduces memory usage and makes the code more efficient.

2.2 '--alternate'
=================

Begin in alternate macro mode, see *note '.altmacro': Altmacro.

2.3 '-D'
========

This option has no effect whatsoever, but it is accepted to make it more
likely that scripts written for other assemblers also work with 'as'.

2.4 Work Faster: '-f'
=====================

'-f' should only be used when assembling programs written by a (trusted)
compiler.  '-f' stops the assembler from doing whitespace and comment
preprocessing on the input file(s) before assembling them.  *Note
Preprocessing: Preprocessing.

     _Warning:_ if you use '-f' when the files actually need to be
     preprocessed (if they contain comments, for example), 'as' does not
     work correctly.

2.5 '.include' Search Path: '-I' PATH
=====================================

Use this option to add a PATH to the list of directories 'as' searches
for files specified in '.include' directives (*note '.include':
Include.).  You may use '-I' as many times as necessary to include a
variety of paths.  The current working directory is always searched
first; after that, 'as' searches any '-I' directories in the same order
as they were specified (left to right) on the command line.

2.6 Difference Tables: '-K'
===========================

On the machine specific family, this option is allowed, but has no
effect.  It is permitted for compatibility with the GNU assembler on
other platforms, where it can be used to warn when the assembler alters
the machine code generated for '.word' directives in difference tables.
The machine specific family does not have the addressing limitations
that sometimes lead to this alteration on other platforms.

2.7 Include Local Symbols: '-L'
===============================

Symbols beginning with system-specific local label prefixes, typically
'.L' for ELF systems or 'L' for traditional a.out systems, are called
"local symbols".  *Note Symbol Names::.  Normally you do not see such
symbols when debugging, because they are intended for the use of
programs (like compilers) that compose assembler programs, not for your
notice.  Normally both 'as' and 'ld' discard such symbols, so you do not
normally debug with them.

   This option tells 'as' to retain those local symbols in the object
file.  Usually if you do this you also tell the linker 'ld' to preserve
those symbols.

2.8 Configuring listing output: '--listing'
===========================================

The listing feature of the assembler can be enabled via the command line
switch '-a' (*note a::).  This feature combines the input source file(s)
with a hex dump of the corresponding locations in the output object
file, and displays them as a listing file.  The format of this listing
can be controlled by directives inside the assembler source (i.e.,
'.list' (*note List::), '.title' (*note Title::), '.sbttl' (*note
Sbttl::), '.psize' (*note Psize::), and '.eject' (*note Eject::) and
also by the following switches:

'--listing-lhs-width='number''
     Sets the maximum width, in words, of the first line of the hex byte
     dump.  This dump appears on the left hand side of the listing
     output.

'--listing-lhs-width2='number''
     Sets the maximum width, in words, of any further lines of the hex
     byte dump for a given input source line.  If this value is not
     specified, it defaults to being the same as the value specified for
     '--listing-lhs-width'.  If neither switch is used the default is to
     one.

'--listing-rhs-width='number''
     Sets the maximum width, in characters, of the source line that is
     displayed alongside the hex dump.  The default value for this
     parameter is 100.  The source line is displayed on the right hand
     side of the listing output.

'--listing-cont-lines='number''
     Sets the maximum number of continuation lines of hex dump that will
     be displayed for a given single line of source input.  The default
     value is 4.

2.9 Assemble in MRI Compatibility Mode: '-M'
============================================

The '-M' or '--mri' option selects MRI compatibility mode.  This changes
the syntax and pseudo-op handling of 'as' to make it compatible with the
'ASM68K' or the 'ASM960' (depending upon the configured target)
assembler from Microtec Research.  The exact nature of the MRI syntax
will not be documented here; see the MRI manuals for more information.
Note in particular that the handling of macros and macro arguments is
somewhat different.  The purpose of this option is to permit assembling
existing MRI assembler code using 'as'.

   The MRI compatibility is not complete.  Certain operations of the MRI
assembler depend upon its object file format, and can not be supported
using other object file formats.  Supporting these would require
enhancing each object file format individually.  These are:

   * global symbols in common section

     The m68k MRI assembler supports common sections which are merged by
     the linker.  Other object file formats do not support this.  'as'
     handles common sections by treating them as a single common symbol.
     It permits local symbols to be defined within a common section, but
     it can not support global symbols, since it has no way to describe
     them.

   * complex relocations

     The MRI assemblers support relocations against a negated section
     address, and relocations which combine the start addresses of two
     or more sections.  These are not support by other object file
     formats.

   * 'END' pseudo-op specifying start address

     The MRI 'END' pseudo-op permits the specification of a start
     address.  This is not supported by other object file formats.  The
     start address may instead be specified using the '-e' option to the
     linker, or in a linker script.

   * 'IDNT', '.ident' and 'NAME' pseudo-ops

     The MRI 'IDNT', '.ident' and 'NAME' pseudo-ops assign a module name
     to the output file.  This is not supported by other object file
     formats.

   * 'ORG' pseudo-op

     The m68k MRI 'ORG' pseudo-op begins an absolute section at a given
     address.  This differs from the usual 'as' '.org' pseudo-op, which
     changes the location within the current section.  Absolute sections
     are not supported by other object file formats.  The address of a
     section may be assigned within a linker script.

   There are some other features of the MRI assembler which are not
supported by 'as', typically either because they are difficult or
because they seem of little consequence.  Some of these may be supported
in future releases.

   * EBCDIC strings

     EBCDIC strings are not supported.

   * packed binary coded decimal

     Packed binary coded decimal is not supported.  This means that the
     'DC.P' and 'DCB.P' pseudo-ops are not supported.

   * 'FEQU' pseudo-op

     The m68k 'FEQU' pseudo-op is not supported.

   * 'NOOBJ' pseudo-op

     The m68k 'NOOBJ' pseudo-op is not supported.

   * 'OPT' branch control options

     The m68k 'OPT' branch control options--'B', 'BRS', 'BRB', 'BRL',
     and 'BRW'--are ignored.  'as' automatically relaxes all branches,
     whether forward or backward, to an appropriate size, so these
     options serve no purpose.

   * 'OPT' list control options

     The following m68k 'OPT' list control options are ignored: 'C',
     'CEX', 'CL', 'CRE', 'E', 'G', 'I', 'M', 'MEX', 'MC', 'MD', 'X'.

   * other 'OPT' options

     The following m68k 'OPT' options are ignored: 'NEST', 'O', 'OLD',
     'OP', 'P', 'PCO', 'PCR', 'PCS', 'R'.

   * 'OPT' 'D' option is default

     The m68k 'OPT' 'D' option is the default, unlike the MRI assembler.
     'OPT NOD' may be used to turn it off.

   * 'XREF' pseudo-op.

     The m68k 'XREF' pseudo-op is ignored.

   * '.debug' pseudo-op

     The i960 '.debug' pseudo-op is not supported.

   * '.extended' pseudo-op

     The i960 '.extended' pseudo-op is not supported.

   * '.list' pseudo-op.

     The various options of the i960 '.list' pseudo-op are not
     supported.

   * '.optimize' pseudo-op

     The i960 '.optimize' pseudo-op is not supported.

   * '.output' pseudo-op

     The i960 '.output' pseudo-op is not supported.

   * '.setreal' pseudo-op

     The i960 '.setreal' pseudo-op is not supported.

2.10 Dependency Tracking: '--MD'
================================

'as' can generate a dependency file for the file it creates.  This file
consists of a single rule suitable for 'make' describing the
dependencies of the main source file.

   The rule is written to the file named in its argument.

   This feature is used in the automatic updating of makefiles.

2.11 Name the Object File: '-o'
===============================

There is always one object file output when you run 'as'.  By default it
has the name 'a.out'.  You use this option (which takes exactly one
filename) to give the object file a different name.

   Whatever the object file is called, 'as' overwrites any existing file
of the same name.

2.12 Join Data and Text Sections: '-R'
======================================

'-R' tells 'as' to write the object file as if all data-section data
lives in the text section.  This is only done at the very last moment:
your binary data are the same, but data section parts are relocated
differently.  The data section part of your object file is zero bytes
long because all its bytes are appended to the text section.  (*Note
Sections and Relocation: Sections.)

   When you specify '-R' it would be possible to generate shorter
address displacements (because we do not have to cross between text and
data section).  We refrain from doing this simply for compatibility with
older versions of 'as'.  In future, '-R' may work this way.

   When 'as' is configured for COFF or ELF output, this option is only
useful if you use sections named '.text' and '.data'.

2.13 Display Assembly Statistics: '--statistics'
================================================

Use '--statistics' to display two statistics about the resources used by
'as': the maximum amount of space allocated during the assembly (in
bytes), and the total execution time taken for the assembly (in CPU
seconds).

2.14 Compatible Output: '--traditional-format'
==============================================

For some targets, the output of 'as' is different in some ways from the
output of some existing assembler.  This switch requests 'as' to use the
traditional format instead.

   For example, it disables the exception frame optimizations which 'as'
normally does by default on 'gcc' output.

2.15 Announce Version: '-v'
===========================

You can find out what version of as is running by including the option
'-v' (which you can also spell as '-version') on the command line.

2.16 Control Warnings: '-W', '--warn', '--no-warn', '--fatal-warnings'
======================================================================

'as' should never give a warning or error message when assembling
compiler output.  But programs written by people often cause 'as' to
give a warning that a particular assumption was made.  All such warnings
are directed to the standard error file.

   If you use the '-W' and '--no-warn' options, no warnings are issued.
This only affects the warning messages: it does not change any
particular of how 'as' assembles your file.  Errors, which stop the
assembly, are still reported.

   If you use the '--fatal-warnings' option, 'as' considers files that
generate warnings to be in error.

   You can switch these options off again by specifying '--warn', which
causes warnings to be output as usual.

2.17 Generate Object File in Spite of Errors: '-Z'
==================================================

After an error message, 'as' normally produces no output.  If for some
reason you are interested in object file output even after 'as' gives an
error message on your program, use the '-Z' option.  If there are any
errors, 'as' continues anyways, and writes an object file after a final
warning message of the form 'N errors, M warnings, generating bad object
file.'

3 Syntax
********

This chapter describes the machine-independent syntax allowed in a
source file.  'as' syntax is similar to what many other assemblers use;
it is inspired by the BSD 4.2 assembler.

3.1 Preprocessing
=================

The 'as' internal preprocessor:
   * adjusts and removes extra whitespace.  It leaves one space or tab
     before the keywords on a line, and turns any other whitespace on
     the line into a single space.

   * removes all comments, replacing them with a single space, or an
     appropriate number of newlines.

   * converts character constants into the appropriate numeric values.

   It does not do macro processing, include file handling, or anything
else you may get from your C compiler's preprocessor.  You can do
include file processing with the '.include' directive (*note '.include':
Include.).  You can use the GNU C compiler driver to get other "CPP"
style preprocessing by giving the input file a '.S' suffix.  *Note
Options Controlling the Kind of Output: (gcc.info)Overall Options.

   Excess whitespace, comments, and character constants cannot be used
in the portions of the input text that are not preprocessed.

   If the first line of an input file is '#NO_APP' or if you use the
'-f' option, whitespace and comments are not removed from the input
file.  Within an input file, you can ask for whitespace and comment
removal in specific portions of the by putting a line that says '#APP'
before the text that may contain whitespace or comments, and putting a
line that says '#NO_APP' after this text.  This feature is mainly intend
to support 'asm' statements in compilers whose output is otherwise free
of comments and whitespace.

3.2 Whitespace
==============

"Whitespace" is one or more blanks or tabs, in any order.  Whitespace is
used to separate symbols, and to make programs neater for people to
read.  Unless within character constants (*note Character Constants:
Characters.), any whitespace means the same as exactly one space.

3.3 Comments
============

There are two ways of rendering comments to 'as'.  In both cases the
comment is equivalent to one space.

   Anything from '/*' through the next '*/' is a comment.  This means
you may not nest these comments.

     /*
       The only way to include a newline ('\n') in a comment
       is to use this sort of comment.
     */

     /* This sort of comment does not nest. */

   Anything from the "line comment" character to the next newline is
considered a comment and is ignored.  The line comment character is '@'
on the ARM; '#' on the i386 and x86-64; '#' for Motorola PowerPC; '!' on
the SPARC; see *note Machine Dependencies::.

   To be compatible with past assemblers, lines that begin with '#' have
a special interpretation.  Following the '#' should be an absolute
expression (*note Expressions::): the logical line number of the _next_
line.  Then a string (*note Strings: Strings.) is allowed: if present it
is a new logical file name.  The rest of the line, if any, should be
whitespace.

   If the first non-whitespace characters on the line are not numeric,
the line is ignored.  (Just like a comment.)

                               # This is an ordinary comment.
     # 42-6 "new_file_name"    # New logical file name
                               # This is logical line # 36.
   This feature is deprecated, and may disappear from future versions of
'as'.

3.4 Symbols
===========

A "symbol" is one or more characters chosen from the set of all letters
(both upper and lower case), digits and the three characters '_.$'.  No
symbol may begin with a digit.  Case is significant.  There is no length
limit: all characters are significant.  Symbols are delimited by
characters not in that set, or by the beginning of a file (since the
source program must end with a newline, the end of a file is not a
possible symbol delimiter).  *Note Symbols::.

3.5 Statements
==============

A "statement" ends at a newline character ('\n') or at a semicolon
(';').  The newline or semicolon is considered part of the preceding
statement.  Newlines and semicolons within character constants are an
exception: they do not end statements.

   It is an error to end any statement with end-of-file: the last
character of any input file should be a newline.

   An empty statement is allowed, and may include whitespace.  It is
ignored.

   A statement begins with zero or more labels, optionally followed by a
key symbol which determines what kind of statement it is.  The key
symbol determines the syntax of the rest of the statement.  If the
symbol begins with a dot '.' then the statement is an assembler
directive: typically valid for any computer.  If the symbol begins with
a letter the statement is an assembly language "instruction": it
assembles into a machine language instruction.

   A label is a symbol immediately followed by a colon (':').
Whitespace before a label or after a colon is permitted, but you may not
have whitespace between a label's symbol and its colon.  *Note Labels::.

     label:     .directive    followed by something
     another_label:           # This is an empty statement.
                instruction   operand_1, operand_2, ...

3.6 Constants
=============

A constant is a number, written so that its value is known by
inspection, without knowing any context.  Like this:
     .byte  74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
     .ascii "Ring the bell\7"                  # A string constant.
     .octa  0x123456789abcdef0123456789ABCDEF0 # A bignum.
     .float 0f-314159265358979323846264338327\
     95028841971.693993751E-40                 # - pi, a flonum.

3.6.1 Character Constants
-------------------------

There are two kinds of character constants.  A "character" stands for
one character in one byte and its value may be used in numeric
expressions.  String constants (properly called string _literals_) are
potentially many bytes and their values may not be used in arithmetic
expressions.

3.6.1.1 Strings
...............

A "string" is written between double-quotes.  It may contain
double-quotes or null characters.  The way to get special characters
into a string is to "escape" these characters: precede them with a
backslash '\' character.  For example '\\' represents one backslash: the
first '\' is an escape which tells 'as' to interpret the second
character literally as a backslash (which prevents 'as' from recognizing
the second '\' as an escape character).  The complete list of escapes
follows.

'\b'
     Mnemonic for backspace; for ASCII this is octal code 010.

'\f'
     Mnemonic for FormFeed; for ASCII this is octal code 014.

'\n'
     Mnemonic for newline; for ASCII this is octal code 012.

'\r'
     Mnemonic for carriage-Return; for ASCII this is octal code 015.

'\t'
     Mnemonic for horizontal Tab; for ASCII this is octal code 011.

'\ DIGIT DIGIT DIGIT'
     An octal character code.  The numeric code is 3 octal digits.  For
     compatibility with other Unix systems, 8 and 9 are accepted as
     digits: for example, '\008' has the value 010, and '\009' the value
     011.

'\x HEX-DIGITS...'
     A hex character code.  All trailing hex digits are combined.
     Either upper or lower case 'x' works.

'\\'
     Represents one '\' character.

'\"'
     Represents one '"' character.  Needed in strings to represent this
     character, because an unescaped '"' would end the string.

'\ ANYTHING-ELSE'
     Any other character when escaped by '\' gives a warning, but
     assembles as if the '\' was not present.  The idea is that if you
     used an escape sequence you clearly didn't want the literal
     interpretation of the following character.  However 'as' has no
     other interpretation, so 'as' knows it is giving you the wrong code
     and warns you of the fact.

   Which characters are escapable, and what those escapes represent,
varies widely among assemblers.  The current set is what we think the
BSD 4.2 assembler recognizes, and is a subset of what most C compilers
recognize.  If you are in doubt, do not use an escape sequence.

3.6.1.2 Characters
..................

A single character may be written as a single quote immediately followed
by that character.  The same escapes apply to characters as to strings.
So if you want to write the character backslash, you must write ''\\'
where the first '\' escapes the second '\'.  As you can see, the quote
is an acute accent, not a grave accent.  A newline (or semicolon ';')
immediately following an acute accent is taken as a literal character
and does not count as the end of a statement.  The value of a character
constant in a numeric expression is the machine's byte-wide code for
that character.  'as' assumes your character code is ASCII: ''A' means
65, ''B' means 66, and so on.

3.6.2 Number Constants
----------------------

'as' distinguishes three kinds of numbers according to how they are
stored in the target machine.  _Integers_ are numbers that would fit
into an 'int' in the C language.  _Bignums_ are integers, but they are
stored in more than 32 bits.  _Flonums_ are floating point numbers,
described below.

3.6.2.1 Integers
................

A binary integer is '0b' or '0B' followed by zero or more of the binary
digits '01'.

   An octal integer is '0' followed by zero or more of the octal digits
('01234567').

   A decimal integer starts with a non-zero digit followed by zero or
more digits ('0123456789').

   A hexadecimal integer is '0x' or '0X' followed by one or more
hexadecimal digits chosen from '0123456789abcdefABCDEF'.

   Integers have the usual values.  To denote a negative integer, use
the prefix operator '-' discussed under expressions (*note Prefix
Operators: Prefix Ops.).

3.6.2.2 Bignums
...............

A "bignum" has the same syntax and semantics as an integer except that
the number (or its negative) takes more than 32 bits to represent in
binary.  The distinction is made because in some places integers are
permitted while bignums are not.

3.6.2.3 Flonums
...............

A "flonum" represents a floating point number.  The translation is
indirect: a decimal floating point number from the text is converted by
'as' to a generic binary floating point number of more than sufficient
precision.  This generic floating point number is converted to a
particular computer's floating point format (or formats) by a portion of
'as' specialized to that computer.

   A flonum is written by writing (in order)
   * The digit '0'.

   * A letter, to tell 'as' the rest of the number is a flonum.

   * An optional sign: either '+' or '-'.

   * An optional "integer part": zero or more decimal digits.

   * An optional "fractional part": '.' followed by zero or more decimal
     digits.

   * An optional exponent, consisting of:

        * An 'E' or 'e'.
        * Optional sign: either '+' or '-'.
        * One or more decimal digits.

   At least one of the integer part or the fractional part must be
present.  The floating point number has the usual base-10 value.

   'as' does all processing using integers.  Flonums are computed
independently of any floating point hardware in the computer running
'as'.

4 Sections and Relocation
*************************

4.1 Background
==============

Roughly, a section is a range of addresses, with no gaps; all data "in"
those addresses is treated the same for some particular purpose.  For
example there may be a "read only" section.

   The linker 'ld' reads many object files (partial programs) and
combines their contents to form a runnable program.  When 'as' emits an
object file, the partial program is assumed to start at address 0.  'ld'
assigns the final addresses for the partial program, so that different
partial programs do not overlap.  This is actually an
oversimplification, but it suffices to explain how 'as' uses sections.

   'ld' moves blocks of bytes of your program to their run-time
addresses.  These blocks slide to their run-time addresses as rigid
units; their length does not change and neither does the order of bytes
within them.  Such a rigid unit is called a _section_.  Assigning
run-time addresses to sections is called "relocation".  It includes the
task of adjusting mentions of object-file addresses so they refer to the
proper run-time addresses.

   An object file written by 'as' has at least three sections, any of
which may be empty.  These are named "text", "data" and "bss" sections.

   'as' can also generate whatever other named sections you specify
using the '.section' directive (*note '.section': Section.).  If you do
not use any directives that place output in the '.text' or '.data'
sections, these sections still exist, but are empty.

   Within the object file, the text section starts at address '0', the
data section follows, and the bss section follows the data section.

   To let 'ld' know which data changes when the sections are relocated,
and how to change that data, 'as' also writes to the object file details
of the relocation needed.  To perform relocation 'ld' must know, each
time an address in the object file is mentioned:
   * Where in the object file is the beginning of this reference to an
     address?
   * How long (in bytes) is this reference?
   * Which section does the address refer to?  What is the numeric value
     of
          (ADDRESS) - (START-ADDRESS OF SECTION)?
   * Is the reference to an address "Program-Counter relative"?

   In fact, every address 'as' ever uses is expressed as
     (SECTION) + (OFFSET INTO SECTION)
Further, most expressions 'as' computes have this section-relative
nature.

   In this manual we use the notation {SECNAME N} to mean "offset N into
section SECNAME."

   Apart from text, data and bss sections you need to know about the
"absolute" section.  When 'ld' mixes partial programs, addresses in the
absolute section remain unchanged.  For example, address '{absolute 0}'
is "relocated" to run-time address 0 by 'ld'.  Although the linker never
arranges two partial programs' data sections with overlapping addresses
after linking, _by definition_ their absolute sections must overlap.
Address '{absolute 239}' in one part of a program is always the same
address when the program is running as address '{absolute 239}' in any
other part of the program.

   The idea of sections is extended to the "undefined" section.  Any
address whose section is unknown at assembly time is by definition
rendered {undefined U}--where U is filled in later.  Since numbers are
always defined, the only way to generate an undefined address is to
mention an undefined symbol.  A reference to a named common block would
be such a symbol: its value is unknown at assembly time so it has
section _undefined_.

   By analogy the word _section_ is used to describe groups of sections
in the linked program.  'ld' puts all partial programs' text sections in
contiguous addresses in the linked program.  It is customary to refer to
the _text section_ of a program, meaning all the addresses of all
partial programs' text sections.  Likewise for data and bss sections.

   Some sections are manipulated by 'ld'; others are invented for use of
'as' and have no meaning except during assembly.

4.2 Linker Sections
===================

'ld' deals with just four kinds of sections, summarized below.

*named sections*
     These sections hold your program.  'as' and 'ld' treat them as
     separate but equal sections.  Anything you can say of one section
     is true of another.  When the program is running, however, it is
     customary for the text section to be unalterable.  The text section
     is often shared among processes: it contains instructions,
     constants and the like.  The data section of a running program is
     usually alterable: for example, C variables would be stored in the
     data section.

*bss section*
     This section contains zeroed bytes when your program begins
     running.  It is used to hold uninitialized variables or common
     storage.  The length of each partial program's bss section is
     important, but because it starts out containing zeroed bytes there
     is no need to store explicit zero bytes in the object file.  The
     bss section was invented to eliminate those explicit zeros from
     object files.

*absolute section*
     Address 0 of this section is always "relocated" to runtime address
     0.  This is useful if you want to refer to an address that 'ld'
     must not change when relocating.  In this sense we speak of
     absolute addresses being "unrelocatable": they do not change during
     relocation.

*undefined section*
     This "section" is a catch-all for address references to objects not
     in the preceding sections.

   An idealized example of three relocatable sections follows.  The
example uses the traditional section names '.text' and '.data'.  Memory
addresses are on the horizontal axis.

                           +-----+----+--+
     partial program # 1:  |ttttt|dddd|00|
                           +-----+----+--+

                           text   data bss
                           seg.   seg. seg.

                           +---+---+---+
     partial program # 2:  |TTT|DDD|000|
                           +---+---+---+

                           +--+---+-----+--+----+---+-----+~~
     linked program:       |  |TTT|ttttt|  |dddd|DDD|00000|
                           +--+---+-----+--+----+---+-----+~~

         addresses:        0 ...

4.3 Assembler Internal Sections
===============================

These sections are meant only for the internal use of 'as'.  They have
no meaning at run-time.  You do not really need to know about these
sections for most purposes; but they can be mentioned in 'as' warning
messages, so it might be helpful to have an idea of their meanings to
'as'.  These sections are used to permit the value of every expression
in your assembly language program to be a section-relative address.

ASSEMBLER-INTERNAL-LOGIC-ERROR!
     An internal assembler logic error has been found.  This means there
     is a bug in the assembler.

expr section
     The assembler stores complex expression internally as combinations
     of symbols.  When it needs to represent an expression as a symbol,
     it puts it in the expr section.

4.4 Sub-Sections
================

You may have separate groups of data in named sections that you want to
end up near to each other in the object file, even though they are not
contiguous in the assembler source.  'as' allows you to use
"subsections" for this purpose.  Within each section, there can be
numbered subsections with values from 0 to 8192.  Objects assembled into
the same subsection go into the object file together with other objects
in the same subsection.  For example, a compiler might want to store
constants in the text section, but might not want to have them
interspersed with the program being assembled.  In this case, the
compiler could issue a '.text 0' before each section of code being
output, and a '.text 1' before each group of constants being output.

   Subsections are optional.  If you do not use subsections, everything
goes in subsection number zero.

   Subsections appear in your object file in numeric order, lowest
numbered to highest.  (All this to be compatible with other people's
assemblers.)  The object file contains no representation of subsections;
'ld' and other programs that manipulate object files see no trace of
them.  They just see all your text subsections as a text section, and
all your data subsections as a data section.

   To specify which subsection you want subsequent statements assembled
into, use a numeric argument to specify it, in a '.text EXPRESSION' or a
'.data EXPRESSION' statement.  You can also use the '.subsection'
directive (*note SubSection::) to specify a subsection: '.subsection
EXPRESSION'.  EXPRESSION should be an absolute expression (*note
Expressions::).  If you just say '.text' then '.text 0' is assumed.
Likewise '.data' means '.data 0'.  Assembly begins in 'text 0'.  For
instance:
     .text 0     # The default subsection is text 0 anyway.
     .ascii "This lives in the first text subsection. *"
     .text 1
     .ascii "But this lives in the second text subsection."
     .data 0
     .ascii "This lives in the data section,"
     .ascii "in the first data subsection."
     .text 0
     .ascii "This lives in the first text section,"
     .ascii "immediately following the asterisk (*)."

   Each section has a "location counter" incremented by one for every
byte assembled into that section.  Because subsections are merely a
convenience restricted to 'as' there is no concept of a subsection
location counter.  There is no way to directly manipulate a location
counter--but the '.align' directive changes it, and any label definition
captures its current value.  The location counter of the section where
statements are being assembled is said to be the "active" location
counter.

4.5 bss Section
===============

The bss section is used for local common variable storage.  You may
allocate address space in the bss section, but you may not dictate data
to load into it before your program executes.  When your program starts
running, all the contents of the bss section are zeroed bytes.

   The '.lcomm' pseudo-op defines a symbol in the bss section; see *note
'.lcomm': Lcomm.

   The '.comm' pseudo-op may be used to declare a common symbol, which
is another form of uninitialized symbol; see *note '.comm': Comm.

5 Symbols
*********

Symbols are a central concept: the programmer uses symbols to name
things, the linker uses symbols to link, and the debugger uses symbols
to debug.

     _Warning:_ 'as' does not place symbols in the object file in the
     same order they were declared.  This may break some debuggers.

5.1 Labels
==========

A "label" is written as a symbol immediately followed by a colon ':'.
The symbol then represents the current value of the active location
counter, and is, for example, a suitable instruction operand.  You are
warned if you use the same symbol to represent two different locations:
the first definition overrides any other definitions.

5.2 Giving Symbols Other Values
===============================

A symbol can be given an arbitrary value by writing a symbol, followed
by an equals sign '=', followed by an expression (*note Expressions::).
This is equivalent to using the '.set' directive.  *Note '.set': Set.
In the same way, using a double equals sign '=''=' here represents an
equivalent of the '.eqv' directive.  *Note '.eqv': Eqv.

5.3 Symbol Names
================

Symbol names begin with a letter or with one of '._'.  On most machines,
you can also use '$' in symbol names; exceptions are noted in *note
Machine Dependencies::.  That character may be followed by any string of
digits, letters, dollar signs (unless otherwise noted for a particular
target machine), and underscores.

   Case of letters is significant: 'foo' is a different symbol name than
'Foo'.

   Each symbol has exactly one name.  Each name in an assembly language
program refers to exactly one symbol.  You may use that symbol name any
number of times in a program.

Local Symbol Names
------------------

A local symbol is any symbol beginning with certain local label
prefixes.  By default, the local label prefix is '.L' for ELF systems or
'L' for traditional a.out systems, but each target may have its own set
of local label prefixes.

   Local symbols are defined and used within the assembler, but they are
normally not saved in object files.  Thus, they are not visible when
debugging.  You may use the '-L' option (*note Include Local Symbols:
'-L': L.) to retain the local symbols in the object files.

Local Labels
------------

Local labels help compilers and programmers use names temporarily.  They
create symbols which are guaranteed to be unique over the entire scope
of the input source code and which can be referred to by a simple
notation.  To define a local label, write a label of the form 'N:'
(where N represents any positive integer).  To refer to the most recent
previous definition of that label write 'Nb', using the same number as
when you defined the label.  To refer to the next definition of a local
label, write 'Nf'--the 'b' stands for "backwards" and the 'f' stands for
"forwards".

   There is no restriction on how you can use these labels, and you can
reuse them too.  So that it is possible to repeatedly define the same
local label (using the same number 'N'), although you can only refer to
the most recently defined local label of that number (for a backwards
reference) or the next definition of a specific local label for a
forward reference.  It is also worth noting that the first 10 local
labels ('0:'...'9:') are implemented in a slightly more efficient manner
than the others.

   Here is an example:

     1:        branch 1f
     2:        branch 1b
     1:        branch 2f
     2:        branch 1b

   Which is the equivalent of:

     label_1:  branch label_3
     label_2:  branch label_1
     label_3:  branch label_4
     label_4:  branch label_3

   Local label names are only a notational device.  They are immediately
transformed into more conventional symbol names before the assembler
uses them.  The symbol names are stored in the symbol table, appear in
error messages, and are optionally emitted to the object file.  The
names are constructed using these parts:

'_local label prefix_'
     All local symbols begin with the system-specific local label
     prefix.  Normally both 'as' and 'ld' forget symbols that start with
     the local label prefix.  These labels are used for symbols you are
     never intended to see.  If you use the '-L' option then 'as'
     retains these symbols in the object file.  If you also instruct
     'ld' to retain these symbols, you may use them in debugging.

'NUMBER'
     This is the number that was used in the local label definition.  So
     if the label is written '55:' then the number is '55'.

'C-B'
     This unusual character is included so you do not accidentally
     invent a symbol of the same name.  The character has ASCII value of
     '\002' (control-B).

'_ordinal number_'
     This is a serial number to keep the labels distinct.  The first
     definition of '0:' gets the number '1'.  The 15th definition of
     '0:' gets the number '15', and so on.  Likewise the first
     definition of '1:' gets the number '1' and its 15th definition gets
     '15' as well.

   So for example, the first '1:' may be named '.L1C-B1', and the 44th
'3:' may be named '.L3C-B44'.

Dollar Local Labels
-------------------

'as' also supports an even more local form of local labels called dollar
labels.  These labels go out of scope (i.e., they become undefined) as
soon as a non-local label is defined.  Thus they remain valid for only a
small region of the input source code.  Normal local labels, by
contrast, remain in scope for the entire file, or until they are
redefined by another occurrence of the same local label.

   Dollar labels are defined in exactly the same way as ordinary local
labels, except that instead of being terminated by a colon, they are
terminated by a dollar sign, e.g., '55$'.

   They can also be distinguished from ordinary local labels by their
transformed names which use ASCII character '\001' (control-A) as the
magic character to distinguish them from ordinary labels.  For example,
the fifth definition of '6$' may be named '.L6'C-A'5'.

5.4 The Special Dot Symbol
==========================

The special symbol '.' refers to the current address that 'as' is
assembling into.  Thus, the expression 'melvin: .long .' defines
'melvin' to contain its own address.  Assigning a value to '.' is
treated the same as a '.org' directive.  Thus, the expression '.=.+4' is
the same as saying '.space 4'.

5.5 Symbol Attributes
=====================

Every symbol has, as well as its name, the attributes "Value" and
"Type".  Depending on output format, symbols can also have auxiliary
attributes.  The detailed definitions are in 'a.out.h'.

   If you use a symbol without defining it, 'as' assumes zero for all
these attributes, and probably won't warn you.  This makes the symbol an
externally defined symbol, which is generally what you would want.

5.5.1 Value
-----------

The value of a symbol is (usually) 32 bits.  For a symbol which labels a
location in the text, data, bss or absolute sections the value is the
number of addresses from the start of that section to the label.
Naturally for text, data and bss sections the value of a symbol changes
as 'ld' changes section base addresses during linking.  Absolute
symbols' values do not change during linking: that is why they are
called absolute.

   The value of an undefined symbol is treated in a special way.  If it
is 0 then the symbol is not defined in this assembler source file, and
'ld' tries to determine its value from other files linked into the same
program.  You make this kind of symbol simply by mentioning a symbol
name without defining it.  A non-zero value represents a '.comm' common
declaration.  The value is how much common storage to reserve, in bytes
(addresses).  The symbol refers to the first address of the allocated
storage.

5.5.2 Type
----------

The type attribute of a symbol contains relocation (section)
information, any flag settings indicating that a symbol is external, and
(optionally), other information for linkers and debuggers.  The exact
format depends on the object-code output format in use.

6 Expressions
*************

An "expression" specifies an address or numeric value.  Whitespace may
precede and/or follow an expression.

   The result of an expression must be an absolute number, or else an
offset into a particular section.  If an expression is not absolute, and
there is not enough information when 'as' sees the expression to know
its section, a second pass over the source program might be necessary to
interpret the expression--but the second pass is currently not
implemented.  'as' aborts with an error message in this situation.

6.1 Empty Expressions
=====================

An empty expression has no value: it is just whitespace or null.
Wherever an absolute expression is required, you may omit the
expression, and 'as' assumes a value of (absolute) 0.  This is
compatible with other assemblers.

6.2 Integer Expressions
=======================

An "integer expression" is one or more _arguments_ delimited by
_operators_.

6.2.1 Arguments
---------------

"Arguments" are symbols, numbers or subexpressions.  In other contexts
arguments are sometimes called "arithmetic operands".  In this manual,
to avoid confusing them with the "instruction operands" of the machine
language, we use the term "argument" to refer to parts of expressions
only, reserving the word "operand" to refer only to machine instruction
operands.

   Symbols are evaluated to yield {SECTION NNN} where SECTION is one of
text, data, bss, absolute, or undefined.  NNN is a signed, 2's
complement 32 bit integer.

   Numbers are usually integers.

   A number can be a flonum or bignum.  In this case, you are warned
that only the low order 32 bits are used, and 'as' pretends these 32
bits are an integer.  You may write integer-manipulating instructions
that act on exotic constants, compatible with other assemblers.

   Subexpressions are a left parenthesis '(' followed by an integer
expression, followed by a right parenthesis ')'; or a prefix operator
followed by an argument.

6.2.2 Operators
---------------

"Operators" are arithmetic functions, like '+' or '%'.  Prefix operators
are followed by an argument.  Infix operators appear between their
arguments.  Operators may be preceded and/or followed by whitespace.

6.2.3 Prefix Operator
---------------------

'as' has the following "prefix operators".  They each take one argument,
which must be absolute.

'-'
     "Negation".  Two's complement negation.
'~'
     "Complementation".  Bitwise not.

6.2.4 Infix Operators
---------------------

"Infix operators" take two arguments, one on either side.  Operators
have precedence, but operations with equal precedence are performed left
to right.  Apart from '+' or '-', both arguments must be absolute, and
the result is absolute.

  1. Highest Precedence

     '*'
          "Multiplication".

     '/'
          "Division".  Truncation is the same as the C operator '/'

     '%'
          "Remainder".

     '<<'
          "Shift Left".  Same as the C operator '<<'.

     '>>'
          "Shift Right".  Same as the C operator '>>'.

  2. Intermediate precedence

     '|'

          "Bitwise Inclusive Or".

     '&'
          "Bitwise And".

     '^'
          "Bitwise Exclusive Or".

     '!'
          "Bitwise Or Not".

  3. Low Precedence

     '+'
          "Addition".  If either argument is absolute, the result has
          the section of the other argument.  You may not add together
          arguments from different sections.

     '-'
          "Subtraction".  If the right argument is absolute, the result
          has the section of the left argument.  If both arguments are
          in the same section, the result is absolute.  You may not
          subtract arguments from different sections.

     '=='
          "Is Equal To"
     '<>'
     '!='
          "Is Not Equal To"
     '<'
          "Is Less Than"
     '>'
          "Is Greater Than"
     '>='
          "Is Greater Than Or Equal To"
     '<='
          "Is Less Than Or Equal To"

          The comparison operators can be used as infix operators.  A
          true results has a value of -1 whereas a false result has a
          value of 0.  Note, these operators perform signed comparisons.

  4. Lowest Precedence

     '&&'
          "Logical And".

     '||'
          "Logical Or".

          These two logical operations can be used to combine the
          results of sub expressions.  Note, unlike the comparison
          operators a true result returns a value of 1 but a false
          results does still return 0.  Also note that the logical or
          operator has a slightly lower precedence than logical and.

   In short, it's only meaningful to add or subtract the _offsets_ in an
address; you can only have a defined section in one of the two
arguments.

7 Assembler Directives
**********************

All assembler directives have names that begin with a period ('.').  The
rest of the name is letters, usually in lower case.

   This chapter discusses directives that are available regardless of
the target machine configuration for the GNU assembler.

7.1 '.abort'
============

This directive stops the assembly immediately.  It is for compatibility
with other assemblers.  The original idea was that the assembly language
source would be piped into the assembler.  If the sender of the source
quit, it could use this directive tells 'as' to quit also.  One day
'.abort' will not be supported.

7.2 '.align ABS-EXPR, ABS-EXPR, ABS-EXPR'
=========================================

Pad the location counter (in the current subsection) to a particular
storage boundary.  The first expression (which must be absolute) is the
alignment required, as described below.

   The second expression (also absolute) gives the fill value to be
stored in the padding bytes.  It (and the comma) may be omitted.  If it
is omitted, the padding bytes are normally zero.  However, on some
systems, if the section is marked as containing code and the fill value
is omitted, the space is filled with no-op instructions.

   The third expression is also absolute, and is also optional.  If it
is present, it is the maximum number of bytes that should be skipped by
this alignment directive.  If doing the alignment would require skipping
more bytes than the specified maximum, then the alignment is not done at
all.  You can omit the fill value (the second argument) entirely by
simply using two commas after the required alignment; this can be useful
if you want the alignment to be filled with no-op instructions when
appropriate.

   The way the required alignment is specified varies from system to
system.  For the arc, hppa, i386 using ELF, i860, iq2000, m68k, or32,
s390, sparc, tic4x, tic80 and xtensa, the first expression is the
alignment request in bytes.  For example '.align 8' advances the
location counter until it is a multiple of 8.  If the location counter
is already a multiple of 8, no change is needed.  For the tic54x, the
first expression is the alignment request in words.

   For other systems, including the i386 using a.out format, and the arm
and strongarm, it is the number of low-order zero bits the location
counter must have after advancement.  For example '.align 3' advances
the location counter until it a multiple of 8.  If the location counter
is already a multiple of 8, no change is needed.

   This inconsistency is due to the different behaviors of the various
native assemblers for these systems which GAS must emulate.  GAS also
provides '.balign' and '.p2align' directives, described later, which
have a consistent behavior across all architectures (but are specific to
GAS).

7.3 '.ascii "STRING"'...
========================

'.ascii' expects zero or more string literals (*note Strings::)
separated by commas.  It assembles each string (with no automatic
trailing zero byte) into consecutive addresses.

7.4 '.asciz "STRING"'...
========================

'.asciz' is just like '.ascii', but each string is followed by a zero
byte.  The "z" in '.asciz' stands for "zero".

7.5 '.balign[wl] ABS-EXPR, ABS-EXPR, ABS-EXPR'
==============================================

Pad the location counter (in the current subsection) to a particular
storage boundary.  The first expression (which must be absolute) is the
alignment request in bytes.  For example '.balign 8' advances the
location counter until it is a multiple of 8.  If the location counter
is already a multiple of 8, no change is needed.

   The second expression (also absolute) gives the fill value to be
stored in the padding bytes.  It (and the comma) may be omitted.  If it
is omitted, the padding bytes are normally zero.  However, on some
systems, if the section is marked as containing code and the fill value
is omitted, the space is filled with no-op instructions.

   The third expression is also absolute, and is also optional.  If it
is present, it is the maximum number of bytes that should be skipped by
this alignment directive.  If doing the alignment would require skipping
more bytes than the specified maximum, then the alignment is not done at
all.  You can omit the fill value (the second argument) entirely by
simply using two commas after the required alignment; this can be useful
if you want the alignment to be filled with no-op instructions when
appropriate.

   The '.balignw' and '.balignl' directives are variants of the
'.balign' directive.  The '.balignw' directive treats the fill pattern
as a two byte word value.  The '.balignl' directives treats the fill
pattern as a four byte longword value.  For example, '.balignw 4,0x368d'
will align to a multiple of 4.  If it skips two bytes, they will be
filled in with the value 0x368d (the exact placement of the bytes
depends upon the endianness of the processor).  If it skips 1 or 3
bytes, the fill value is undefined.

7.6 '.byte EXPRESSIONS'
=======================

'.byte' expects zero or more expressions, separated by commas.  Each
expression is assembled into the next byte.

7.7 '.comm SYMBOL , LENGTH '
============================

'.comm' declares a common symbol named SYMBOL.  When linking, a common
symbol in one object file may be merged with a defined or common symbol
of the same name in another object file.  If 'ld' does not see a
definition for the symbol-just one or more common symbols-then it will
allocate LENGTH bytes of uninitialized memory.  LENGTH must be an
absolute expression.  If 'ld' sees multiple common symbols with the same
name, and they do not all have the same size, it will allocate space
using the largest size.

   When using ELF, the '.comm' directive takes an optional third
argument.  This is the desired alignment of the symbol, specified as a
byte boundary (for example, an alignment of 16 means that the least
significant 4 bits of the address should be zero).  The alignment must
be an absolute expression, and it must be a power of two.  If 'ld'
allocates uninitialized memory for the common symbol, it will use the
alignment when placing the symbol.  If no alignment is specified, 'as'
will set the alignment to the largest power of two less than or equal to
the size of the symbol, up to a maximum of 16.

7.8 '.cfi_startproc [simple]'
=============================

'.cfi_startproc' is used at the beginning of each function that should
have an entry in '.eh_frame'.  It initializes some internal data
structures.  Don't forget to close the function by '.cfi_endproc'.

   Unless '.cfi_startproc' is used along with parameter 'simple' it also
emits some architecture dependent initial CFI instructions.

7.9 '.cfi_endproc'
==================

'.cfi_endproc' is used at the end of a function where it closes its
unwind entry previously opened by '.cfi_startproc', and emits it to
'.eh_frame'.

7.10 '.cfi_personality ENCODING [, EXP]'
========================================

'.cfi_personality' defines personality routine and its encoding.
ENCODING must be a constant determining how the personality should be
encoded.  If it is 255 ('DW_EH_PE_omit'), second argument is not
present, otherwise second argument should be a constant or a symbol
name.  When using indirect encodings, the symbol provided should be the
location where personality can be loaded from, not the personality
routine itself.  The default after '.cfi_startproc' is '.cfi_personality
0xff', no personality routine.

7.11 '.cfi_lsda ENCODING [, EXP]'
=================================

'.cfi_lsda' defines LSDA and its encoding.  ENCODING must be a constant
determining how the LSDA should be encoded.  If it is 255
('DW_EH_PE_omit'), second argument is not present, otherwise second
argument should be a constant or a symbol name.  The default after
'.cfi_startproc' is '.cfi_lsda 0xff', no LSDA.

7.12 '.cfi_def_cfa REGISTER, OFFSET'
====================================

'.cfi_def_cfa' defines a rule for computing CFA as: take address from
REGISTER and add OFFSET to it.

7.13 '.cfi_def_cfa_register REGISTER'
=====================================

'.cfi_def_cfa_register' modifies a rule for computing CFA. From now on
REGISTER will be used instead of the old one.  Offset remains the same.

7.14 '.cfi_def_cfa_offset OFFSET'
=================================

'.cfi_def_cfa_offset' modifies a rule for computing CFA. Register
remains the same, but OFFSET is new.  Note that it is the absolute
offset that will be added to a defined register to compute CFA address.

7.15 '.cfi_adjust_cfa_offset OFFSET'
====================================

Same as '.cfi_def_cfa_offset' but OFFSET is a relative value that is
added/substracted from the previous offset.

7.16 '.cfi_offset REGISTER, OFFSET'
===================================

Previous value of REGISTER is saved at offset OFFSET from CFA.

7.17 '.cfi_rel_offset REGISTER, OFFSET'
=======================================

Previous value of REGISTER is saved at offset OFFSET from the current
CFA register.  This is transformed to '.cfi_offset' using the known
displacement of the CFA register from the CFA. This is often easier to
use, because the number will match the code it's annotating.

7.18 '.cfi_register REGISTER1, REGISTER2'
=========================================

Previous value of REGISTER1 is saved in register REGISTER2.

7.19 '.cfi_restore REGISTER'
============================

'.cfi_restore' says that the rule for REGISTER is now the same as it was
at the beginning of the function, after all initial instruction added by
'.cfi_startproc' were executed.

7.20 '.cfi_undefined REGISTER'
==============================

From now on the previous value of REGISTER can't be restored anymore.

7.21 '.cfi_same_value REGISTER'
===============================

Current value of REGISTER is the same like in the previous frame, i.e.
no restoration needed.

7.22 '.cfi_remember_state',
===========================

First save all current rules for all registers by '.cfi_remember_state',
then totally screw them up by subsequent '.cfi_*' directives and when
everything is hopelessly bad, use '.cfi_restore_state' to restore the
previous saved state.

7.23 '.cfi_return_column REGISTER'
==================================

Change return column REGISTER, i.e.  the return address is either
directly in REGISTER or can be accessed by rules for REGISTER.

7.24 '.cfi_signal_frame'
========================

Mark current function as signal trampoline.

7.25 '.cfi_window_save'
=======================

SPARC register window has been saved.

7.26 '.cfi_escape' EXPRESSION[, ...]
====================================

Allows the user to add arbitrary bytes to the unwind info.  One might
use this to add OS-specific CFI opcodes, or generic CFI opcodes that GAS
does not yet support.

7.27 '.file FILENO FILENAME'
============================

When emitting dwarf2 line number information '.file' assigns filenames
to the '.debug_line' file name table.  The FILENO operand should be a
unique positive integer to use as the index of the entry in the table.
The FILENAME operand is a C string literal.

   The detail of filename indices is exposed to the user because the
filename table is shared with the '.debug_info' section of the dwarf2
debugging information, and thus the user must know the exact indices
that table entries will have.

7.28 '.loc FILENO LINENO [COLUMN] [OPTIONS]'
============================================

The '.loc' directive will add row to the '.debug_line' line number
matrix corresponding to the immediately following assembly instruction.
The FILENO, LINENO, and optional COLUMN arguments will be applied to the
'.debug_line' state machine before the row is added.

   The OPTIONS are a sequence of the following tokens in any order:

'basic_block'
     This option will set the 'basic_block' register in the
     '.debug_line' state machine to 'true'.

'prologue_end'
     This option will set the 'prologue_end' register in the
     '.debug_line' state machine to 'true'.

'epilogue_begin'
     This option will set the 'epilogue_begin' register in the
     '.debug_line' state machine to 'true'.

'is_stmt VALUE'
     This option will set the 'is_stmt' register in the '.debug_line'
     state machine to 'value', which must be either 0 or 1.

'isa VALUE'
     This directive will set the 'isa' register in the '.debug_line'
     state machine to VALUE, which must be an unsigned integer.

7.29 '.loc_mark_blocks ENABLE'
==============================

The '.loc_mark_blocks' directive makes the assembler emit an entry to
the '.debug_line' line number matrix with the 'basic_block' register in
the state machine set whenever a code label is seen.  The ENABLE
argument should be either 1 or 0, to enable or disable this function
respectively.

7.30 '.data SUBSECTION'
=======================

'.data' tells 'as' to assemble the following statements onto the end of
the data subsection numbered SUBSECTION (which is an absolute
expression).  If SUBSECTION is omitted, it defaults to zero.

7.31 '.double FLONUMS'
======================

'.double' expects zero or more flonums, separated by commas.  It
assembles floating point numbers.

7.32 '.eject'
=============

Force a page break at this point, when generating assembly listings.

7.33 '.else'
============

'.else' is part of the 'as' support for conditional assembly; see *note
'.if': If.  It marks the beginning of a section of code to be assembled
if the condition for the preceding '.if' was false.

7.34 '.elseif'
==============

'.elseif' is part of the 'as' support for conditional assembly; see
*note '.if': If.  It is shorthand for beginning a new '.if' block that
would otherwise fill the entire '.else' section.

7.35 '.end'
===========

'.end' marks the end of the assembly file.  'as' does not process
anything in the file past the '.end' directive.

7.36 '.endfunc'
===============

'.endfunc' marks the end of a function specified with '.func'.

7.37 '.endif'
=============

'.endif' is part of the 'as' support for conditional assembly; it marks
the end of a block of code that is only assembled conditionally.  *Note
'.if': If.

7.38 '.equ SYMBOL, EXPRESSION'
==============================

This directive sets the value of SYMBOL to EXPRESSION.  It is synonymous
with '.set'; see *note '.set': Set.

7.39 '.equiv SYMBOL, EXPRESSION'
================================

The '.equiv' directive is like '.equ' and '.set', except that the
assembler will signal an error if SYMBOL is already defined.  Note a
symbol which has been referenced but not actually defined is considered
to be undefined.

   Except for the contents of the error message, this is roughly
equivalent to
     .ifdef SYM
     .err
     .endif
     .equ SYM,VAL
   plus it protects the symbol from later redefinition.

7.40 '.eqv SYMBOL, EXPRESSION'
==============================

The '.eqv' directive is like '.equiv', but no attempt is made to
evaluate the expression or any part of it immediately.  Instead each
time the resulting symbol is used in an expression, a snapshot of its
current value is taken.

7.41 '.err'
===========

If 'as' assembles a '.err' directive, it will print an error message
and, unless the '-Z' option was used, it will not generate an object
file.  This can be used to signal an error in conditionally compiled
code.

7.42 '.error "STRING"'
======================

Similarly to '.err', this directive emits an error, but you can specify
a string that will be emitted as the error message.  If you don't
specify the message, it defaults to '".error directive invoked in source
file"'.  *Note Error and Warning Messages: Errors.

      .error "This code has not been assembled and tested."

7.43 '.exitm'
=============

Exit early from the current macro definition.  *Note Macro::.

7.44 '.extern'
==============

'.extern' is accepted in the source program--for compatibility with
other assemblers--but it is ignored.  'as' treats all undefined symbols
as external.

7.45 '.fail EXPRESSION'
=======================

Generates an error or a warning.  If the value of the EXPRESSION is 500
or more, 'as' will print a warning message.  If the value is less than
500, 'as' will print an error message.  The message will include the
value of EXPRESSION.  This can occasionally be useful inside complex
nested macros or conditional assembly.

7.46 '.file STRING'
===================

'.file' tells 'as' that we are about to start a new logical file.
STRING is the new file name.  In general, the filename is recognized
whether or not it is surrounded by quotes '"'; but if you wish to
specify an empty file name, you must give the quotes-'""'.  This
statement may go away in future: it is only recognized to be compatible
with old 'as' programs.

7.47 '.fill REPEAT , SIZE , VALUE'
==================================

REPEAT, SIZE and VALUE are absolute expressions.  This emits REPEAT
copies of SIZE bytes.  REPEAT may be zero or more.  SIZE may be zero or
more, but if it is more than 8, then it is deemed to have the value 8,
compatible with other people's assemblers.  The contents of each REPEAT
bytes is taken from an 8-byte number.  The highest order 4 bytes are
zero.  The lowest order 4 bytes are VALUE rendered in the byte-order of
an integer on the computer 'as' is assembling for.  Each SIZE bytes in a
repetition is taken from the lowest order SIZE bytes of this number.
Again, this bizarre behavior is compatible with other people's
assemblers.

   SIZE and VALUE are optional.  If the second comma and VALUE are
absent, VALUE is assumed zero.  If the first comma and following tokens
are absent, SIZE is assumed to be 1.

7.48 '.float FLONUMS'
=====================

This directive assembles zero or more flonums, separated by commas.  It
has the same effect as '.single'.

7.49 '.func NAME[,LABEL]'
=========================

'.func' emits debugging information to denote function NAME, and is
ignored unless the file is assembled with debugging enabled.  Only
'--gstabs[+]' is currently supported.  LABEL is the entry point of the
function and if omitted NAME prepended with the 'leading char' is used.
'leading char' is usually '_' or nothing, depending on the target.  All
functions are currently defined to have 'void' return type.  The
function must be terminated with '.endfunc'.

7.50 '.global SYMBOL', '.globl SYMBOL'
======================================

'.global' makes the symbol visible to 'ld'.  If you define SYMBOL in
your partial program, its value is made available to other partial
programs that are linked with it.  Otherwise, SYMBOL takes its
attributes from a symbol of the same name from another file linked into
the same program.

   Both spellings ('.globl' and '.global') are accepted, for
compatibility with other assemblers.

7.51 '.hidden NAMES'
====================

This is one of the ELF visibility directives.  The other two are
'.internal' (*note '.internal': Internal.) and '.protected' (*note
'.protected': Protected.).

   This directive overrides the named symbols default visibility (which
is set by their binding: local, global or weak).  The directive sets the
visibility to 'hidden' which means that the symbols are not visible to
other components.  Such symbols are always considered to be 'protected'
as well.

7.52 '.hword EXPRESSIONS'
=========================

This expects zero or more EXPRESSIONS, and emits a 16 bit number for
each.

   This directive is a synonym for '.short'.

7.53 '.ident'
=============

This directive is used by some assemblers to place tags in object files.
The behavior of this directive varies depending on the target.  When
using the a.out object file format, 'as' simply accepts the directive
for source-file compatibility with existing assemblers, but does not
emit anything for it.  When using COFF, comments are emitted to the
'.comment' or '.rdata' section, depending on the target.  When using
ELF, comments are emitted to the '.comment' section.

7.54 '.if ABSOLUTE EXPRESSION'
==============================

'.if' marks the beginning of a section of code which is only considered
part of the source program being assembled if the argument (which must
be an ABSOLUTE EXPRESSION) is non-zero.  The end of the conditional
section of code must be marked by '.endif' (*note '.endif': Endif.);
optionally, you may include code for the alternative condition, flagged
by '.else' (*note '.else': Else.).  If you have several conditions to
check, '.elseif' may be used to avoid nesting blocks if/else within each
subsequent '.else' block.

   The following variants of '.if' are also supported:
'.ifdef SYMBOL'
     Assembles the following section of code if the specified SYMBOL has
     been defined.  Note a symbol which has been referenced but not yet
     defined is considered to be undefined.

'.ifb TEXT'
     Assembles the following section of code if the operand is blank
     (empty).

'.ifc STRING1,STRING2'
     Assembles the following section of code if the two strings are the
     same.  The strings may be optionally quoted with single quotes.  If
     they are not quoted, the first string stops at the first comma, and
     the second string stops at the end of the line.  Strings which
     contain whitespace should be quoted.  The string comparison is case
     sensitive.

'.ifeq ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is zero.

'.ifeqs STRING1,STRING2'
     Another form of '.ifc'.  The strings must be quoted using double
     quotes.

'.ifge ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is greater
     than or equal to zero.

'.ifgt ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is greater
     than zero.

'.ifle ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is less
     than or equal to zero.

'.iflt ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is less
     than zero.

'.ifnb TEXT'
     Like '.ifb', but the sense of the test is reversed: this assembles
     the following section of code if the operand is non-blank
     (non-empty).

'.ifnc STRING1,STRING2.'
     Like '.ifc', but the sense of the test is reversed: this assembles
     the following section of code if the two strings are not the same.

'.ifndef SYMBOL'
'.ifnotdef SYMBOL'
     Assembles the following section of code if the specified SYMBOL has
     not been defined.  Both spelling variants are equivalent.  Note a
     symbol which has been referenced but not yet defined is considered
     to be undefined.

'.ifne ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is not
     equal to zero (in other words, this is equivalent to '.if').

'.ifnes STRING1,STRING2'
     Like '.ifeqs', but the sense of the test is reversed: this
     assembles the following section of code if the two strings are not
     the same.

7.55 '.incbin "FILE"[,SKIP[,COUNT]]'
====================================

The 'incbin' directive includes FILE verbatim at the current location.
You can control the search paths used with the '-I' command-line option
(*note Command-Line Options: Invoking.).  Quotation marks are required
around FILE.

   The SKIP argument skips a number of bytes from the start of the FILE.
The COUNT argument indicates the maximum number of bytes to read.  Note
that the data is not aligned in any way, so it is the user's
responsibility to make sure that proper alignment is provided both
before and after the 'incbin' directive.

7.56 '.include "FILE"'
======================

This directive provides a way to include supporting files at specified
points in your source program.  The code from FILE is assembled as if it
followed the point of the '.include'; when the end of the included file
is reached, assembly of the original file continues.  You can control
the search paths used with the '-I' command-line option (*note
Command-Line Options: Invoking.).  Quotation marks are required around
FILE.

7.57 '.int EXPRESSIONS'
=======================

Expect zero or more EXPRESSIONS, of any section, separated by commas.
For each expression, emit a number that, at run time, is the value of
that expression.  The byte order and bit size of the number depends on
what kind of target the assembly is for.

7.58 '.internal NAMES'
======================

This is one of the ELF visibility directives.  The other two are
'.hidden' (*note '.hidden': Hidden.) and '.protected' (*note
'.protected': Protected.).

   This directive overrides the named symbols default visibility (which
is set by their binding: local, global or weak).  The directive sets the
visibility to 'internal' which means that the symbols are considered to
be 'hidden' (i.e., not visible to other components), and that some
extra, processor specific processing must also be performed upon the
symbols as well.

7.59 '.irp SYMBOL,VALUES'...
============================

Evaluate a sequence of statements assigning different values to SYMBOL.
The sequence of statements starts at the '.irp' directive, and is
terminated by an '.endr' directive.  For each VALUE, SYMBOL is set to
VALUE, and the sequence of statements is assembled.  If no VALUE is
listed, the sequence of statements is assembled once, with SYMBOL set to
the null string.  To refer to SYMBOL within the sequence of statements,
use \SYMBOL.

   For example, assembling

             .irp    param,1,2,3
             move    d\param,sp@-
             .endr

   is equivalent to assembling

             move    d1,sp@-
             move    d2,sp@-
             move    d3,sp@-

   For some caveats with the spelling of SYMBOL, see also *note Macro::.

7.60 '.irpc SYMBOL,VALUES'...
=============================

Evaluate a sequence of statements assigning different values to SYMBOL.
The sequence of statements starts at the '.irpc' directive, and is
terminated by an '.endr' directive.  For each character in VALUE, SYMBOL
is set to the character, and the sequence of statements is assembled.
If no VALUE is listed, the sequence of statements is assembled once,
with SYMBOL set to the null string.  To refer to SYMBOL within the
sequence of statements, use \SYMBOL.

   For example, assembling

             .irpc    param,123
             move    d\param,sp@-
             .endr

   is equivalent to assembling

             move    d1,sp@-
             move    d2,sp@-
             move    d3,sp@-

   For some caveats with the spelling of SYMBOL, see also the discussion
at *Note Macro::.

7.61 '.lcomm SYMBOL , LENGTH'
=============================

Reserve LENGTH (an absolute expression) bytes for a local common denoted
by SYMBOL.  The section and value of SYMBOL are those of the new local
common.  The addresses are allocated in the bss section, so that at
run-time the bytes start off zeroed.  SYMBOL is not declared global
(*note '.global': Global.), so is normally not visible to 'ld'.

7.62 '.lflags'
==============

'as' accepts this directive, for compatibility with other assemblers,
but ignores it.

7.63 '.line LINE-NUMBER'
========================

Even though this is a directive associated with the 'a.out' or 'b.out'
object-code formats, 'as' still recognizes it when producing COFF
output, and treats '.line' as though it were the COFF '.ln' _if_ it is
found outside a '.def'/'.endef' pair.

   Inside a '.def', '.line' is, instead, one of the directives used by
compilers to generate auxiliary symbol information for debugging.

7.64 '.linkonce [TYPE]'
=======================

Mark the current section so that the linker only includes a single copy
of it.  This may be used to include the same section in several
different object files, but ensure that the linker will only include it
once in the final output file.  The '.linkonce' pseudo-op must be used
for each instance of the section.  Duplicate sections are detected based
on the section name, so it should be unique.

   This directive is only supported by a few object file formats; as of
this writing, the only object file format which supports it is the
Portable Executable format used on Windows NT.

   The TYPE argument is optional.  If specified, it must be one of the
following strings.  For example:
     .linkonce same_size
   Not all types may be supported on all object file formats.

'discard'
     Silently discard duplicate sections.  This is the default.

'one_only'
     Warn if there are duplicate sections, but still keep only one copy.

'same_size'
     Warn if any of the duplicates have different sizes.

'same_contents'
     Warn if any of the duplicates do not have exactly the same
     contents.

7.65 '.ln LINE-NUMBER'
======================

'.ln' is a synonym for '.line'.

7.66 '.mri VAL'
===============

If VAL is non-zero, this tells 'as' to enter MRI mode.  If VAL is zero,
this tells 'as' to exit MRI mode.  This change affects code assembled
until the next '.mri' directive, or until the end of the file.  *Note
MRI mode: M.

7.67 '.list'
============

Control (in conjunction with the '.nolist' directive) whether or not
assembly listings are generated.  These two directives maintain an
internal counter (which is zero initially).  '.list' increments the
counter, and '.nolist' decrements it.  Assembly listings are generated
whenever the counter is greater than zero.

   By default, listings are disabled.  When you enable them (with the
'-a' command line option; *note Command-Line Options: Invoking.), the
initial value of the listing counter is one.

7.68 '.long EXPRESSIONS'
========================

'.long' is the same as '.int'.  *Note '.int': Int.

7.69 '.macro'
=============

The commands '.macro' and '.endm' allow you to define macros that
generate assembly output.  For example, this definition specifies a
macro 'sum' that puts a sequence of numbers into memory:

             .macro  sum from=0, to=5
             .long   \from
             .if     \to-\from
             sum     "(\from+1)",\to
             .endif
             .endm

With that definition, 'SUM 0,5' is equivalent to this assembly input:

             .long   0
             .long   1
             .long   2
             .long   3
             .long   4
             .long   5

'.macro MACNAME'
'.macro MACNAME MACARGS ...'
     Begin the definition of a macro called MACNAME.  If your macro
     definition requires arguments, specify their names after the macro
     name, separated by commas or spaces.  You can qualify the macro
     argument to indicate whether all invocations must specify a
     non-blank value (through ':'req''), or whether it takes all of the
     remaining arguments (through ':'vararg'').  You can supply a
     default value for any macro argument by following the name with
     '=DEFLT'.  You cannot define two macros with the same MACNAME
     unless it has been subject to the '.purgem' directive (*note
     Purgem::) between the two definitions.  For example, these are all
     valid '.macro' statements:

     '.macro comm'
          Begin the definition of a macro called 'comm', which takes no
          arguments.

     '.macro plus1 p, p1'
     '.macro plus1 p p1'
          Either statement begins the definition of a macro called
          'plus1', which takes two arguments; within the macro
          definition, write '\p' or '\p1' to evaluate the arguments.

     '.macro reserve_str p1=0 p2'
          Begin the definition of a macro called 'reserve_str', with two
          arguments.  The first argument has a default value, but not
          the second.  After the definition is complete, you can call
          the macro either as 'reserve_str A,B' (with '\p1' evaluating
          to A and '\p2' evaluating to B), or as 'reserve_str ,B' (with
          '\p1' evaluating as the default, in this case '0', and '\p2'
          evaluating to B).

     '.macro m p1:req, p2=0, p3:vararg'
          Begin the definition of a macro called 'm', with at least
          three arguments.  The first argument must always have a value
          specified, but not the second, which instead has a default
          value.  The third formal will get assigned all remaining
          arguments specified at invocation time.

          When you call a macro, you can specify the argument values
          either by position, or by keyword.  For example, 'sum 9,17' is
          equivalent to 'sum to=17, from=9'.

     Note that since each of the MACARGS can be an identifier exactly as
     any other one permitted by the target architecture, there may be
     occasional problems if the target hand-crafts special meanings to
     certain characters when they occur in a special position.  For
     example, if the colon (':') is generally permitted to be part of a
     symbol name, but the architecture specific code special-cases it
     when occurring as the final character of a symbol (to denote a
     label), then the macro parameter replacement code will have no way
     of knowing that and consider the whole construct (including the
     colon) an identifier, and check only this identifier for being the
     subject to parameter substitution.  So for example this macro
     definition:

          	.macro label l
          \l:
          	.endm

     might not work as expected.  Invoking 'label foo' might not create
     a label called 'foo' but instead just insert the text '\l:' into
     the assembler source, probably generating an error about an
     unrecognised identifier.

     Similarly problems might occur with the period character ('.')
     which is often allowed inside opcode names (and hence identifier
     names).  So for example constructing a macro to build an opcode
     from a base name and a length specifier like this:

          	.macro opcode base length
                  \base.\length
          	.endm

     and invoking it as 'opcode store l' will not create a 'store.l'
     instruction but instead generate some kind of error as the
     assembler tries to interpret the text '\base.\length'.

     There are several possible ways around this problem:

     'Insert white space'
          If it is possible to use white space characters then this is
          the simplest solution.  eg:

               	.macro label l
               \l :
               	.endm

     'Use '\()''
          The string '\()' can be used to separate the end of a macro
          argument from the following text.  eg:

               	.macro opcode base length
                       \base\().\length
               	.endm

     'Use the alternate macro syntax mode'
          In the alternative macro syntax mode the ampersand character
          ('&') can be used as a separator.  eg:

               	.altmacro
               	.macro label l
               l&:
               	.endm

     Note: this problem of correctly identifying string parameters to
     pseudo ops also applies to the identifiers used in '.irp' (*note
     Irp::) and '.irpc' (*note Irpc::) as well.

'.endm'
     Mark the end of a macro definition.

'.exitm'
     Exit early from the current macro definition.

'\@'
     'as' maintains a counter of how many macros it has executed in this
     pseudo-variable; you can copy that number to your output with '\@',
     but _only within a macro definition_.

'LOCAL NAME [ , ... ]'
     _Warning: 'LOCAL' is only available if you select "alternate macro
     syntax" with '--alternate' or '.altmacro'._  *Note '.altmacro':
     Altmacro.

7.70 '.altmacro'
================

Enable alternate macro mode, enabling:

'LOCAL NAME [ , ... ]'
     One additional directive, 'LOCAL', is available.  It is used to
     generate a string replacement for each of the NAME arguments, and
     replace any instances of NAME in each macro expansion.  The
     replacement string is unique in the assembly, and different for
     each separate macro expansion.  'LOCAL' allows you to write macros
     that define symbols, without fear of conflict between separate
     macro expansions.

'String delimiters'
     You can write strings delimited in these other ways besides
     '"STRING"':

     ''STRING''
          You can delimit strings with single-quote characters.

     '<STRING>'
          You can delimit strings with matching angle brackets.

'single-character string escape'
     To include any single character literally in a string (even if the
     character would otherwise have some special meaning), you can
     prefix the character with '!' (an exclamation mark).  For example,
     you can write '<4.3 !> 5.4!!>' to get the literal text '4.3 >
     5.4!'.

'Expression results as strings'
     You can write '%EXPR' to evaluate the expression EXPR and use the
     result as a string.

7.71 '.noaltmacro'
==================

Disable alternate macro mode.  *Note Altmacro::.

7.72 '.nolist'
==============

Control (in conjunction with the '.list' directive) whether or not
assembly listings are generated.  These two directives maintain an
internal counter (which is zero initially).  '.list' increments the
counter, and '.nolist' decrements it.  Assembly listings are generated
whenever the counter is greater than zero.

7.73 '.octa BIGNUMS'
====================

This directive expects zero or more bignums, separated by commas.  For
each bignum, it emits a 16-byte integer.

   The term "octa" comes from contexts in which a "word" is two bytes;
hence _octa_-word for 16 bytes.

7.74 '.org NEW-LC , FILL'
=========================

Advance the location counter of the current section to NEW-LC.  NEW-LC
is either an absolute expression or an expression with the same section
as the current subsection.  That is, you can't use '.org' to cross
sections: if NEW-LC has the wrong section, the '.org' directive is
ignored.  To be compatible with former assemblers, if the section of
NEW-LC is absolute, 'as' issues a warning, then pretends the section of
NEW-LC is the same as the current subsection.

   '.org' may only increase the location counter, or leave it unchanged;
you cannot use '.org' to move the location counter backwards.

   Because 'as' tries to assemble programs in one pass, NEW-LC may not
be undefined.  If you really detest this restriction we eagerly await a
chance to share your improved assembler.

   Beware that the origin is relative to the start of the section, not
to the start of the subsection.  This is compatible with other people's
assemblers.

   When the location counter (of the current subsection) is advanced,
the intervening bytes are filled with FILL which should be an absolute
expression.  If the comma and FILL are omitted, FILL defaults to zero.

7.75 '.p2align[wl] ABS-EXPR, ABS-EXPR, ABS-EXPR'
================================================

Pad the location counter (in the current subsection) to a particular
storage boundary.  The first expression (which must be absolute) is the
number of low-order zero bits the location counter must have after
advancement.  For example '.p2align 3' advances the location counter
until it a multiple of 8.  If the location counter is already a multiple
of 8, no change is needed.

   The second expression (also absolute) gives the fill value to be
stored in the padding bytes.  It (and the comma) may be omitted.  If it
is omitted, the padding bytes are normally zero.  However, on some
systems, if the section is marked as containing code and the fill value
is omitted, the space is filled with no-op instructions.

   The third expression is also absolute, and is also optional.  If it
is present, it is the maximum number of bytes that should be skipped by
this alignment directive.  If doing the alignment would require skipping
more bytes than the specified maximum, then the alignment is not done at
all.  You can omit the fill value (the second argument) entirely by
simply using two commas after the required alignment; this can be useful
if you want the alignment to be filled with no-op instructions when
appropriate.

   The '.p2alignw' and '.p2alignl' directives are variants of the
'.p2align' directive.  The '.p2alignw' directive treats the fill pattern
as a two byte word value.  The '.p2alignl' directives treats the fill
pattern as a four byte longword value.  For example, '.p2alignw
2,0x368d' will align to a multiple of 4.  If it skips two bytes, they
will be filled in with the value 0x368d (the exact placement of the
bytes depends upon the endianness of the processor).  If it skips 1 or 3
bytes, the fill value is undefined.

7.76 '.previous'
================

This is one of the ELF section stack manipulation directives.  The
others are '.section' (*note Section::), '.subsection' (*note
SubSection::), '.pushsection' (*note PushSection::), and '.popsection'
(*note PopSection::).

   This directive swaps the current section (and subsection) with most
recently referenced section (and subsection) prior to this one.
Multiple '.previous' directives in a row will flip between two sections
(and their subsections).

   In terms of the section stack, this directive swaps the current
section with the top section on the section stack.

7.77 '.popsection'
==================

This is one of the ELF section stack manipulation directives.  The
others are '.section' (*note Section::), '.subsection' (*note
SubSection::), '.pushsection' (*note PushSection::), and '.previous'
(*note Previous::).

   This directive replaces the current section (and subsection) with the
top section (and subsection) on the section stack.  This section is
popped off the stack.

7.78 '.print STRING'
====================

'as' will print STRING on the standard output during assembly.  You must
put STRING in double quotes.

7.79 '.protected NAMES'
=======================

This is one of the ELF visibility directives.  The other two are
'.hidden' (*note Hidden::) and '.internal' (*note Internal::).

   This directive overrides the named symbols default visibility (which
is set by their binding: local, global or weak).  The directive sets the
visibility to 'protected' which means that any references to the symbols
from within the components that defines them must be resolved to the
definition in that component, even if a definition in another component
would normally preempt this.

7.80 '.psize LINES , COLUMNS'
=============================

Use this directive to declare the number of lines--and, optionally, the
number of columns--to use for each page, when generating listings.

   If you do not use '.psize', listings use a default line-count of 60.
You may omit the comma and COLUMNS specification; the default width is
200 columns.

   'as' generates formfeeds whenever the specified number of lines is
exceeded (or whenever you explicitly request one, using '.eject').

   If you specify LINES as '0', no formfeeds are generated save those
explicitly specified with '.eject'.

7.81 '.purgem NAME'
===================

Undefine the macro NAME, so that later uses of the string will not be
expanded.  *Note Macro::.

7.82 '.pushsection NAME , SUBSECTION'
=====================================

This is one of the ELF section stack manipulation directives.  The
others are '.section' (*note Section::), '.subsection' (*note
SubSection::), '.popsection' (*note PopSection::), and '.previous'
(*note Previous::).

   This directive pushes the current section (and subsection) onto the
top of the section stack, and then replaces the current section and
subsection with 'name' and 'subsection'.

7.83 '.quad BIGNUMS'
====================

'.quad' expects zero or more bignums, separated by commas.  For each
bignum, it emits an 8-byte integer.  If the bignum won't fit in 8 bytes,
it prints a warning message; and just takes the lowest order 8 bytes of
the bignum.

   The term "quad" comes from contexts in which a "word" is two bytes;
hence _quad_-word for 8 bytes.

7.84 '.reloc OFFSET, RELOC_NAME[, EXPRESSION]'
==============================================

Generate a relocation at OFFSET of type RELOC_NAME with value
EXPRESSION.  If OFFSET is a number, the relocation is generated in the
current section.  If OFFSET is an expression that resolves to a symbol
plus offset, the relocation is generated in the given symbol's section.
EXPRESSION, if present, must resolve to a symbol plus addend or to an
absolute value, but note that not all targets support an addend.  e.g.
ELF REL targets such as i386 store an addend in the section contents
rather than in the relocation.  This low level interface does not
support addends stored in the section.

7.85 '.rept COUNT'
==================

Repeat the sequence of lines between the '.rept' directive and the next
'.endr' directive COUNT times.

   For example, assembling

             .rept   3
             .long   0
             .endr

   is equivalent to assembling

             .long   0
             .long   0
             .long   0

7.86 '.sbttl "SUBHEADING"'
==========================

Use SUBHEADING as the title (third line, immediately after the title
line) when generating assembly listings.

   This directive affects subsequent pages, as well as the current page
if it appears within ten lines of the top of a page.

7.87 '.section NAME'
====================

Use the '.section' directive to assemble the following code into a
section named NAME.

   This directive is only supported for targets that actually support
arbitrarily named sections; on 'a.out' targets, for example, it is not
accepted, even with a standard 'a.out' section name.

   This is one of the ELF section stack manipulation directives.  The
others are '.subsection' (*note SubSection::), '.pushsection' (*note
PushSection::), '.popsection' (*note PopSection::), and '.previous'
(*note Previous::).

   For ELF targets, the '.section' directive is used like this:

     .section NAME [, "FLAGS"[, @TYPE[,FLAG_SPECIFIC_ARGUMENTS]]]

   The optional FLAGS argument is a quoted string which may contain any
combination of the following characters:
'a'
     section is allocatable
'w'
     section is writable
'x'
     section is executable
'M'
     section is mergeable
'S'
     section contains zero terminated strings
'G'
     section is a member of a section group
'T'
     section is used for thread-local-storage

   The optional TYPE argument may contain one of the following
constants:
'@progbits'
     section contains data
'@nobits'
     section does not contain data (i.e., section only occupies space)
'@note'
     section contains data which is used by things other than the
     program
'@init_array'
     section contains an array of pointers to init functions
'@fini_array'
     section contains an array of pointers to finish functions
'@preinit_array'
     section contains an array of pointers to pre-init functions

   Many targets only support the first three section types.

   Note on targets where the '@' character is the start of a comment (eg
ARM) then another character is used instead.  For example the ARM port
uses the '%' character.

   If FLAGS contains the 'M' symbol then the TYPE argument must be
specified as well as an extra argument--ENTSIZE--like this:

     .section NAME , "FLAGS"M, @TYPE, ENTSIZE

   Sections with the 'M' flag but not 'S' flag must contain fixed size
constants, each ENTSIZE octets long.  Sections with both 'M' and 'S'
must contain zero terminated strings where each character is ENTSIZE
bytes long.  The linker may remove duplicates within sections with the
same name, same entity size and same flags.  ENTSIZE must be an absolute
expression.

   If FLAGS contains the 'G' symbol then the TYPE argument must be
present along with an additional field like this:

     .section NAME , "FLAGS"G, @TYPE, GROUPNAME[, LINKAGE]

   The GROUPNAME field specifies the name of the section group to which
this particular section belongs.  The optional linkage field can
contain:
'comdat'
     indicates that only one copy of this section should be retained
'.gnu.linkonce'
     an alias for comdat

   Note: if both the M and G flags are present then the fields for the
Merge flag should come first, like this:

     .section NAME , "FLAGS"MG, @TYPE, ENTSIZE, GROUPNAME[, LINKAGE]

   If no flags are specified, the default flags depend upon the section
name.  If the section name is not recognized, the default will be for
the section to have none of the above flags: it will not be allocated in
memory, nor writable, nor executable.  The section will contain data.

   For ELF targets, the assembler supports another type of '.section'
directive for compatibility with the Solaris assembler:

     .section "NAME"[, FLAGS...]

   Note that the section name is quoted.  There may be a sequence of
comma separated flags:
'#alloc'
     section is allocatable
'#write'
     section is writable
'#execinstr'
     section is executable
'#tls'
     section is used for thread local storage

   This directive replaces the current section and subsection.  See the
contents of the gas testsuite directory 'gas/testsuite/gas/elf' for some
examples of how this directive and the other section stack directives
work.

7.88 '.set SYMBOL, EXPRESSION'
==============================

Set the value of SYMBOL to EXPRESSION.  This changes SYMBOL's value and
type to conform to EXPRESSION.  If SYMBOL was flagged as external, it
remains flagged (*note Symbol Attributes::).

   You may '.set' a symbol many times in the same assembly.

   If you '.set' a global symbol, the value stored in the object file is
the last value stored into it.

7.89 '.short EXPRESSIONS'
=========================

This expects zero or more EXPRESSIONS, and emits a 16 bit number for
each.

7.90 '.single FLONUMS'
======================

This directive assembles zero or more flonums, separated by commas.  It
has the same effect as '.float'.

7.91 '.size'
============

This directive is used to set the size associated with a symbol.

   For ELF targets, the '.size' directive is used like this:

     .size NAME , EXPRESSION

   This directive sets the size associated with a symbol NAME.  The size
in bytes is computed from EXPRESSION which can make use of label
arithmetic.  This directive is typically used to set the size of
function symbols.

7.92 '.sleb128 EXPRESSIONS'
===========================

SLEB128 stands for "signed little endian base 128."  This is a compact,
variable length representation of numbers used by the DWARF symbolic
debugging format.  *Note '.uleb128': Uleb128.

7.93 '.skip SIZE , FILL'
========================

This directive emits SIZE bytes, each of value FILL.  Both SIZE and FILL
are absolute expressions.  If the comma and FILL are omitted, FILL is
assumed to be zero.  This is the same as '.space'.

7.94 '.space SIZE , FILL'
=========================

This directive emits SIZE bytes, each of value FILL.  Both SIZE and FILL
are absolute expressions.  If the comma and FILL are omitted, FILL is
assumed to be zero.  This is the same as '.skip'.

7.95 '.stabd, .stabn, .stabs'
=============================

There are three directives that begin '.stab'.  All emit symbols (*note
Symbols::), for use by symbolic debuggers.  The symbols are not entered
in the 'as' hash table: they cannot be referenced elsewhere in the
source file.  Up to five fields are required:

STRING
     This is the symbol's name.  It may contain any character except
     '\000', so is more general than ordinary symbol names.  Some
     debuggers used to code arbitrarily complex structures into symbol
     names using this field.

TYPE
     An absolute expression.  The symbol's type is set to the low 8 bits
     of this expression.  Any bit pattern is permitted, but 'ld' and
     debuggers choke on silly bit patterns.

OTHER
     An absolute expression.  The symbol's "other" attribute is set to
     the low 8 bits of this expression.

DESC
     An absolute expression.  The symbol's descriptor is set to the low
     16 bits of this expression.

VALUE
     An absolute expression which becomes the symbol's value.

   If a warning is detected while reading a '.stabd', '.stabn', or
'.stabs' statement, the symbol has probably already been created; you
get a half-formed symbol in your object file.  This is compatible with
earlier assemblers!

'.stabd TYPE , OTHER , DESC'

     The "name" of the symbol generated is not even an empty string.  It
     is a null pointer, for compatibility.  Older assemblers used a null
     pointer so they didn't waste space in object files with empty
     strings.

     The symbol's value is set to the location counter, relocatably.
     When your program is linked, the value of this symbol is the
     address of the location counter when the '.stabd' was assembled.

'.stabn TYPE , OTHER , DESC , VALUE'
     The name of the symbol is set to the empty string '""'.

'.stabs STRING , TYPE , OTHER , DESC , VALUE'
     All five fields are specified.

7.96 '.string' "STR"
====================

Copy the characters in STR to the object file.  You may specify more
than one string to copy, separated by commas.  Unless otherwise
specified for a particular machine, the assembler marks the end of each
string with a 0 byte.  You can use any of the escape sequences described
in *note Strings: Strings.

7.97 '.struct EXPRESSION'
=========================

Switch to the absolute section, and set the section offset to
EXPRESSION, which must be an absolute expression.  You might use this as
follows:
             .struct 0
     field1:
             .struct field1 + 4
     field2:
             .struct field2 + 4
     field3:
   This would define the symbol 'field1' to have the value 0, the symbol
'field2' to have the value 4, and the symbol 'field3' to have the value
8.  Assembly would be left in the absolute section, and you would need
to use a '.section' directive of some sort to change to some other
section before further assembly.

7.98 '.subsection NAME'
=======================

This is one of the ELF section stack manipulation directives.  The
others are '.section' (*note Section::), '.pushsection' (*note
PushSection::), '.popsection' (*note PopSection::), and '.previous'
(*note Previous::).

   This directive replaces the current subsection with 'name'.  The
current section is not changed.  The replaced subsection is put onto the
section stack in place of the then current top of stack subsection.

7.99 '.symver'
==============

Use the '.symver' directive to bind symbols to specific version nodes
within a source file.  This is only supported on ELF platforms, and is
typically used when assembling files to be linked into a shared library.
There are cases where it may make sense to use this in objects to be
bound into an application itself so as to override a versioned symbol
from a shared library.

   For ELF targets, the '.symver' directive can be used like this:
     .symver NAME, NAME2@NODENAME
   If the symbol NAME is defined within the file being assembled, the
'.symver' directive effectively creates a symbol alias with the name
NAME2@NODENAME, and in fact the main reason that we just don't try and
create a regular alias is that the @ character isn't permitted in symbol
names.  The NAME2 part of the name is the actual name of the symbol by
which it will be externally referenced.  The name NAME itself is merely
a name of convenience that is used so that it is possible to have
definitions for multiple versions of a function within a single source
file, and so that the compiler can unambiguously know which version of a
function is being mentioned.  The NODENAME portion of the alias should
be the name of a node specified in the version script supplied to the
linker when building a shared library.  If you are attempting to
override a versioned symbol from a shared library, then NODENAME should
correspond to the nodename of the symbol you are trying to override.

   If the symbol NAME is not defined within the file being assembled,
all references to NAME will be changed to NAME2@NODENAME.  If no
reference to NAME is made, NAME2@NODENAME will be removed from the
symbol table.

   Another usage of the '.symver' directive is:
     .symver NAME, NAME2@@NODENAME
   In this case, the symbol NAME must exist and be defined within the
file being assembled.  It is similar to NAME2@NODENAME.  The difference
is NAME2@@NODENAME will also be used to resolve references to NAME2 by
the linker.

   The third usage of the '.symver' directive is:
     .symver NAME, NAME2@@@NODENAME
   When NAME is not defined within the file being assembled, it is
treated as NAME2@NODENAME.  When NAME is defined within the file being
assembled, the symbol name, NAME, will be changed to NAME2@@NODENAME.

7.100 '.text SUBSECTION'
========================

Tells 'as' to assemble the following statements onto the end of the text
subsection numbered SUBSECTION, which is an absolute expression.  If
SUBSECTION is omitted, subsection number zero is used.

7.101 '.title "HEADING"'
========================

Use HEADING as the title (second line, immediately after the source file
name and pagenumber) when generating assembly listings.

   This directive affects subsequent pages, as well as the current page
if it appears within ten lines of the top of a page.

7.102 '.type'
=============

This directive is used to set the type of a symbol.

   For ELF targets, the '.type' directive is used like this:

     .type NAME , TYPE DESCRIPTION

   This sets the type of symbol NAME to be either a function symbol or
an object symbol.  There are five different syntaxes supported for the
TYPE DESCRIPTION field, in order to provide compatibility with various
other assemblers.

   Because some of the characters used in these syntaxes (such as '@'
and '#') are comment characters for some architectures, some of the
syntaxes below do not work on all architectures.  The first variant will
be accepted by the GNU assembler on all architectures so that variant
should be used for maximum portability, if you do not need to assemble
your code with other assemblers.

   The syntaxes supported are:

       .type <name> STT_FUNCTION
       .type <name> STT_OBJECT

       .type <name>,#function
       .type <name>,#object

       .type <name>,@function
       .type <name>,@object

       .type <name>,%function
       .type <name>,%object

       .type <name>,"function"
       .type <name>,"object"

7.103 '.uleb128 EXPRESSIONS'
============================

ULEB128 stands for "unsigned little endian base 128."  This is a
compact, variable length representation of numbers used by the DWARF
symbolic debugging format.  *Note '.sleb128': Sleb128.

7.104 '.version "STRING"'
=========================

This directive creates a '.note' section and places into it an ELF
formatted note of type NT_VERSION. The note's name is set to 'string'.

7.105 '.vtable_entry TABLE, OFFSET'
===================================

This directive finds or creates a symbol 'table' and creates a
'VTABLE_ENTRY' relocation for it with an addend of 'offset'.

7.106 '.vtable_inherit CHILD, PARENT'
=====================================

This directive finds the symbol 'child' and finds or creates the symbol
'parent' and then creates a 'VTABLE_INHERIT' relocation for the parent
whose addend is the value of the child symbol.  As a special case the
parent name of '0' is treated as referring to the '*ABS*' section.

7.107 '.warning "STRING"'
=========================

Similar to the directive '.error' (*note '.error "STRING"': Error.), but
just emits a warning.

7.108 '.weak NAMES'
===================

This directive sets the weak attribute on the comma separated list of
symbol 'names'.  If the symbols do not already exist, they will be
created.

   On COFF targets other than PE, weak symbols are a GNU extension.
This directive sets the weak attribute on the comma separated list of
symbol 'names'.  If the symbols do not already exist, they will be
created.

   On the PE target, weak symbols are supported natively as weak
aliases.  When a weak symbol is created that is not an alias, GAS
creates an alternate symbol to hold the default value.

7.109 '.weakref ALIAS, TARGET'
==============================

This directive creates an alias to the target symbol that enables the
symbol to be referenced with weak-symbol semantics, but without actually
making it weak.  If direct references or definitions of the symbol are
present, then the symbol will not be weak, but if all references to it
are through weak references, the symbol will be marked as weak in the
symbol table.

   The effect is equivalent to moving all references to the alias to a
separate assembly source file, renaming the alias to the symbol in it,
declaring the symbol as weak there, and running a reloadable link to
merge the object files resulting from the assembly of the new source
file and the old source file that had the references to the alias
removed.

   The alias itself never makes to the symbol table, and is entirely
handled within the assembler.

7.110 '.word EXPRESSIONS'
=========================

This directive expects zero or more EXPRESSIONS, of any section,
separated by commas.  For each expression, 'as' emits a 32-bit number.

7.111 Deprecated Directives
===========================

One day these directives won't work.  They are included for
compatibility with older assemblers.
.abort
.line

8 ARM Dependent Features
************************

8.1 Options
===========

'-mcpu=PROCESSOR[+EXTENSION...]'
     This option specifies the target processor.  The assembler will
     issue an error message if an attempt is made to assemble an
     instruction which will not execute on the target processor.  The
     following processor names are recognized: 'arm1', 'arm2', 'arm250',
     'arm3', 'arm6', 'arm60', 'arm600', 'arm610', 'arm620', 'arm7',
     'arm7m', 'arm7d', 'arm7dm', 'arm7di', 'arm7dmi', 'arm70', 'arm700',
     'arm700i', 'arm710', 'arm710t', 'arm720', 'arm720t', 'arm740t',
     'arm710c', 'arm7100', 'arm7500', 'arm7500fe', 'arm7t', 'arm7tdmi',
     'arm7tdmi-s', 'arm8', 'arm810', 'strongarm', 'strongarm1',
     'strongarm110', 'strongarm1100', 'strongarm1110', 'arm9', 'arm920',
     'arm920t', 'arm922t', 'arm940t', 'arm9tdmi', 'arm9e', 'arm926e',
     'arm926ej-s', 'arm946e-r0', 'arm946e', 'arm946e-s', 'arm966e-r0',
     'arm966e', 'arm966e-s', 'arm968e-s', 'arm10t', 'arm10tdmi',
     'arm10e', 'arm1020', 'arm1020t', 'arm1020e', 'arm1022e',
     'arm1026ej-s', 'arm1136j-s', 'arm1136jf-s', 'arm1156t2-s',
     'arm1156t2f-s', 'arm1176jz-s', 'arm1176jzf-s', 'mpcore',
     'mpcorenovfp', 'cortex-a8', 'cortex-r4', 'cortex-m3', 'ep9312'
     (ARM920 with Cirrus Maverick coprocessor), 'i80200' (Intel XScale
     processor) 'iwmmxt' (Intel(r) XScale processor with Wireless
     MMX(tm) technology coprocessor) and 'xscale'.  The special name
     'all' may be used to allow the assembler to accept instructions
     valid for any ARM processor.

     In addition to the basic instruction set, the assembler can be told
     to accept various extension mnemonics that extend the processor
     using the co-processor instruction space.  For example,
     '-mcpu=arm920+maverick' is equivalent to specifying '-mcpu=ep9312'.
     The following extensions are currently supported: '+maverick'
     '+iwmmxt' and '+xscale'.

'-march=ARCHITECTURE[+EXTENSION...]'
     This option specifies the target architecture.  The assembler will
     issue an error message if an attempt is made to assemble an
     instruction which will not execute on the target architecture.  The
     following architecture names are recognized: 'armv1', 'armv2',
     'armv2a', 'armv2s', 'armv3', 'armv3m', 'armv4', 'armv4xm',
     'armv4t', 'armv4txm', 'armv5', 'armv5t', 'armv5txm', 'armv5te',
     'armv5texp', 'armv6', 'armv6j', 'armv6k', 'armv6z', 'armv6zk',
     'armv7', 'armv7-a', 'armv7-r', 'armv7-m', 'iwmmxt' and 'xscale'.
     If both '-mcpu' and '-march' are specified, the assembler will use
     the setting for '-mcpu'.

     The architecture option can be extended with the same instruction
     set extension options as the '-mcpu' option.

'-mfpu=FLOATING-POINT-FORMAT'

     This option specifies the floating point format to assemble for.
     The assembler will issue an error message if an attempt is made to
     assemble an instruction which will not execute on the target
     floating point unit.  The following format options are recognized:
     'softfpa', 'fpe', 'fpe2', 'fpe3', 'fpa', 'fpa10', 'fpa11',
     'arm7500fe', 'softvfp', 'softvfp+vfp', 'vfp', 'vfp10', 'vfp10-r0',
     'vfp9', 'vfpxd', 'arm1020t', 'arm1020e', 'arm1136jf-s' and
     'maverick'.

     In addition to determining which instructions are assembled, this
     option also affects the way in which the '.double' assembler
     directive behaves when assembling little-endian code.

     The default is dependent on the processor selected.  For
     Architecture 5 or later, the default is to assembler for VFP
     instructions; for earlier architectures the default is to assemble
     for FPA instructions.

'-mthumb'
     This option specifies that the assembler should start assembling
     Thumb instructions; that is, it should behave as though the file
     starts with a '.code 16' directive.

'-mthumb-interwork'
     This option specifies that the output generated by the assembler
     should be marked as supporting interworking.

'-mapcs [26|32]'
     This option specifies that the output generated by the assembler
     should be marked as supporting the indicated version of the Arm
     Procedure.  Calling Standard.

'-matpcs'
     This option specifies that the output generated by the assembler
     should be marked as supporting the Arm/Thumb Procedure Calling
     Standard.  If enabled this option will cause the assembler to
     create an empty debugging section in the object file called
     .arm.atpcs.  Debuggers can use this to determine the ABI being used
     by.

'-mapcs-float'
     This indicates the floating point variant of the APCS should be
     used.  In this variant floating point arguments are passed in FP
     registers rather than integer registers.

'-mapcs-reentrant'
     This indicates that the reentrant variant of the APCS should be
     used.  This variant supports position independent code.

'-mfloat-abi=ABI'
     This option specifies that the output generated by the assembler
     should be marked as using specified floating point ABI. The
     following values are recognized: 'soft', 'softfp' and 'hard'.

'-meabi=VER'
     This option specifies which EABI version the produced object files
     should conform to.  The following values are recognized: 'gnu', '4'
     and '5'.

'-EB'
     This option specifies that the output generated by the assembler
     should be marked as being encoded for a big-endian processor.

'-EL'
     This option specifies that the output generated by the assembler
     should be marked as being encoded for a little-endian processor.

'-k'
     This option specifies that the output of the assembler should be
     marked as position-independent code (PIC).

8.2 Syntax
==========

8.2.1 Special Characters
------------------------

The presence of a '@' on a line indicates the start of a comment that
extends to the end of the current line.  If a '#' appears as the first
character of a line, the whole line is treated as a comment.

   The ';' character can be used instead of a newline to separate
statements.

   Either '#' or '$' can be used to indicate immediate operands.

   *TODO* Explain about /data modifier on symbols.

8.2.2 Register Names
--------------------

*TODO* Explain about ARM register naming, and the predefined names.

8.2.3 ARM relocation generation
-------------------------------

Specific data relocations can be generated by putting the relocation
name in parentheses after the symbol name.  For example:

             .word foo(TARGET1)

   This will generate an 'R_ARM_TARGET1' relocation against the symbol
FOO.  The following relocations are supported: 'GOT', 'GOTOFF',
'TARGET1', 'TARGET2', 'SBREL', 'TLSGD', 'TLSLDM', 'TLSLDO', 'GOTTPOFF'
and 'TPOFF'.

   For compatibility with older toolchains the assembler also accepts
'(PLT)' after branch targets.  This will generate the deprecated
'R_ARM_PLT32' relocation.

   Relocations for 'MOVW' and 'MOVT' instructions can be generated by
prefixing the value with '#:lower16:' and '#:upper16' respectively.  For
example to load the 32-bit address of foo into r0:

             MOVW r0, #:lower16:foo
             MOVT r0, #:upper16:foo

8.3 Floating Point
==================

The ARM family uses IEEE floating-point numbers.

8.4 ARM Machine Directives
==========================

'.align EXPRESSION [, EXPRESSION]'
     This is the generic .ALIGN directive.  For the ARM however if the
     first argument is zero (ie no alignment is needed) the assembler
     will behave as if the argument had been 2 (ie pad to the next four
     byte boundary).  This is for compatibility with ARM's own
     assembler.

'NAME .req REGISTER NAME'
     This creates an alias for REGISTER NAME called NAME.  For example:

                  foo .req r0

'.unreq ALIAS-NAME'
     This undefines a register alias which was previously defined using
     the 'req', 'dn' or 'qn' directives.  For example:

                  foo .req r0
                  .unreq foo

     An error occurs if the name is undefined.  Note - this pseudo op
     can be used to delete builtin in register name aliases (eg 'r0').
     This should only be done if it is really necessary.

'NAME .dn REGISTER NAME [.TYPE] [[INDEX]]'
'NAME .qn REGISTER NAME [.TYPE] [[INDEX]]'

     The 'dn' and 'qn' directives are used to create typed and/or
     indexed register aliases for use in Advanced SIMD Extension (Neon)
     instructions.  The former should be used to create aliases of
     double-precision registers, and the latter to create aliases of
     quad-precision registers.

     If these directives are used to create typed aliases, those aliases
     can be used in Neon instructions instead of writing types after the
     mnemonic or after each operand.  For example:

                  x .dn d2.f32
                  y .dn d3.f32
                  z .dn d4.f32[1]
                  vmul x,y,z

     This is equivalent to writing the following:

                  vmul.f32 d2,d3,d4[1]

     Aliases created using 'dn' or 'qn' can be destroyed using 'unreq'.

'.code [16|32]'
     This directive selects the instruction set being generated.  The
     value 16 selects Thumb, with the value 32 selecting ARM.

'.thumb'
     This performs the same action as .CODE 16.

'.arm'
     This performs the same action as .CODE 32.

'.force_thumb'
     This directive forces the selection of Thumb instructions, even if
     the target processor does not support those instructions

'.thumb_func'
     This directive specifies that the following symbol is the name of a
     Thumb encoded function.  This information is necessary in order to
     allow the assembler and linker to generate correct code for
     interworking between Arm and Thumb instructions and should be used
     even if interworking is not going to be performed.  The presence of
     this directive also implies '.thumb'

     This directive is not neccessary when generating EABI objects.  On
     these targets the encoding is implicit when generating Thumb code.

'.thumb_set'
     This performs the equivalent of a '.set' directive in that it
     creates a symbol which is an alias for another symbol (possibly not
     yet defined).  This directive also has the added property in that
     it marks the aliased symbol as being a thumb function entry point,
     in the same way that the '.thumb_func' directive does.

'.ltorg'
     This directive causes the current contents of the literal pool to
     be dumped into the current section (which is assumed to be the
     .text section) at the current location (aligned to a word
     boundary).  'GAS' maintains a separate literal pool for each
     section and each sub-section.  The '.ltorg' directive will only
     affect the literal pool of the current section and sub-section.  At
     the end of assembly all remaining, un-empty literal pools will
     automatically be dumped.

     Note - older versions of 'GAS' would dump the current literal pool
     any time a section change occurred.  This is no longer done, since
     it prevents accurate control of the placement of literal pools.

'.pool'
     This is a synonym for .ltorg.

'.unwind_fnstart'
     Marks the start of a function with an unwind table entry.

'.unwind_fnend'
     Marks the end of a function with an unwind table entry.  The unwind
     index table entry is created when this directive is processed.

     If no personality routine has been specified then standard
     personality routine 0 or 1 will be used, depending on the number of
     unwind opcodes required.

'.cantunwind'
     Prevents unwinding through the current function.  No personality
     routine or exception table data is required or permitted.

'.personality NAME'
     Sets the personality routine for the current function to NAME.

'.personalityindex INDEX'
     Sets the personality routine for the current function to the EABI
     standard routine number INDEX

'.handlerdata'
     Marks the end of the current function, and the start of the
     exception table entry for that function.  Anything between this
     directive and the '.fnend' directive will be added to the exception
     table entry.

     Must be preceded by a '.personality' or '.personalityindex'
     directive.

'.save REGLIST'
     Generate unwinder annotations to restore the registers in REGLIST.
     The format of REGLIST is the same as the corresponding
     store-multiple instruction.

     _core registers_
            .save {r4, r5, r6, lr}
            stmfd sp!, {r4, r5, r6, lr}
     _FPA registers_
            .save f4, 2
            sfmfd f4, 2, [sp]!
     _VFP registers_
            .save {d8, d9, d10}
            fstmdx sp!, {d8, d9, d10}
     _iWMMXt registers_
            .save {wr10, wr11}
            wstrd wr11, [sp, #-8]!
            wstrd wr10, [sp, #-8]!
          or
            .save wr11
            wstrd wr11, [sp, #-8]!
            .save wr10
            wstrd wr10, [sp, #-8]!

'.vsave VFP-REGLIST'
     Generate unwinder annotations to restore the VFP registers in
     VFP-REGLIST using FLDMD. Also works for VFPv3 registers that are to
     be restored using VLDM. The format of VFP-REGLIST is the same as
     the corresponding store-multiple instruction.

     _VFP registers_
            .vsave {d8, d9, d10}
            fstmdd sp!, {d8, d9, d10}
     _VFPv3 registers_
            .vsave {d15, d16, d17}
            vstm sp!, {d15, d16, d17}

     Since FLDMX and FSTMX are now deprecated, this directive should be
     used in favour of '.save' for saving VFP registers for ARMv6 and
     above.

'.pad #COUNT'
     Generate unwinder annotations for a stack adjustment of COUNT
     bytes.  A positive value indicates the function prologue allocated
     stack space by decrementing the stack pointer.

'.movsp REG [, #OFFSET]'
     Tell the unwinder that REG contains an offset from the current
     stack pointer.  If OFFSET is not specified then it is assumed to be
     zero.

'.setfp FPREG, SPREG [, #OFFSET]'
     Make all unwinder annotations relaive to a frame pointer.  Without
     this the unwinder will use offsets from the stack pointer.

     The syntax of this directive is the same as the 'sub' or 'mov'
     instruction used to set the frame pointer.  SPREG must be either
     'sp' or mentioned in a previous '.movsp' directive.

          .movsp ip
          mov ip, sp
          ...
          .setfp fp, ip, #4
          sub fp, ip, #4

'.raw OFFSET, BYTE1, ...'
     Insert one of more arbitary unwind opcode bytes, which are known to
     adjust the stack pointer by OFFSET bytes.

     For example '.unwind_raw 4, 0xb1, 0x01' is equivalent to '.save
     {r0}'

'.cpu NAME'
     Select the target processor.  Valid values for NAME are the same as
     for the '-mcpu' commandline option.

'.arch NAME'
     Select the target architecture.  Valid values for NAME are the same
     as for the '-march' commandline option.

'.object_arch NAME'
     Override the architecture recorded in the EABI object attribute
     section.  Valid values for NAME are the same as for the '.arch'
     directive.  Typically this is useful when code uses runtime
     detection of CPU features.

'.fpu NAME'
     Select the floating point unit to assemble for.  Valid values for
     NAME are the same as for the '-mfpu' commandline option.

'.eabi_attribute TAG, VALUE'
     Set the EABI object attribute number TAG to VALUE.  The value is
     either a 'number', '"string"', or 'number, "string"' depending on
     the tag.

8.5 Opcodes
===========

'as' implements all the standard ARM opcodes.  It also implements
several pseudo opcodes, including several synthetic load instructions.

'NOP'
            nop

     This pseudo op will always evaluate to a legal ARM instruction that
     does nothing.  Currently it will evaluate to MOV r0, r0.

'LDR'
            ldr <register> , = <expression>

     If expression evaluates to a numeric constant then a MOV or MVN
     instruction will be used in place of the LDR instruction, if the
     constant can be generated by either of these instructions.
     Otherwise the constant will be placed into the nearest literal pool
     (if it not already there) and a PC relative LDR instruction will be
     generated.

'ADR'
            adr <register> <label>

     This instruction will load the address of LABEL into the indicated
     register.  The instruction will evaluate to a PC relative ADD or
     SUB instruction depending upon where the label is located.  If the
     label is out of range, or if it is not defined in the same file
     (and section) as the ADR instruction, then an error will be
     generated.  This instruction will not make use of the literal pool.

'ADRL'
            adrl <register> <label>

     This instruction will load the address of LABEL into the indicated
     register.  The instruction will evaluate to one or two PC relative
     ADD or SUB instructions depending upon where the label is located.
     If a second instruction is not needed a NOP instruction will be
     generated in its place, so that this instruction is always 8 bytes
     long.

     If the label is out of range, or if it is not defined in the same
     file (and section) as the ADRL instruction, then an error will be
     generated.  This instruction will not make use of the literal pool.

   For information on the ARM or Thumb instruction sets, see 'ARM
Software Development Toolkit Reference Manual', Advanced RISC Machines
Ltd.

8.6 Mapping Symbols
===================

The ARM ELF specification requires that special symbols be inserted into
object files to mark certain features:

'$a'
     At the start of a region of code containing ARM instructions.

'$t'
     At the start of a region of code containing THUMB instructions.

'$d'
     At the start of a region of data.

   The assembler will automatically insert these symbols for you - there
is no need to code them yourself.  Support for tagging symbols ($b, $f,
$p and $m) which is also mentioned in the current ARM ELF specification
is not implemented.  This is because they have been dropped from the new
EABI and so tools cannot rely upon their presence.

9 80386 Dependent Features
**************************

The i386 version 'as' supports both the original Intel 386 architecture
in both 16 and 32-bit mode as well as AMD x86-64 architecture extending
the Intel architecture to 64-bits.

9.1 Options
===========

The i386 version of 'as' has a few machine dependent options:

'--32 | --64'
     Select the word size, either 32 bits or 64 bits.  Selecting 32-bit
     implies Intel i386 architecture, while 64-bit implies AMD x86-64
     architecture.

     These options are only available with the ELF object file format,
     and require that the necessary BFD support has been included (on a
     32-bit platform you have to add -enable-64-bit-bfd to configure
     enable 64-bit usage and use x86-64 as target platform).

'-n'
     By default, x86 GAS replaces multiple nop instructions used for
     alignment within code sections with multi-byte nop instructions
     such as leal 0(%esi,1),%esi.  This switch disables the
     optimization.

'--divide'
     On SVR4-derived platforms, the character '/' is treated as a
     comment character, which means that it cannot be used in
     expressions.  The '--divide' option turns '/' into a normal
     character.  This does not disable '/' at the beginning of a line
     starting a comment, or affect using '#' for starting a comment.

'-march=CPU'
     This option specifies an instruction set architecture for
     generating instructions.  The following architectures are
     recognized: 'i8086', 'i186', 'i286', 'i386', 'i486', 'i586',
     'i686', 'pentium', 'pentiumpro', 'pentiumii', 'pentiumiii',
     'pentium4', 'prescott', 'nocona', 'core', 'core2', 'k6', 'k6_2',
     'athlon', 'sledgehammer', 'opteron', 'k8', 'generic32' and
     'generic64'.

     This option only affects instructions generated by the assembler.
     The '.arch' directive will take precedent.

'-mtune=CPU'
     This option specifies a processor to optimize for.  When used in
     conjunction with the '-march' option, only instructions of the
     processor specified by the '-march' option will be generated.

     Valid CPU values are identical to '-march=CPU'.

9.2 AT&T Syntax versus Intel Syntax
===================================

'as' now supports assembly using Intel assembler syntax.
'.intel_syntax' selects Intel mode, and '.att_syntax' switches back to
the usual AT&T mode for compatibility with the output of 'gcc'.  Either
of these directives may have an optional argument, 'prefix', or
'noprefix' specifying whether registers require a '%' prefix.  AT&T
System V/386 assembler syntax is quite different from Intel syntax.  We
mention these differences because almost all 80386 documents use Intel
syntax.  Notable differences between the two syntaxes are:

   * AT&T immediate operands are preceded by '$'; Intel immediate
     operands are undelimited (Intel 'push 4' is AT&T 'pushl $4').  AT&T
     register operands are preceded by '%'; Intel register operands are
     undelimited.  AT&T absolute (as opposed to PC relative) jump/call
     operands are prefixed by '*'; they are undelimited in Intel syntax.

   * AT&T and Intel syntax use the opposite order for source and
     destination operands.  Intel 'add eax, 4' is 'addl $4, %eax'.  The
     'source, dest' convention is maintained for compatibility with
     previous Unix assemblers.  Note that instructions with more than
     one source operand, such as the 'enter' instruction, do _not_ have
     reversed order.  *note i386-Bugs::.

   * In AT&T syntax the size of memory operands is determined from the
     last character of the instruction mnemonic.  Mnemonic suffixes of
     'b', 'w', 'l' and 'q' specify byte (8-bit), word (16-bit), long
     (32-bit) and quadruple word (64-bit) memory references.  Intel
     syntax accomplishes this by prefixing memory operands (_not_ the
     instruction mnemonics) with 'byte ptr', 'word ptr', 'dword ptr' and
     'qword ptr'.  Thus, Intel 'mov al, byte ptr FOO' is 'movb FOO, %al'
     in AT&T syntax.

   * Immediate form long jumps and calls are 'lcall/ljmp $SECTION,
     $OFFSET' in AT&T syntax; the Intel syntax is 'call/jmp far
     SECTION:OFFSET'.  Also, the far return instruction is 'lret
     $STACK-ADJUST' in AT&T syntax; Intel syntax is 'ret far
     STACK-ADJUST'.

   * The AT&T assembler does not provide support for multiple section
     programs.  Unix style systems expect all programs to be single
     sections.

9.3 Instruction Naming
======================

Instruction mnemonics are suffixed with one character modifiers which
specify the size of operands.  The letters 'b', 'w', 'l' and 'q' specify
byte, word, long and quadruple word operands.  If no suffix is specified
by an instruction then 'as' tries to fill in the missing suffix based on
the destination register operand (the last one by convention).  Thus,
'mov %ax, %bx' is equivalent to 'movw %ax, %bx'; also, 'mov $1, %bx' is
equivalent to 'movw $1, bx'.  Note that this is incompatible with the
AT&T Unix assembler which assumes that a missing mnemonic suffix implies
long operand size.  (This incompatibility does not affect compiler
output since compilers always explicitly specify the mnemonic suffix.)

   Almost all instructions have the same names in AT&T and Intel format.
There are a few exceptions.  The sign extend and zero extend
instructions need two sizes to specify them.  They need a size to
sign/zero extend _from_ and a size to zero extend _to_.  This is
accomplished by using two instruction mnemonic suffixes in AT&T syntax.
Base names for sign extend and zero extend are 'movs...' and 'movz...'
in AT&T syntax ('movsx' and 'movzx' in Intel syntax).  The instruction
mnemonic suffixes are tacked on to this base name, the _from_ suffix
before the _to_ suffix.  Thus, 'movsbl %al, %edx' is AT&T syntax for
"move sign extend _from_ %al _to_ %edx."  Possible suffixes, thus, are
'bl' (from byte to long), 'bw' (from byte to word), 'wl' (from word to
long), 'bq' (from byte to quadruple word), 'wq' (from word to quadruple
word), and 'lq' (from long to quadruple word).

   The Intel-syntax conversion instructions

   * 'cbw' -- sign-extend byte in '%al' to word in '%ax',

   * 'cwde' -- sign-extend word in '%ax' to long in '%eax',

   * 'cwd' -- sign-extend word in '%ax' to long in '%dx:%ax',

   * 'cdq' -- sign-extend dword in '%eax' to quad in '%edx:%eax',

   * 'cdqe' -- sign-extend dword in '%eax' to quad in '%rax' (x86-64
     only),

   * 'cqo' -- sign-extend quad in '%rax' to octuple in '%rdx:%rax'
     (x86-64 only),

are called 'cbtw', 'cwtl', 'cwtd', 'cltd', 'cltq', and 'cqto' in AT&T
naming.  'as' accepts either naming for these instructions.

   Far call/jump instructions are 'lcall' and 'ljmp' in AT&T syntax, but
are 'call far' and 'jump far' in Intel convention.

9.4 Register Naming
===================

Register operands are always prefixed with '%'.  The 80386 registers
consist of

   * the 8 32-bit registers '%eax' (the accumulator), '%ebx', '%ecx',
     '%edx', '%edi', '%esi', '%ebp' (the frame pointer), and '%esp' (the
     stack pointer).

   * the 8 16-bit low-ends of these: '%ax', '%bx', '%cx', '%dx', '%di',
     '%si', '%bp', and '%sp'.

   * the 8 8-bit registers: '%ah', '%al', '%bh', '%bl', '%ch', '%cl',
     '%dh', and '%dl' (These are the high-bytes and low-bytes of '%ax',
     '%bx', '%cx', and '%dx')

   * the 6 section registers '%cs' (code section), '%ds' (data section),
     '%ss' (stack section), '%es', '%fs', and '%gs'.

   * the 3 processor control registers '%cr0', '%cr2', and '%cr3'.

   * the 6 debug registers '%db0', '%db1', '%db2', '%db3', '%db6', and
     '%db7'.

   * the 2 test registers '%tr6' and '%tr7'.

   * the 8 floating point register stack '%st' or equivalently '%st(0)',
     '%st(1)', '%st(2)', '%st(3)', '%st(4)', '%st(5)', '%st(6)', and
     '%st(7)'.  These registers are overloaded by 8 MMX registers
     '%mm0', '%mm1', '%mm2', '%mm3', '%mm4', '%mm5', '%mm6' and '%mm7'.

   * the 8 SSE registers registers '%xmm0', '%xmm1', '%xmm2', '%xmm3',
     '%xmm4', '%xmm5', '%xmm6' and '%xmm7'.

   The AMD x86-64 architecture extends the register set by:

   * enhancing the 8 32-bit registers to 64-bit: '%rax' (the
     accumulator), '%rbx', '%rcx', '%rdx', '%rdi', '%rsi', '%rbp' (the
     frame pointer), '%rsp' (the stack pointer)

   * the 8 extended registers '%r8'-'%r15'.

   * the 8 32-bit low ends of the extended registers: '%r8d'-'%r15d'

   * the 8 16-bit low ends of the extended registers: '%r8w'-'%r15w'

   * the 8 8-bit low ends of the extended registers: '%r8b'-'%r15b'

   * the 4 8-bit registers: '%sil', '%dil', '%bpl', '%spl'.

   * the 8 debug registers: '%db8'-'%db15'.

   * the 8 SSE registers: '%xmm8'-'%xmm15'.

9.5 Instruction Prefixes
========================

Instruction prefixes are used to modify the following instruction.  They
are used to repeat string instructions, to provide section overrides, to
perform bus lock operations, and to change operand and address sizes.
(Most instructions that normally operate on 32-bit operands will use
16-bit operands if the instruction has an "operand size" prefix.)
Instruction prefixes are best written on the same line as the
instruction they act upon.  For example, the 'scas' (scan string)
instruction is repeated with:

             repne scas %es:(%edi),%al

   You may also place prefixes on the lines immediately preceding the
instruction, but this circumvents checks that 'as' does with prefixes,
and will not work with all prefixes.

   Here is a list of instruction prefixes:

   * Section override prefixes 'cs', 'ds', 'ss', 'es', 'fs', 'gs'.
     These are automatically added by specifying using the
     SECTION:MEMORY-OPERAND form for memory references.

   * Operand/Address size prefixes 'data16' and 'addr16' change 32-bit
     operands/addresses into 16-bit operands/addresses, while 'data32'
     and 'addr32' change 16-bit ones (in a '.code16' section) into
     32-bit operands/addresses.  These prefixes _must_ appear on the
     same line of code as the instruction they modify.  For example, in
     a 16-bit '.code16' section, you might write:

                  addr32 jmpl *(%ebx)

   * The bus lock prefix 'lock' inhibits interrupts during execution of
     the instruction it precedes.  (This is only valid with certain
     instructions; see a 80386 manual for details).

   * The wait for coprocessor prefix 'wait' waits for the coprocessor to
     complete the current instruction.  This should never be needed for
     the 80386/80387 combination.

   * The 'rep', 'repe', and 'repne' prefixes are added to string
     instructions to make them repeat '%ecx' times ('%cx' times if the
     current address size is 16-bits).
   * The 'rex' family of prefixes is used by x86-64 to encode extensions
     to i386 instruction set.  The 'rex' prefix has four bits -- an
     operand size overwrite ('64') used to change operand size from
     32-bit to 64-bit and X, Y and Z extensions bits used to extend the
     register set.

     You may write the 'rex' prefixes directly.  The 'rex64xyz'
     instruction emits 'rex' prefix with all the bits set.  By omitting
     the '64', 'x', 'y' or 'z' you may write other prefixes as well.
     Normally, there is no need to write the prefixes explicitly, since
     gas will automatically generate them based on the instruction
     operands.

9.6 Memory References
=====================

An Intel syntax indirect memory reference of the form

     SECTION:[BASE + INDEX*SCALE + DISP]

is translated into the AT&T syntax

     SECTION:DISP(BASE, INDEX, SCALE)

where BASE and INDEX are the optional 32-bit base and index registers,
DISP is the optional displacement, and SCALE, taking the values 1, 2, 4,
and 8, multiplies INDEX to calculate the address of the operand.  If no
SCALE is specified, SCALE is taken to be 1.  SECTION specifies the
optional section register for the memory operand, and may override the
default section register (see a 80386 manual for section register
defaults).  Note that section overrides in AT&T syntax _must_ be
preceded by a '%'.  If you specify a section override which coincides
with the default section register, 'as' does _not_ output any section
register override prefixes to assemble the given instruction.  Thus,
section overrides can be specified to emphasize which section register
is used for a given memory operand.

   Here are some examples of Intel and AT&T style memory references:

AT&T: '-4(%ebp)', Intel: '[ebp - 4]'
     BASE is '%ebp'; DISP is '-4'.  SECTION is missing, and the default
     section is used ('%ss' for addressing with '%ebp' as the base
     register).  INDEX, SCALE are both missing.

AT&T: 'foo(,%eax,4)', Intel: '[foo + eax*4]'
     INDEX is '%eax' (scaled by a SCALE 4); DISP is 'foo'.  All other
     fields are missing.  The section register here defaults to '%ds'.

AT&T: 'foo(,1)'; Intel '[foo]'
     This uses the value pointed to by 'foo' as a memory operand.  Note
     that BASE and INDEX are both missing, but there is only _one_ ','.
     This is a syntactic exception.

AT&T: '%gs:foo'; Intel 'gs:foo'
     This selects the contents of the variable 'foo' with section
     register SECTION being '%gs'.

   Absolute (as opposed to PC relative) call and jump operands must be
prefixed with '*'.  If no '*' is specified, 'as' always chooses PC
relative addressing for jump/call labels.

   Any instruction that has a memory operand, but no register operand,
_must_ specify its size (byte, word, long, or quadruple) with an
instruction mnemonic suffix ('b', 'w', 'l' or 'q', respectively).

   The x86-64 architecture adds an RIP (instruction pointer relative)
addressing.  This addressing mode is specified by using 'rip' as a base
register.  Only constant offsets are valid.  For example:

AT&T: '1234(%rip)', Intel: '[rip + 1234]'
     Points to the address 1234 bytes past the end of the current
     instruction.

AT&T: 'symbol(%rip)', Intel: '[rip + symbol]'
     Points to the 'symbol' in RIP relative way, this is shorter than
     the default absolute addressing.

   Other addressing modes remain unchanged in x86-64 architecture,
except registers used are 64-bit instead of 32-bit.

9.7 Handling of Jump Instructions
=================================

Jump instructions are always optimized to use the smallest possible
displacements.  This is accomplished by using byte (8-bit) displacement
jumps whenever the target is sufficiently close.  If a byte displacement
is insufficient a long displacement is used.  We do not support word
(16-bit) displacement jumps in 32-bit mode (i.e.  prefixing the jump
instruction with the 'data16' instruction prefix), since the 80386
insists upon masking '%eip' to 16 bits after the word displacement is
added.  (See also *note i386-Arch::)

   Note that the 'jcxz', 'jecxz', 'loop', 'loopz', 'loope', 'loopnz' and
'loopne' instructions only come in byte displacements, so that if you
use these instructions ('gcc' does not use them) you may get an error
message (and incorrect code).  The AT&T 80386 assembler tries to get
around this problem by expanding 'jcxz foo' to

              jcxz cx_zero
              jmp cx_nonzero
     cx_zero: jmp foo
     cx_nonzero:

9.8 Floating Point
==================

All 80387 floating point types except packed BCD are supported.  (BCD
support may be added without much difficulty).  These data types are
16-, 32-, and 64- bit integers, and single (32-bit), double (64-bit),
and extended (80-bit) precision floating point.  Each supported type has
an instruction mnemonic suffix and a constructor associated with it.
Instruction mnemonic suffixes specify the operand's data type.
Constructors build these data types into memory.

   * Floating point constructors are '.float' or '.single', '.double',
     and '.tfloat' for 32-, 64-, and 80-bit formats.  These correspond
     to instruction mnemonic suffixes 's', 'l', and 't'.  't' stands for
     80-bit (ten byte) real.  The 80387 only supports this format via
     the 'fldt' (load 80-bit real to stack top) and 'fstpt' (store
     80-bit real and pop stack) instructions.

   * Integer constructors are '.word', '.long' or '.int', and '.quad'
     for the 16-, 32-, and 64-bit integer formats.  The corresponding
     instruction mnemonic suffixes are 's' (single), 'l' (long), and 'q'
     (quad).  As with the 80-bit real format, the 64-bit 'q' format is
     only present in the 'fildq' (load quad integer to stack top) and
     'fistpq' (store quad integer and pop stack) instructions.

   Register to register operations should not use instruction mnemonic
suffixes.  'fstl %st, %st(1)' will give a warning, and be assembled as
if you wrote 'fst %st, %st(1)', since all register to register
operations use 80-bit floating point operands.  (Contrast this with
'fstl %st, mem', which converts '%st' from 80-bit to 64-bit floating
point format, then stores the result in the 4 byte location 'mem')

9.9 Intel's MMX and AMD's 3DNow! SIMD Operations
================================================

'as' supports Intel's MMX instruction set (SIMD instructions for integer
data), available on Intel's Pentium MMX processors and Pentium II
processors, AMD's K6 and K6-2 processors, Cyrix' M2 processor, and
probably others.  It also supports AMD's 3DNow! instruction set (SIMD
instructions for 32-bit floating point data) available on AMD's K6-2
processor and possibly others in the future.

   Currently, 'as' does not support Intel's floating point SIMD, Katmai
(KNI).

   The eight 64-bit MMX operands, also used by 3DNow!, are called
'%mm0', '%mm1', ...  '%mm7'.  They contain eight 8-bit integers, four
16-bit integers, two 32-bit integers, one 64-bit integer, or two 32-bit
floating point values.  The MMX registers cannot be used at the same
time as the floating point stack.

   See Intel and AMD documentation, keeping in mind that the operand
order in instructions is reversed from the Intel syntax.

9.10 Writing 16-bit Code
========================

While 'as' normally writes only "pure" 32-bit i386 code or 64-bit x86-64
code depending on the default configuration, it also supports writing
code to run in real mode or in 16-bit protected mode code segments.  To
do this, put a '.code16' or '.code16gcc' directive before the assembly
language instructions to be run in 16-bit mode.  You can switch 'as'
back to writing normal 32-bit code with the '.code32' directive.

   '.code16gcc' provides experimental support for generating 16-bit code
from gcc, and differs from '.code16' in that 'call', 'ret', 'enter',
'leave', 'push', 'pop', 'pusha', 'popa', 'pushf', and 'popf'
instructions default to 32-bit size.  This is so that the stack pointer
is manipulated in the same way over function calls, allowing access to
function parameters at the same stack offsets as in 32-bit mode.
'.code16gcc' also automatically adds address size prefixes where
necessary to use the 32-bit addressing modes that gcc generates.

   The code which 'as' generates in 16-bit mode will not necessarily run
on a 16-bit pre-80386 processor.  To write code that runs on such a
processor, you must refrain from using _any_ 32-bit constructs which
require 'as' to output address or operand size prefixes.

   Note that writing 16-bit code instructions by explicitly specifying a
prefix or an instruction mnemonic suffix within a 32-bit code section
generates different machine instructions than those generated for a
16-bit code segment.  In a 32-bit code section, the following code
generates the machine opcode bytes '66 6a 04', which pushes the value
'4' onto the stack, decrementing '%esp' by 2.

             pushw $4

   The same code in a 16-bit code section would generate the machine
opcode bytes '6a 04' (i.e., without the operand size prefix), which is
correct since the processor default operand size is assumed to be 16
bits in a 16-bit code section.

9.11 AT&T Syntax bugs
=====================

The UnixWare assembler, and probably other AT&T derived ix86 Unix
assemblers, generate floating point instructions with reversed source
and destination registers in certain cases.  Unfortunately, gcc and
possibly many other programs use this reversed syntax, so we're stuck
with it.

   For example

             fsub %st,%st(3)
results in '%st(3)' being updated to '%st - %st(3)' rather than the
expected '%st(3) - %st'.  This happens with all the non-commutative
arithmetic floating point operations with two register operands where
the source register is '%st' and the destination register is '%st(i)'.

9.12 Specifying CPU Architecture
================================

'as' may be told to assemble for a particular CPU (sub-)architecture
with the '.arch CPU_TYPE' directive.  This directive enables a warning
when gas detects an instruction that is not supported on the CPU
specified.  The choices for CPU_TYPE are:

'i8086'        'i186'         'i286'         'i386'
'i486'         'i586'         'i686'         'pentium'
'pentiumpro'   'pentiumii'    'pentiumiii'   'pentium4'
'prescott'     'nocona'       'core'         'core2'
'amdfam10'
'k6'           'athlon'       'sledgehammer' 'k8'
'.mmx'         '.sse'         '.sse2'        '.sse3'
'.ssse3'       '.sse4.1'      '.sse4.2'      '.sse4'
'.sse4a'       '.3dnow'       '.3dnowa'      '.padlock'
'.pacifica'    '.svme'        '.abm'

   Apart from the warning, there are only two other effects on 'as'
operation; Firstly, if you specify a CPU other than 'i486', then shift
by one instructions such as 'sarl $1, %eax' will automatically use a two
byte opcode sequence.  The larger three byte opcode sequence is used on
the 486 (and when no architecture is specified) because it executes
faster on the 486.  Note that you can explicitly request the two byte
opcode by writing 'sarl %eax'.  Secondly, if you specify 'i8086',
'i186', or 'i286', _and_ '.code16' or '.code16gcc' then byte offset
conditional jumps will be promoted when necessary to a two instruction
sequence consisting of a conditional jump of the opposite sense around
an unconditional jump to the target.

   Following the CPU architecture (but not a sub-architecture, which are
those starting with a dot), you may specify 'jumps' or 'nojumps' to
control automatic promotion of conditional jumps.  'jumps' is the
default, and enables jump promotion; All external jumps will be of the
long variety, and file-local jumps will be promoted as necessary.
(*note i386-Jumps::) 'nojumps' leaves external conditional jumps as byte
offset jumps, and warns about file-local conditional jumps that 'as'
promotes.  Unconditional jumps are treated as for 'jumps'.

   For example

      .arch i8086,nojumps

9.13 Notes
==========

There is some trickery concerning the 'mul' and 'imul' instructions that
deserves mention.  The 16-, 32-, 64- and 128-bit expanding multiplies
(base opcode '0xf6'; extension 4 for 'mul' and 5 for 'imul') can be
output only in the one operand form.  Thus, 'imul %ebx, %eax' does _not_
select the expanding multiply; the expanding multiply would clobber the
'%edx' register, and this would confuse 'gcc' output.  Use 'imul %ebx'
to get the 64-bit product in '%edx:%eax'.

   We have added a two operand form of 'imul' when the first operand is
an immediate mode expression and the second operand is a register.  This
is just a shorthand, so that, multiplying '%eax' by 69, for example, can
be done with 'imul $69, %eax' rather than 'imul $69, %eax, %eax'.

10 IA-64 Dependent Features
***************************

10.1 Options
============

'-mconstant-gp'
     This option instructs the assembler to mark the resulting object
     file as using the "constant GP" model.  With this model, it is
     assumed that the entire program uses a single global pointer (GP)
     value.  Note that this option does not in any fashion affect the
     machine code emitted by the assembler.  All it does is turn on the
     EF_IA_64_CONS_GP flag in the ELF file header.

'-mauto-pic'
     This option instructs the assembler to mark the resulting object
     file as using the "constant GP without function descriptor" data
     model.  This model is like the "constant GP" model, except that it
     additionally does away with function descriptors.  What this means
     is that the address of a function refers directly to the function's
     code entry-point.  Normally, such an address would refer to a
     function descriptor, which contains both the code entry-point and
     the GP-value needed by the function.  Note that this option does
     not in any fashion affect the machine code emitted by the
     assembler.  All it does is turn on the EF_IA_64_NOFUNCDESC_CONS_GP
     flag in the ELF file header.

'-milp32'
'-milp64'
'-mlp64'
'-mp64'
     These options select the data model.  The assembler defaults to
     '-mlp64' (LP64 data model).

'-mle'
'-mbe'
     These options select the byte order.  The '-mle' option selects
     little-endian byte order (default) and '-mbe' selects big-endian
     byte order.  Note that IA-64 machine code always uses little-endian
     byte order.

'-mtune=itanium1'
'-mtune=itanium2'
     Tune for a particular IA-64 CPU, ITANIUM1 or ITANIUM2.  The default
     is ITANIUM2.

'-munwind-check=warning'
'-munwind-check=error'
     These options control what the assembler will do when performing
     consistency checks on unwind directives.  '-munwind-check=warning'
     will make the assembler issue a warning when an unwind directive
     check fails.  This is the default.  '-munwind-check=error' will
     make the assembler issue an error when an unwind directive check
     fails.

'-mhint.b=ok'
'-mhint.b=warning'
'-mhint.b=error'
     These options control what the assembler will do when the 'hint.b'
     instruction is used.  '-mhint.b=ok' will make the assembler accept
     'hint.b'.  '-mint.b=warning' will make the assembler issue a
     warning when 'hint.b' is used.  '-mhint.b=error' will make the
     assembler treat 'hint.b' as an error, which is the default.

'-x'
'-xexplicit'
     These options turn on dependency violation checking.

'-xauto'
     This option instructs the assembler to automatically insert stop
     bits where necessary to remove dependency violations.  This is the
     default mode.

'-xnone'
     This option turns off dependency violation checking.

'-xdebug'
     This turns on debug output intended to help tracking down bugs in
     the dependency violation checker.

'-xdebugn'
     This is a shortcut for -xnone -xdebug.

'-xdebugx'
     This is a shortcut for -xexplicit -xdebug.

10.2 Syntax
===========

The assembler syntax closely follows the IA-64 Assembly Language
Reference Guide.

10.2.1 Special Characters
-------------------------

'//' is the line comment token.

   ';' can be used instead of a newline to separate statements.

10.2.2 Register Names
---------------------

The 128 integer registers are referred to as 'rN'.  The 128
floating-point registers are referred to as 'fN'.  The 128 application
registers are referred to as 'arN'.  The 128 control registers are
referred to as 'crN'.  The 64 one-bit predicate registers are referred
to as 'pN'.  The 8 branch registers are referred to as 'bN'.  In
addition, the assembler defines a number of aliases: 'gp' ('r1'), 'sp'
('r12'), 'rp' ('b0'), 'ret0' ('r8'), 'ret1' ('r9'), 'ret2' ('r10'),
'ret3' ('r9'), 'fargN' ('f8+N'), and 'fretN' ('f8+N').

   For convenience, the assembler also defines aliases for all named
application and control registers.  For example, 'ar.bsp' refers to the
register backing store pointer ('ar17').  Similarly, 'cr.eoi' refers to
the end-of-interrupt register ('cr67').

10.2.3 IA-64 Processor-Status-Register (PSR) Bit Names
------------------------------------------------------

The assembler defines bit masks for each of the bits in the IA-64
processor status register.  For example, 'psr.ic' corresponds to a value
of 0x2000.  These masks are primarily intended for use with the
'ssm'/'sum' and 'rsm'/'rum' instructions, but they can be used anywhere
else where an integer constant is expected.

10.3 Opcodes
============

For detailed information on the IA-64 machine instruction set, see the
IA-64 Architecture Handbook
(http://developer.intel.com/design/itanium/arch_spec.htm).

11 MIPS Dependent Features
**************************

GNU 'as' for MIPS architectures supports several different MIPS
processors, and MIPS ISA levels I through V, MIPS32, and MIPS64.  For
information about the MIPS instruction set, see 'MIPS RISC
Architecture', by Kane and Heindrich (Prentice-Hall).  For an overview
of MIPS assembly conventions, see "Appendix D: Assembly Language
Programming" in the same work.

11.1 Assembler options
======================

The MIPS configurations of GNU 'as' support these special options:

'-G NUM'
     This option sets the largest size of an object that can be
     referenced implicitly with the 'gp' register.  It is only accepted
     for targets that use ECOFF format.  The default value is 8.

'-EB'
'-EL'
     Any MIPS configuration of 'as' can select big-endian or
     little-endian output at run time (unlike the other GNU development
     tools, which must be configured for one or the other).  Use '-EB'
     to select big-endian output, and '-EL' for little-endian.

'-KPIC'
     Generate SVR4-style PIC. This option tells the assembler to
     generate SVR4-style position-independent macro expansions.  It also
     tells the assembler to mark the output file as PIC.

'-mvxworks-pic'
     Generate VxWorks PIC. This option tells the assembler to generate
     VxWorks-style position-independent macro expansions.

'-mips1'
'-mips2'
'-mips3'
'-mips4'
'-mips5'
'-mips32'
'-mips32r2'
'-mips64'
'-mips64r2'
     Generate code for a particular MIPS Instruction Set Architecture
     level.  '-mips1' corresponds to the R2000 and R3000 processors,
     '-mips2' to the R6000 processor, '-mips3' to the R4000 processor,
     and '-mips4' to the R8000 and R10000 processors.  '-mips5',
     '-mips32', '-mips32r2', '-mips64', and '-mips64r2' correspond to
     generic MIPS V, MIPS32, MIPS32 RELEASE 2, MIPS64, and MIPS64
     RELEASE 2 ISA processors, respectively.  You can also switch
     instruction sets during the assembly; see *note Directives to
     override the ISA level: MIPS ISA.

'-mgp32'
'-mfp32'
     Some macros have different expansions for 32-bit and 64-bit
     registers.  The register sizes are normally inferred from the ISA
     and ABI, but these flags force a certain group of registers to be
     treated as 32 bits wide at all times.  '-mgp32' controls the size
     of general-purpose registers and '-mfp32' controls the size of
     floating-point registers.

     The '.set gp=32' and '.set fp=32' directives allow the size of
     registers to be changed for parts of an object.  The default value
     is restored by '.set gp=default' and '.set fp=default'.

     On some MIPS variants there is a 32-bit mode flag; when this flag
     is set, 64-bit instructions generate a trap.  Also, some 32-bit
     OSes only save the 32-bit registers on a context switch, so it is
     essential never to use the 64-bit registers.

'-mgp64'
'-mfp64'
     Assume that 64-bit registers are available.  This is provided in
     the interests of symmetry with '-mgp32' and '-mfp32'.

     The '.set gp=64' and '.set fp=64' directives allow the size of
     registers to be changed for parts of an object.  The default value
     is restored by '.set gp=default' and '.set fp=default'.

'-mips16'
'-no-mips16'
     Generate code for the MIPS 16 processor.  This is equivalent to
     putting '.set mips16' at the start of the assembly file.
     '-no-mips16' turns off this option.

'-msmartmips'
'-mno-smartmips'
     Enables the SmartMIPS extensions to the MIPS32 instruction set,
     which provides a number of new instructions which target smartcard
     and cryptographic applications.  This is equivalent to putting
     '.set smartmips' at the start of the assembly file.
     '-mno-smartmips' turns off this option.

'-mips3d'
'-no-mips3d'
     Generate code for the MIPS-3D Application Specific Extension.  This
     tells the assembler to accept MIPS-3D instructions.  '-no-mips3d'
     turns off this option.

'-mdmx'
'-no-mdmx'
     Generate code for the MDMX Application Specific Extension.  This
     tells the assembler to accept MDMX instructions.  '-no-mdmx' turns
     off this option.

'-mdsp'
'-mno-dsp'
     Generate code for the DSP Release 1 Application Specific Extension.
     This tells the assembler to accept DSP Release 1 instructions.
     '-mno-dsp' turns off this option.

'-mdspr2'
'-mno-dspr2'
     Generate code for the DSP Release 2 Application Specific Extension.
     This option implies -mdsp.  This tells the assembler to accept DSP
     Release 2 instructions.  '-mno-dspr2' turns off this option.

'-mmt'
'-mno-mt'
     Generate code for the MT Application Specific Extension.  This
     tells the assembler to accept MT instructions.  '-mno-mt' turns off
     this option.

'-mfix7000'
'-mno-fix7000'
     Cause nops to be inserted if the read of the destination register
     of an mfhi or mflo instruction occurs in the following two
     instructions.

'-mfix-vr4120'
'-no-mfix-vr4120'
     Insert nops to work around certain VR4120 errata.  This option is
     intended to be used on GCC-generated code: it is not designed to
     catch all problems in hand-written assembler code.

'-mfix-vr4130'
'-no-mfix-vr4130'
     Insert nops to work around the VR4130 'mflo'/'mfhi' errata.

'-m4010'
'-no-m4010'
     Generate code for the LSI R4010 chip.  This tells the assembler to
     accept the R4010 specific instructions ('addciu', 'ffc', etc.), and
     to not schedule 'nop' instructions around accesses to the 'HI' and
     'LO' registers.  '-no-m4010' turns off this option.

'-m4650'
'-no-m4650'
     Generate code for the MIPS R4650 chip.  This tells the assembler to
     accept the 'mad' and 'madu' instruction, and to not schedule 'nop'
     instructions around accesses to the 'HI' and 'LO' registers.
     '-no-m4650' turns off this option.

'-m3900'
'-no-m3900'
'-m4100'
'-no-m4100'
     For each option '-mNNNN', generate code for the MIPS RNNNN chip.
     This tells the assembler to accept instructions specific to that
     chip, and to schedule for that chip's hazards.

'-march=CPU'
     Generate code for a particular MIPS cpu.  It is exactly equivalent
     to '-mCPU', except that there are more value of CPU understood.
     Valid CPU value are:

          2000, 3000, 3900, 4000, 4010, 4100, 4111, vr4120, vr4130,
          vr4181, 4300, 4400, 4600, 4650, 5000, rm5200, rm5230, rm5231,
          rm5261, rm5721, vr5400, vr5500, 6000, rm7000, 8000, rm9000,
          10000, 12000, 4kc, 4km, 4kp, 4ksc, 4kec, 4kem, 4kep, 4ksd,
          m4k, m4kp, 24kc, 24kf, 24kx, 24kec, 24kef, 24kex, 34kc, 34kf,
          34kx, 74kc, 74kf, 74kx, 5kc, 5kf, 20kc, 25kf, sb1, sb1a

'-mtune=CPU'
     Schedule and tune for a particular MIPS cpu.  Valid CPU values are
     identical to '-march=CPU'.

'-mabi=ABI'
     Record which ABI the source code uses.  The recognized arguments
     are: '32', 'n32', 'o64', '64' and 'eabi'.

'-msym32'
'-mno-sym32'
     Equivalent to adding '.set sym32' or '.set nosym32' to the
     beginning of the assembler input.  *Note MIPS symbol sizes::.

'-nocpp'
     This option is ignored.  It is accepted for command-line
     compatibility with other assemblers, which use it to turn off C
     style preprocessing.  With GNU 'as', there is no need for '-nocpp',
     because the GNU assembler itself never runs the C preprocessor.

'--construct-floats'
'--no-construct-floats'
     The '--no-construct-floats' option disables the construction of
     double width floating point constants by loading the two halves of
     the value into the two single width floating point registers that
     make up the double width register.  This feature is useful if the
     processor support the FR bit in its status register, and this bit
     is known (by the programmer) to be set.  This bit prevents the
     aliasing of the double width register by the single width
     registers.

     By default '--construct-floats' is selected, allowing construction
     of these floating point constants.

'--trap'
'--no-break'
     'as' automatically macro expands certain division and
     multiplication instructions to check for overflow and division by
     zero.  This option causes 'as' to generate code to take a trap
     exception rather than a break exception when an error is detected.
     The trap instructions are only supported at Instruction Set
     Architecture level 2 and higher.

'--break'
'--no-trap'
     Generate code to take a break exception rather than a trap
     exception when an error is detected.  This is the default.

'-mpdr'
'-mno-pdr'
     Control generation of '.pdr' sections.  Off by default on IRIX, on
     elsewhere.

'-mshared'
'-mno-shared'
     When generating code using the Unix calling conventions (selected
     by '-KPIC' or '-mcall_shared'), gas will normally generate code
     which can go into a shared library.  The '-mno-shared' option tells
     gas to generate code which uses the calling convention, but can not
     go into a shared library.  The resulting code is slightly more
     efficient.  This option only affects the handling of the '.cpload'
     and '.cpsetup' pseudo-ops.

11.2 MIPS ECOFF object code
===========================

Assembling for a MIPS ECOFF target supports some additional sections
besides the usual '.text', '.data' and '.bss'.  The additional sections
are '.rdata', used for read-only data, '.sdata', used for small data,
and '.sbss', used for small common objects.

   When assembling for ECOFF, the assembler uses the '$gp' ('$28')
register to form the address of a "small object".  Any object in the
'.sdata' or '.sbss' sections is considered "small" in this sense.  For
external objects, or for objects in the '.bss' section, you can use the
'gcc' '-G' option to control the size of objects addressed via '$gp';
the default value is 8, meaning that a reference to any object eight
bytes or smaller uses '$gp'.  Passing '-G 0' to 'as' prevents it from
using the '$gp' register on the basis of object size (but the assembler
uses '$gp' for objects in '.sdata' or 'sbss' in any case).  The size of
an object in the '.bss' section is set by the '.comm' or '.lcomm'
directive that defines it.  The size of an external object may be set
with the '.extern' directive.  For example, '.extern sym,4' declares
that the object at 'sym' is 4 bytes in length, whie leaving 'sym'
otherwise undefined.

   Using small ECOFF objects requires linker support, and assumes that
the '$gp' register is correctly initialized (normally done automatically
by the startup code).  MIPS ECOFF assembly code must not modify the
'$gp' register.

11.3 Directives for debugging information
=========================================

MIPS ECOFF 'as' supports several directives used for generating
debugging information which are not support by traditional MIPS
assemblers.  These are '.def', '.endef', '.dim', '.file', '.scl',
'.size', '.tag', '.type', '.val', '.stabd', '.stabn', and '.stabs'.  The
debugging information generated by the three '.stab' directives can only
be read by GDB, not by traditional MIPS debuggers (this enhancement is
required to fully support C++ debugging).  These directives are
primarily used by compilers, not assembly language programmers!

11.4 Directives to override the size of symbols
===============================================

The n64 ABI allows symbols to have any 64-bit value.  Although this
provides a great deal of flexibility, it means that some macros have
much longer expansions than their 32-bit counterparts.  For example, the
non-PIC expansion of 'dla $4,sym' is usually:

     lui     $4,%highest(sym)
     lui     $1,%hi(sym)
     daddiu  $4,$4,%higher(sym)
     daddiu  $1,$1,%lo(sym)
     dsll32  $4,$4,0
     daddu   $4,$4,$1

   whereas the 32-bit expansion is simply:

     lui     $4,%hi(sym)
     daddiu  $4,$4,%lo(sym)

   n64 code is sometimes constructed in such a way that all symbolic
constants are known to have 32-bit values, and in such cases, it's
preferable to use the 32-bit expansion instead of the 64-bit expansion.

   You can use the '.set sym32' directive to tell the assembler that,
from this point on, all expressions of the form 'SYMBOL' or 'SYMBOL +
OFFSET' have 32-bit values.  For example:

     .set sym32
     dla     $4,sym
     lw      $4,sym+16
     sw      $4,sym+0x8000($4)

   will cause the assembler to treat 'sym', 'sym+16' and 'sym+0x8000' as
32-bit values.  The handling of non-symbolic addresses is not affected.

   The directive '.set nosym32' ends a '.set sym32' block and reverts to
the normal behavior.  It is also possible to change the symbol size
using the command-line options '-msym32' and '-mno-sym32'.

   These options and directives are always accepted, but at present,
they have no effect for anything other than n64.

11.5 Directives to override the ISA level
=========================================

GNU 'as' supports an additional directive to change the MIPS Instruction
Set Architecture level on the fly: '.set mipsN'.  N should be a number
from 0 to 5, or 32, 32r2, 64 or 64r2.  The values other than 0 make the
assembler accept instructions for the corresponding ISA level, from that
point on in the assembly.  '.set mipsN' affects not only which
instructions are permitted, but also how certain macros are expanded.
'.set mips0' restores the ISA level to its original level: either the
level you selected with command line options, or the default for your
configuration.  You can use this feature to permit specific MIPS3
instructions while assembling in 32 bit mode.  Use this directive with
care!

   The '.set arch=CPU' directive provides even finer control.  It
changes the effective CPU target and allows the assembler to use
instructions specific to a particular CPU. All CPUs supported by the
'-march' command line option are also selectable by this directive.  The
original value is restored by '.set arch=default'.

   The directive '.set mips16' puts the assembler into MIPS 16 mode, in
which it will assemble instructions for the MIPS 16 processor.  Use
'.set nomips16' to return to normal 32 bit mode.

   Traditional MIPS assemblers do not support this directive.

11.6 Directives for extending MIPS 16 bit instructions
======================================================

By default, MIPS 16 instructions are automatically extended to 32 bits
when necessary.  The directive '.set noautoextend' will turn this off.
When '.set noautoextend' is in effect, any 32 bit instruction must be
explicitly extended with the '.e' modifier (e.g., 'li.e $4,1000').  The
directive '.set autoextend' may be used to once again automatically
extend instructions when necessary.

   This directive is only meaningful when in MIPS 16 mode.  Traditional
MIPS assemblers do not support this directive.

11.7 Directive to mark data as an instruction
=============================================

The '.insn' directive tells 'as' that the following data is actually
instructions.  This makes a difference in MIPS 16 mode: when loading the
address of a label which precedes instructions, 'as' automatically adds
1 to the value, so that jumping to the loaded address will do the right
thing.

11.8 Directives to save and restore options
===========================================

The directives '.set push' and '.set pop' may be used to save and
restore the current settings for all the options which are controlled by
'.set'.  The '.set push' directive saves the current settings on a
stack.  The '.set pop' directive pops the stack and restores the
settings.

   These directives can be useful inside an macro which must change an
option such as the ISA level or instruction reordering but does not want
to change the state of the code which invoked the macro.

   Traditional MIPS assemblers do not support these directives.

11.9 Directives to control generation of MIPS ASE instructions
==============================================================

The directive '.set mips3d' makes the assembler accept instructions from
the MIPS-3D Application Specific Extension from that point on in the
assembly.  The '.set nomips3d' directive prevents MIPS-3D instructions
from being accepted.

   The directive '.set smartmips' makes the assembler accept
instructions from the SmartMIPS Application Specific Extension to the
MIPS32 ISA from that point on in the assembly.  The '.set nosmartmips'
directive prevents SmartMIPS instructions from being accepted.

   The directive '.set mdmx' makes the assembler accept instructions
from the MDMX Application Specific Extension from that point on in the
assembly.  The '.set nomdmx' directive prevents MDMX instructions from
being accepted.

   The directive '.set dsp' makes the assembler accept instructions from
the DSP Release 1 Application Specific Extension from that point on in
the assembly.  The '.set nodsp' directive prevents DSP Release 1
instructions from being accepted.

   The directive '.set dspr2' makes the assembler accept instructions
from the DSP Release 2 Application Specific Extension from that point on
in the assembly.  This dirctive implies '.set dsp'.  The '.set nodspr2'
directive prevents DSP Release 2 instructions from being accepted.

   The directive '.set mt' makes the assembler accept instructions from
the MT Application Specific Extension from that point on in the
assembly.  The '.set nomt' directive prevents MT instructions from being
accepted.

   Traditional MIPS assemblers do not support these directives.

12 PowerPC Dependent Features
*****************************

12.1 Options
============

The PowerPC chip family includes several successive levels, using the
same core instruction set, but including a few additional instructions
at each level.  There are exceptions to this however.  For details on
what instructions each variant supports, please see the chip's
architecture reference manual.

   The following table lists all available PowerPC options.

'-mpwrx | -mpwr2'
     Generate code for POWER/2 (RIOS2).

'-mpwr'
     Generate code for POWER (RIOS1)

'-m601'
     Generate code for PowerPC 601.

'-mppc, -mppc32, -m603, -m604'
     Generate code for PowerPC 603/604.

'-m403, -m405'
     Generate code for PowerPC 403/405.

'-m440'
     Generate code for PowerPC 440.  BookE and some 405 instructions.

'-m7400, -m7410, -m7450, -m7455'
     Generate code for PowerPC 7400/7410/7450/7455.

'-mppc64, -m620'
     Generate code for PowerPC 620/625/630.

'-me500, -me500x2'
     Generate code for Motorola e500 core complex.

'-mspe'
     Generate code for Motorola SPE instructions.

'-mppc64bridge'
     Generate code for PowerPC 64, including bridge insns.

'-mbooke64'
     Generate code for 64-bit BookE.

'-mbooke, mbooke32'
     Generate code for 32-bit BookE.

'-me300'
     Generate code for PowerPC e300 family.

'-maltivec'
     Generate code for processors with AltiVec instructions.

'-mpower4'
     Generate code for Power4 architecture.

'-mpower5'
     Generate code for Power5 architecture.

'-mpower6'
     Generate code for Power6 architecture.

'-mcell'
     Generate code for Cell Broadband Engine architecture.

'-mcom'
     Generate code Power/PowerPC common instructions.

'-many'
     Generate code for any architecture (PWR/PWRX/PPC).

'-mregnames'
     Allow symbolic names for registers.

'-mno-regnames'
     Do not allow symbolic names for registers.

'-mrelocatable'
     Support for GCC's -mrelocatable option.

'-mrelocatable-lib'
     Support for GCC's -mrelocatable-lib option.

'-memb'
     Set PPC_EMB bit in ELF flags.

'-mlittle, -mlittle-endian'
     Generate code for a little endian machine.

'-mbig, -mbig-endian'
     Generate code for a big endian machine.

'-msolaris'
     Generate code for Solaris.

'-mno-solaris'
     Do not generate code for Solaris.

12.2 PowerPC Assembler Directives
=================================

A number of assembler directives are available for PowerPC. The
following table is far from complete.

'.machine "string"'
     This directive allows you to change the machine for which code is
     generated.  '"string"' may be any of the -m cpu selection options
     (without the -m) enclosed in double quotes, '"push"', or '"pop"'.
     '.machine "push"' saves the currently selected cpu, which may be
     restored with '.machine "pop"'.

13 SPARC Dependent Features
***************************

13.1 Options
============

The SPARC chip family includes several successive levels, using the same
core instruction set, but including a few additional instructions at
each level.  There are exceptions to this however.  For details on what
instructions each variant supports, please see the chip's architecture
reference manual.

   By default, 'as' assumes the core instruction set (SPARC v6), but
"bumps" the architecture level as needed: it switches to successively
higher architectures as it encounters instructions that only exist in
the higher levels.

   If not configured for SPARC v9 ('sparc64-*-*') GAS will not bump
passed sparclite by default, an option must be passed to enable the v9
instructions.

   GAS treats sparclite as being compatible with v8, unless an
architecture is explicitly requested.  SPARC v9 is always incompatible
with sparclite.

'-Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite'
'-Av8plus | -Av8plusa | -Av9 | -Av9a'
     Use one of the '-A' options to select one of the SPARC
     architectures explicitly.  If you select an architecture
     explicitly, 'as' reports a fatal error if it encounters an
     instruction or feature requiring an incompatible or higher level.

     '-Av8plus' and '-Av8plusa' select a 32 bit environment.

     '-Av9' and '-Av9a' select a 64 bit environment and are not
     available unless GAS is explicitly configured with 64 bit
     environment support.

     '-Av8plusa' and '-Av9a' enable the SPARC V9 instruction set with
     UltraSPARC extensions.

'-xarch=v8plus | -xarch=v8plusa'
     For compatibility with the Solaris v9 assembler.  These options are
     equivalent to -Av8plus and -Av8plusa, respectively.

'-bump'
     Warn whenever it is necessary to switch to another level.  If an
     architecture level is explicitly requested, GAS will not issue
     warnings until that level is reached, and will then bump the level
     as required (except between incompatible levels).

'-32 | -64'
     Select the word size, either 32 bits or 64 bits.  These options are
     only available with the ELF object file format, and require that
     the necessary BFD support has been included.

13.2 Enforcing aligned data
===========================

SPARC GAS normally permits data to be misaligned.  For example, it
permits the '.long' pseudo-op to be used on a byte boundary.  However,
the native SunOS and Solaris assemblers issue an error when they see
misaligned data.

   You can use the '--enforce-aligned-data' option to make SPARC GAS
also issue an error about misaligned data, just as the SunOS and Solaris
assemblers do.

   The '--enforce-aligned-data' option is not the default because gcc
issues misaligned data pseudo-ops when it initializes certain packed
data structures (structures defined using the 'packed' attribute).  You
may have to assemble with GAS in order to initialize packed data
structures in your own code.

13.3 Floating Point
===================

The Sparc uses IEEE floating-point numbers.

13.4 Sparc Machine Directives
=============================

The Sparc version of 'as' supports the following additional machine
directives:

'.align'
     This must be followed by the desired alignment in bytes.

'.common'
     This must be followed by a symbol name, a positive number, and
     '"bss"'.  This behaves somewhat like '.comm', but the syntax is
     different.

'.half'
     This is functionally identical to '.short'.

'.nword'
     On the Sparc, the '.nword' directive produces native word sized
     value, ie.  if assembling with -32 it is equivalent to '.word', if
     assembling with -64 it is equivalent to '.xword'.

'.proc'
     This directive is ignored.  Any text following it on the same line
     is also ignored.

'.register'
     This directive declares use of a global application or system
     register.  It must be followed by a register name %g2, %g3, %g6 or
     %g7, comma and the symbol name for that register.  If symbol name
     is '#scratch', it is a scratch register, if it is '#ignore', it
     just suppresses any errors about using undeclared global register,
     but does not emit any information about it into the object file.
     This can be useful e.g.  if you save the register before use and
     restore it after.

'.reserve'
     This must be followed by a symbol name, a positive number, and
     '"bss"'.  This behaves somewhat like '.lcomm', but the syntax is
     different.

'.seg'
     This must be followed by '"text"', '"data"', or '"data1"'.  It
     behaves like '.text', '.data', or '.data 1'.

'.skip'
     This is functionally identical to the '.space' directive.

'.word'
     On the Sparc, the '.word' directive produces 32 bit values, instead
     of the 16 bit values it produces on many other machines.

'.xword'
     On the Sparc V9 processor, the '.xword' directive produces 64 bit
     values.

14 Reporting Bugs
*****************

Your bug reports play an essential role in making 'as' reliable.

   Reporting a bug may help you by bringing a solution to your problem,
or it may not.  But in any case the principal function of a bug report
is to help the entire community by making the next version of 'as' work
better.  Bug reports are your contribution to the maintenance of 'as'.

   In order for a bug report to serve its purpose, you must include the
information that enables us to fix the bug.

14.1 Have You Found a Bug?
==========================

If you are not sure whether you have found a bug, here are some
guidelines:

   * If the assembler gets a fatal signal, for any input whatever, that
     is a 'as' bug.  Reliable assemblers never crash.

   * If 'as' produces an error message for valid input, that is a bug.

   * If 'as' does not produce an error message for invalid input, that
     is a bug.  However, you should note that your idea of "invalid
     input" might be our idea of "an extension" or "support for
     traditional practice".

   * If you are an experienced user of assemblers, your suggestions for
     improvement of 'as' are welcome in any case.

14.2 How to Report Bugs
=======================

A number of companies and individuals offer support for GNU products.
If you obtained 'as' from a support organization, we recommend you
contact that organization first.

   You can find contact information for many support companies and
individuals in the file 'etc/SERVICE' in the GNU Emacs distribution.

   The fundamental principle of reporting bugs usefully is this: *report
all the facts*.  If you are not sure whether to state a fact or leave it
out, state it!

   Often people omit facts because they think they know what causes the
problem and assume that some details do not matter.  Thus, you might
assume that the name of a symbol you use in an example does not matter.
Well, probably it does not, but one cannot be sure.  Perhaps the bug is
a stray memory reference which happens to fetch from the location where
that name is stored in memory; perhaps, if the name were different, the
contents of that location would fool the assembler into doing the right
thing despite the bug.  Play it safe and give a specific, complete
example.  That is the easiest thing for you to do, and the most helpful.

   Keep in mind that the purpose of a bug report is to enable us to fix
the bug if it is new to us.  Therefore, always write your bug reports on
the assumption that the bug has not been reported previously.

   Sometimes people give a few sketchy facts and ask, "Does this ring a
bell?"  This cannot help us fix a bug, so it is basically useless.  We
respond by asking for enough details to enable us to investigate.  You
might as well expedite matters by sending them to begin with.

   To enable us to fix the bug, you should include all these things:

   * The version of 'as'.  'as' announces it if you start it with the
     '--version' argument.

     Without this, we will not know whether there is any point in
     looking for the bug in the current version of 'as'.

   * Any patches you may have applied to the 'as' source.

   * The type of machine you are using, and the operating system name
     and version number.

   * What compiler (and its version) was used to compile 'as'--e.g.
     "'gcc-2.7'".

   * The command arguments you gave the assembler to assemble your
     example and observe the bug.  To guarantee you will not omit
     something important, list them all.  A copy of the Makefile (or the
     output from make) is sufficient.

     If we were to try to guess the arguments, we would probably guess
     wrong and then we might not encounter the bug.

   * A complete input file that will reproduce the bug.  If the bug is
     observed when the assembler is invoked via a compiler, send the
     assembler source, not the high level language source.  Most
     compilers will produce the assembler source when run with the '-S'
     option.  If you are using 'gcc', use the options '-v --save-temps';
     this will save the assembler source in a file with an extension of
     '.s', and also show you exactly how 'as' is being run.

   * A description of what behavior you observe that you believe is
     incorrect.  For example, "It gets a fatal signal."

     Of course, if the bug is that 'as' gets a fatal signal, then we
     will certainly notice it.  But if the bug is incorrect output, we
     might not notice unless it is glaringly wrong.  You might as well
     not give us a chance to make a mistake.

     Even if the problem you experience is a fatal signal, you should
     still say so explicitly.  Suppose something strange is going on,
     such as, your copy of 'as' is out of sync, or you have encountered
     a bug in the C library on your system.  (This has happened!)  Your
     copy might crash and ours would not.  If you told us to expect a
     crash, then when ours fails to crash, we would know that the bug
     was not happening for us.  If you had not told us to expect a
     crash, then we would not be able to draw any conclusion from our
     observations.

   * If you wish to suggest changes to the 'as' source, send us context
     diffs, as generated by 'diff' with the '-u', '-c', or '-p' option.
     Always send diffs from the old file to the new file.  If you even
     discuss something in the 'as' source, refer to it by context, not
     by line number.

     The line numbers in our development sources will not match those in
     your sources.  Your line numbers would convey no useful information
     to us.

   Here are some things that are not necessary:

   * A description of the envelope of the bug.

     Often people who encounter a bug spend a lot of time investigating
     which changes to the input file will make the bug go away and which
     changes will not affect it.

     This is often time consuming and not very useful, because the way
     we will find the bug is by running a single example under the
     debugger with breakpoints, not by pure deduction from a series of
     examples.  We recommend that you save your time for something else.

     Of course, if you can find a simpler example to report _instead_ of
     the original one, that is a convenience for us.  Errors in the
     output will be easier to spot, running under the debugger will take
     less time, and so on.

     However, simplification is not vital; if you do not want to do
     this, report the bug anyway and send us the entire test case you
     used.

   * A patch for the bug.

     A patch for the bug does help us if it is a good one.  But do not
     omit the necessary information, such as the test case, on the
     assumption that a patch is all we need.  We might see problems with
     your patch and decide to fix the problem another way, or we might
     not understand it at all.

     Sometimes with a program as complicated as 'as' it is very hard to
     construct an example that will make the program follow a certain
     path through the code.  If you do not send us the example, we will
     not be able to construct one, so we will not be able to verify that
     the bug is fixed.

     And if we cannot understand what bug you are trying to fix, or why
     your patch should be an improvement, we will not install it.  A
     test case will help us to understand.

   * A guess about what the bug is or what it depends on.

     Such guesses are usually wrong.  Even we cannot guess right about
     such things without first using the debugger to find the facts.

15 Acknowledgements
*******************

If you have contributed to GAS and your name isn't listed here, it is
not meant as a slight.  We just don't know about it.  Send mail to the
maintainer, and we'll correct the situation.  Currently the maintainer
is Ken Raeburn (email address 'raeburn@cygnus.com').

   Dean Elsner wrote the original GNU assembler for the VAX.(1)

   Jay Fenlason maintained GAS for a while, adding support for
GDB-specific debug information and the 68k series machines, most of the
preprocessing pass, and extensive changes in 'messages.c',
'input-file.c', 'write.c'.

   K. Richard Pixley maintained GAS for a while, adding various
enhancements and many bug fixes, including merging support for several
processors, breaking GAS up to handle multiple object file format back
ends (including heavy rewrite, testing, an integration of the coff and
b.out back ends), adding configuration including heavy testing and
verification of cross assemblers and file splits and renaming, converted
GAS to strictly ANSI C including full prototypes, added support for
m680[34]0 and cpu32, did considerable work on i960 including a COFF port
(including considerable amounts of reverse engineering), a SPARC opcode
file rewrite, DECstation, rs6000, and hp300hpux host ports, updated
"know" assertions and made them work, much other reorganization,
cleanup, and lint.

   Ken Raeburn wrote the high-level BFD interface code to replace most
of the code in format-specific I/O modules.

   The original VMS support was contributed by David L. Kashtan.  Eric
Youngdale has done much work with it since.

   The Intel 80386 machine description was written by Eliot Dresselhaus.

   Minh Tran-Le at IntelliCorp contributed some AIX 386 support.

   The Motorola 88k machine description was contributed by Devon Bowen
of Buffalo University and Torbjorn Granlund of the Swedish Institute of
Computer Science.

   Keith Knowles at the Open Software Foundation wrote the original MIPS
back end ('tc-mips.c', 'tc-mips.h'), and contributed Rose format support
(which hasn't been merged in yet).  Ralph Campbell worked with the MIPS
code to support a.out format.

   Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k,
tc-h8300), and IEEE 695 object file format (obj-ieee), was written by
Steve Chamberlain of Cygnus Support.  Steve also modified the COFF back
end to use BFD for some low-level operations, for use with the H8/300
and AMD 29k targets.

   John Gilmore built the AMD 29000 support, added '.include' support,
and simplified the configuration of which versions accept which
directives.  He updated the 68k machine description so that Motorola's
opcodes always produced fixed-size instructions (e.g., 'jsr'), while
synthetic instructions remained shrinkable ('jbsr').  John fixed many
bugs, including true tested cross-compilation support, and one bug in
relaxation that took a week and required the proverbial one-bit fix.

   Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax
for the 68k, completed support for some COFF targets (68k, i386 SVR3,
and SCO Unix), added support for MIPS ECOFF and ELF targets, wrote the
initial RS/6000 and PowerPC assembler, and made a few other minor
patches.

   Steve Chamberlain made GAS able to generate listings.

   Hewlett-Packard contributed support for the HP9000/300.

   Jeff Law wrote GAS and BFD support for the native HPPA object format
(SOM) along with a fairly extensive HPPA testsuite (for both SOM and ELF
object formats).  This work was supported by both the Center for
Software Science at the University of Utah and Cygnus Support.

   Support for ELF format files has been worked on by Mark Eichin of
Cygnus Support (original, incomplete implementation for SPARC), Pete
Hoogenboom and Jeff Law at the University of Utah (HPPA mainly), Michael
Meissner of the Open Software Foundation (i386 mainly), and Ken Raeburn
of Cygnus Support (sparc, and some initial 64-bit support).

   Linas Vepstas added GAS support for the ESA/390 "IBM 370"
architecture.

   Richard Henderson rewrote the Alpha assembler.  Klaus Kaempf wrote
GAS and BFD support for openVMS/Alpha.

   Timothy Wall, Michael Hayes, and Greg Smart contributed to the
various tic* flavors.

   David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from
Tensilica, Inc. added support for Xtensa processors.

   Several engineers at Cygnus Support have also provided many small bug
fixes and configuration enhancements.

   Many others have contributed large or small bugfixes and
enhancements.  If you have contributed significant work and are not
mentioned on this list, and want to be, let us know.  Some of the
history has been lost; we are not intentionally leaving anyone out.

Appendix A GNU Free Documentation License
*****************************************

                        Version 1.1, March 2000

     Copyright (C) 2000, 2003 Free Software Foundation, Inc.
     51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

     Everyone is permitted to copy and distribute verbatim copies
     of this license document, but changing it is not allowed.

  0. PREAMBLE

     The purpose of this License is to make a manual, textbook, or other
     written document "free" in the sense of freedom: to assure everyone
     the effective freedom to copy and redistribute it, with or without
     modifying it, either commercially or noncommercially.  Secondarily,
     this License preserves for the author and publisher a way to get
     credit for their work, while not being considered responsible for
     modifications made by others.

     This License is a kind of "copyleft", which means that derivative
     works of the document must themselves be free in the same sense.
     It complements the GNU General Public License, which is a copyleft
     license designed for free software.

     We have designed this License in order to use it for manuals for
     free software, because free software needs free documentation: a
     free program should come with manuals providing the same freedoms
     that the software does.  But this License is not limited to
     software manuals; it can be used for any textual work, regardless
     of subject matter or whether it is published as a printed book.  We
     recommend this License principally for works whose purpose is
     instruction or reference.


  1. APPLICABILITY AND DEFINITIONS

     This License applies to any manual or other work that contains a
     notice placed by the copyright holder saying it can be distributed
     under the terms of this License.  The "Document", below, refers to
     any such manual or work.  Any member of the public is a licensee,
     and is addressed as "you."

     A "Modified Version" of the Document means any work containing the
     Document or a portion of it, either copied verbatim, or with
     modifications and/or translated into another language.

     A "Secondary Section" is a named appendix or a front-matter section
     of the Document that deals exclusively with the relationship of the
     publishers or authors of the Document to the Document's overall
     subject (or to related matters) and contains nothing that could
     fall directly within that overall subject.  (For example, if the
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     may not explain any mathematics.)  The relationship could be a
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     The "Invariant Sections" are certain Secondary Sections whose
     titles are designated, as being those of Invariant Sections, in the
     notice that says that the Document is released under this License.

     The "Cover Texts" are certain short passages of text that are
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     A "Transparent" copy of the Document means a machine-readable copy,
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     Examples of suitable formats for Transparent copies include plain
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     The "Title Page" means, for a printed book, the title page itself,
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     material this License requires to appear in the title page.  For
     works in formats which do not have any title page as such, "Title
     Page" means the text near the most prominent appearance of the
     work's title, preceding the beginning of the body of the text.

  2. VERBATIM COPYING

     You may copy and distribute the Document in any medium, either
     commercially or noncommercially, provided that this License, the
     copyright notices, and the license notice saying this License
     applies to the Document are reproduced in all copies, and that you
     add no other conditions whatsoever to those of this License.  You
     may not use technical measures to obstruct or control the reading
     or further copying of the copies you make or distribute.  However,
     you may accept compensation in exchange for copies.  If you
     distribute a large enough number of copies you must also follow the
     conditions in section 3.

     You may also lend copies, under the same conditions stated above,
     and you may publicly display copies.

  3. COPYING IN QUANTITY

     If you publish printed copies of the Document numbering more than
     100, and the Document's license notice requires Cover Texts, you
     must enclose the copies in covers that carry, clearly and legibly,
     all these Cover Texts: Front-Cover Texts on the front cover, and
     Back-Cover Texts on the back cover.  Both covers must also clearly
     and legibly identify you as the publisher of these copies.  The
     front cover must present the full title with all words of the title
     equally prominent and visible.  You may add other material on the
     covers in addition.  Copying with changes limited to the covers, as
     long as they preserve the title of the Document and satisfy these
     conditions, can be treated as verbatim copying in other respects.

     If the required texts for either cover are too voluminous to fit
     legibly, you should put the first ones listed (as many as fit
     reasonably) on the actual cover, and continue the rest onto
     adjacent pages.

     If you publish or distribute Opaque copies of the Document
     numbering more than 100, you must either include a machine-readable
     Transparent copy along with each Opaque copy, or state in or with
     each Opaque copy a publicly-accessible computer-network location
     containing a complete Transparent copy of the Document, free of
     added material, which the general network-using public has access
     to download anonymously at no charge using public-standard network
     protocols.  If you use the latter option, you must take reasonably
     prudent steps, when you begin distribution of Opaque copies in
     quantity, to ensure that this Transparent copy will remain thus
     accessible at the stated location until at least one year after the
     last time you distribute an Opaque copy (directly or through your
     agents or retailers) of that edition to the public.

     It is requested, but not required, that you contact the authors of
     the Document well before redistributing any large number of copies,
     to give them a chance to provide you with an updated version of the
     Document.

  4. MODIFICATIONS

     You may copy and distribute a Modified Version of the Document
     under the conditions of sections 2 and 3 above, provided that you
     release the Modified Version under precisely this License, with the
     Modified Version filling the role of the Document, thus licensing
     distribution and modification of the Modified Version to whoever
     possesses a copy of it.  In addition, you must do these things in
     the Modified Version:

     A. Use in the Title Page (and on the covers, if any) a title
     distinct from that of the Document, and from those of previous
     versions (which should, if there were any, be listed in the History
     section of the Document).  You may use the same title as a previous
     version if the original publisher of that version gives permission.
     B. List on the Title Page, as authors, one or more persons or
     entities responsible for authorship of the modifications in the
     Modified Version, together with at least five of the principal
     authors of the Document (all of its principal authors, if it has
     less than five).
     C. State on the Title page the name of the publisher of the
     Modified Version, as the publisher.
     D. Preserve all the copyright notices of the Document.
     E. Add an appropriate copyright notice for your modifications
     adjacent to the other copyright notices.
     F. Include, immediately after the copyright notices, a license
     notice giving the public permission to use the Modified Version
     under the terms of this License, in the form shown in the Addendum
     below.
     G. Preserve in that license notice the full lists of Invariant
     Sections and required Cover Texts given in the Document's license
     notice.
     H. Include an unaltered copy of this License.
     I. Preserve the section entitled "History", and its title, and add
     to it an item stating at least the title, year, new authors, and
     publisher of the Modified Version as given on the Title Page.  If
     there is no section entitled "History" in the Document, create one
     stating the title, year, authors, and publisher of the Document as
     given on its Title Page, then add an item describing the Modified
     Version as stated in the previous sentence.
     J. Preserve the network location, if any, given in the Document for
     public access to a Transparent copy of the Document, and likewise
     the network locations given in the Document for previous versions
     it was based on.  These may be placed in the "History" section.
     You may omit a network location for a work that was published at
     least four years before the Document itself, or if the original
     publisher of the version it refers to gives permission.
     K. In any section entitled "Acknowledgements" or "Dedications",
     preserve the section's title, and preserve in the section all the
     substance and tone of each of the contributor acknowledgements
     and/or dedications given therein.
     L. Preserve all the Invariant Sections of the Document, unaltered
     in their text and in their titles.  Section numbers or the
     equivalent are not considered part of the section titles.
     M. Delete any section entitled "Endorsements."  Such a section may
     not be included in the Modified Version.
     N. Do not retitle any existing section as "Endorsements" or to
     conflict in title with any Invariant Section.

     If the Modified Version includes new front-matter sections or
     appendices that qualify as Secondary Sections and contain no
     material copied from the Document, you may at your option designate
     some or all of these sections as invariant.  To do this, add their
     titles to the list of Invariant Sections in the Modified Version's
     license notice.  These titles must be distinct from any other
     section titles.

     You may add a section entitled "Endorsements", provided it contains
     nothing but endorsements of your Modified Version by various
     parties-for example, statements of peer review or that the text has
     been approved by an organization as the authoritative definition of
     a standard.

     You may add a passage of up to five words as a Front-Cover Text,
     and a passage of up to 25 words as a Back-Cover Text, to the end of
     the list of Cover Texts in the Modified Version.  Only one passage
     of Front-Cover Text and one of Back-Cover Text may be added by (or
     through arrangements made by) any one entity.  If the Document
     already includes a cover text for the same cover, previously added
     by you or by arrangement made by the same entity you are acting on
     behalf of, you may not add another; but you may replace the old
     one, on explicit permission from the previous publisher that added
     the old one.

     The author(s) and publisher(s) of the Document do not by this
     License give permission to use their names for publicity for or to
     assert or imply endorsement of any Modified Version.

  5. COMBINING DOCUMENTS

     You may combine the Document with other documents released under
     this License, under the terms defined in section 4 above for
     modified versions, provided that you include in the combination all
     of the Invariant Sections of all of the original documents,
     unmodified, and list them all as Invariant Sections of your
     combined work in its license notice.

     The combined work need only contain one copy of this License, and
     multiple identical Invariant Sections may be replaced with a single
     copy.  If there are multiple Invariant Sections with the same name
     but different contents, make the title of each such section unique
     by adding at the end of it, in parentheses, the name of the
     original author or publisher of that section if known, or else a
     unique number.  Make the same adjustment to the section titles in
     the list of Invariant Sections in the license notice of the
     combined work.

     In the combination, you must combine any sections entitled
     "History" in the various original documents, forming one section
     entitled "History"; likewise combine any sections entitled
     "Acknowledgements", and any sections entitled "Dedications."  You
     must delete all sections entitled "Endorsements."

  6. COLLECTIONS OF DOCUMENTS

     You may make a collection consisting of the Document and other
     documents released under this License, and replace the individual
     copies of this License in the various documents with a single copy
     that is included in the collection, provided that you follow the
     rules of this License for verbatim copying of each of the documents
     in all other respects.

     You may extract a single document from such a collection, and
     distribute it individually under this License, provided you insert
     a copy of this License into the extracted document, and follow this
     License in all other respects regarding verbatim copying of that
     document.

  7. AGGREGATION WITH INDEPENDENT WORKS

     A compilation of the Document or its derivatives with other
     separate and independent documents or works, in or on a volume of a
     storage or distribution medium, does not as a whole count as a
     Modified Version of the Document, provided no compilation copyright
     is claimed for the compilation.  Such a compilation is called an
     "aggregate", and this License does not apply to the other
     self-contained works thus compiled with the Document, on account of
     their being thus compiled, if they are not themselves derivative
     works of the Document.

     If the Cover Text requirement of section 3 is applicable to these
     copies of the Document, then if the Document is less than one
     quarter of the entire aggregate, the Document's Cover Texts may be
     placed on covers that surround only the Document within the
     aggregate.  Otherwise they must appear on covers around the whole
     aggregate.

  8. TRANSLATION

     Translation is considered a kind of modification, so you may
     distribute translations of the Document under the terms of section
     4.  Replacing Invariant Sections with translations requires special
     permission from their copyright holders, but you may include
     translations of some or all Invariant Sections in addition to the
     original versions of these Invariant Sections.  You may include a
     translation of this License provided that you also include the
     original English version of this License.  In case of a
     disagreement between the translation and the original English
     version of this License, the original English version will prevail.

  9. TERMINATION

     You may not copy, modify, sublicense, or distribute the Document
     except as expressly provided for under this License.  Any other
     attempt to copy, modify, sublicense or distribute the Document is
     void, and will automatically terminate your rights under this
     License.  However, parties who have received copies, or rights,
     from you under this License will not have their licenses terminated
     so long as such parties remain in full compliance.

  10. FUTURE REVISIONS OF THIS LICENSE

     The Free Software Foundation may publish new, revised versions of
     the GNU Free Documentation License from time to time.  Such new
     versions will be similar in spirit to the present version, but may
     differ in detail to address new problems or concerns.  See
     http://www.gnu.org/copyleft/.

     Each version of the License is given a distinguishing version
     number.  If the Document specifies that a particular numbered
     version of this License "or any later version" applies to it, you
     have the option of following the terms and conditions either of
     that specified version or of any later version that has been
     published (not as a draft) by the Free Software Foundation.  If the
     Document does not specify a version number of this License, you may
     choose any version ever published (not as a draft) by the Free
     Software Foundation.

ADDENDUM: How to use this License for your documents
====================================================

To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:

     Copyright (C)  YEAR  YOUR NAME.
     Permission is granted to copy, distribute and/or modify this document
     under the terms of the GNU Free Documentation License, Version 1.1
     or any later version published by the Free Software Foundation;
     with the Invariant Sections being LIST THEIR TITLES, with the
     Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
     A copy of the license is included in the section entitled "GNU
     Free Documentation License."

   If you have no Invariant Sections, write "with no Invariant Sections"
instead of saying which ones are invariant.  If you have no Front-Cover
Texts, write "no Front-Cover Texts" instead of "Front-Cover Texts being
LIST"; likewise for Back-Cover Texts.

   If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of free
software license, such as the GNU General Public License, to permit
their use in free software.

   ---------- Footnotes ----------

   (1) Any more details?

AS Index
********

* Menu:

* #:                                     Comments.           (line 1306)
* #APP:                                  Preprocessing.      (line 1268)
* #NO_APP:                               Preprocessing.      (line 1268)
* '$a':                                  ARM Mapping Symbols.
                                                             (line 4193)
* '$d':                                  ARM Mapping Symbols.
                                                             (line 4199)
* '$t':                                  ARM Mapping Symbols.
                                                             (line 4196)
* --:                                    Command Line.       (line  760)
* '--32' option, i386:                   i386-Options.       (line 4220)
* '--32' option, x86-64:                 i386-Options.       (line 4220)
* '--64' option, i386:                   i386-Options.       (line 4220)
* '--64' option, x86-64:                 i386-Options.       (line 4220)
* --alternate:                           alternate.          (line  929)
* '--divide' option, i386:               i386-Options.       (line 4236)
* --enforce-aligned-data:                Sparc-Aligned-Data. (line 5460)
* --fatal-warnings:                      W.                  (line 1222)
* --hash-size=NUMBER:                    Overview.           (line  459)
* --listing-cont-lines:                  listing.            (line 1015)
* --listing-lhs-width:                   listing.            (line  997)
* --listing-lhs-width2:                  listing.            (line 1002)
* --listing-rhs-width:                   listing.            (line 1009)
* --MD:                                  MD.                 (line 1149)
* --no-warn:                             W.                  (line 1217)
* --statistics:                          statistics.         (line 1188)
* --traditional-format:                  traditional-format. (line 1196)
* --warn:                                W.                  (line 1225)
* -a:                                    a.                  (line  894)
* -ac:                                   a.                  (line  894)
* -ad:                                   a.                  (line  894)
* -ah:                                   a.                  (line  894)
* -al:                                   a.                  (line  894)
* -an:                                   a.                  (line  894)
* -as:                                   a.                  (line  894)
* -Asparclet:                            Sparc-Opts.         (line 5421)
* -Asparclite:                           Sparc-Opts.         (line 5421)
* -Av6:                                  Sparc-Opts.         (line 5421)
* -Av8:                                  Sparc-Opts.         (line 5421)
* -Av9:                                  Sparc-Opts.         (line 5421)
* -Av9a:                                 Sparc-Opts.         (line 5421)
* -construct-floats:                     MIPS Opts.          (line 5056)
* -D:                                    D.                  (line  934)
* '-eabi=' command line option, ARM:     ARM Options.        (line 3844)
* '-EB' command line option, ARM:        ARM Options.        (line 3849)
* '-EB' option (MIPS):                   MIPS Opts.          (line 4879)
* '-EL' command line option, ARM:        ARM Options.        (line 3853)
* '-EL' option (MIPS):                   MIPS Opts.          (line 4879)
* -f:                                    f.                  (line  940)
* '-G' option (MIPS):                    MIPS Opts.          (line 4874)
* -I PATH:                               I.                  (line  952)
* -K:                                    K.                  (line  962)
* '-k' command line option, ARM:         ARM Options.        (line 3857)
* '-KPIC' option, MIPS:                  MIPS Opts.          (line 4887)
* -L:                                    L.                  (line  972)
* -M:                                    M.                  (line 1022)
* '-mapcs' command line option, ARM:     ARM Options.        (line 3817)
* '-mapcs-float' command line option, ARM: ARM Options.      (line 3830)
* '-mapcs-reentrant' command line option, ARM: ARM Options.  (line 3835)
* '-march=' command line option, ARM:    ARM Options.        (line 3773)
* '-march=' option, i386:                i386-Options.       (line 4243)
* '-march=' option, x86-64:              i386-Options.       (line 4243)
* '-matpcs' command line option, ARM:    ARM Options.        (line 3822)
* '-mconstant-gp' command line option, IA-64: IA-64 Options. (line 4733)
* '-mcpu=' command line option, ARM:     ARM Options.        (line 3742)
* '-mfloat-abi=' command line option, ARM: ARM Options.      (line 3839)
* '-mfpu=' command line option, ARM:     ARM Options.        (line 3788)
* -mno-sym32:                            MIPS Opts.          (line 5045)
* -msym32:                               MIPS Opts.          (line 5045)
* '-mthumb' command line option, ARM:    ARM Options.        (line 3808)
* '-mthumb-interwork' command line option, ARM: ARM Options. (line 3813)
* '-mtune=' option, i386:                i386-Options.       (line 4255)
* '-mtune=' option, x86-64:              i386-Options.       (line 4255)
* '-mvxworks-pic' option, MIPS:          MIPS Opts.          (line 4892)
* -no-construct-floats:                  MIPS Opts.          (line 5056)
* '-nocpp' ignored (MIPS):               MIPS Opts.          (line 5048)
* -o:                                    o.                  (line 1160)
* -R:                                    R.                  (line 1170)
* -v:                                    v.                  (line 1206)
* -version:                              v.                  (line 1206)
* -W:                                    W.                  (line 1217)
* '.' (symbol):                          Dot.                (line 1898)
* '.arch' directive, ARM:                ARM Directives.     (line 4118)
* '.cantunwind' directive, ARM:          ARM Directives.     (line 4022)
* '.cpu' directive, ARM:                 ARM Directives.     (line 4114)
* '.eabi_attribute' directive, ARM:      ARM Directives.     (line 4132)
* '.fnend' directive, ARM:               ARM Directives.     (line 4014)
* '.fnstart' directive, ARM:             ARM Directives.     (line 4011)
* '.fpu' directive, ARM:                 ARM Directives.     (line 4128)
* '.handlerdata' directive, ARM:         ARM Directives.     (line 4033)
* '.insn':                               MIPS insn.          (line 5223)
* '.ltorg' directive, ARM:               ARM Directives.     (line 3994)
* '.movsp' directive, ARM:               ARM Directives.     (line 4088)
* .o:                                    Object.             (line  827)
* '.object_arch' directive, ARM:         ARM Directives.     (line 4122)
* '.pad' directive, ARM:                 ARM Directives.     (line 4083)
* '.personality' directive, ARM:         ARM Directives.     (line 4026)
* '.personalityindex' directive, ARM:    ARM Directives.     (line 4029)
* '.pool' directive, ARM:                ARM Directives.     (line 4008)
* '.save' directive, ARM:                ARM Directives.     (line 4042)
* '.set arch=CPU':                       MIPS ISA.           (line 5195)
* '.set autoextend':                     MIPS autoextend.    (line 5210)
* '.set dsp':                            MIPS ASE instruction generation overrides.
                                                             (line 5262)
* '.set dspr2':                          MIPS ASE instruction generation overrides.
                                                             (line 5267)
* '.set mdmx':                           MIPS ASE instruction generation overrides.
                                                             (line 5257)
* '.set mips3d':                         MIPS ASE instruction generation overrides.
                                                             (line 5247)
* '.set mipsN':                          MIPS ISA.           (line 5183)
* '.set mt':                             MIPS ASE instruction generation overrides.
                                                             (line 5272)
* '.set noautoextend':                   MIPS autoextend.    (line 5210)
* '.set nodsp':                          MIPS ASE instruction generation overrides.
                                                             (line 5262)
* '.set nodspr2':                        MIPS ASE instruction generation overrides.
                                                             (line 5267)
* '.set nomdmx':                         MIPS ASE instruction generation overrides.
                                                             (line 5257)
* '.set nomips3d':                       MIPS ASE instruction generation overrides.
                                                             (line 5247)
* '.set nomt':                           MIPS ASE instruction generation overrides.
                                                             (line 5272)
* '.set nosmartmips':                    MIPS ASE instruction generation overrides.
                                                             (line 5252)
* '.set nosym32':                        MIPS symbol sizes.  (line 5140)
* '.set pop':                            MIPS option stack.  (line 5232)
* '.set push':                           MIPS option stack.  (line 5232)
* '.set smartmips':                      MIPS ASE instruction generation overrides.
                                                             (line 5252)
* '.set sym32':                          MIPS symbol sizes.  (line 5140)
* '.setfp' directive, ARM:               ARM Directives.     (line 4093)
* '.unwind_raw' directive, ARM:          ARM Directives.     (line 4107)
* '.vsave' directive, ARM:               ARM Directives.     (line 4066)
* 16-bit code, i386:                     i386-16bit.         (line 4615)
* 3DNow!, i386:                          i386-SIMD.          (line 4593)
* 3DNow!, x86-64:                        i386-SIMD.          (line 4593)
* ':' (label):                           Statements.         (line 1355)
* '\"' (doublequote character):          Strings.            (line 1423)
* '\b' (backspace character):            Strings.            (line 1395)
* '\DDD' (octal character code):         Strings.            (line 1410)
* '\f' (formfeed character):             Strings.            (line 1398)
* '\n' (newline character):              Strings.            (line 1401)
* '\r' (carriage return character):      Strings.            (line 1404)
* '\t' (tab):                            Strings.            (line 1407)
* '\XD...' (hex character code):         Strings.            (line 1416)
* '\\' ('\' character):                  Strings.            (line 1420)
* a.out:                                 Object.             (line  827)
* 'abort' directive:                     Abort.              (line 2114)
* absolute section:                      Ld Sections.        (line 1632)
* addition, permitted arguments:         Infix Ops.          (line 2055)
* addresses:                             Expressions.        (line 1946)
* addresses, format of:                  Secs Background.    (line 1573)
* 'ADR reg,<label>' pseudo op, ARM:      ARM Opcodes.        (line 4159)
* 'ADRL reg,<label>' pseudo op, ARM:     ARM Opcodes.        (line 4169)
* advancing location counter:            Org.                (line 3101)
* 'align' directive:                     Align.              (line 2123)
* 'align' directive, ARM:                ARM Directives.     (line 3915)
* 'align' directive, SPARC:              Sparc-Directives.   (line 5481)
* arch directive, i386:                  i386-Arch.          (line 4670)
* arch directive, x86-64:                i386-Arch.          (line 4670)
* architectures, PowerPC:                PowerPC-Opts.       (line 5285)
* architectures, SPARC:                  Sparc-Opts.         (line 5402)
* arguments for addition:                Infix Ops.          (line 2055)
* arguments for subtraction:             Infix Ops.          (line 2060)
* arguments in expressions:              Arguments.          (line 1973)
* arithmetic functions:                  Operators.          (line 1998)
* arithmetic operands:                   Arguments.          (line 1973)
* ARM data relocations:                  ARM-Relocations.    (line 3886)
* 'arm' directive, ARM:                  ARM Directives.     (line 3969)
* ARM floating point (IEEE):             ARM Floating Point. (line 3910)
* ARM identifiers:                       ARM-Chars.          (line 3876)
* ARM immediate character:               ARM-Chars.          (line 3874)
* ARM line comment character:            ARM-Chars.          (line 3867)
* ARM line separator:                    ARM-Chars.          (line 3871)
* ARM machine directives:                ARM Directives.     (line 3915)
* ARM opcodes:                           ARM Opcodes.        (line 4140)
* ARM options (none):                    ARM Options.        (line 3742)
* ARM register names:                    ARM-Regs.           (line 3881)
* ARM support:                           Machine Dependencies.
                                                             (line 3739)
* 'ascii' directive:                     Ascii.              (line 2165)
* 'asciz' directive:                     Asciz.              (line 2172)
* assembler bugs, reporting:             Bug Reporting.      (line 5566)
* assembler crash:                       Bug Criteria.       (line 5550)
* assembler internal logic error:        As Sections.        (line 1674)
* assembler version:                     v.                  (line 1206)
* assembler, and linker:                 Secs Background.    (line 1535)
* assembly listings, enabling:           a.                  (line  894)
* assigning values to symbols:           Setting Symbols.    (line 1772)
* assigning values to symbols <1>:       Equ.                (line 2471)
* attributes, symbol:                    Symbol Attributes.  (line 1907)
* att_syntax pseudo op, i386:            i386-Syntax.        (line 4265)
* att_syntax pseudo op, x86-64:          i386-Syntax.        (line 4265)
* Av7:                                   Sparc-Opts.         (line 5421)
* backslash ('\\'):                      Strings.            (line 1420)
* backspace ('\b'):                      Strings.            (line 1395)
* 'balign' directive:                    Balign.             (line 2178)
* 'balignl' directive:                   Balign.             (line 2199)
* 'balignw' directive:                   Balign.             (line 2199)
* big endian output, MIPS:               Overview.           (line  560)
* big-endian output, MIPS:               MIPS Opts.          (line 4879)
* bignums:                               Bignums.            (line 1485)
* binary files, including:               Incbin.             (line 2707)
* binary integers:                       Integers.           (line 1466)
* bit names, IA-64:                      IA-64-Bits.         (line 4846)
* bss section:                           Ld Sections.        (line 1623)
* bss section <1>:                       bss.                (line 1739)
* bug criteria:                          Bug Criteria.       (line 5547)
* bug reports:                           Bug Reporting.      (line 5566)
* bugs in assembler:                     Reporting Bugs.     (line 5534)
* bus lock prefixes, i386:               i386-Prefixes.      (line 4444)
* 'byte' directive:                      Byte.               (line 2211)
* call instructions, i386:               i386-Mnemonics.     (line 4353)
* call instructions, x86-64:             i386-Mnemonics.     (line 4353)
* carriage return ('\r'):                Strings.            (line 1404)
* 'cfi_endproc' directive:               CFI directives.     (line 2249)
* 'cfi_startproc' directive:             CFI directives.     (line 2239)
* character constants:                   Characters.         (line 1377)
* character escape codes:                Strings.            (line 1395)
* character, single:                     Chars.              (line 1443)
* characters used in symbols:            Symbol Intro.       (line 1325)
* 'code' directive, ARM:                 ARM Directives.     (line 3962)
* 'code16' directive, i386:              i386-16bit.         (line 4615)
* 'code16gcc' directive, i386:           i386-16bit.         (line 4615)
* 'code32' directive, i386:              i386-16bit.         (line 4615)
* 'code64' directive, i386:              i386-16bit.         (line 4615)
* 'code64' directive, x86-64:            i386-16bit.         (line 4615)
* COMDAT:                                Linkonce.           (line 2831)
* 'comm' directive:                      Comm.               (line 2217)
* command line conventions:              Command Line.       (line  756)
* comments:                              Comments.           (line 1288)
* comments, removed by preprocessor:     Preprocessing.      (line 1253)
* 'common' directive, SPARC:             Sparc-Directives.   (line 5484)
* common sections:                       Linkonce.           (line 2831)
* common variable storage:               bss.                (line 1739)
* comparison expressions:                Infix Ops.          (line 2066)
* conditional assembly:                  If.                 (line 2629)
* constant, single character:            Chars.              (line 1443)
* constants:                             Constants.          (line 1366)
* constants, bignum:                     Bignums.            (line 1485)
* constants, character:                  Characters.         (line 1377)
* constants, converted by preprocessor:  Preprocessing.      (line 1256)
* constants, floating point:             Flonums.            (line 1493)
* constants, integer:                    Integers.           (line 1466)
* constants, number:                     Numbers.            (line 1457)
* constants, string:                     Strings.            (line 1386)
* conversion instructions, i386:         i386-Mnemonics.     (line 4334)
* conversion instructions, x86-64:       i386-Mnemonics.     (line 4334)
* coprocessor wait, i386:                i386-Prefixes.      (line 4448)
* crash of assembler:                    Bug Criteria.       (line 5550)
* current address:                       Dot.                (line 1898)
* current address, advancing:            Org.                (line 3101)
* data alignment on SPARC:               Sparc-Aligned-Data. (line 5455)
* data and text sections, joining:       R.                  (line 1170)
* 'data' directive:                      Data.               (line 2421)
* data relocations, ARM:                 ARM-Relocations.    (line 3886)
* debuggers, and symbol order:           Symbols.            (line 1757)
* decimal integers:                      Integers.           (line 1472)
* dependency tracking:                   MD.                 (line 1149)
* deprecated directives:                 Deprecated.         (line 3731)
* directives and instructions:           Statements.         (line 1347)
* directives for PowerPC:                PowerPC-Pseudo.     (line 5386)
* directives, machine independent:       Pseudo Ops.         (line 2105)
* 'dn' and 'qn' directives, ARM:         ARM Directives.     (line 3938)
* dollar local symbols:                  Symbol Names.       (line 1879)
* dot (symbol):                          Dot.                (line 1898)
* 'double' directive:                    Double.             (line 2428)
* 'double' directive, i386:              i386-Float.         (line 4569)
* 'double' directive, x86-64:            i386-Float.         (line 4569)
* doublequote ('\"'):                    Strings.            (line 1423)
* ECOFF sections:                        MIPS Object.        (line 5100)
* eight-byte integer:                    Quad.               (line 3245)
* 'eject' directive:                     Eject.              (line 2434)
* ELF symbol type:                       Type.               (line 3620)
* 'else' directive:                      Else.               (line 2439)
* 'elseif' directive:                    Elseif.             (line 2446)
* empty expressions:                     Empty Exprs.        (line 1959)
* emulation:                             Overview.           (line  663)
* 'end' directive:                       End.                (line 2453)
* 'endfunc' directive:                   Endfunc.            (line 2459)
* endianness, MIPS:                      Overview.           (line  560)
* 'endif' directive:                     Endif.              (line 2464)
* 'endm' directive:                      Macro.              (line 3025)
* EOF, newline must precede:             Statements.         (line 1341)
* 'equ' directive:                       Equ.                (line 2471)
* 'equiv' directive:                     Equiv.              (line 2477)
* 'eqv' directive:                       Eqv.                (line 2493)
* 'err' directive:                       Err.                (line 2501)
* error directive:                       Error.              (line 2509)
* error messages:                        Errors.             (line  844)
* error on valid input:                  Bug Criteria.       (line 5553)
* errors, caused by warnings:            W.                  (line 1222)
* errors, continuing after:              Z.                  (line 1231)
* escape codes, character:               Strings.            (line 1395)
* 'exitm' directive:                     Macro.              (line 3028)
* expr (internal section):               As Sections.        (line 1678)
* expression arguments:                  Arguments.          (line 1973)
* expressions:                           Expressions.        (line 1946)
* expressions, comparison:               Infix Ops.          (line 2066)
* expressions, empty:                    Empty Exprs.        (line 1959)
* expressions, integer:                  Integer Exprs.      (line 1967)
* 'extern' directive:                    Extern.             (line 2524)
* 'fail' directive:                      Fail.               (line 2531)
* faster processing ('-f'):              f.                  (line  940)
* fatal signal:                          Bug Criteria.       (line 5550)
* 'file' directive:                      LNS directives.     (line 2369)
* 'file' directive <1>:                  File.               (line 2540)
* file name, logical:                    File.               (line 2540)
* files, including:                      Include.            (line 2721)
* files, input:                          Input Files.        (line  780)
* 'fill' directive:                      Fill.               (line 2550)
* filling memory:                        Skip.               (line 3452)
* filling memory <1>:                    Space.              (line 3459)
* 'float' directive:                     Float.              (line 2568)
* 'float' directive, i386:               i386-Float.         (line 4569)
* 'float' directive, x86-64:             i386-Float.         (line 4569)
* floating point numbers:                Flonums.            (line 1493)
* floating point numbers (double):       Double.             (line 2428)
* floating point numbers (single):       Float.              (line 2568)
* floating point numbers (single) <1>:   Single.             (line 3425)
* floating point, ARM (IEEE):            ARM Floating Point. (line 3910)
* floating point, i386:                  i386-Float.         (line 4561)
* floating point, SPARC (IEEE):          Sparc-Float.        (line 5473)
* floating point, x86-64:                i386-Float.         (line 4561)
* flonums:                               Flonums.            (line 1493)
* 'force_thumb' directive, ARM:          ARM Directives.     (line 3972)
* format of error messages:              Errors.             (line  861)
* format of warning messages:            Errors.             (line  850)
* formfeed ('\f'):                       Strings.            (line 1398)
* 'func' directive:                      Func.               (line 2574)
* functions, in expressions:             Operators.          (line 1998)
* 'global' directive:                    Global.             (line 2585)
* 'gp' register, MIPS:                   MIPS Object.        (line 5105)
* grouping data:                         Sub-Sections.       (line 1686)
* 'half' directive, SPARC:               Sparc-Directives.   (line 5489)
* hex character code ('\XD...'):         Strings.            (line 1416)
* hexadecimal integers:                  Integers.           (line 1475)
* 'hidden' directive:                    Hidden.             (line 2597)
* 'hword' directive:                     hword.              (line 2610)
* i386 16-bit code:                      i386-16bit.         (line 4615)
* i386 arch directive:                   i386-Arch.          (line 4670)
* i386 att_syntax pseudo op:             i386-Syntax.        (line 4265)
* i386 conversion instructions:          i386-Mnemonics.     (line 4334)
* i386 floating point:                   i386-Float.         (line 4561)
* i386 immediate operands:               i386-Syntax.        (line 4274)
* i386 instruction naming:               i386-Mnemonics.     (line 4309)
* i386 instruction prefixes:             i386-Prefixes.      (line 4414)
* i386 intel_syntax pseudo op:           i386-Syntax.        (line 4265)
* i386 jump optimization:                i386-Jumps.         (line 4538)
* i386 jump, call, return:               i386-Syntax.        (line 4296)
* i386 jump/call operands:               i386-Syntax.        (line 4274)
* i386 memory references:                i386-Memory.        (line 4471)
* i386 'mul', 'imul' instructions:       i386-Notes.         (line 4714)
* i386 options:                          i386-Options.       (line 4218)
* i386 register operands:                i386-Syntax.        (line 4274)
* i386 registers:                        i386-Regs.          (line 4359)
* i386 sections:                         i386-Syntax.        (line 4302)
* i386 size suffixes:                    i386-Syntax.        (line 4287)
* i386 source, destination operands:     i386-Syntax.        (line 4280)
* i386 support:                          .                   (line 4211)
* i386 syntax compatibility:             i386-Syntax.        (line 4265)
* i80306 support:                        .                   (line 4211)
* IA-64 line comment character:          IA-64-Chars.        (line 4822)
* IA-64 line separator:                  IA-64-Chars.        (line 4824)
* IA-64 options:                         IA-64 Options.      (line 4733)
* IA-64 Processor-status-Register bit names: IA-64-Bits.     (line 4846)
* IA-64 registers:                       IA-64-Regs.         (line 4829)
* IA-64 support:                         .                   (line 4730)
* IA-64 Syntax:                          IA-64 Options.      (line 4812)
* 'ident' directive:                     Ident.              (line 2618)
* identifiers, ARM:                      ARM-Chars.          (line 3876)
* 'if' directive:                        If.                 (line 2629)
* 'ifb' directive:                       If.                 (line 2644)
* 'ifc' directive:                       If.                 (line 2648)
* 'ifdef' directive:                     If.                 (line 2639)
* 'ifeq' directive:                      If.                 (line 2656)
* 'ifeqs' directive:                     If.                 (line 2659)
* 'ifge' directive:                      If.                 (line 2663)
* 'ifgt' directive:                      If.                 (line 2667)
* 'ifle' directive:                      If.                 (line 2671)
* 'iflt' directive:                      If.                 (line 2675)
* 'ifnb' directive:                      If.                 (line 2679)
* 'ifnc' directive:                      If.                 (line 2684)
* 'ifndef' directive:                    If.                 (line 2688)
* 'ifne' directive:                      If.                 (line 2695)
* 'ifnes' directive:                     If.                 (line 2699)
* 'ifnotdef' directive:                  If.                 (line 2688)
* immediate character, ARM:              ARM-Chars.          (line 3874)
* immediate operands, i386:              i386-Syntax.        (line 4274)
* immediate operands, x86-64:            i386-Syntax.        (line 4274)
* 'imul' instruction, i386:              i386-Notes.         (line 4714)
* 'imul' instruction, x86-64:            i386-Notes.         (line 4714)
* 'incbin' directive:                    Incbin.             (line 2707)
* 'include' directive:                   Include.            (line 2721)
* 'include' directive search path:       I.                  (line  952)
* infix operators:                       Infix Ops.          (line 2016)
* inhibiting interrupts, i386:           i386-Prefixes.      (line 4444)
* input:                                 Input Files.        (line  780)
* input file linenumbers:                Input Files.        (line  809)
* instruction naming, i386:              i386-Mnemonics.     (line 4309)
* instruction naming, x86-64:            i386-Mnemonics.     (line 4309)
* instruction prefixes, i386:            i386-Prefixes.      (line 4414)
* instructions and directives:           Statements.         (line 1347)
* 'int' directive:                       Int.                (line 2732)
* 'int' directive, i386:                 i386-Float.         (line 4576)
* 'int' directive, x86-64:               i386-Float.         (line 4576)
* integer expressions:                   Integer Exprs.      (line 1967)
* integer, 16-byte:                      Octa.               (line 3092)
* integer, 8-byte:                       Quad.               (line 3245)
* integers:                              Integers.           (line 1466)
* integers, 16-bit:                      hword.              (line 2610)
* integers, 32-bit:                      Int.                (line 2732)
* integers, binary:                      Integers.           (line 1466)
* integers, decimal:                     Integers.           (line 1472)
* integers, hexadecimal:                 Integers.           (line 1475)
* integers, octal:                       Integers.           (line 1469)
* integers, one byte:                    Byte.               (line 2211)
* intel_syntax pseudo op, i386:          i386-Syntax.        (line 4265)
* intel_syntax pseudo op, x86-64:        i386-Syntax.        (line 4265)
* internal assembler sections:           As Sections.        (line 1667)
* 'internal' directive:                  Internal.           (line 2740)
* invalid input:                         Bug Criteria.       (line 5555)
* invocation summary:                    Overview.           (line  249)
* 'irp' directive:                       Irp.                (line 2754)
* 'irpc' directive:                      Irpc.               (line 2779)
* joining text and data sections:        R.                  (line 1170)
* jump instructions, i386:               i386-Mnemonics.     (line 4353)
* jump instructions, x86-64:             i386-Mnemonics.     (line 4353)
* jump optimization, i386:               i386-Jumps.         (line 4538)
* jump optimization, x86-64:             i386-Jumps.         (line 4538)
* jump/call operands, i386:              i386-Syntax.        (line 4274)
* jump/call operands, x86-64:            i386-Syntax.        (line 4274)
* label (':'):                           Statements.         (line 1355)
* labels:                                Labels.             (line 1763)
* 'lcomm' directive:                     Lcomm.              (line 2805)
* ld:                                    Object.             (line  836)
* 'LDR reg,=<label>' pseudo op, ARM:     ARM Opcodes.        (line 4149)
* length of symbols:                     Symbol Intro.       (line 1331)
* 'lflags' directive (ignored):          Lflags.             (line 2814)
* line comment character:                Comments.           (line 1301)
* line comment character, ARM:           ARM-Chars.          (line 3867)
* line comment character, IA-64:         IA-64-Chars.        (line 4822)
* 'line' directive:                      Line.               (line 2820)
* line numbers, in input files:          Input Files.        (line  809)
* line numbers, in warnings/errors:      Errors.             (line  854)
* line separator character:              Statements.         (line 1336)
* line separator, ARM:                   ARM-Chars.          (line 3871)
* line separator, IA-64:                 IA-64-Chars.        (line 4824)
* lines starting with '#':               Comments.           (line 1306)
* linker:                                Object.             (line  836)
* linker, and assembler:                 Secs Background.    (line 1535)
* 'linkonce' directive:                  Linkonce.           (line 2831)
* 'list' directive:                      List.               (line 2876)
* listing control, turning off:          Nolist.             (line 3083)
* listing control, turning on:           List.               (line 2876)
* listing control: new page:             Eject.              (line 2434)
* listing control: paper size:           Psize.              (line 3208)
* listing control: subtitle:             Sbttl.              (line 3284)
* listing control: title line:           Title.              (line 3609)
* listings, enabling:                    a.                  (line  894)
* little endian output, MIPS:            Overview.           (line  563)
* little-endian output, MIPS:            MIPS Opts.          (line 4879)
* 'ln' directive:                        Ln.                 (line 2863)
* 'loc' directive:                       LNS directives.     (line 2382)
* local common symbols:                  Lcomm.              (line 2805)
* local labels:                          Symbol Names.       (line 1810)
* local symbol names:                    Symbol Names.       (line 1797)
* local symbols, retaining in output:    L.                  (line  972)
* location counter:                      Dot.                (line 1898)
* location counter, advancing:           Org.                (line 3101)
* 'loc_mark_blocks' directive:           LNS directives.     (line 2412)
* logical file name:                     File.               (line 2540)
* logical line number:                   Line.               (line 2820)
* logical line numbers:                  Comments.           (line 1306)
* 'long' directive:                      Long.               (line 2889)
* 'long' directive, i386:                i386-Float.         (line 4576)
* 'long' directive, x86-64:              i386-Float.         (line 4576)
* machine directives, ARM:               ARM Directives.     (line 3915)
* machine directives, SPARC:             Sparc-Directives.   (line 5478)
* machine independent directives:        Pseudo Ops.         (line 2105)
* machine instructions (not covered):    Manual.             (line  716)
* machine-independent syntax:            Syntax.             (line 1241)
* 'macro' directive:                     Macro.              (line 2916)
* macros:                                Macro.              (line 2894)
* macros, count executed:                Macro.              (line 3030)
* make rules:                            MD.                 (line 1149)
* manual, structure and purpose:         Manual.             (line  708)
* Maximum number of continuation lines:  listing.            (line 1015)
* memory references, i386:               i386-Memory.        (line 4471)
* memory references, x86-64:             i386-Memory.        (line 4471)
* merging text and data sections:        R.                  (line 1170)
* messages from assembler:               Errors.             (line  844)
* minus, permitted arguments:            Infix Ops.          (line 2060)
* MIPS architecture options:             MIPS Opts.          (line 4895)
* MIPS big-endian output:                MIPS Opts.          (line 4879)
* MIPS CPU override:                     MIPS ISA.           (line 5195)
* MIPS debugging directives:             MIPS Stabs.         (line 5128)
* MIPS DSP Release 1 instruction generation override: MIPS ASE instruction generation overrides.
                                                             (line 5262)
* MIPS DSP Release 2 instruction generation override: MIPS ASE instruction generation overrides.
                                                             (line 5267)
* MIPS ECOFF sections:                   MIPS Object.        (line 5100)
* MIPS endianness:                       Overview.           (line  560)
* MIPS ISA:                              Overview.           (line  566)
* MIPS ISA override:                     MIPS ISA.           (line 5183)
* MIPS little-endian output:             MIPS Opts.          (line 4879)
* MIPS MDMX instruction generation override: MIPS ASE instruction generation overrides.
                                                             (line 5257)
* MIPS MIPS-3D instruction generation override: MIPS ASE instruction generation overrides.
                                                             (line 5247)
* MIPS MT instruction generation override: MIPS ASE instruction generation overrides.
                                                             (line 5272)
* MIPS option stack:                     MIPS option stack.  (line 5232)
* MIPS processor:                        .                   (line 4862)
* MMX, i386:                             i386-SIMD.          (line 4593)
* MMX, x86-64:                           i386-SIMD.          (line 4593)
* mnemonic suffixes, i386:               i386-Syntax.        (line 4287)
* mnemonic suffixes, x86-64:             i386-Syntax.        (line 4287)
* MOVW and MOVT relocations, ARM:        ARM-Relocations.    (line 3900)
* MRI compatibility mode:                M.                  (line 1022)
* 'mri' directive:                       MRI.                (line 2868)
* MRI mode, temporarily:                 MRI.                (line 2868)
* 'mul' instruction, i386:               i386-Notes.         (line 4714)
* 'mul' instruction, x86-64:             i386-Notes.         (line 4714)
* named section:                         Section.            (line 3293)
* named sections:                        Ld Sections.        (line 1613)
* names, symbol:                         Symbol Names.       (line 1781)
* naming object file:                    o.                  (line 1160)
* new page, in listings:                 Eject.              (line 2434)
* newline ('\n'):                        Strings.            (line 1401)
* newline, required at file end:         Statements.         (line 1341)
* 'nolist' directive:                    Nolist.             (line 3083)
* 'NOP' pseudo op, ARM:                  ARM Opcodes.        (line 4143)
* null-terminated strings:               Asciz.              (line 2172)
* number constants:                      Numbers.            (line 1457)
* number of macros executed:             Macro.              (line 3030)
* numbered subsections:                  Sub-Sections.       (line 1686)
* numbers, 16-bit:                       hword.              (line 2610)
* numeric values:                        Expressions.        (line 1946)
* 'nword' directive, SPARC:              Sparc-Directives.   (line 5492)
* object file:                           Object.             (line  827)
* object file format:                    Object Formats.     (line  746)
* object file name:                      o.                  (line 1160)
* object file, after errors:             Z.                  (line 1231)
* obsolescent directives:                Deprecated.         (line 3731)
* 'octa' directive:                      Octa.               (line 3092)
* octal character code ('\DDD'):         Strings.            (line 1410)
* octal integers:                        Integers.           (line 1469)
* opcodes for ARM:                       ARM Opcodes.        (line 4140)
* operand delimiters, i386:              i386-Syntax.        (line 4274)
* operand delimiters, x86-64:            i386-Syntax.        (line 4274)
* operands in expressions:               Arguments.          (line 1973)
* operator precedence:                   Infix Ops.          (line 2021)
* operators, in expressions:             Operators.          (line 1998)
* operators, permitted arguments:        Infix Ops.          (line 2016)
* option summary:                        Overview.           (line  249)
* options for ARM (none):                ARM Options.        (line 3742)
* options for i386:                      i386-Options.       (line 4218)
* options for IA-64:                     IA-64 Options.      (line 4733)
* options for PowerPC:                   PowerPC-Opts.       (line 5285)
* options for SPARC:                     Sparc-Opts.         (line 5402)
* options for x86-64:                    i386-Options.       (line 4218)
* options, all versions of assembler:    Invoking.           (line  870)
* options, command line:                 Command Line.       (line  763)
* 'org' directive:                       Org.                (line 3101)
* output file:                           Object.             (line  827)
* 'p2align' directive:                   P2align.            (line 3127)
* 'p2alignl' directive:                  P2align.            (line 3149)
* 'p2alignw' directive:                  P2align.            (line 3149)
* padding the location counter:          Align.              (line 2123)
* padding the location counter given a power of two: P2align.
                                                             (line 3127)
* padding the location counter given number of bytes: Balign.
                                                             (line 2178)
* page, in listings:                     Eject.              (line 2434)
* paper size, for listings:              Psize.              (line 3208)
* paths for '.include':                  I.                  (line  952)
* patterns, writing in memory:           Fill.               (line 2550)
* PIC code generation for ARM:           ARM Options.        (line 3857)
* PIC selection, MIPS:                   MIPS Opts.          (line 4887)
* plus, permitted arguments:             Infix Ops.          (line 2055)
* 'popsection' directive:                PopSection.         (line 3177)
* PowerPC architectures:                 PowerPC-Opts.       (line 5285)
* PowerPC directives:                    PowerPC-Pseudo.     (line 5386)
* PowerPC options:                       PowerPC-Opts.       (line 5285)
* PowerPC support:                       .                   (line 5282)
* precedence of operators:               Infix Ops.          (line 2021)
* precision, floating point:             Flonums.            (line 1493)
* prefix operators:                      Prefix Ops.         (line 2005)
* prefixes, i386:                        i386-Prefixes.      (line 4414)
* preprocessing:                         Preprocessing.      (line 1248)
* preprocessing, turning on and off:     Preprocessing.      (line 1268)
* 'previous' directive:                  Previous.           (line 3161)
* 'print' directive:                     Print.              (line 3189)
* 'proc' directive, SPARC:               Sparc-Directives.   (line 5497)
* 'protected' directive:                 Protected.          (line 3195)
* pseudo-ops, machine independent:       Pseudo Ops.         (line 2105)
* 'psize' directive:                     Psize.              (line 3208)
* PSR bits:                              IA-64-Bits.         (line 4846)
* 'purgem' directive:                    Purgem.             (line 3224)
* purpose of GNU assembler:              GNU Assembler.      (line  734)
* 'pushsection' directive:               PushSection.        (line 3230)
* 'quad' directive:                      Quad.               (line 3242)
* 'quad' directive, i386:                i386-Float.         (line 4576)
* 'quad' directive, x86-64:              i386-Float.         (line 4576)
* real-mode code, i386:                  i386-16bit.         (line 4615)
* 'register' directive, SPARC:           Sparc-Directives.   (line 5501)
* register names, ARM:                   ARM-Regs.           (line 3881)
* register names, IA-64:                 IA-64-Regs.         (line 4829)
* register operands, i386:               i386-Syntax.        (line 4274)
* register operands, x86-64:             i386-Syntax.        (line 4274)
* registers, i386:                       i386-Regs.          (line 4359)
* registers, x86-64:                     i386-Regs.          (line 4359)
* 'reloc' directive:                     Reloc.              (line 3253)
* relocation:                            Sections.           (line 1528)
* relocation example:                    Ld Sections.        (line 1643)
* repeat prefixes, i386:                 i386-Prefixes.      (line 4452)
* reporting bugs in assembler:           Reporting Bugs.     (line 5534)
* 'rept' directive:                      Rept.               (line 3266)
* 'req' directive, ARM:                  ARM Directives.     (line 3922)
* 'reserve' directive, SPARC:            Sparc-Directives.   (line 5511)
* return instructions, i386:             i386-Syntax.        (line 4296)
* return instructions, x86-64:           i386-Syntax.        (line 4296)
* REX prefixes, i386:                    i386-Prefixes.      (line 4454)
* 'sbttl' directive:                     Sbttl.              (line 3284)
* search path for '.include':            I.                  (line  952)
* 'section' directive (ELF version):     Section.            (line 3305)
* section override prefixes, i386:       i386-Prefixes.      (line 4431)
* Section Stack:                         Previous.           (line 3161)
* Section Stack <1>:                     PopSection.         (line 3177)
* Section Stack <2>:                     PushSection.        (line 3230)
* Section Stack <3>:                     Section.            (line 3300)
* Section Stack <4>:                     SubSection.         (line 3545)
* section-relative addressing:           Secs Background.    (line 1573)
* sections:                              Sections.           (line 1528)
* sections in messages, internal:        As Sections.        (line 1667)
* sections, i386:                        i386-Syntax.        (line 4302)
* sections, named:                       Ld Sections.        (line 1613)
* sections, x86-64:                      i386-Syntax.        (line 4302)
* 'seg' directive, SPARC:                Sparc-Directives.   (line 5516)
* 'set' directive:                       Set.                (line 3407)
* 'short' directive:                     Short.              (line 3419)
* SIMD, i386:                            i386-SIMD.          (line 4593)
* SIMD, x86-64:                          i386-SIMD.          (line 4593)
* single character constant:             Chars.              (line 1443)
* 'single' directive:                    Single.             (line 3425)
* 'single' directive, i386:              i386-Float.         (line 4569)
* 'single' directive, x86-64:            i386-Float.         (line 4569)
* sixteen bit integers:                  hword.              (line 2610)
* sixteen byte integer:                  Octa.               (line 3092)
* 'size' directive (ELF version):        Size.               (line 3433)
* size prefixes, i386:                   i386-Prefixes.      (line 4435)
* sizes operands, i386:                  i386-Syntax.        (line 4287)
* sizes operands, x86-64:                i386-Syntax.        (line 4287)
* 'skip' directive:                      Skip.               (line 3452)
* 'skip' directive, SPARC:               Sparc-Directives.   (line 5520)
* 'sleb128' directive:                   Sleb128.            (line 3445)
* small objects, MIPS ECOFF:             MIPS Object.        (line 5105)
* SmartMIPS instruction generation override: MIPS ASE instruction generation overrides.
                                                             (line 5252)
* source program:                        Input Files.        (line  780)
* source, destination operands; i386:    i386-Syntax.        (line 4280)
* source, destination operands; x86-64:  i386-Syntax.        (line 4280)
* 'space' directive:                     Space.              (line 3459)
* space used, maximum for assembly:      statistics.         (line 1188)
* SPARC architectures:                   Sparc-Opts.         (line 5402)
* SPARC data alignment:                  Sparc-Aligned-Data. (line 5455)
* SPARC floating point (IEEE):           Sparc-Float.        (line 5473)
* SPARC machine directives:              Sparc-Directives.   (line 5478)
* SPARC options:                         Sparc-Opts.         (line 5402)
* SPARC support:                         .                   (line 5399)
* 'stabd' directive:                     Stab.               (line 3498)
* 'stabn' directive:                     Stab.               (line 3509)
* 'stabs' directive:                     Stab.               (line 3512)
* 'stabX' directives:                    Stab.               (line 3466)
* standard assembler sections:           Secs Background.    (line 1550)
* standard input, as input file:         Command Line.       (line  760)
* statement separator character:         Statements.         (line 1336)
* statement separator, ARM:              ARM-Chars.          (line 3871)
* statement separator, IA-64:            IA-64-Chars.        (line 4824)
* statements, structure of:              Statements.         (line 1336)
* statistics, about assembly:            statistics.         (line 1188)
* stopping the assembly:                 Abort.              (line 2114)
* string constants:                      Strings.            (line 1386)
* 'string' directive:                    String.             (line 3518)
* string literals:                       Ascii.              (line 2165)
* string, copying to object file:        String.             (line 3518)
* 'struct' directive:                    Struct.             (line 3527)
* subexpressions:                        Arguments.          (line 1991)
* 'subsection' directive:                SubSection.         (line 3545)
* subtitles for listings:                Sbttl.              (line 3284)
* subtraction, permitted arguments:      Infix Ops.          (line 2060)
* summary of options:                    Overview.           (line  249)
* supporting files, including:           Include.            (line 2721)
* suppressing warnings:                  W.                  (line 1217)
* symbol attributes:                     Symbol Attributes.  (line 1907)
* symbol names:                          Symbol Names.       (line 1781)
* symbol names, local:                   Symbol Names.       (line 1797)
* symbol names, temporary:               Symbol Names.       (line 1810)
* symbol type:                           Symbol Type.        (line 1938)
* symbol type, ELF:                      Type.               (line 3620)
* symbol value:                          Symbol Value.       (line 1918)
* symbol value, setting:                 Set.                (line 3407)
* symbol values, assigning:              Setting Symbols.    (line 1772)
* symbol versioning:                     Symver.             (line 3557)
* symbol, common:                        Comm.               (line 2217)
* symbol, making visible to linker:      Global.             (line 2585)
* symbolic debuggers, information for:   Stab.               (line 3466)
* symbols:                               Symbols.            (line 1753)
* symbols, assigning values to:          Equ.                (line 2471)
* symbols, local common:                 Lcomm.              (line 2805)
* 'symver' directive:                    Symver.             (line 3557)
* syntax compatibility, i386:            i386-Syntax.        (line 4265)
* syntax compatibility, x86-64:          i386-Syntax.        (line 4265)
* syntax, machine-independent:           Syntax.             (line 1241)
* tab ('\t'):                            Strings.            (line 1407)
* temporary symbol names:                Symbol Names.       (line 1810)
* text and data sections, joining:       R.                  (line 1170)
* 'text' directive:                      Text.               (line 3602)
* 'tfloat' directive, i386:              i386-Float.         (line 4569)
* 'tfloat' directive, x86-64:            i386-Float.         (line 4569)
* 'thumb' directive, ARM:                ARM Directives.     (line 3966)
* Thumb support:                         Machine Dependencies.
                                                             (line 3739)
* 'thumb_func' directive, ARM:           ARM Directives.     (line 3976)
* 'thumb_set' directive, ARM:            ARM Directives.     (line 3987)
* time, total for assembly:              statistics.         (line 1188)
* 'title' directive:                     Title.              (line 3609)
* trusted compiler:                      f.                  (line  940)
* turning preprocessing on and off:      Preprocessing.      (line 1268)
* 'type' directive (ELF version):        Type.               (line 3620)
* type of a symbol:                      Symbol Type.        (line 1938)
* 'uleb128' directive:                   Uleb128.            (line 3656)
* undefined section:                     Ld Sections.        (line 1639)
* 'unreq' directive, ARM:                ARM Directives.     (line 3927)
* value of a symbol:                     Symbol Value.       (line 1918)
* 'version' directive:                   Version.            (line 3663)
* version of assembler:                  v.                  (line 1206)
* versions of symbols:                   Symver.             (line 3557)
* visibility:                            Hidden.             (line 2597)
* visibility <1>:                        Internal.           (line 2740)
* visibility <2>:                        Protected.          (line 3195)
* 'vtable_entry' directive:              VTableEntry.        (line 3669)
* 'vtable_inherit' directive:            VTableInherit.      (line 3675)
* warning directive:                     Warning.            (line 3683)
* warning messages:                      Errors.             (line  844)
* warnings, causing error:               W.                  (line 1222)
* warnings, suppressing:                 W.                  (line 1217)
* warnings, switching on:                W.                  (line 1225)
* 'weak' directive:                      Weak.               (line 3689)
* 'weakref' directive:                   Weakref.            (line 3705)
* whitespace:                            Whitespace.         (line 1280)
* whitespace, removed by preprocessor:   Preprocessing.      (line 1249)
* Width of continuation lines of disassembly output: listing.
                                                             (line 1002)
* Width of first line disassembly output: listing.           (line  997)
* Width of source line output:           listing.            (line 1009)
* 'word' directive:                      Word.               (line 3725)
* 'word' directive, i386:                i386-Float.         (line 4576)
* 'word' directive, SPARC:               Sparc-Directives.   (line 5523)
* 'word' directive, x86-64:              i386-Float.         (line 4576)
* writing patterns in memory:            Fill.               (line 2550)
* x86-64 arch directive:                 i386-Arch.          (line 4670)
* x86-64 att_syntax pseudo op:           i386-Syntax.        (line 4265)
* x86-64 conversion instructions:        i386-Mnemonics.     (line 4334)
* x86-64 floating point:                 i386-Float.         (line 4561)
* x86-64 immediate operands:             i386-Syntax.        (line 4274)
* x86-64 instruction naming:             i386-Mnemonics.     (line 4309)
* x86-64 intel_syntax pseudo op:         i386-Syntax.        (line 4265)
* x86-64 jump optimization:              i386-Jumps.         (line 4538)
* x86-64 jump, call, return:             i386-Syntax.        (line 4296)
* x86-64 jump/call operands:             i386-Syntax.        (line 4274)
* x86-64 memory references:              i386-Memory.        (line 4471)
* x86-64 options:                        i386-Options.       (line 4218)
* x86-64 register operands:              i386-Syntax.        (line 4274)
* x86-64 registers:                      i386-Regs.          (line 4359)
* x86-64 sections:                       i386-Syntax.        (line 4302)
* x86-64 size suffixes:                  i386-Syntax.        (line 4287)
* x86-64 source, destination operands:   i386-Syntax.        (line 4280)
* x86-64 support:                        .                   (line 4211)
* x86-64 syntax compatibility:           i386-Syntax.        (line 4265)
* 'xword' directive, SPARC:              Sparc-Directives.   (line 5527)
* zero-terminated strings:               Asciz.              (line 2172)

START-INFO-DIR-ENTRY
* As: (as).                     The GNU assembler.
* Gas: (as).                    The GNU assembler.
END-INFO-DIR-ENTRY

Using as
1 Overview
  1.1 Structure of this Manual
  1.2 The GNU Assembler
  1.3 Object File Formats
  1.4 Command Line
  1.5 Input Files
  1.6 Output (Object) File
  1.7 Error and Warning Messages
2 Command-Line Options
  2.1 Enable Listings: '-a[cdhlns]'
  2.2 '--alternate'
  2.3 '-D'
  2.4 Work Faster: '-f'
  2.5 '.include' Search Path: '-I' PATH
  2.6 Difference Tables: '-K'
  2.7 Include Local Symbols: '-L'
  2.8 Configuring listing output: '--listing'
  2.9 Assemble in MRI Compatibility Mode: '-M'
  2.10 Dependency Tracking: '--MD'
  2.11 Name the Object File: '-o'
  2.12 Join Data and Text Sections: '-R'
  2.13 Display Assembly Statistics: '--statistics'
  2.14 Compatible Output: '--traditional-format'
  2.15 Announce Version: '-v'
  2.16 Control Warnings: '-W', '--warn', '--no-warn', '--fatal-warnings'
  2.17 Generate Object File in Spite of Errors: '-Z'
3 Syntax
  3.1 Preprocessing
  3.2 Whitespace
  3.3 Comments
  3.4 Symbols
  3.5 Statements
  3.6 Constants
    3.6.1 Character Constants
      3.6.1.1 Strings
      3.6.1.2 Characters
    3.6.2 Number Constants
      3.6.2.1 Integers
      3.6.2.2 Bignums
      3.6.2.3 Flonums
4 Sections and Relocation
  4.1 Background
  4.2 Linker Sections
  4.3 Assembler Internal Sections
  4.4 Sub-Sections
  4.5 bss Section
5 Symbols
  5.1 Labels
  5.2 Giving Symbols Other Values
  5.3 Symbol Names
  5.4 The Special Dot Symbol
  5.5 Symbol Attributes
    5.5.1 Value
    5.5.2 Type
6 Expressions
  6.1 Empty Expressions
  6.2 Integer Expressions
    6.2.1 Arguments
    6.2.2 Operators
    6.2.3 Prefix Operator
    6.2.4 Infix Operators
7 Assembler Directives
  7.1 '.abort'
  7.2 '.align ABS-EXPR, ABS-EXPR, ABS-EXPR'
  7.3 '.ascii "STRING"'...
  7.4 '.asciz "STRING"'...
  7.5 '.balign[wl] ABS-EXPR, ABS-EXPR, ABS-EXPR'
  7.6 '.byte EXPRESSIONS'
  7.7 '.comm SYMBOL , LENGTH '
  7.8 '.cfi_startproc [simple]'
  7.9 '.cfi_endproc'
  7.10 '.cfi_personality ENCODING [, EXP]'
  7.11 '.cfi_lsda ENCODING [, EXP]'
  7.12 '.cfi_def_cfa REGISTER, OFFSET'
  7.13 '.cfi_def_cfa_register REGISTER'
  7.14 '.cfi_def_cfa_offset OFFSET'
  7.15 '.cfi_adjust_cfa_offset OFFSET'
  7.16 '.cfi_offset REGISTER, OFFSET'
  7.17 '.cfi_rel_offset REGISTER, OFFSET'
  7.18 '.cfi_register REGISTER1, REGISTER2'
  7.19 '.cfi_restore REGISTER'
  7.20 '.cfi_undefined REGISTER'
  7.21 '.cfi_same_value REGISTER'
  7.22 '.cfi_remember_state',
  7.23 '.cfi_return_column REGISTER'
  7.24 '.cfi_signal_frame'
  7.25 '.cfi_window_save'
  7.26 '.cfi_escape' EXPRESSION[, ...]
  7.27 '.file FILENO FILENAME'
  7.28 '.loc FILENO LINENO [COLUMN] [OPTIONS]'
  7.29 '.loc_mark_blocks ENABLE'
  7.30 '.data SUBSECTION'
  7.31 '.double FLONUMS'
  7.32 '.eject'
  7.33 '.else'
  7.34 '.elseif'
  7.35 '.end'
  7.36 '.endfunc'
  7.37 '.endif'
  7.38 '.equ SYMBOL, EXPRESSION'
  7.39 '.equiv SYMBOL, EXPRESSION'
  7.40 '.eqv SYMBOL, EXPRESSION'
  7.41 '.err'
  7.42 '.error "STRING"'
  7.43 '.exitm'
  7.44 '.extern'
  7.45 '.fail EXPRESSION'
  7.46 '.file STRING'
  7.47 '.fill REPEAT , SIZE , VALUE'
  7.48 '.float FLONUMS'
  7.49 '.func NAME[,LABEL]'
  7.50 '.global SYMBOL', '.globl SYMBOL'
  7.51 '.hidden NAMES'
  7.52 '.hword EXPRESSIONS'
  7.53 '.ident'
  7.54 '.if ABSOLUTE EXPRESSION'
  7.55 '.incbin "FILE"[,SKIP[,COUNT]]'
  7.56 '.include "FILE"'
  7.57 '.int EXPRESSIONS'
  7.58 '.internal NAMES'
  7.59 '.irp SYMBOL,VALUES'...
  7.60 '.irpc SYMBOL,VALUES'...
  7.61 '.lcomm SYMBOL , LENGTH'
  7.62 '.lflags'
  7.63 '.line LINE-NUMBER'
  7.64 '.linkonce [TYPE]'
  7.65 '.ln LINE-NUMBER'
  7.66 '.mri VAL'
  7.67 '.list'
  7.68 '.long EXPRESSIONS'
  7.69 '.macro'
  7.70 '.altmacro'
  7.71 '.noaltmacro'
  7.72 '.nolist'
  7.73 '.octa BIGNUMS'
  7.74 '.org NEW-LC , FILL'
  7.75 '.p2align[wl] ABS-EXPR, ABS-EXPR, ABS-EXPR'
  7.76 '.previous'
  7.77 '.popsection'
  7.78 '.print STRING'
  7.79 '.protected NAMES'
  7.80 '.psize LINES , COLUMNS'
  7.81 '.purgem NAME'
  7.82 '.pushsection NAME , SUBSECTION'
  7.83 '.quad BIGNUMS'
  7.84 '.reloc OFFSET, RELOC_NAME[, EXPRESSION]'
  7.85 '.rept COUNT'
  7.86 '.sbttl "SUBHEADING"'
  7.87 '.section NAME'
  7.88 '.set SYMBOL, EXPRESSION'
  7.89 '.short EXPRESSIONS'
  7.90 '.single FLONUMS'
  7.91 '.size'
  7.92 '.sleb128 EXPRESSIONS'
  7.93 '.skip SIZE , FILL'
  7.94 '.space SIZE , FILL'
  7.95 '.stabd, .stabn, .stabs'
  7.96 '.string' "STR"
  7.97 '.struct EXPRESSION'
  7.98 '.subsection NAME'
  7.99 '.symver'
  7.100 '.text SUBSECTION'
  7.101 '.title "HEADING"'
  7.102 '.type'
  7.103 '.uleb128 EXPRESSIONS'
  7.104 '.version "STRING"'
  7.105 '.vtable_entry TABLE, OFFSET'
  7.106 '.vtable_inherit CHILD, PARENT'
  7.107 '.warning "STRING"'
  7.108 '.weak NAMES'
  7.109 '.weakref ALIAS, TARGET'
  7.110 '.word EXPRESSIONS'
  7.111 Deprecated Directives
8 ARM Dependent Features
  8.1 Options
  8.2 Syntax
    8.2.1 Special Characters
    8.2.2 Register Names
    8.2.3 ARM relocation generation
  8.3 Floating Point
  8.4 ARM Machine Directives
  8.5 Opcodes
  8.6 Mapping Symbols
9 80386 Dependent Features
  9.1 Options
  9.2 AT&T Syntax versus Intel Syntax
  9.3 Instruction Naming
  9.4 Register Naming
  9.5 Instruction Prefixes
  9.6 Memory References
  9.7 Handling of Jump Instructions
  9.8 Floating Point
  9.9 Intel's MMX and AMD's 3DNow! SIMD Operations
  9.10 Writing 16-bit Code
  9.11 AT&T Syntax bugs
  9.12 Specifying CPU Architecture
  9.13 Notes
10 IA-64 Dependent Features
  10.1 Options
  10.2 Syntax
    10.2.1 Special Characters
    10.2.2 Register Names
    10.2.3 IA-64 Processor-Status-Register (PSR) Bit Names
  10.3 Opcodes
11 MIPS Dependent Features
  11.1 Assembler options
  11.2 MIPS ECOFF object code
  11.3 Directives for debugging information
  11.4 Directives to override the size of symbols
  11.5 Directives to override the ISA level
  11.6 Directives for extending MIPS 16 bit instructions
  11.7 Directive to mark data as an instruction
  11.8 Directives to save and restore options
  11.9 Directives to control generation of MIPS ASE instructions
12 PowerPC Dependent Features
  12.1 Options
  12.2 PowerPC Assembler Directives
13 SPARC Dependent Features
  13.1 Options
  13.2 Enforcing aligned data
  13.3 Floating Point
  13.4 Sparc Machine Directives
14 Reporting Bugs
  14.1 Have You Found a Bug?
  14.2 How to Report Bugs
15 Acknowledgements
Appendix A GNU Free Documentation License
  ADDENDUM: How to use this License for your documents
AS Index
Using as
********

This file is a user guide to the GNU assembler 'as' version "2.17.50
[FreeBSD] 2007-07-03".  This version of the file describes 'as'
configured to generate code for machine specific architectures.

   This document is distributed under the terms of the GNU Free
Documentation License.  A copy of the license is included in the section
entitled "GNU Free Documentation License".

1 Overview
**********

Here is a brief summary of how to invoke 'as'.  For details, see *note
Command-Line Options: Invoking.

     as [-a[cdhlns][=FILE]] [-alternate] [-D]
      [-defsym SYM=VAL] [-f] [-g] [-gstabs]
      [-gstabs+] [-gdwarf-2] [-help] [-I DIR] [-J]
      [-K] [-L] [-listing-lhs-width=NUM]
      [-listing-lhs-width2=NUM] [-listing-rhs-width=NUM]
      [-listing-cont-lines=NUM] [-keep-locals] [-o
      OBJFILE] [-R] [-reduce-memory-overheads] [-statistics]
      [-v] [-version] [-version] [-W] [-warn]
      [-fatal-warnings] [-w] [-x] [-Z] [@FILE]
      [-target-help] [TARGET-OPTIONS]
      [-|FILES ...]

     _Target ARM options:_
        [-mcpu=PROCESSOR[+EXTENSION...]]
        [-march=ARCHITECTURE[+EXTENSION...]]
        [-mfpu=FLOATING-POINT-FORMAT]
        [-mfloat-abi=ABI]
        [-meabi=VER]
        [-mthumb]
        [-EB|-EL]
        [-mapcs-32|-mapcs-26|-mapcs-float|
         -mapcs-reentrant]
        [-mthumb-interwork] [-k]

     _Target i386 options:_
        [-32|-64] [-n]
        [-march=CPU] [-mtune=CPU]

     _Target IA-64 options:_
        [-mconstant-gp|-mauto-pic]
        [-milp32|-milp64|-mlp64|-mp64]
        [-mle|mbe]
        [-mtune=itanium1|-mtune=itanium2]
        [-munwind-check=warning|-munwind-check=error]
        [-mhint.b=ok|-mhint.b=warning|-mhint.b=error]
        [-x|-xexplicit] [-xauto] [-xdebug]

     _Target MIPS options:_
        [-nocpp] [-EL] [-EB] [-O[OPTIMIZATION LEVEL]]
        [-g[DEBUG LEVEL]] [-G NUM] [-KPIC] [-call_shared]
        [-non_shared] [-xgot [-mvxworks-pic]
        [-mabi=ABI] [-32] [-n32] [-64] [-mfp32] [-mgp32]
        [-march=CPU] [-mtune=CPU] [-mips1] [-mips2]
        [-mips3] [-mips4] [-mips5] [-mips32] [-mips32r2]
        [-mips64] [-mips64r2]
        [-construct-floats] [-no-construct-floats]
        [-trap] [-no-break] [-break] [-no-trap]
        [-mfix7000] [-mno-fix7000]
        [-mips16] [-no-mips16]
        [-msmartmips] [-mno-smartmips]
        [-mips3d] [-no-mips3d]
        [-mdmx] [-no-mdmx]
        [-mdsp] [-mno-dsp]
        [-mdspr2] [-mno-dspr2]
        [-mmt] [-mno-mt]
        [-mdebug] [-no-mdebug]
        [-mpdr] [-mno-pdr]

     _Target PowerPC options:_
        [-mpwrx|-mpwr2|-mpwr|-m601|-mppc|-mppc32|-m603|-m604|
         -m403|-m405|-mppc64|-m620|-mppc64bridge|-mbooke|
         -mbooke32|-mbooke64]
        [-mcom|-many|-maltivec] [-memb]
        [-mregnames|-mno-regnames]
        [-mrelocatable|-mrelocatable-lib]
        [-mlittle|-mlittle-endian|-mbig|-mbig-endian]
        [-msolaris|-mno-solaris]

     _Target SPARC options:_
        [-Av6|-Av7|-Av8|-Asparclet|-Asparclite
         -Av8plus|-Av8plusa|-Av9|-Av9a]
        [-xarch=v8plus|-xarch=v8plusa] [-bump]
        [-32|-64]



'@FILE'
     Read command-line options from FILE.  The options read are inserted
     in place of the original @FILE option.  If FILE does not exist, or
     cannot be read, then the option will be treated literally, and not
     removed.

     Options in FILE are separated by whitespace.  A whitespace
     character may be included in an option by surrounding the entire
     option in either single or double quotes.  Any character (including
     a backslash) may be included by prefixing the character to be
     included with a backslash.  The FILE may itself contain additional
     @FILE options; any such options will be processed recursively.

'-a[cdhlmns]'
     Turn on listings, in any of a variety of ways:

     '-ac'
          omit false conditionals

     '-ad'
          omit debugging directives

     '-ah'
          include high-level source

     '-al'
          include assembly

     '-am'
          include macro expansions

     '-an'
          omit forms processing

     '-as'
          include symbols

     '=file'
          set the name of the listing file

     You may combine these options; for example, use '-aln' for assembly
     listing without forms processing.  The '=file' option, if used,
     must be the last one.  By itself, '-a' defaults to '-ahls'.

'--alternate'
     Begin in alternate macro mode.  *Note '.altmacro': Altmacro.

'-D'
     Ignored.  This option is accepted for script compatibility with
     calls to other assemblers.

'--defsym SYM=VALUE'
     Define the symbol SYM to be VALUE before assembling the input file.
     VALUE must be an integer constant.  As in C, a leading '0x'
     indicates a hexadecimal value, and a leading '0' indicates an octal
     value.  The value of the symbol can be overridden inside a source
     file via the use of a '.set' pseudo-op.

'-f'
     "fast"--skip whitespace and comment preprocessing (assume source is
     compiler output).

'-g'
'--gen-debug'
     Generate debugging information for each assembler source line using
     whichever debug format is preferred by the target.  This currently
     means either STABS, ECOFF or DWARF2.

'--gstabs'
     Generate stabs debugging information for each assembler line.  This
     may help debugging assembler code, if the debugger can handle it.

'--gstabs+'
     Generate stabs debugging information for each assembler line, with
     GNU extensions that probably only gdb can handle, and that could
     make other debuggers crash or refuse to read your program.  This
     may help debugging assembler code.  Currently the only GNU
     extension is the location of the current working directory at
     assembling time.

'--gdwarf-2'
     Generate DWARF2 debugging information for each assembler line.
     This may help debugging assembler code, if the debugger can handle
     it.  Note--this option is only supported by some targets, not all
     of them.

'--help'
     Print a summary of the command line options and exit.

'--target-help'
     Print a summary of all target specific options and exit.

'-I DIR'
     Add directory DIR to the search list for '.include' directives.

'-J'
     Don't warn about signed overflow.

'-K'
     This option is accepted but has no effect on the machine specific
     family.

'-L'
'--keep-locals'
     Keep (in the symbol table) local symbols.  These symbols start with
     system-specific local label prefixes, typically '.L' for ELF
     systems or 'L' for traditional a.out systems.  *Note Symbol
     Names::.

'--listing-lhs-width=NUMBER'
     Set the maximum width, in words, of the output data column for an
     assembler listing to NUMBER.

'--listing-lhs-width2=NUMBER'
     Set the maximum width, in words, of the output data column for
     continuation lines in an assembler listing to NUMBER.

'--listing-rhs-width=NUMBER'
     Set the maximum width of an input source line, as displayed in a
     listing, to NUMBER bytes.

'--listing-cont-lines=NUMBER'
     Set the maximum number of lines printed in a listing for a single
     line of input to NUMBER + 1.

'-o OBJFILE'
     Name the object-file output from 'as' OBJFILE.

'-R'
     Fold the data section into the text section.

     Set the default size of GAS's hash tables to a prime number close
     to NUMBER.  Increasing this value can reduce the length of time it
     takes the assembler to perform its tasks, at the expense of
     increasing the assembler's memory requirements.  Similarly reducing
     this value can reduce the memory requirements at the expense of
     speed.

'--reduce-memory-overheads'
     This option reduces GAS's memory requirements, at the expense of
     making the assembly processes slower.  Currently this switch is a
     synonym for '--hash-size=4051', but in the future it may have other
     effects as well.

'--statistics'
     Print the maximum space (in bytes) and total time (in seconds) used
     by assembly.

'--strip-local-absolute'
     Remove local absolute symbols from the outgoing symbol table.

'-v'
'-version'
     Print the 'as' version.

'--version'
     Print the 'as' version and exit.

'-W'
'--no-warn'
     Suppress warning messages.

'--fatal-warnings'
     Treat warnings as errors.

'--warn'
     Don't suppress warning messages or treat them as errors.

'-w'
     Ignored.

'-x'
     Ignored.

'-Z'
     Generate an object file even after errors.

'-- | FILES ...'
     Standard input, or source files to assemble.

   The following options are available when as is configured for the ARM
processor family.

'-mcpu=PROCESSOR[+EXTENSION...]'
     Specify which ARM processor variant is the target.
'-march=ARCHITECTURE[+EXTENSION...]'
     Specify which ARM architecture variant is used by the target.
'-mfpu=FLOATING-POINT-FORMAT'
     Select which Floating Point architecture is the target.
'-mfloat-abi=ABI'
     Select which floating point ABI is in use.
'-mthumb'
     Enable Thumb only instruction decoding.
'-mapcs-32 | -mapcs-26 | -mapcs-float | -mapcs-reentrant'
     Select which procedure calling convention is in use.
'-EB | -EL'
     Select either big-endian (-EB) or little-endian (-EL) output.
'-mthumb-interwork'
     Specify that the code has been generated with interworking between
     Thumb and ARM code in mind.
'-k'
     Specify that PIC code has been generated.

   The following options are available when 'as' is configured for the
SPARC architecture:

'-Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite'
'-Av8plus | -Av8plusa | -Av9 | -Av9a'
     Explicitly select a variant of the SPARC architecture.

     '-Av8plus' and '-Av8plusa' select a 32 bit environment.  '-Av9' and
     '-Av9a' select a 64 bit environment.

     '-Av8plusa' and '-Av9a' enable the SPARC V9 instruction set with
     UltraSPARC extensions.

'-xarch=v8plus | -xarch=v8plusa'
     For compatibility with the Solaris v9 assembler.  These options are
     equivalent to -Av8plus and -Av8plusa, respectively.

'-bump'
     Warn when the assembler switches to another architecture.

   The following options are available when as is configured for a MIPS
processor.

'-G NUM'
     This option sets the largest size of an object that can be
     referenced implicitly with the 'gp' register.  It is only accepted
     for targets that use ECOFF format, such as a DECstation running
     Ultrix.  The default value is 8.

'-EB'
     Generate "big endian" format output.

'-EL'
     Generate "little endian" format output.

'-mips1'
'-mips2'
'-mips3'
'-mips4'
'-mips5'
'-mips32'
'-mips32r2'
'-mips64'
'-mips64r2'
     Generate code for a particular MIPS Instruction Set Architecture
     level.  '-mips1' is an alias for '-march=r3000', '-mips2' is an
     alias for '-march=r6000', '-mips3' is an alias for '-march=r4000'
     and '-mips4' is an alias for '-march=r8000'.  '-mips5', '-mips32',
     '-mips32r2', '-mips64', and '-mips64r2' correspond to generic 'MIPS
     V', 'MIPS32', 'MIPS32 Release 2', 'MIPS64', and 'MIPS64 Release 2'
     ISA processors, respectively.

'-march=CPU'
     Generate code for a particular MIPS cpu.

'-mtune=CPU'
     Schedule and tune for a particular MIPS cpu.

'-mfix7000'
'-mno-fix7000'
     Cause nops to be inserted if the read of the destination register
     of an mfhi or mflo instruction occurs in the following two
     instructions.

'-mdebug'
'-no-mdebug'
     Cause stabs-style debugging output to go into an ECOFF-style
     .mdebug section instead of the standard ELF .stabs sections.

'-mpdr'
'-mno-pdr'
     Control generation of '.pdr' sections.

'-mgp32'
'-mfp32'
     The register sizes are normally inferred from the ISA and ABI, but
     these flags force a certain group of registers to be treated as 32
     bits wide at all times.  '-mgp32' controls the size of
     general-purpose registers and '-mfp32' controls the size of
     floating-point registers.

'-mips16'
'-no-mips16'
     Generate code for the MIPS 16 processor.  This is equivalent to
     putting '.set mips16' at the start of the assembly file.
     '-no-mips16' turns off this option.

'-msmartmips'
'-mno-smartmips'
     Enables the SmartMIPS extension to the MIPS32 instruction set.
     This is equivalent to putting '.set smartmips' at the start of the
     assembly file.  '-mno-smartmips' turns off this option.

'-mips3d'
'-no-mips3d'
     Generate code for the MIPS-3D Application Specific Extension.  This
     tells the assembler to accept MIPS-3D instructions.  '-no-mips3d'
     turns off this option.

'-mdmx'
'-no-mdmx'
     Generate code for the MDMX Application Specific Extension.  This
     tells the assembler to accept MDMX instructions.  '-no-mdmx' turns
     off this option.

'-mdsp'
'-mno-dsp'
     Generate code for the DSP Release 1 Application Specific Extension.
     This tells the assembler to accept DSP Release 1 instructions.
     '-mno-dsp' turns off this option.

'-mdspr2'
'-mno-dspr2'
     Generate code for the DSP Release 2 Application Specific Extension.
     This option implies -mdsp.  This tells the assembler to accept DSP
     Release 2 instructions.  '-mno-dspr2' turns off this option.

'-mmt'
'-mno-mt'
     Generate code for the MT Application Specific Extension.  This
     tells the assembler to accept MT instructions.  '-mno-mt' turns off
     this option.

'--construct-floats'
'--no-construct-floats'
     The '--no-construct-floats' option disables the construction of
     double width floating point constants by loading the two halves of
     the value into the two single width floating point registers that
     make up the double width register.  By default '--construct-floats'
     is selected, allowing construction of these floating point
     constants.

'--emulation=NAME'
     This option causes 'as' to emulate 'as' configured for some other
     target, in all respects, including output format (choosing between
     ELF and ECOFF only), handling of pseudo-opcodes which may generate
     debugging information or store symbol table information, and
     default endianness.  The available configuration names are:
     'mipsecoff', 'mipself', 'mipslecoff', 'mipsbecoff', 'mipslelf',
     'mipsbelf'.  The first two do not alter the default endianness from
     that of the primary target for which the assembler was configured;
     the others change the default to little- or big-endian as indicated
     by the 'b' or 'l' in the name.  Using '-EB' or '-EL' will override
     the endianness selection in any case.

     This option is currently supported only when the primary target
     'as' is configured for is a MIPS ELF or ECOFF target.  Furthermore,
     the primary target or others specified with '--enable-targets=...'
     at configuration time must include support for the other format, if
     both are to be available.  For example, the Irix 5 configuration
     includes support for both.

     Eventually, this option will support more configurations, with more
     fine-grained control over the assembler's behavior, and will be
     supported for more processors.

'-nocpp'
     'as' ignores this option.  It is accepted for compatibility with
     the native tools.

'--trap'
'--no-trap'
'--break'
'--no-break'
     Control how to deal with multiplication overflow and division by
     zero.  '--trap' or '--no-break' (which are synonyms) take a trap
     exception (and only work for Instruction Set Architecture level 2
     and higher); '--break' or '--no-trap' (also synonyms, and the
     default) take a break exception.

'-n'
     When this option is used, 'as' will issue a warning every time it
     generates a nop instruction from a macro.

1.1 Structure of this Manual
============================

This manual is intended to describe what you need to know to use GNU
'as'.  We cover the syntax expected in source files, including notation
for symbols, constants, and expressions; the directives that 'as'
understands; and of course how to invoke 'as'.

   We also cover special features in the machine specific configuration
of 'as', including assembler directives.

   On the other hand, this manual is _not_ intended as an introduction
to programming in assembly language--let alone programming in general!
In a similar vein, we make no attempt to introduce the machine
architecture; we do _not_ describe the instruction set, standard
mnemonics, registers or addressing modes that are standard to a
particular architecture.

1.2 The GNU Assembler
=====================

GNU 'as' is really a family of assemblers.  This manual describes 'as',
a member of that family which is configured for the machine specific
architectures.  If you use (or have used) the GNU assembler on one
architecture, you should find a fairly similar environment when you use
it on another architecture.  Each version has much in common with the
others, including object file formats, most assembler directives (often
called "pseudo-ops") and assembler syntax.

   'as' is primarily intended to assemble the output of the GNU C
compiler 'gcc' for use by the linker 'ld'.  Nevertheless, we've tried to
make 'as' assemble correctly everything that other assemblers for the
same machine would assemble.

   Unlike older assemblers, 'as' is designed to assemble a source
program in one pass of the source file.  This has a subtle impact on the
'.org' directive (*note '.org': Org.).

1.3 Object File Formats
=======================

The GNU assembler can be configured to produce several alternative
object file formats.  For the most part, this does not affect how you
write assembly language programs; but directives for debugging symbols
are typically different in different file formats.  *Note Symbol
Attributes: Symbol Attributes.  For the machine specific target, 'as' is
configured to produce ELF format object files.

1.4 Command Line
================

After the program name 'as', the command line may contain options and
file names.  Options may appear in any order, and may be before, after,
or between file names.  The order of file names is significant.

   '--' (two hyphens) by itself names the standard input file
explicitly, as one of the files for 'as' to assemble.

   Except for '--' any command line argument that begins with a hyphen
('-') is an option.  Each option changes the behavior of 'as'.  No
option changes the way another option works.  An option is a '-'
followed by one or more letters; the case of the letter is important.
All options are optional.

   Some options expect exactly one file name to follow them.  The file
name may either immediately follow the option's letter (compatible with
older assemblers) or it may be the next command argument (GNU standard).
These two command lines are equivalent:

     as -o my-object-file.o mumble.s
     as -omy-object-file.o mumble.s

1.5 Input Files
===============

We use the phrase "source program", abbreviated "source", to describe
the program input to one run of 'as'.  The program may be in one or more
files; how the source is partitioned into files doesn't change the
meaning of the source.

   The source program is a concatenation of the text in all the files,
in the order specified.

   Each time you run 'as' it assembles exactly one source program.  The
source program is made up of one or more files.  (The standard input is
also a file.)

   You give 'as' a command line that has zero or more input file names.
The input files are read (from left file name to right).  A command line
argument (in any position) that has no special meaning is taken to be an
input file name.

   If you give 'as' no file names it attempts to read one input file
from the 'as' standard input, which is normally your terminal.  You may
have to type <ctl-D> to tell 'as' there is no more program to assemble.

   Use '--' if you need to explicitly name the standard input file in
your command line.

   If the source is empty, 'as' produces a small, empty object file.

Filenames and Line-numbers
--------------------------

There are two ways of locating a line in the input file (or files) and
either may be used in reporting error messages.  One way refers to a
line number in a physical file; the other refers to a line number in a
"logical" file.  *Note Error and Warning Messages: Errors.

   "Physical files" are those files named in the command line given to
'as'.

   "Logical files" are simply names declared explicitly by assembler
directives; they bear no relation to physical files.  Logical file names
help error messages reflect the original source file, when 'as' source
is itself synthesized from other files.  'as' understands the '#'
directives emitted by the 'gcc' preprocessor.  See also *note '.file':
File.

1.6 Output (Object) File
========================

Every time you run 'as' it produces an output file, which is your
assembly language program translated into numbers.  This file is the
object file.  Its default name is 'a.out'.  You can give it another name
by using the '-o' option.  Conventionally, object file names end with
'.o'.  The default name is used for historical reasons: older assemblers
were capable of assembling self-contained programs directly into a
runnable program.  (For some formats, this isn't currently possible, but
it can be done for the 'a.out' format.)

   The object file is meant for input to the linker 'ld'.  It contains
assembled program code, information to help 'ld' integrate the assembled
program into a runnable file, and (optionally) symbolic information for
the debugger.

1.7 Error and Warning Messages
==============================

'as' may write warnings and error messages to the standard error file
(usually your terminal).  This should not happen when a compiler runs
'as' automatically.  Warnings report an assumption made so that 'as'
could keep assembling a flawed program; errors report a grave problem
that stops the assembly.

   Warning messages have the format

     file_name:NNN:Warning Message Text

(where NNN is a line number).  If a logical file name has been given
(*note '.file': File.) it is used for the filename, otherwise the name
of the current input file is used.  If a logical line number was given
then it is used to calculate the number printed, otherwise the actual
line in the current source file is printed.  The message text is
intended to be self explanatory (in the grand Unix tradition).

   Error messages have the format
     file_name:NNN:FATAL:Error Message Text
   The file name and line number are derived as for warning messages.
The actual message text may be rather less explanatory because many of
them aren't supposed to happen.

2 Command-Line Options
**********************

This chapter describes command-line options available in _all_ versions
of the GNU assembler; see *note Machine Dependencies::, for options
specific to the machine specific target.

   If you are invoking 'as' via the GNU C compiler, you can use the
'-Wa' option to pass arguments through to the assembler.  The assembler
arguments must be separated from each other (and the '-Wa') by commas.
For example:

     gcc -c -g -O -Wa,-alh,-L file.c

This passes two options to the assembler: '-alh' (emit a listing to
standard output with high-level and assembly source) and '-L' (retain
local symbols in the symbol table).

   Usually you do not need to use this '-Wa' mechanism, since many
compiler command-line options are automatically passed to the assembler
by the compiler.  (You can call the GNU compiler driver with the '-v'
option to see precisely what options it passes to each compilation pass,
including the assembler.)

2.1 Enable Listings: '-a[cdhlns]'
=================================

These options enable listing output from the assembler.  By itself, '-a'
requests high-level, assembly, and symbols listing.  You can use other
letters to select specific options for the list: '-ah' requests a
high-level language listing, '-al' requests an output-program assembly
listing, and '-as' requests a symbol table listing.  High-level listings
require that a compiler debugging option like '-g' be used, and that
assembly listings ('-al') be requested also.

   Use the '-ac' option to omit false conditionals from a listing.  Any
lines which are not assembled because of a false '.if' (or '.ifdef', or
any other conditional), or a true '.if' followed by an '.else', will be
omitted from the listing.

   Use the '-ad' option to omit debugging directives from the listing.

   Once you have specified one of these options, you can further control
listing output and its appearance using the directives '.list',
'.nolist', '.psize', '.eject', '.title', and '.sbttl'.  The '-an' option
turns off all forms processing.  If you do not request listing output
with one of the '-a' options, the listing-control directives have no
effect.

   The letters after '-a' may be combined into one option, _e.g._,
'-aln'.

   Note if the assembler source is coming from the standard input (e.g.,
because it is being created by 'gcc' and the '-pipe' command line switch
is being used) then the listing will not contain any comments or
preprocessor directives.  This is because the listing code buffers input
source lines from stdin only after they have been preprocessed by the
assembler.  This reduces memory usage and makes the code more efficient.

2.2 '--alternate'
=================

Begin in alternate macro mode, see *note '.altmacro': Altmacro.

2.3 '-D'
========

This option has no effect whatsoever, but it is accepted to make it more
likely that scripts written for other assemblers also work with 'as'.

2.4 Work Faster: '-f'
=====================

'-f' should only be used when assembling programs written by a (trusted)
compiler.  '-f' stops the assembler from doing whitespace and comment
preprocessing on the input file(s) before assembling them.  *Note
Preprocessing: Preprocessing.

     _Warning:_ if you use '-f' when the files actually need to be
     preprocessed (if they contain comments, for example), 'as' does not
     work correctly.

2.5 '.include' Search Path: '-I' PATH
=====================================

Use this option to add a PATH to the list of directories 'as' searches
for files specified in '.include' directives (*note '.include':
Include.).  You may use '-I' as many times as necessary to include a
variety of paths.  The current working directory is always searched
first; after that, 'as' searches any '-I' directories in the same order
as they were specified (left to right) on the command line.

2.6 Difference Tables: '-K'
===========================

On the machine specific family, this option is allowed, but has no
effect.  It is permitted for compatibility with the GNU assembler on
other platforms, where it can be used to warn when the assembler alters
the machine code generated for '.word' directives in difference tables.
The machine specific family does not have the addressing limitations
that sometimes lead to this alteration on other platforms.

2.7 Include Local Symbols: '-L'
===============================

Symbols beginning with system-specific local label prefixes, typically
'.L' for ELF systems or 'L' for traditional a.out systems, are called
"local symbols".  *Note Symbol Names::.  Normally you do not see such
symbols when debugging, because they are intended for the use of
programs (like compilers) that compose assembler programs, not for your
notice.  Normally both 'as' and 'ld' discard such symbols, so you do not
normally debug with them.

   This option tells 'as' to retain those local symbols in the object
file.  Usually if you do this you also tell the linker 'ld' to preserve
those symbols.

2.8 Configuring listing output: '--listing'
===========================================

The listing feature of the assembler can be enabled via the command line
switch '-a' (*note a::).  This feature combines the input source file(s)
with a hex dump of the corresponding locations in the output object
file, and displays them as a listing file.  The format of this listing
can be controlled by directives inside the assembler source (i.e.,
'.list' (*note List::), '.title' (*note Title::), '.sbttl' (*note
Sbttl::), '.psize' (*note Psize::), and '.eject' (*note Eject::) and
also by the following switches:

'--listing-lhs-width='number''
     Sets the maximum width, in words, of the first line of the hex byte
     dump.  This dump appears on the left hand side of the listing
     output.

'--listing-lhs-width2='number''
     Sets the maximum width, in words, of any further lines of the hex
     byte dump for a given input source line.  If this value is not
     specified, it defaults to being the same as the value specified for
     '--listing-lhs-width'.  If neither switch is used the default is to
     one.

'--listing-rhs-width='number''
     Sets the maximum width, in characters, of the source line that is
     displayed alongside the hex dump.  The default value for this
     parameter is 100.  The source line is displayed on the right hand
     side of the listing output.

'--listing-cont-lines='number''
     Sets the maximum number of continuation lines of hex dump that will
     be displayed for a given single line of source input.  The default
     value is 4.

2.9 Assemble in MRI Compatibility Mode: '-M'
============================================

The '-M' or '--mri' option selects MRI compatibility mode.  This changes
the syntax and pseudo-op handling of 'as' to make it compatible with the
'ASM68K' or the 'ASM960' (depending upon the configured target)
assembler from Microtec Research.  The exact nature of the MRI syntax
will not be documented here; see the MRI manuals for more information.
Note in particular that the handling of macros and macro arguments is
somewhat different.  The purpose of this option is to permit assembling
existing MRI assembler code using 'as'.

   The MRI compatibility is not complete.  Certain operations of the MRI
assembler depend upon its object file format, and can not be supported
using other object file formats.  Supporting these would require
enhancing each object file format individually.  These are:

   * global symbols in common section

     The m68k MRI assembler supports common sections which are merged by
     the linker.  Other object file formats do not support this.  'as'
     handles common sections by treating them as a single common symbol.
     It permits local symbols to be defined within a common section, but
     it can not support global symbols, since it has no way to describe
     them.

   * complex relocations

     The MRI assemblers support relocations against a negated section
     address, and relocations which combine the start addresses of two
     or more sections.  These are not support by other object file
     formats.

   * 'END' pseudo-op specifying start address

     The MRI 'END' pseudo-op permits the specification of a start
     address.  This is not supported by other object file formats.  The
     start address may instead be specified using the '-e' option to the
     linker, or in a linker script.

   * 'IDNT', '.ident' and 'NAME' pseudo-ops

     The MRI 'IDNT', '.ident' and 'NAME' pseudo-ops assign a module name
     to the output file.  This is not supported by other object file
     formats.

   * 'ORG' pseudo-op

     The m68k MRI 'ORG' pseudo-op begins an absolute section at a given
     address.  This differs from the usual 'as' '.org' pseudo-op, which
     changes the location within the current section.  Absolute sections
     are not supported by other object file formats.  The address of a
     section may be assigned within a linker script.

   There are some other features of the MRI assembler which are not
supported by 'as', typically either because they are difficult or
because they seem of little consequence.  Some of these may be supported
in future releases.

   * EBCDIC strings

     EBCDIC strings are not supported.

   * packed binary coded decimal

     Packed binary coded decimal is not supported.  This means that the
     'DC.P' and 'DCB.P' pseudo-ops are not supported.

   * 'FEQU' pseudo-op

     The m68k 'FEQU' pseudo-op is not supported.

   * 'NOOBJ' pseudo-op

     The m68k 'NOOBJ' pseudo-op is not supported.

   * 'OPT' branch control options

     The m68k 'OPT' branch control options--'B', 'BRS', 'BRB', 'BRL',
     and 'BRW'--are ignored.  'as' automatically relaxes all branches,
     whether forward or backward, to an appropriate size, so these
     options serve no purpose.

   * 'OPT' list control options

     The following m68k 'OPT' list control options are ignored: 'C',
     'CEX', 'CL', 'CRE', 'E', 'G', 'I', 'M', 'MEX', 'MC', 'MD', 'X'.

   * other 'OPT' options

     The following m68k 'OPT' options are ignored: 'NEST', 'O', 'OLD',
     'OP', 'P', 'PCO', 'PCR', 'PCS', 'R'.

   * 'OPT' 'D' option is default

     The m68k 'OPT' 'D' option is the default, unlike the MRI assembler.
     'OPT NOD' may be used to turn it off.

   * 'XREF' pseudo-op.

     The m68k 'XREF' pseudo-op is ignored.

   * '.debug' pseudo-op

     The i960 '.debug' pseudo-op is not supported.

   * '.extended' pseudo-op

     The i960 '.extended' pseudo-op is not supported.

   * '.list' pseudo-op.

     The various options of the i960 '.list' pseudo-op are not
     supported.

   * '.optimize' pseudo-op

     The i960 '.optimize' pseudo-op is not supported.

   * '.output' pseudo-op

     The i960 '.output' pseudo-op is not supported.

   * '.setreal' pseudo-op

     The i960 '.setreal' pseudo-op is not supported.

2.10 Dependency Tracking: '--MD'
================================

'as' can generate a dependency file for the file it creates.  This file
consists of a single rule suitable for 'make' describing the
dependencies of the main source file.

   The rule is written to the file named in its argument.

   This feature is used in the automatic updating of makefiles.

2.11 Name the Object File: '-o'
===============================

There is always one object file output when you run 'as'.  By default it
has the name 'a.out'.  You use this option (which takes exactly one
filename) to give the object file a different name.

   Whatever the object file is called, 'as' overwrites any existing file
of the same name.

2.12 Join Data and Text Sections: '-R'
======================================

'-R' tells 'as' to write the object file as if all data-section data
lives in the text section.  This is only done at the very last moment:
your binary data are the same, but data section parts are relocated
differently.  The data section part of your object file is zero bytes
long because all its bytes are appended to the text section.  (*Note
Sections and Relocation: Sections.)

   When you specify '-R' it would be possible to generate shorter
address displacements (because we do not have to cross between text and
data section).  We refrain from doing this simply for compatibility with
older versions of 'as'.  In future, '-R' may work this way.

   When 'as' is configured for COFF or ELF output, this option is only
useful if you use sections named '.text' and '.data'.

2.13 Display Assembly Statistics: '--statistics'
================================================

Use '--statistics' to display two statistics about the resources used by
'as': the maximum amount of space allocated during the assembly (in
bytes), and the total execution time taken for the assembly (in CPU
seconds).

2.14 Compatible Output: '--traditional-format'
==============================================

For some targets, the output of 'as' is different in some ways from the
output of some existing assembler.  This switch requests 'as' to use the
traditional format instead.

   For example, it disables the exception frame optimizations which 'as'
normally does by default on 'gcc' output.

2.15 Announce Version: '-v'
===========================

You can find out what version of as is running by including the option
'-v' (which you can also spell as '-version') on the command line.

2.16 Control Warnings: '-W', '--warn', '--no-warn', '--fatal-warnings'
======================================================================

'as' should never give a warning or error message when assembling
compiler output.  But programs written by people often cause 'as' to
give a warning that a particular assumption was made.  All such warnings
are directed to the standard error file.

   If you use the '-W' and '--no-warn' options, no warnings are issued.
This only affects the warning messages: it does not change any
particular of how 'as' assembles your file.  Errors, which stop the
assembly, are still reported.

   If you use the '--fatal-warnings' option, 'as' considers files that
generate warnings to be in error.

   You can switch these options off again by specifying '--warn', which
causes warnings to be output as usual.

2.17 Generate Object File in Spite of Errors: '-Z'
==================================================

After an error message, 'as' normally produces no output.  If for some
reason you are interested in object file output even after 'as' gives an
error message on your program, use the '-Z' option.  If there are any
errors, 'as' continues anyways, and writes an object file after a final
warning message of the form 'N errors, M warnings, generating bad object
file.'

3 Syntax
********

This chapter describes the machine-independent syntax allowed in a
source file.  'as' syntax is similar to what many other assemblers use;
it is inspired by the BSD 4.2 assembler.

3.1 Preprocessing
=================

The 'as' internal preprocessor:
   * adjusts and removes extra whitespace.  It leaves one space or tab
     before the keywords on a line, and turns any other whitespace on
     the line into a single space.

   * removes all comments, replacing them with a single space, or an
     appropriate number of newlines.

   * converts character constants into the appropriate numeric values.

   It does not do macro processing, include file handling, or anything
else you may get from your C compiler's preprocessor.  You can do
include file processing with the '.include' directive (*note '.include':
Include.).  You can use the GNU C compiler driver to get other "CPP"
style preprocessing by giving the input file a '.S' suffix.  *Note
Options Controlling the Kind of Output: (gcc.info)Overall Options.

   Excess whitespace, comments, and character constants cannot be used
in the portions of the input text that are not preprocessed.

   If the first line of an input file is '#NO_APP' or if you use the
'-f' option, whitespace and comments are not removed from the input
file.  Within an input file, you can ask for whitespace and comment
removal in specific portions of the by putting a line that says '#APP'
before the text that may contain whitespace or comments, and putting a
line that says '#NO_APP' after this text.  This feature is mainly intend
to support 'asm' statements in compilers whose output is otherwise free
of comments and whitespace.

3.2 Whitespace
==============

"Whitespace" is one or more blanks or tabs, in any order.  Whitespace is
used to separate symbols, and to make programs neater for people to
read.  Unless within character constants (*note Character Constants:
Characters.), any whitespace means the same as exactly one space.

3.3 Comments
============

There are two ways of rendering comments to 'as'.  In both cases the
comment is equivalent to one space.

   Anything from '/*' through the next '*/' is a comment.  This means
you may not nest these comments.

     /*
       The only way to include a newline ('\n') in a comment
       is to use this sort of comment.
     */

     /* This sort of comment does not nest. */

   Anything from the "line comment" character to the next newline is
considered a comment and is ignored.  The line comment character is '@'
on the ARM; '#' on the i386 and x86-64; '#' for Motorola PowerPC; '!' on
the SPARC; see *note Machine Dependencies::.

   To be compatible with past assemblers, lines that begin with '#' have
a special interpretation.  Following the '#' should be an absolute
expression (*note Expressions::): the logical line number of the _next_
line.  Then a string (*note Strings: Strings.) is allowed: if present it
is a new logical file name.  The rest of the line, if any, should be
whitespace.

   If the first non-whitespace characters on the line are not numeric,
the line is ignored.  (Just like a comment.)

                               # This is an ordinary comment.
     # 42-6 "new_file_name"    # New logical file name
                               # This is logical line # 36.
   This feature is deprecated, and may disappear from future versions of
'as'.

3.4 Symbols
===========

A "symbol" is one or more characters chosen from the set of all letters
(both upper and lower case), digits and the three characters '_.$'.  No
symbol may begin with a digit.  Case is significant.  There is no length
limit: all characters are significant.  Symbols are delimited by
characters not in that set, or by the beginning of a file (since the
source program must end with a newline, the end of a file is not a
possible symbol delimiter).  *Note Symbols::.

3.5 Statements
==============

A "statement" ends at a newline character ('\n') or at a semicolon
(';').  The newline or semicolon is considered part of the preceding
statement.  Newlines and semicolons within character constants are an
exception: they do not end statements.

   It is an error to end any statement with end-of-file: the last
character of any input file should be a newline.

   An empty statement is allowed, and may include whitespace.  It is
ignored.

   A statement begins with zero or more labels, optionally followed by a
key symbol which determines what kind of statement it is.  The key
symbol determines the syntax of the rest of the statement.  If the
symbol begins with a dot '.' then the statement is an assembler
directive: typically valid for any computer.  If the symbol begins with
a letter the statement is an assembly language "instruction": it
assembles into a machine language instruction.

   A label is a symbol immediately followed by a colon (':').
Whitespace before a label or after a colon is permitted, but you may not
have whitespace between a label's symbol and its colon.  *Note Labels::.

     label:     .directive    followed by something
     another_label:           # This is an empty statement.
                instruction   operand_1, operand_2, ...

3.6 Constants
=============

A constant is a number, written so that its value is known by
inspection, without knowing any context.  Like this:
     .byte  74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
     .ascii "Ring the bell\7"                  # A string constant.
     .octa  0x123456789abcdef0123456789ABCDEF0 # A bignum.
     .float 0f-314159265358979323846264338327\
     95028841971.693993751E-40                 # - pi, a flonum.

3.6.1 Character Constants
-------------------------

There are two kinds of character constants.  A "character" stands for
one character in one byte and its value may be used in numeric
expressions.  String constants (properly called string _literals_) are
potentially many bytes and their values may not be used in arithmetic
expressions.

3.6.1.1 Strings
...............

A "string" is written between double-quotes.  It may contain
double-quotes or null characters.  The way to get special characters
into a string is to "escape" these characters: precede them with a
backslash '\' character.  For example '\\' represents one backslash: the
first '\' is an escape which tells 'as' to interpret the second
character literally as a backslash (which prevents 'as' from recognizing
the second '\' as an escape character).  The complete list of escapes
follows.

'\b'
     Mnemonic for backspace; for ASCII this is octal code 010.

'\f'
     Mnemonic for FormFeed; for ASCII this is octal code 014.

'\n'
     Mnemonic for newline; for ASCII this is octal code 012.

'\r'
     Mnemonic for carriage-Return; for ASCII this is octal code 015.

'\t'
     Mnemonic for horizontal Tab; for ASCII this is octal code 011.

'\ DIGIT DIGIT DIGIT'
     An octal character code.  The numeric code is 3 octal digits.  For
     compatibility with other Unix systems, 8 and 9 are accepted as
     digits: for example, '\008' has the value 010, and '\009' the value
     011.

'\x HEX-DIGITS...'
     A hex character code.  All trailing hex digits are combined.
     Either upper or lower case 'x' works.

'\\'
     Represents one '\' character.

'\"'
     Represents one '"' character.  Needed in strings to represent this
     character, because an unescaped '"' would end the string.

'\ ANYTHING-ELSE'
     Any other character when escaped by '\' gives a warning, but
     assembles as if the '\' was not present.  The idea is that if you
     used an escape sequence you clearly didn't want the literal
     interpretation of the following character.  However 'as' has no
     other interpretation, so 'as' knows it is giving you the wrong code
     and warns you of the fact.

   Which characters are escapable, and what those escapes represent,
varies widely among assemblers.  The current set is what we think the
BSD 4.2 assembler recognizes, and is a subset of what most C compilers
recognize.  If you are in doubt, do not use an escape sequence.

3.6.1.2 Characters
..................

A single character may be written as a single quote immediately followed
by that character.  The same escapes apply to characters as to strings.
So if you want to write the character backslash, you must write ''\\'
where the first '\' escapes the second '\'.  As you can see, the quote
is an acute accent, not a grave accent.  A newline (or semicolon ';')
immediately following an acute accent is taken as a literal character
and does not count as the end of a statement.  The value of a character
constant in a numeric expression is the machine's byte-wide code for
that character.  'as' assumes your character code is ASCII: ''A' means
65, ''B' means 66, and so on.

3.6.2 Number Constants
----------------------

'as' distinguishes three kinds of numbers according to how they are
stored in the target machine.  _Integers_ are numbers that would fit
into an 'int' in the C language.  _Bignums_ are integers, but they are
stored in more than 32 bits.  _Flonums_ are floating point numbers,
described below.

3.6.2.1 Integers
................

A binary integer is '0b' or '0B' followed by zero or more of the binary
digits '01'.

   An octal integer is '0' followed by zero or more of the octal digits
('01234567').

   A decimal integer starts with a non-zero digit followed by zero or
more digits ('0123456789').

   A hexadecimal integer is '0x' or '0X' followed by one or more
hexadecimal digits chosen from '0123456789abcdefABCDEF'.

   Integers have the usual values.  To denote a negative integer, use
the prefix operator '-' discussed under expressions (*note Prefix
Operators: Prefix Ops.).

3.6.2.2 Bignums
...............

A "bignum" has the same syntax and semantics as an integer except that
the number (or its negative) takes more than 32 bits to represent in
binary.  The distinction is made because in some places integers are
permitted while bignums are not.

3.6.2.3 Flonums
...............

A "flonum" represents a floating point number.  The translation is
indirect: a decimal floating point number from the text is converted by
'as' to a generic binary floating point number of more than sufficient
precision.  This generic floating point number is converted to a
particular computer's floating point format (or formats) by a portion of
'as' specialized to that computer.

   A flonum is written by writing (in order)
   * The digit '0'.

   * A letter, to tell 'as' the rest of the number is a flonum.

   * An optional sign: either '+' or '-'.

   * An optional "integer part": zero or more decimal digits.

   * An optional "fractional part": '.' followed by zero or more decimal
     digits.

   * An optional exponent, consisting of:

        * An 'E' or 'e'.
        * Optional sign: either '+' or '-'.
        * One or more decimal digits.

   At least one of the integer part or the fractional part must be
present.  The floating point number has the usual base-10 value.

   'as' does all processing using integers.  Flonums are computed
independently of any floating point hardware in the computer running
'as'.

4 Sections and Relocation
*************************

4.1 Background
==============

Roughly, a section is a range of addresses, with no gaps; all data "in"
those addresses is treated the same for some particular purpose.  For
example there may be a "read only" section.

   The linker 'ld' reads many object files (partial programs) and
combines their contents to form a runnable program.  When 'as' emits an
object file, the partial program is assumed to start at address 0.  'ld'
assigns the final addresses for the partial program, so that different
partial programs do not overlap.  This is actually an
oversimplification, but it suffices to explain how 'as' uses sections.

   'ld' moves blocks of bytes of your program to their run-time
addresses.  These blocks slide to their run-time addresses as rigid
units; their length does not change and neither does the order of bytes
within them.  Such a rigid unit is called a _section_.  Assigning
run-time addresses to sections is called "relocation".  It includes the
task of adjusting mentions of object-file addresses so they refer to the
proper run-time addresses.

   An object file written by 'as' has at least three sections, any of
which may be empty.  These are named "text", "data" and "bss" sections.

   'as' can also generate whatever other named sections you specify
using the '.section' directive (*note '.section': Section.).  If you do
not use any directives that place output in the '.text' or '.data'
sections, these sections still exist, but are empty.

   Within the object file, the text section starts at address '0', the
data section follows, and the bss section follows the data section.

   To let 'ld' know which data changes when the sections are relocated,
and how to change that data, 'as' also writes to the object file details
of the relocation needed.  To perform relocation 'ld' must know, each
time an address in the object file is mentioned:
   * Where in the object file is the beginning of this reference to an
     address?
   * How long (in bytes) is this reference?
   * Which section does the address refer to?  What is the numeric value
     of
          (ADDRESS) - (START-ADDRESS OF SECTION)?
   * Is the reference to an address "Program-Counter relative"?

   In fact, every address 'as' ever uses is expressed as
     (SECTION) + (OFFSET INTO SECTION)
Further, most expressions 'as' computes have this section-relative
nature.

   In this manual we use the notation {SECNAME N} to mean "offset N into
section SECNAME."

   Apart from text, data and bss sections you need to know about the
"absolute" section.  When 'ld' mixes partial programs, addresses in the
absolute section remain unchanged.  For example, address '{absolute 0}'
is "relocated" to run-time address 0 by 'ld'.  Although the linker never
arranges two partial programs' data sections with overlapping addresses
after linking, _by definition_ their absolute sections must overlap.
Address '{absolute 239}' in one part of a program is always the same
address when the program is running as address '{absolute 239}' in any
other part of the program.

   The idea of sections is extended to the "undefined" section.  Any
address whose section is unknown at assembly time is by definition
rendered {undefined U}--where U is filled in later.  Since numbers are
always defined, the only way to generate an undefined address is to
mention an undefined symbol.  A reference to a named common block would
be such a symbol: its value is unknown at assembly time so it has
section _undefined_.

   By analogy the word _section_ is used to describe groups of sections
in the linked program.  'ld' puts all partial programs' text sections in
contiguous addresses in the linked program.  It is customary to refer to
the _text section_ of a program, meaning all the addresses of all
partial programs' text sections.  Likewise for data and bss sections.

   Some sections are manipulated by 'ld'; others are invented for use of
'as' and have no meaning except during assembly.

4.2 Linker Sections
===================

'ld' deals with just four kinds of sections, summarized below.

*named sections*
     These sections hold your program.  'as' and 'ld' treat them as
     separate but equal sections.  Anything you can say of one section
     is true of another.  When the program is running, however, it is
     customary for the text section to be unalterable.  The text section
     is often shared among processes: it contains instructions,
     constants and the like.  The data section of a running program is
     usually alterable: for example, C variables would be stored in the
     data section.

*bss section*
     This section contains zeroed bytes when your program begins
     running.  It is used to hold uninitialized variables or common
     storage.  The length of each partial program's bss section is
     important, but because it starts out containing zeroed bytes there
     is no need to store explicit zero bytes in the object file.  The
     bss section was invented to eliminate those explicit zeros from
     object files.

*absolute section*
     Address 0 of this section is always "relocated" to runtime address
     0.  This is useful if you want to refer to an address that 'ld'
     must not change when relocating.  In this sense we speak of
     absolute addresses being "unrelocatable": they do not change during
     relocation.

*undefined section*
     This "section" is a catch-all for address references to objects not
     in the preceding sections.

   An idealized example of three relocatable sections follows.  The
example uses the traditional section names '.text' and '.data'.  Memory
addresses are on the horizontal axis.

                           +-----+----+--+
     partial program # 1:  |ttttt|dddd|00|
                           +-----+----+--+

                           text   data bss
                           seg.   seg. seg.

                           +---+---+---+
     partial program # 2:  |TTT|DDD|000|
                           +---+---+---+

                           +--+---+-----+--+----+---+-----+~~
     linked program:       |  |TTT|ttttt|  |dddd|DDD|00000|
                           +--+---+-----+--+----+---+-----+~~

         addresses:        0 ...

4.3 Assembler Internal Sections
===============================

These sections are meant only for the internal use of 'as'.  They have
no meaning at run-time.  You do not really need to know about these
sections for most purposes; but they can be mentioned in 'as' warning
messages, so it might be helpful to have an idea of their meanings to
'as'.  These sections are used to permit the value of every expression
in your assembly language program to be a section-relative address.

ASSEMBLER-INTERNAL-LOGIC-ERROR!
     An internal assembler logic error has been found.  This means there
     is a bug in the assembler.

expr section
     The assembler stores complex expression internally as combinations
     of symbols.  When it needs to represent an expression as a symbol,
     it puts it in the expr section.

4.4 Sub-Sections
================

You may have separate groups of data in named sections that you want to
end up near to each other in the object file, even though they are not
contiguous in the assembler source.  'as' allows you to use
"subsections" for this purpose.  Within each section, there can be
numbered subsections with values from 0 to 8192.  Objects assembled into
the same subsection go into the object file together with other objects
in the same subsection.  For example, a compiler might want to store
constants in the text section, but might not want to have them
interspersed with the program being assembled.  In this case, the
compiler could issue a '.text 0' before each section of code being
output, and a '.text 1' before each group of constants being output.

   Subsections are optional.  If you do not use subsections, everything
goes in subsection number zero.

   Subsections appear in your object file in numeric order, lowest
numbered to highest.  (All this to be compatible with other people's
assemblers.)  The object file contains no representation of subsections;
'ld' and other programs that manipulate object files see no trace of
them.  They just see all your text subsections as a text section, and
all your data subsections as a data section.

   To specify which subsection you want subsequent statements assembled
into, use a numeric argument to specify it, in a '.text EXPRESSION' or a
'.data EXPRESSION' statement.  You can also use the '.subsection'
directive (*note SubSection::) to specify a subsection: '.subsection
EXPRESSION'.  EXPRESSION should be an absolute expression (*note
Expressions::).  If you just say '.text' then '.text 0' is assumed.
Likewise '.data' means '.data 0'.  Assembly begins in 'text 0'.  For
instance:
     .text 0     # The default subsection is text 0 anyway.
     .ascii "This lives in the first text subsection. *"
     .text 1
     .ascii "But this lives in the second text subsection."
     .data 0
     .ascii "This lives in the data section,"
     .ascii "in the first data subsection."
     .text 0
     .ascii "This lives in the first text section,"
     .ascii "immediately following the asterisk (*)."

   Each section has a "location counter" incremented by one for every
byte assembled into that section.  Because subsections are merely a
convenience restricted to 'as' there is no concept of a subsection
location counter.  There is no way to directly manipulate a location
counter--but the '.align' directive changes it, and any label definition
captures its current value.  The location counter of the section where
statements are being assembled is said to be the "active" location
counter.

4.5 bss Section
===============

The bss section is used for local common variable storage.  You may
allocate address space in the bss section, but you may not dictate data
to load into it before your program executes.  When your program starts
running, all the contents of the bss section are zeroed bytes.

   The '.lcomm' pseudo-op defines a symbol in the bss section; see *note
'.lcomm': Lcomm.

   The '.comm' pseudo-op may be used to declare a common symbol, which
is another form of uninitialized symbol; see *note '.comm': Comm.

5 Symbols
*********

Symbols are a central concept: the programmer uses symbols to name
things, the linker uses symbols to link, and the debugger uses symbols
to debug.

     _Warning:_ 'as' does not place symbols in the object file in the
     same order they were declared.  This may break some debuggers.

5.1 Labels
==========

A "label" is written as a symbol immediately followed by a colon ':'.
The symbol then represents the current value of the active location
counter, and is, for example, a suitable instruction operand.  You are
warned if you use the same symbol to represent two different locations:
the first definition overrides any other definitions.

5.2 Giving Symbols Other Values
===============================

A symbol can be given an arbitrary value by writing a symbol, followed
by an equals sign '=', followed by an expression (*note Expressions::).
This is equivalent to using the '.set' directive.  *Note '.set': Set.
In the same way, using a double equals sign '=''=' here represents an
equivalent of the '.eqv' directive.  *Note '.eqv': Eqv.

5.3 Symbol Names
================

Symbol names begin with a letter or with one of '._'.  On most machines,
you can also use '$' in symbol names; exceptions are noted in *note
Machine Dependencies::.  That character may be followed by any string of
digits, letters, dollar signs (unless otherwise noted for a particular
target machine), and underscores.

   Case of letters is significant: 'foo' is a different symbol name than
'Foo'.

   Each symbol has exactly one name.  Each name in an assembly language
program refers to exactly one symbol.  You may use that symbol name any
number of times in a program.

Local Symbol Names
------------------

A local symbol is any symbol beginning with certain local label
prefixes.  By default, the local label prefix is '.L' for ELF systems or
'L' for traditional a.out systems, but each target may have its own set
of local label prefixes.

   Local symbols are defined and used within the assembler, but they are
normally not saved in object files.  Thus, they are not visible when
debugging.  You may use the '-L' option (*note Include Local Symbols:
'-L': L.) to retain the local symbols in the object files.

Local Labels
------------

Local labels help compilers and programmers use names temporarily.  They
create symbols which are guaranteed to be unique over the entire scope
of the input source code and which can be referred to by a simple
notation.  To define a local label, write a label of the form 'N:'
(where N represents any positive integer).  To refer to the most recent
previous definition of that label write 'Nb', using the same number as
when you defined the label.  To refer to the next definition of a local
label, write 'Nf'--the 'b' stands for "backwards" and the 'f' stands for
"forwards".

   There is no restriction on how you can use these labels, and you can
reuse them too.  So that it is possible to repeatedly define the same
local label (using the same number 'N'), although you can only refer to
the most recently defined local label of that number (for a backwards
reference) or the next definition of a specific local label for a
forward reference.  It is also worth noting that the first 10 local
labels ('0:'...'9:') are implemented in a slightly more efficient manner
than the others.

   Here is an example:

     1:        branch 1f
     2:        branch 1b
     1:        branch 2f
     2:        branch 1b

   Which is the equivalent of:

     label_1:  branch label_3
     label_2:  branch label_1
     label_3:  branch label_4
     label_4:  branch label_3

   Local label names are only a notational device.  They are immediately
transformed into more conventional symbol names before the assembler
uses them.  The symbol names are stored in the symbol table, appear in
error messages, and are optionally emitted to the object file.  The
names are constructed using these parts:

'_local label prefix_'
     All local symbols begin with the system-specific local label
     prefix.  Normally both 'as' and 'ld' forget symbols that start with
     the local label prefix.  These labels are used for symbols you are
     never intended to see.  If you use the '-L' option then 'as'
     retains these symbols in the object file.  If you also instruct
     'ld' to retain these symbols, you may use them in debugging.

'NUMBER'
     This is the number that was used in the local label definition.  So
     if the label is written '55:' then the number is '55'.

'C-B'
     This unusual character is included so you do not accidentally
     invent a symbol of the same name.  The character has ASCII value of
     '\002' (control-B).

'_ordinal number_'
     This is a serial number to keep the labels distinct.  The first
     definition of '0:' gets the number '1'.  The 15th definition of
     '0:' gets the number '15', and so on.  Likewise the first
     definition of '1:' gets the number '1' and its 15th definition gets
     '15' as well.

   So for example, the first '1:' may be named '.L1C-B1', and the 44th
'3:' may be named '.L3C-B44'.

Dollar Local Labels
-------------------

'as' also supports an even more local form of local labels called dollar
labels.  These labels go out of scope (i.e., they become undefined) as
soon as a non-local label is defined.  Thus they remain valid for only a
small region of the input source code.  Normal local labels, by
contrast, remain in scope for the entire file, or until they are
redefined by another occurrence of the same local label.

   Dollar labels are defined in exactly the same way as ordinary local
labels, except that instead of being terminated by a colon, they are
terminated by a dollar sign, e.g., '55$'.

   They can also be distinguished from ordinary local labels by their
transformed names which use ASCII character '\001' (control-A) as the
magic character to distinguish them from ordinary labels.  For example,
the fifth definition of '6$' may be named '.L6'C-A'5'.

5.4 The Special Dot Symbol
==========================

The special symbol '.' refers to the current address that 'as' is
assembling into.  Thus, the expression 'melvin: .long .' defines
'melvin' to contain its own address.  Assigning a value to '.' is
treated the same as a '.org' directive.  Thus, the expression '.=.+4' is
the same as saying '.space 4'.

5.5 Symbol Attributes
=====================

Every symbol has, as well as its name, the attributes "Value" and
"Type".  Depending on output format, symbols can also have auxiliary
attributes.  The detailed definitions are in 'a.out.h'.

   If you use a symbol without defining it, 'as' assumes zero for all
these attributes, and probably won't warn you.  This makes the symbol an
externally defined symbol, which is generally what you would want.

5.5.1 Value
-----------

The value of a symbol is (usually) 32 bits.  For a symbol which labels a
location in the text, data, bss or absolute sections the value is the
number of addresses from the start of that section to the label.
Naturally for text, data and bss sections the value of a symbol changes
as 'ld' changes section base addresses during linking.  Absolute
symbols' values do not change during linking: that is why they are
called absolute.

   The value of an undefined symbol is treated in a special way.  If it
is 0 then the symbol is not defined in this assembler source file, and
'ld' tries to determine its value from other files linked into the same
program.  You make this kind of symbol simply by mentioning a symbol
name without defining it.  A non-zero value represents a '.comm' common
declaration.  The value is how much common storage to reserve, in bytes
(addresses).  The symbol refers to the first address of the allocated
storage.

5.5.2 Type
----------

The type attribute of a symbol contains relocation (section)
information, any flag settings indicating that a symbol is external, and
(optionally), other information for linkers and debuggers.  The exact
format depends on the object-code output format in use.

6 Expressions
*************

An "expression" specifies an address or numeric value.  Whitespace may
precede and/or follow an expression.

   The result of an expression must be an absolute number, or else an
offset into a particular section.  If an expression is not absolute, and
there is not enough information when 'as' sees the expression to know
its section, a second pass over the source program might be necessary to
interpret the expression--but the second pass is currently not
implemented.  'as' aborts with an error message in this situation.

6.1 Empty Expressions
=====================

An empty expression has no value: it is just whitespace or null.
Wherever an absolute expression is required, you may omit the
expression, and 'as' assumes a value of (absolute) 0.  This is
compatible with other assemblers.

6.2 Integer Expressions
=======================

An "integer expression" is one or more _arguments_ delimited by
_operators_.

6.2.1 Arguments
---------------

"Arguments" are symbols, numbers or subexpressions.  In other contexts
arguments are sometimes called "arithmetic operands".  In this manual,
to avoid confusing them with the "instruction operands" of the machine
language, we use the term "argument" to refer to parts of expressions
only, reserving the word "operand" to refer only to machine instruction
operands.

   Symbols are evaluated to yield {SECTION NNN} where SECTION is one of
text, data, bss, absolute, or undefined.  NNN is a signed, 2's
complement 32 bit integer.

   Numbers are usually integers.

   A number can be a flonum or bignum.  In this case, you are warned
that only the low order 32 bits are used, and 'as' pretends these 32
bits are an integer.  You may write integer-manipulating instructions
that act on exotic constants, compatible with other assemblers.

   Subexpressions are a left parenthesis '(' followed by an integer
expression, followed by a right parenthesis ')'; or a prefix operator
followed by an argument.

6.2.2 Operators
---------------

"Operators" are arithmetic functions, like '+' or '%'.  Prefix operators
are followed by an argument.  Infix operators appear between their
arguments.  Operators may be preceded and/or followed by whitespace.

6.2.3 Prefix Operator
---------------------

'as' has the following "prefix operators".  They each take one argument,
which must be absolute.

'-'
     "Negation".  Two's complement negation.
'~'
     "Complementation".  Bitwise not.

6.2.4 Infix Operators
---------------------

"Infix operators" take two arguments, one on either side.  Operators
have precedence, but operations with equal precedence are performed left
to right.  Apart from '+' or '-', both arguments must be absolute, and
the result is absolute.

  1. Highest Precedence

     '*'
          "Multiplication".

     '/'
          "Division".  Truncation is the same as the C operator '/'

     '%'
          "Remainder".

     '<<'
          "Shift Left".  Same as the C operator '<<'.

     '>>'
          "Shift Right".  Same as the C operator '>>'.

  2. Intermediate precedence

     '|'

          "Bitwise Inclusive Or".

     '&'
          "Bitwise And".

     '^'
          "Bitwise Exclusive Or".

     '!'
          "Bitwise Or Not".

  3. Low Precedence

     '+'
          "Addition".  If either argument is absolute, the result has
          the section of the other argument.  You may not add together
          arguments from different sections.

     '-'
          "Subtraction".  If the right argument is absolute, the result
          has the section of the left argument.  If both arguments are
          in the same section, the result is absolute.  You may not
          subtract arguments from different sections.

     '=='
          "Is Equal To"
     '<>'
     '!='
          "Is Not Equal To"
     '<'
          "Is Less Than"
     '>'
          "Is Greater Than"
     '>='
          "Is Greater Than Or Equal To"
     '<='
          "Is Less Than Or Equal To"

          The comparison operators can be used as infix operators.  A
          true results has a value of -1 whereas a false result has a
          value of 0.  Note, these operators perform signed comparisons.

  4. Lowest Precedence

     '&&'
          "Logical And".

     '||'
          "Logical Or".

          These two logical operations can be used to combine the
          results of sub expressions.  Note, unlike the comparison
          operators a true result returns a value of 1 but a false
          results does still return 0.  Also note that the logical or
          operator has a slightly lower precedence than logical and.

   In short, it's only meaningful to add or subtract the _offsets_ in an
address; you can only have a defined section in one of the two
arguments.

7 Assembler Directives
**********************

All assembler directives have names that begin with a period ('.').  The
rest of the name is letters, usually in lower case.

   This chapter discusses directives that are available regardless of
the target machine configuration for the GNU assembler.

7.1 '.abort'
============

This directive stops the assembly immediately.  It is for compatibility
with other assemblers.  The original idea was that the assembly language
source would be piped into the assembler.  If the sender of the source
quit, it could use this directive tells 'as' to quit also.  One day
'.abort' will not be supported.

7.2 '.align ABS-EXPR, ABS-EXPR, ABS-EXPR'
=========================================

Pad the location counter (in the current subsection) to a particular
storage boundary.  The first expression (which must be absolute) is the
alignment required, as described below.

   The second expression (also absolute) gives the fill value to be
stored in the padding bytes.  It (and the comma) may be omitted.  If it
is omitted, the padding bytes are normally zero.  However, on some
systems, if the section is marked as containing code and the fill value
is omitted, the space is filled with no-op instructions.

   The third expression is also absolute, and is also optional.  If it
is present, it is the maximum number of bytes that should be skipped by
this alignment directive.  If doing the alignment would require skipping
more bytes than the specified maximum, then the alignment is not done at
all.  You can omit the fill value (the second argument) entirely by
simply using two commas after the required alignment; this can be useful
if you want the alignment to be filled with no-op instructions when
appropriate.

   The way the required alignment is specified varies from system to
system.  For the arc, hppa, i386 using ELF, i860, iq2000, m68k, or32,
s390, sparc, tic4x, tic80 and xtensa, the first expression is the
alignment request in bytes.  For example '.align 8' advances the
location counter until it is a multiple of 8.  If the location counter
is already a multiple of 8, no change is needed.  For the tic54x, the
first expression is the alignment request in words.

   For other systems, including the i386 using a.out format, and the arm
and strongarm, it is the number of low-order zero bits the location
counter must have after advancement.  For example '.align 3' advances
the location counter until it a multiple of 8.  If the location counter
is already a multiple of 8, no change is needed.

   This inconsistency is due to the different behaviors of the various
native assemblers for these systems which GAS must emulate.  GAS also
provides '.balign' and '.p2align' directives, described later, which
have a consistent behavior across all architectures (but are specific to
GAS).

7.3 '.ascii "STRING"'...
========================

'.ascii' expects zero or more string literals (*note Strings::)
separated by commas.  It assembles each string (with no automatic
trailing zero byte) into consecutive addresses.

7.4 '.asciz "STRING"'...
========================

'.asciz' is just like '.ascii', but each string is followed by a zero
byte.  The "z" in '.asciz' stands for "zero".

7.5 '.balign[wl] ABS-EXPR, ABS-EXPR, ABS-EXPR'
==============================================

Pad the location counter (in the current subsection) to a particular
storage boundary.  The first expression (which must be absolute) is the
alignment request in bytes.  For example '.balign 8' advances the
location counter until it is a multiple of 8.  If the location counter
is already a multiple of 8, no change is needed.

   The second expression (also absolute) gives the fill value to be
stored in the padding bytes.  It (and the comma) may be omitted.  If it
is omitted, the padding bytes are normally zero.  However, on some
systems, if the section is marked as containing code and the fill value
is omitted, the space is filled with no-op instructions.

   The third expression is also absolute, and is also optional.  If it
is present, it is the maximum number of bytes that should be skipped by
this alignment directive.  If doing the alignment would require skipping
more bytes than the specified maximum, then the alignment is not done at
all.  You can omit the fill value (the second argument) entirely by
simply using two commas after the required alignment; this can be useful
if you want the alignment to be filled with no-op instructions when
appropriate.

   The '.balignw' and '.balignl' directives are variants of the
'.balign' directive.  The '.balignw' directive treats the fill pattern
as a two byte word value.  The '.balignl' directives treats the fill
pattern as a four byte longword value.  For example, '.balignw 4,0x368d'
will align to a multiple of 4.  If it skips two bytes, they will be
filled in with the value 0x368d (the exact placement of the bytes
depends upon the endianness of the processor).  If it skips 1 or 3
bytes, the fill value is undefined.

7.6 '.byte EXPRESSIONS'
=======================

'.byte' expects zero or more expressions, separated by commas.  Each
expression is assembled into the next byte.

7.7 '.comm SYMBOL , LENGTH '
============================

'.comm' declares a common symbol named SYMBOL.  When linking, a common
symbol in one object file may be merged with a defined or common symbol
of the same name in another object file.  If 'ld' does not see a
definition for the symbol-just one or more common symbols-then it will
allocate LENGTH bytes of uninitialized memory.  LENGTH must be an
absolute expression.  If 'ld' sees multiple common symbols with the same
name, and they do not all have the same size, it will allocate space
using the largest size.

   When using ELF, the '.comm' directive takes an optional third
argument.  This is the desired alignment of the symbol, specified as a
byte boundary (for example, an alignment of 16 means that the least
significant 4 bits of the address should be zero).  The alignment must
be an absolute expression, and it must be a power of two.  If 'ld'
allocates uninitialized memory for the common symbol, it will use the
alignment when placing the symbol.  If no alignment is specified, 'as'
will set the alignment to the largest power of two less than or equal to
the size of the symbol, up to a maximum of 16.

7.8 '.cfi_startproc [simple]'
=============================

'.cfi_startproc' is used at the beginning of each function that should
have an entry in '.eh_frame'.  It initializes some internal data
structures.  Don't forget to close the function by '.cfi_endproc'.

   Unless '.cfi_startproc' is used along with parameter 'simple' it also
emits some architecture dependent initial CFI instructions.

7.9 '.cfi_endproc'
==================

'.cfi_endproc' is used at the end of a function where it closes its
unwind entry previously opened by '.cfi_startproc', and emits it to
'.eh_frame'.

7.10 '.cfi_personality ENCODING [, EXP]'
========================================

'.cfi_personality' defines personality routine and its encoding.
ENCODING must be a constant determining how the personality should be
encoded.  If it is 255 ('DW_EH_PE_omit'), second argument is not
present, otherwise second argument should be a constant or a symbol
name.  When using indirect encodings, the symbol provided should be the
location where personality can be loaded from, not the personality
routine itself.  The default after '.cfi_startproc' is '.cfi_personality
0xff', no personality routine.

7.11 '.cfi_lsda ENCODING [, EXP]'
=================================

'.cfi_lsda' defines LSDA and its encoding.  ENCODING must be a constant
determining how the LSDA should be encoded.  If it is 255
('DW_EH_PE_omit'), second argument is not present, otherwise second
argument should be a constant or a symbol name.  The default after
'.cfi_startproc' is '.cfi_lsda 0xff', no LSDA.

7.12 '.cfi_def_cfa REGISTER, OFFSET'
====================================

'.cfi_def_cfa' defines a rule for computing CFA as: take address from
REGISTER and add OFFSET to it.

7.13 '.cfi_def_cfa_register REGISTER'
=====================================

'.cfi_def_cfa_register' modifies a rule for computing CFA. From now on
REGISTER will be used instead of the old one.  Offset remains the same.

7.14 '.cfi_def_cfa_offset OFFSET'
=================================

'.cfi_def_cfa_offset' modifies a rule for computing CFA. Register
remains the same, but OFFSET is new.  Note that it is the absolute
offset that will be added to a defined register to compute CFA address.

7.15 '.cfi_adjust_cfa_offset OFFSET'
====================================

Same as '.cfi_def_cfa_offset' but OFFSET is a relative value that is
added/substracted from the previous offset.

7.16 '.cfi_offset REGISTER, OFFSET'
===================================

Previous value of REGISTER is saved at offset OFFSET from CFA.

7.17 '.cfi_rel_offset REGISTER, OFFSET'
=======================================

Previous value of REGISTER is saved at offset OFFSET from the current
CFA register.  This is transformed to '.cfi_offset' using the known
displacement of the CFA register from the CFA. This is often easier to
use, because the number will match the code it's annotating.

7.18 '.cfi_register REGISTER1, REGISTER2'
=========================================

Previous value of REGISTER1 is saved in register REGISTER2.

7.19 '.cfi_restore REGISTER'
============================

'.cfi_restore' says that the rule for REGISTER is now the same as it was
at the beginning of the function, after all initial instruction added by
'.cfi_startproc' were executed.

7.20 '.cfi_undefined REGISTER'
==============================

From now on the previous value of REGISTER can't be restored anymore.

7.21 '.cfi_same_value REGISTER'
===============================

Current value of REGISTER is the same like in the previous frame, i.e.
no restoration needed.

7.22 '.cfi_remember_state',
===========================

First save all current rules for all registers by '.cfi_remember_state',
then totally screw them up by subsequent '.cfi_*' directives and when
everything is hopelessly bad, use '.cfi_restore_state' to restore the
previous saved state.

7.23 '.cfi_return_column REGISTER'
==================================

Change return column REGISTER, i.e.  the return address is either
directly in REGISTER or can be accessed by rules for REGISTER.

7.24 '.cfi_signal_frame'
========================

Mark current function as signal trampoline.

7.25 '.cfi_window_save'
=======================

SPARC register window has been saved.

7.26 '.cfi_escape' EXPRESSION[, ...]
====================================

Allows the user to add arbitrary bytes to the unwind info.  One might
use this to add OS-specific CFI opcodes, or generic CFI opcodes that GAS
does not yet support.

7.27 '.file FILENO FILENAME'
============================

When emitting dwarf2 line number information '.file' assigns filenames
to the '.debug_line' file name table.  The FILENO operand should be a
unique positive integer to use as the index of the entry in the table.
The FILENAME operand is a C string literal.

   The detail of filename indices is exposed to the user because the
filename table is shared with the '.debug_info' section of the dwarf2
debugging information, and thus the user must know the exact indices
that table entries will have.

7.28 '.loc FILENO LINENO [COLUMN] [OPTIONS]'
============================================

The '.loc' directive will add row to the '.debug_line' line number
matrix corresponding to the immediately following assembly instruction.
The FILENO, LINENO, and optional COLUMN arguments will be applied to the
'.debug_line' state machine before the row is added.

   The OPTIONS are a sequence of the following tokens in any order:

'basic_block'
     This option will set the 'basic_block' register in the
     '.debug_line' state machine to 'true'.

'prologue_end'
     This option will set the 'prologue_end' register in the
     '.debug_line' state machine to 'true'.

'epilogue_begin'
     This option will set the 'epilogue_begin' register in the
     '.debug_line' state machine to 'true'.

'is_stmt VALUE'
     This option will set the 'is_stmt' register in the '.debug_line'
     state machine to 'value', which must be either 0 or 1.

'isa VALUE'
     This directive will set the 'isa' register in the '.debug_line'
     state machine to VALUE, which must be an unsigned integer.

7.29 '.loc_mark_blocks ENABLE'
==============================

The '.loc_mark_blocks' directive makes the assembler emit an entry to
the '.debug_line' line number matrix with the 'basic_block' register in
the state machine set whenever a code label is seen.  The ENABLE
argument should be either 1 or 0, to enable or disable this function
respectively.

7.30 '.data SUBSECTION'
=======================

'.data' tells 'as' to assemble the following statements onto the end of
the data subsection numbered SUBSECTION (which is an absolute
expression).  If SUBSECTION is omitted, it defaults to zero.

7.31 '.double FLONUMS'
======================

'.double' expects zero or more flonums, separated by commas.  It
assembles floating point numbers.

7.32 '.eject'
=============

Force a page break at this point, when generating assembly listings.

7.33 '.else'
============

'.else' is part of the 'as' support for conditional assembly; see *note
'.if': If.  It marks the beginning of a section of code to be assembled
if the condition for the preceding '.if' was false.

7.34 '.elseif'
==============

'.elseif' is part of the 'as' support for conditional assembly; see
*note '.if': If.  It is shorthand for beginning a new '.if' block that
would otherwise fill the entire '.else' section.

7.35 '.end'
===========

'.end' marks the end of the assembly file.  'as' does not process
anything in the file past the '.end' directive.

7.36 '.endfunc'
===============

'.endfunc' marks the end of a function specified with '.func'.

7.37 '.endif'
=============

'.endif' is part of the 'as' support for conditional assembly; it marks
the end of a block of code that is only assembled conditionally.  *Note
'.if': If.

7.38 '.equ SYMBOL, EXPRESSION'
==============================

This directive sets the value of SYMBOL to EXPRESSION.  It is synonymous
with '.set'; see *note '.set': Set.

7.39 '.equiv SYMBOL, EXPRESSION'
================================

The '.equiv' directive is like '.equ' and '.set', except that the
assembler will signal an error if SYMBOL is already defined.  Note a
symbol which has been referenced but not actually defined is considered
to be undefined.

   Except for the contents of the error message, this is roughly
equivalent to
     .ifdef SYM
     .err
     .endif
     .equ SYM,VAL
   plus it protects the symbol from later redefinition.

7.40 '.eqv SYMBOL, EXPRESSION'
==============================

The '.eqv' directive is like '.equiv', but no attempt is made to
evaluate the expression or any part of it immediately.  Instead each
time the resulting symbol is used in an expression, a snapshot of its
current value is taken.

7.41 '.err'
===========

If 'as' assembles a '.err' directive, it will print an error message
and, unless the '-Z' option was used, it will not generate an object
file.  This can be used to signal an error in conditionally compiled
code.

7.42 '.error "STRING"'
======================

Similarly to '.err', this directive emits an error, but you can specify
a string that will be emitted as the error message.  If you don't
specify the message, it defaults to '".error directive invoked in source
file"'.  *Note Error and Warning Messages: Errors.

      .error "This code has not been assembled and tested."

7.43 '.exitm'
=============

Exit early from the current macro definition.  *Note Macro::.

7.44 '.extern'
==============

'.extern' is accepted in the source program--for compatibility with
other assemblers--but it is ignored.  'as' treats all undefined symbols
as external.

7.45 '.fail EXPRESSION'
=======================

Generates an error or a warning.  If the value of the EXPRESSION is 500
or more, 'as' will print a warning message.  If the value is less than
500, 'as' will print an error message.  The message will include the
value of EXPRESSION.  This can occasionally be useful inside complex
nested macros or conditional assembly.

7.46 '.file STRING'
===================

'.file' tells 'as' that we are about to start a new logical file.
STRING is the new file name.  In general, the filename is recognized
whether or not it is surrounded by quotes '"'; but if you wish to
specify an empty file name, you must give the quotes-'""'.  This
statement may go away in future: it is only recognized to be compatible
with old 'as' programs.

7.47 '.fill REPEAT , SIZE , VALUE'
==================================

REPEAT, SIZE and VALUE are absolute expressions.  This emits REPEAT
copies of SIZE bytes.  REPEAT may be zero or more.  SIZE may be zero or
more, but if it is more than 8, then it is deemed to have the value 8,
compatible with other people's assemblers.  The contents of each REPEAT
bytes is taken from an 8-byte number.  The highest order 4 bytes are
zero.  The lowest order 4 bytes are VALUE rendered in the byte-order of
an integer on the computer 'as' is assembling for.  Each SIZE bytes in a
repetition is taken from the lowest order SIZE bytes of this number.
Again, this bizarre behavior is compatible with other people's
assemblers.

   SIZE and VALUE are optional.  If the second comma and VALUE are
absent, VALUE is assumed zero.  If the first comma and following tokens
are absent, SIZE is assumed to be 1.

7.48 '.float FLONUMS'
=====================

This directive assembles zero or more flonums, separated by commas.  It
has the same effect as '.single'.

7.49 '.func NAME[,LABEL]'
=========================

'.func' emits debugging information to denote function NAME, and is
ignored unless the file is assembled with debugging enabled.  Only
'--gstabs[+]' is currently supported.  LABEL is the entry point of the
function and if omitted NAME prepended with the 'leading char' is used.
'leading char' is usually '_' or nothing, depending on the target.  All
functions are currently defined to have 'void' return type.  The
function must be terminated with '.endfunc'.

7.50 '.global SYMBOL', '.globl SYMBOL'
======================================

'.global' makes the symbol visible to 'ld'.  If you define SYMBOL in
your partial program, its value is made available to other partial
programs that are linked with it.  Otherwise, SYMBOL takes its
attributes from a symbol of the same name from another file linked into
the same program.

   Both spellings ('.globl' and '.global') are accepted, for
compatibility with other assemblers.

7.51 '.hidden NAMES'
====================

This is one of the ELF visibility directives.  The other two are
'.internal' (*note '.internal': Internal.) and '.protected' (*note
'.protected': Protected.).

   This directive overrides the named symbols default visibility (which
is set by their binding: local, global or weak).  The directive sets the
visibility to 'hidden' which means that the symbols are not visible to
other components.  Such symbols are always considered to be 'protected'
as well.

7.52 '.hword EXPRESSIONS'
=========================

This expects zero or more EXPRESSIONS, and emits a 16 bit number for
each.

   This directive is a synonym for '.short'.

7.53 '.ident'
=============

This directive is used by some assemblers to place tags in object files.
The behavior of this directive varies depending on the target.  When
using the a.out object file format, 'as' simply accepts the directive
for source-file compatibility with existing assemblers, but does not
emit anything for it.  When using COFF, comments are emitted to the
'.comment' or '.rdata' section, depending on the target.  When using
ELF, comments are emitted to the '.comment' section.

7.54 '.if ABSOLUTE EXPRESSION'
==============================

'.if' marks the beginning of a section of code which is only considered
part of the source program being assembled if the argument (which must
be an ABSOLUTE EXPRESSION) is non-zero.  The end of the conditional
section of code must be marked by '.endif' (*note '.endif': Endif.);
optionally, you may include code for the alternative condition, flagged
by '.else' (*note '.else': Else.).  If you have several conditions to
check, '.elseif' may be used to avoid nesting blocks if/else within each
subsequent '.else' block.

   The following variants of '.if' are also supported:
'.ifdef SYMBOL'
     Assembles the following section of code if the specified SYMBOL has
     been defined.  Note a symbol which has been referenced but not yet
     defined is considered to be undefined.

'.ifb TEXT'
     Assembles the following section of code if the operand is blank
     (empty).

'.ifc STRING1,STRING2'
     Assembles the following section of code if the two strings are the
     same.  The strings may be optionally quoted with single quotes.  If
     they are not quoted, the first string stops at the first comma, and
     the second string stops at the end of the line.  Strings which
     contain whitespace should be quoted.  The string comparison is case
     sensitive.

'.ifeq ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is zero.

'.ifeqs STRING1,STRING2'
     Another form of '.ifc'.  The strings must be quoted using double
     quotes.

'.ifge ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is greater
     than or equal to zero.

'.ifgt ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is greater
     than zero.

'.ifle ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is less
     than or equal to zero.

'.iflt ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is less
     than zero.

'.ifnb TEXT'
     Like '.ifb', but the sense of the test is reversed: this assembles
     the following section of code if the operand is non-blank
     (non-empty).

'.ifnc STRING1,STRING2.'
     Like '.ifc', but the sense of the test is reversed: this assembles
     the following section of code if the two strings are not the same.

'.ifndef SYMBOL'
'.ifnotdef SYMBOL'
     Assembles the following section of code if the specified SYMBOL has
     not been defined.  Both spelling variants are equivalent.  Note a
     symbol which has been referenced but not yet defined is considered
     to be undefined.

'.ifne ABSOLUTE EXPRESSION'
     Assembles the following section of code if the argument is not
     equal to zero (in other words, this is equivalent to '.if').

'.ifnes STRING1,STRING2'
     Like '.ifeqs', but the sense of the test is reversed: this
     assembles the following section of code if the two strings are not
     the same.

7.55 '.incbin "FILE"[,SKIP[,COUNT]]'
====================================

The 'incbin' directive includes FILE verbatim at the current location.
You can control the search paths used with the '-I' command-line option
(*note Command-Line Options: Invoking.).  Quotation marks are required
around FILE.

   The SKIP argument skips a number of bytes from the start of the FILE.
The COUNT argument indicates the maximum number of bytes to read.  Note
that the data is not aligned in any way, so it is the user's
responsibility to make sure that proper alignment is provided both
before and after the 'incbin' directive.

7.56 '.include "FILE"'
======================

This directive provides a way to include supporting files at specified
points in your source program.  The code from FILE is assembled as if it
followed the point of the '.include'; when the end of the included file
is reached, assembly of the original file continues.  You can control
the search paths used with the '-I' command-line option (*note
Command-Line Options: Invoking.).  Quotation marks are required around
FILE.

7.57 '.int EXPRESSIONS'
=======================

Expect zero or more EXPRESSIONS, of any section, separated by commas.
For each expression, emit a number that, at run time, is the value of
that expression.  The byte order and bit size of the number depends on
what kind of target the assembly is for.

7.58 '.internal NAMES'
======================

This is one of the ELF visibility directives.  The other two are
'.hidden' (*note '.hidden': Hidden.) and '.protected' (*note
'.protected': Protected.).

   This directive overrides the named symbols default visibility (which
is set by their binding: local, global or weak).  The directive sets the
visibility to 'internal' which means that the symbols are considered to
be 'hidden' (i.e., not visible to other components), and that some
extra, processor specific processing must also be performed upon the
symbols as well.

7.59 '.irp SYMBOL,VALUES'...
============================

Evaluate a sequence of statements assigning different values to SYMBOL.
The sequence of statements starts at the '.irp' directive, and is
terminated by an '.endr' directive.  For each VALUE, SYMBOL is set to
VALUE, and the sequence of statements is assembled.  If no VALUE is
listed, the sequence of statements is assembled once, with SYMBOL set to
the null string.  To refer to SYMBOL within the sequence of statements,
use \SYMBOL.

   For example, assembling

             .irp    param,1,2,3
             move    d\param,sp@-
             .endr

   is equivalent to assembling

             move    d1,sp@-
             move    d2,sp@-
             move    d3,sp@-

   For some caveats with the spelling of SYMBOL, see also *note Macro::.

7.60 '.irpc SYMBOL,VALUES'...
=============================

Evaluate a sequence of statements assigning different values to SYMBOL.
The sequence of statements starts at the '.irpc' directive, and is
terminated by an '.endr' directive.  For each character in VALUE, SYMBOL
is set to the character, and the sequence of statements is assembled.
If no VALUE is listed, the sequence of statements is assembled once,
with SYMBOL set to the null string.  To refer to SYMBOL within the
sequence of statements, use \SYMBOL.

   For example, assembling

             .irpc    param,123
             move    d\param,sp@-
             .endr

   is equivalent to assembling

             move    d1,sp@-
             move    d2,sp@-
             move    d3,sp@-

   For some caveats with the spelling of SYMBOL, see also the discussion
at *Note Macro::.

7.61 '.lcomm SYMBOL , LENGTH'
=============================

Reserve LENGTH (an absolute expression) bytes for a local common denoted
by SYMBOL.  The section and value of SYMBOL are those of the new local
common.  The addresses are allocated in the bss section, so that at
run-time the bytes start off zeroed.  SYMBOL is not declared global
(*note '.global': Global.), so is normally not visible to 'ld'.

7.62 '.lflags'
==============

'as' accepts this directive, for compatibility with other assemblers,
but ignores it.

7.63 '.line LINE-NUMBER'
========================

Even though this is a directive associated with the 'a.out' or 'b.out'
object-code formats, 'as' still recognizes it when producing COFF
output, and treats '.line' as though it were the COFF '.ln' _if_ it is
found outside a '.def'/'.endef' pair.

   Inside a '.def', '.line' is, instead, one of the directives used by
compilers to generate auxiliary symbol information for debugging.

7.64 '.linkonce [TYPE]'
=======================

Mark the current section so that the linker only includes a single copy
of it.  This may be used to include the same section in several
different object files, but ensure that the linker will only include it
once in the final output file.  The '.linkonce' pseudo-op must be used
for each instance of the section.  Duplicate sections are detected based
on the section name, so it should be unique.

   This directive is only supported by a few object file formats; as of
this writing, the only object file format which supports it is the
Portable Executable format used on Windows NT.

   The TYPE argument is optional.  If specified, it must be one of the
following strings.  For example:
     .linkonce same_size
   Not all types may be supported on all object file formats.

'discard'
     Silently discard duplicate sections.  This is the default.

'one_only'
     Warn if there are duplicate sections, but still keep only one copy.

'same_size'
     Warn if any of the duplicates have different sizes.

'same_contents'
     Warn if any of the duplicates do not have exactly the same
     contents.

7.65 '.ln LINE-NUMBER'
======================

'.ln' is a synonym for '.line'.

7.66 '.mri VAL'
===============

If VAL is non-zero, this tells 'as' to enter MRI mode.  If VAL is zero,
this tells 'as' to exit MRI mode.  This change affects code assembled
until the next '.mri' directive, or until the end of the file.  *Note
MRI mode: M.

7.67 '.list'
============

Control (in conjunction with the '.nolist' directive) whether or not
assembly listings are generated.  These two directives maintain an
internal counter (which is zero initially).  '.list' increments the
counter, and '.nolist' decrements it.  Assembly listings are generated
whenever the counter is greater than zero.

   By default, listings are disabled.  When you enable them (with the
'-a' command line option; *note Command-Line Options: Invoking.), the
initial value of the listing counter is one.

7.68 '.long EXPRESSIONS'
========================

'.long' is the same as '.int'.  *Note '.int': Int.

7.69 '.macro'
=============

The commands '.macro' and '.endm' allow you to define macros that
generate assembly output.  For example, this definition specifies a
macro 'sum' that puts a sequence of numbers into memory:

             .macro  sum from=0, to=5
             .long   \from
             .if     \to-\from
             sum     "(\from+1)",\to
             .endif
             .endm

With that definition, 'SUM 0,5' is equivalent to this assembly input:

             .long   0
             .long   1
             .long   2
             .long   3
             .long   4
             .long   5

'.macro MACNAME'
'.macro MACNAME MACARGS ...'
     Begin the definition of a macro called MACNAME.  If your macro
     definition requires arguments, specify their names after the macro
     name, separated by commas or spaces.  You can qualify the macro
     argument to indicate whether all invocations must specify a
     non-blank value (through ':'req''), or whether it takes all of the
     remaining arguments (through ':'vararg'').  You can supply a
     default value for any macro argument by following the name with
     '=DEFLT'.  You cannot define two macros with the same MACNAME
     unless it has been subject to the '.purgem' directive (*note
     Purgem::) between the two definitions.  For example, these are all
     valid '.macro' statements:

     '.macro comm'
          Begin the definition of a macro called 'comm', which takes no
          arguments.

     '.macro plus1 p, p1'
     '.macro plus1 p p1'
          Either statement begins the definition of a macro called
          'plus1', which takes two arguments; within the macro
          definition, write '\p' or '\p1' to evaluate the arguments.

     '.macro reserve_str p1=0 p2'
          Begin the definition of a macro called 'reserve_str', with two
          arguments.  The first argument has a default value, but not
          the second.  After the definition is complete, you can call
          the macro either as 'reserve_str A,B' (with '\p1' evaluating
          to A and '\p2' evaluating to B), or as 'reserve_str ,B' (with
          '\p1' evaluating as the default, in this case '0', and '\p2'
          evaluating to B).

     '.macro m p1:req, p2=0, p3:vararg'
          Begin the definition of a macro called 'm', with at least
          three arguments.  The first argument must always have a value
          specified, but not the second, which instead has a default
          value.  The third formal will get assigned all remaining
          arguments specified at invocation time.

          When you call a macro, you can specify the argument values
          either by position, or by keyword.  For example, 'sum 9,17' is
          equivalent to 'sum to=17, from=9'.

     Note that since each of the MACARGS can be an identifier exactly as
     any other one permitted by the target architecture, there may be
     occasional problems if the target hand-crafts special meanings to
     certain characters when they occur in a special position.  For
     example, if the colon (':') is generally permitted to be part of a
     symbol name, but the architecture specific code special-cases it
     when occurring as the final character of a symbol (to denote a
     label), then the macro parameter replacement code will have no way
     of knowing that and consider the whole construct (including the
     colon) an identifier, and check only this identifier for being the
     subject to parameter substitution.  So for example this macro
     definition:

          	.macro label l
          \l:
          	.endm

     might not work as expected.  Invoking 'label foo' might not create
     a label called 'foo' but instead just insert the text '\l:' into
     the assembler source, probably generating an error about an
     unrecognised identifier.

     Similarly problems might occur with the period character ('.')
     which is often allowed inside opcode names (and hence identifier
     names).  So for example constructing a macro to build an opcode
     from a base name and a length specifier like this:

          	.macro opcode base length
                  \base.\length
          	.endm

     and invoking it as 'opcode store l' will not create a 'store.l'
     instruction but instead generate some kind of error as the
     assembler tries to interpret the text '\base.\length'.

     There are several possible ways around this problem:

     'Insert white space'
          If it is possible to use white space characters then this is
          the simplest solution.  eg:

               	.macro label l
               \l :
               	.endm

     'Use '\()''
          The string '\()' can be used to separate the end of a macro
          argument from the following text.  eg:

               	.macro opcode base length
                       \base\().\length
               	.endm

     'Use the alternate macro syntax mode'
          In the alternative macro syntax mode the ampersand character
          ('&') can be used as a separator.  eg:

               	.altmacro
               	.macro label l
               l&:
               	.endm

     Note: this problem of correctly identifying string parameters to
     pseudo ops also applies to the identifiers used in '.irp' (*note
     Irp::) and '.irpc' (*note Irpc::) as well.

'.endm'
     Mark the end of a macro definition.

'.exitm'
     Exit early from the current macro definition.

'\@'
     'as' maintains a counter of how many macros it has executed in this
     pseudo-variable; you can copy that number to your output with '\@',
     but _only within a macro definition_.

'LOCAL NAME [ , ... ]'
     _Warning: 'LOCAL' is only available if you select "alternate macro
     syntax" with '--alternate' or '.altmacro'._  *Note '.altmacro':
     Altmacro.

7.70 '.altmacro'
================

Enable alternate macro mode, enabling:

'LOCAL NAME [ , ... ]'
     One additional directive, 'LOCAL', is available.  It is used to
     generate a string replacement for each of the NAME arguments, and
     replace any instances of NAME in each macro expansion.  The
     replacement string is unique in the assembly, and different for
     each separate macro expansion.  'LOCAL' allows you to write macros
     that define symbols, without fear of conflict between separate
     macro expansions.

'String delimiters'
     You can write strings delimited in these other ways besides
     '"STRING"':

     ''STRING''
          You can delimit strings with single-quote characters.

     '<STRING>'
          You can delimit strings with matching angle brackets.

'single-character string escape'
     To include any single character literally in a string (even if the
     character would otherwise have some special meaning), you can
     prefix the character with '!' (an exclamation mark).  For example,
     you can write '<4.3 !> 5.4!!>' to get the literal text '4.3 >
     5.4!'.

'Expression results as strings'
     You can write '%EXPR' to evaluate the expression EXPR and use the
     result as a string.

7.71 '.noaltmacro'
==================

Disable alternate macro mode.  *Note Altmacro::.

7.72 '.nolist'
==============

Control (in conjunction with the '.list' directive) whether or not
assembly listings are generated.  These two directives maintain an
internal counter (which is zero initially).  '.list' increments the
counter, and '.nolist' decrements it.  Assembly listings are generated
whenever the counter is greater than zero.

7.73 '.octa BIGNUMS'
====================

This directive expects zero or more bignums, separated by commas.  For
each bignum, it emits a 16-byte integer.

   The term "octa" comes from contexts in which a "word" is two bytes;
hence _octa_-word for 16 bytes.

7.74 '.org NEW-LC , FILL'
=========================

Advance the location counter of the current section to NEW-LC.  NEW-LC
is either an absolute expression or an expression with the same section
as the current subsection.  That is, you can't use '.org' to cross
sections: if NEW-LC has the wrong section, the '.org' directive is
ignored.  To be compatible with former assemblers, if the section of
NEW-LC is absolute, 'as' issues a warning, then pretends the section of
NEW-LC is the same as the current subsection.

   '.org' may only increase the location counter, or leave it unchanged;
you cannot use '.org' to move the location counter backwards.

   Because 'as' tries to assemble programs in one pass, NEW-LC may not
be undefined.  If you really detest this restriction we eagerly await a
chance to share your improved assembler.

   Beware that the origin is relative to the start of the section, not
to the start of the subsection.  This is compatible with other people's
assemblers.

   When the location counter (of the current subsection) is advanced,
the intervening bytes are filled with FILL which should be an absolute
expression.  If the comma and FILL are omitted, FILL defaults to zero.

7.75 '.p2align[wl] ABS-EXPR, ABS-EXPR, ABS-EXPR'
================================================

Pad the location counter (in the current subsection) to a particular
storage boundary.  The first expression (which must be absolute) is the
number of low-order zero bits the location counter must have after
advancement.  For example '.p2align 3' advances the location counter
until it a multiple of 8.  If the location counter is already a multiple
of 8, no change is needed.

   The second expression (also absolute) gives the fill value to be
stored in the padding bytes.  It (and the comma) may be omitted.  If it
is omitted, the padding bytes are normally zero.  However, on some
systems, if the section is marked as containing code and the fill value
is omitted, the space is filled with no-op instructions.

   The third expression is also absolute, and is also optional.  If it
is present, it is the maximum number of bytes that should be skipped by
this alignment directive.  If doing the alignment would require skipping
more bytes than the specified maximum, then the alignment is not done at
all.  You can omit the fill value (the second argument) entirely by
simply using two commas after the required alignment; this can be useful
if you want the alignment to be filled with no-op instructions when
appropriate.

   The '.p2alignw' and '.p2alignl' directives are variants of the
'.p2align' directive.  The '.p2alignw' directive treats the fill pattern
as a two byte word value.  The '.p2alignl' directives treats the fill
pattern as a four byte longword value.  For example, '.p2alignw
2,0x368d' will align to a multiple of 4.  If it skips two bytes, they
will be filled in with the value 0x368d (the exact placement of the
bytes depends upon the endianness of the processor).  If it skips 1 or 3
bytes, the fill value is undefined.

7.76 '.previous'
================

This is one of the ELF section stack manipulation directives.  The
others are '.section' (*note Section::), '.subsection' (*note
SubSection::), '.pushsection' (*note PushSection::), and '.popsection'
(*note PopSection::).

   This directive swaps the current section (and subsection) with most
recently referenced section (and subsection) prior to this one.
Multiple '.previous' directives in a row will flip between two sections
(and their subsections).

   In terms of the section stack, this directive swaps the current
section with the top section on the section stack.

7.77 '.popsection'
==================

This is one of the ELF section stack manipulation directives.  The
others are '.section' (*note Section::), '.subsection' (*note
SubSection::), '.pushsection' (*note PushSection::), and '.previous'
(*note Previous::).

   This directive replaces the current section (and subsection) with the
top section (and subsection) on the section stack.  This section is
popped off the stack.

7.78 '.print STRING'
====================

'as' will print STRING on the standard output during assembly.  You must
put STRING in double quotes.

7.79 '.protected NAMES'
=======================

This is one of the ELF visibility directives.  The other two are
'.hidden' (*note Hidden::) and '.internal' (*note Internal::).

   This directive overrides the named symbols default visibility (which
is set by their binding: local, global or weak).  The directive sets the
visibility to 'protected' which means that any references to the symbols
from within the components that defines them must be resolved to the
definition in that component, even if a definition in another component
would normally preempt this.

7.80 '.psize LINES , COLUMNS'
=============================

Use this directive to declare the number of lines--and, optionally, the
number of columns--to use for each page, when generating listings.

   If you do not use '.psize', listings use a default line-count of 60.
You may omit the comma and COLUMNS specification; the default width is
200 columns.

   'as' generates formfeeds whenever the specified number of lines is
exceeded (or whenever you explicitly request one, using '.eject').

   If you specify LINES as '0', no formfeeds are generated save those
explicitly specified with '.eject'.

7.81 '.purgem NAME'
===================

Undefine the macro NAME, so that later uses of the string will not be
expanded.  *Note Macro::.

7.82 '.pushsection NAME , SUBSECTION'
=====================================

This is one of the ELF section stack manipulation directives.  The
others are '.section' (*note Section::), '.subsection' (*note
SubSection::), '.popsection' (*note PopSection::), and '.previous'
(*note Previous::).

   This directive pushes the current section (and subsection) onto the
top of the section stack, and then replaces the current section and
subsection with 'name' and 'subsection'.

7.83 '.quad BIGNUMS'
====================

'.quad' expects zero or more bignums, separated by commas.  For each
bignum, it emits an 8-byte integer.  If the bignum won't fit in 8 bytes,
it prints a warning message; and just takes the lowest order 8 bytes of
the bignum.

   The term "quad" comes from contexts in which a "word" is two bytes;
hence _quad_-word for 8 bytes.

7.84 '.reloc OFFSET, RELOC_NAME[, EXPRESSION]'
==============================================

Generate a relocation at OFFSET of type RELOC_NAME with value
EXPRESSION.  If OFFSET is a number, the relocation is generated in the
current section.  If OFFSET is an expression that resolves to a symbol
plus offset, the relocation is generated in the given symbol's section.
EXPRESSION, if present, must resolve to a symbol plus addend or to an
absolute value, but note that not all targets support an addend.  e.g.
ELF REL targets such as i386 store an addend in the section contents
rather than in the relocation.  This low level interface does not
support addends stored in the section.

7.85 '.rept COUNT'
==================

Repeat the sequence of lines between the '.rept' directive and the next
'.endr' directive COUNT times.

   For example, assembling

             .rept   3
             .long   0
             .endr

   is equivalent to assembling

             .long   0
             .long   0
             .long   0

7.86 '.sbttl "SUBHEADING"'
==========================

Use SUBHEADING as the title (third line, immediately after the title
line) when generating assembly listings.

   This directive affects subsequent pages, as well as the current page
if it appears within ten lines of the top of a page.

7.87 '.section NAME'
====================

Use the '.section' directive to assemble the following code into a
section named NAME.

   This directive is only supported for targets that actually support
arbitrarily named sections; on 'a.out' targets, for example, it is not
accepted, even with a standard 'a.out' section name.

   This is one of the ELF section stack manipulation directives.  The
others are '.subsection' (*note SubSection::), '.pushsection' (*note
PushSection::), '.popsection' (*note PopSection::), and '.previous'
(*note Previous::).

   For ELF targets, the '.section' directive is used like this:

     .section NAME [, "FLAGS"[, @TYPE[,FLAG_SPECIFIC_ARGUMENTS]]]

   The optional FLAGS argument is a quoted string which may contain any
combination of the following characters:
'a'
     section is allocatable
'w'
     section is writable
'x'
     section is executable
'M'
     section is mergeable
'S'
     section contains zero terminated strings
'G'
     section is a member of a section group
'T'
     section is used for thread-local-storage

   The optional TYPE argument may contain one of the following
constants:
'@progbits'
     section contains data
'@nobits'
     section does not contain data (i.e., section only occupies space)
'@note'
     section contains data which is used by things other than the
     program
'@init_array'
     section contains an array of pointers to init functions
'@fini_array'
     section contains an array of pointers to finish functions
'@preinit_array'
     section contains an array of pointers to pre-init functions

   Many targets only support the first three section types.

   Note on targets where the '@' character is the start of a comment (eg
ARM) then another character is used instead.  For example the ARM port
uses the '%' character.

   If FLAGS contains the 'M' symbol then the TYPE argument must be
specified as well as an extra argument--ENTSIZE--like this:

     .section NAME , "FLAGS"M, @TYPE, ENTSIZE

   Sections with the 'M' flag but not 'S' flag must contain fixed size
constants, each ENTSIZE octets long.  Sections with both 'M' and 'S'
must contain zero terminated strings where each character is ENTSIZE
bytes long.  The linker may remove duplicates within sections with the
same name, same entity size and same flags.  ENTSIZE must be an absolute
expression.

   If FLAGS contains the 'G' symbol then the TYPE argument must be
present along with an additional field like this:

     .section NAME , "FLAGS"G, @TYPE, GROUPNAME[, LINKAGE]

   The GROUPNAME field specifies the name of the section group to which
this particular section belongs.  The optional linkage field can
contain:
'comdat'
     indicates that only one copy of this section should be retained
'.gnu.linkonce'
     an alias for comdat

   Note: if both the M and G flags are present then the fields for the
Merge flag should come first, like this:

     .section NAME , "FLAGS"MG, @TYPE, ENTSIZE, GROUPNAME[, LINKAGE]

   If no flags are specified, the default flags depend upon the section
name.  If the section name is not recognized, the default will be for
the section to have none of the above flags: it will not be allocated in
memory, nor writable, nor executable.  The section will contain data.

   For ELF targets, the assembler supports another type of '.section'
directive for compatibility with the Solaris assembler:

     .section "NAME"[, FLAGS...]

   Note that the section name is quoted.  There may be a sequence of
comma separated flags:
'#alloc'
     section is allocatable
'#write'
     section is writable
'#execinstr'
     section is executable
'#tls'
     section is used for thread local storage

   This directive replaces the current section and subsection.  See the
contents of the gas testsuite directory 'gas/testsuite/gas/elf' for some
examples of how this directive and the other section stack directives
work.

7.88 '.set SYMBOL, EXPRESSION'
==============================

Set the value of SYMBOL to EXPRESSION.  This changes SYMBOL's value and
type to conform to EXPRESSION.  If SYMBOL was flagged as external, it
remains flagged (*note Symbol Attributes::).

   You may '.set' a symbol many times in the same assembly.

   If you '.set' a global symbol, the value stored in the object file is
the last value stored into it.

7.89 '.short EXPRESSIONS'
=========================

This expects zero or more EXPRESSIONS, and emits a 16 bit number for
each.

7.90 '.single FLONUMS'
======================

This directive assembles zero or more flonums, separated by commas.  It
has the same effect as '.float'.

7.91 '.size'
============

This directive is used to set the size associated with a symbol.

   For ELF targets, the '.size' directive is used like this:

     .size NAME , EXPRESSION

   This directive sets the size associated with a symbol NAME.  The size
in bytes is computed from EXPRESSION which can make use of label
arithmetic.  This directive is typically used to set the size of
function symbols.

7.92 '.sleb128 EXPRESSIONS'
===========================

SLEB128 stands for "signed little endian base 128."  This is a compact,
variable length representation of numbers used by the DWARF symbolic
debugging format.  *Note '.uleb128': Uleb128.

7.93 '.skip SIZE , FILL'
========================

This directive emits SIZE bytes, each of value FILL.  Both SIZE and FILL
are absolute expressions.  If the comma and FILL are omitted, FILL is
assumed to be zero.  This is the same as '.space'.

7.94 '.space SIZE , FILL'
=========================

This directive emits SIZE bytes, each of value FILL.  Both SIZE and FILL
are absolute expressions.  If the comma and FILL are omitted, FILL is
assumed to be zero.  This is the same as '.skip'.

7.95 '.stabd, .stabn, .stabs'
=============================

There are three directives that begin '.stab'.  All emit symbols (*note
Symbols::), for use by symbolic debuggers.  The symbols are not entered
in the 'as' hash table: they cannot be referenced elsewhere in the
source file.  Up to five fields are required:

STRING
     This is the symbol's name.  It may contain any character except
     '\000', so is more general than ordinary symbol names.  Some
     debuggers used to code arbitrarily complex structures into symbol
     names using this field.

TYPE
     An absolute expression.  The symbol's type is set to the low 8 bits
     of this expression.  Any bit pattern is permitted, but 'ld' and
     debuggers choke on silly bit patterns.

OTHER
     An absolute expression.  The symbol's "other" attribute is set to
     the low 8 bits of this expression.

DESC
     An absolute expression.  The symbol's descriptor is set to the low
     16 bits of this expression.

VALUE
     An absolute expression which becomes the symbol's value.

   If a warning is detected while reading a '.stabd', '.stabn', or
'.stabs' statement, the symbol has probably already been created; you
get a half-formed symbol in your object file.  This is compatible with
earlier assemblers!

'.stabd TYPE , OTHER , DESC'

     The "name" of the symbol generated is not even an empty string.  It
     is a null pointer, for compatibility.  Older assemblers used a null
     pointer so they didn't waste space in object files with empty
     strings.

     The symbol's value is set to the location counter, relocatably.
     When your program is linked, the value of this symbol is the
     address of the location counter when the '.stabd' was assembled.

'.stabn TYPE , OTHER , DESC , VALUE'
     The name of the symbol is set to the empty string '""'.

'.stabs STRING , TYPE , OTHER , DESC , VALUE'
     All five fields are specified.

7.96 '.string' "STR"
====================

Copy the characters in STR to the object file.  You may specify more
than one string to copy, separated by commas.  Unless otherwise
specified for a particular machine, the assembler marks the end of each
string with a 0 byte.  You can use any of the escape sequences described
in *note Strings: Strings.

7.97 '.struct EXPRESSION'
=========================

Switch to the absolute section, and set the section offset to
EXPRESSION, which must be an absolute expression.  You might use this as
follows:
             .struct 0
     field1:
             .struct field1 + 4
     field2:
             .struct field2 + 4
     field3:
   This would define the symbol 'field1' to have the value 0, the symbol
'field2' to have the value 4, and the symbol 'field3' to have the value
8.  Assembly would be left in the absolute section, and you would need
to use a '.section' directive of some sort to change to some other
section before further assembly.

7.98 '.subsection NAME'
=======================

This is one of the ELF section stack manipulation directives.  The
others are '.section' (*note Section::), '.pushsection' (*note
PushSection::), '.popsection' (*note PopSection::), and '.previous'
(*note Previous::).

   This directive replaces the current subsection with 'name'.  The
current section is not changed.  The replaced subsection is put onto the
section stack in place of the then current top of stack subsection.

7.99 '.symver'
==============

Use the '.symver' directive to bind symbols to specific version nodes
within a source file.  This is only supported on ELF platforms, and is
typically used when assembling files to be linked into a shared library.
There are cases where it may make sense to use this in objects to be
bound into an application itself so as to override a versioned symbol
from a shared library.

   For ELF targets, the '.symver' directive can be used like this:
     .symver NAME, NAME2@NODENAME
   If the symbol NAME is defined within the file being assembled, the
'.symver' directive effectively creates a symbol alias with the name
NAME2@NODENAME, and in fact the main reason that we just don't try and
create a regular alias is that the @ character isn't permitted in symbol
names.  The NAME2 part of the name is the actual name of the symbol by
which it will be externally referenced.  The name NAME itself is merely
a name of convenience that is used so that it is possible to have
definitions for multiple versions of a function within a single source
file, and so that the compiler can unambiguously know which version of a
function is being mentioned.  The NODENAME portion of the alias should
be the name of a node specified in the version script supplied to the
linker when building a shared library.  If you are attempting to
override a versioned symbol from a shared library, then NODENAME should
correspond to the nodename of the symbol you are trying to override.

   If the symbol NAME is not defined within the file being assembled,
all references to NAME will be changed to NAME2@NODENAME.  If no
reference to NAME is made, NAME2@NODENAME will be removed from the
symbol table.

   Another usage of the '.symver' directive is:
     .symver NAME, NAME2@@NODENAME
   In this case, the symbol NAME must exist and be defined within the
file being assembled.  It is similar to NAME2@NODENAME.  The difference
is NAME2@@NODENAME will also be used to resolve references to NAME2 by
the linker.

   The third usage of the '.symver' directive is:
     .symver NAME, NAME2@@@NODENAME
   When NAME is not defined within the file being assembled, it is
treated as NAME2@NODENAME.  When NAME is defined within the file being
assembled, the symbol name, NAME, will be changed to NAME2@@NODENAME.

7.100 '.text SUBSECTION'
========================

Tells 'as' to assemble the following statements onto the end of the text
subsection numbered SUBSECTION, which is an absolute expression.  If
SUBSECTION is omitted, subsection number zero is used.

7.101 '.title "HEADING"'
========================

Use HEADING as the title (second line, immediately after the source file
name and pagenumber) when generating assembly listings.

   This directive affects subsequent pages, as well as the current page
if it appears within ten lines of the top of a page.

7.102 '.type'
=============

This directive is used to set the type of a symbol.

   For ELF targets, the '.type' directive is used like this:

     .type NAME , TYPE DESCRIPTION

   This sets the type of symbol NAME to be either a function symbol or
an object symbol.  There are five different syntaxes supported for the
TYPE DESCRIPTION field, in order to provide compatibility with various
other assemblers.

   Because some of the characters used in these syntaxes (such as '@'
and '#') are comment characters for some architectures, some of the
syntaxes below do not work on all architectures.  The first variant will
be accepted by the GNU assembler on all architectures so that variant
should be used for maximum portability, if you do not need to assemble
your code with other assemblers.

   The syntaxes supported are:

       .type <name> STT_FUNCTION
       .type <name> STT_OBJECT

       .type <name>,#function
       .type <name>,#object

       .type <name>,@function
       .type <name>,@object

       .type <name>,%function
       .type <name>,%object

       .type <name>,"function"
       .type <name>,"object"

7.103 '.uleb128 EXPRESSIONS'
============================

ULEB128 stands for "unsigned little endian base 128."  This is a
compact, variable length representation of numbers used by the DWARF
symbolic debugging format.  *Note '.sleb128': Sleb128.

7.104 '.version "STRING"'
=========================

This directive creates a '.note' section and places into it an ELF
formatted note of type NT_VERSION. The note's name is set to 'string'.

7.105 '.vtable_entry TABLE, OFFSET'
===================================

This directive finds or creates a symbol 'table' and creates a
'VTABLE_ENTRY' relocation for it with an addend of 'offset'.

7.106 '.vtable_inherit CHILD, PARENT'
=====================================

This directive finds the symbol 'child' and finds or creates the symbol
'parent' and then creates a 'VTABLE_INHERIT' relocation for the parent
whose addend is the value of the child symbol.  As a special case the
parent name of '0' is treated as referring to the '*ABS*' section.

7.107 '.warning "STRING"'
=========================

Similar to the directive '.error' (*note '.error "STRING"': Error.), but
just emits a warning.

7.108 '.weak NAMES'
===================

This directive sets the weak attribute on the comma separated list of
symbol 'names'.  If the symbols do not already exist, they will be
created.

   On COFF targets other than PE, weak symbols are a GNU extension.
This directive sets the weak attribute on the comma separated list of
symbol 'names'.  If the symbols do not already exist, they will be
created.

   On the PE target, weak symbols are supported natively as weak
aliases.  When a weak symbol is created that is not an alias, GAS
creates an alternate symbol to hold the default value.

7.109 '.weakref ALIAS, TARGET'
==============================

This directive creates an alias to the target symbol that enables the
symbol to be referenced with weak-symbol semantics, but without actually
making it weak.  If direct references or definitions of the symbol are
present, then the symbol will not be weak, but if all references to it
are through weak references, the symbol will be marked as weak in the
symbol table.

   The effect is equivalent to moving all references to the alias to a
separate assembly source file, renaming the alias to the symbol in it,
declaring the symbol as weak there, and running a reloadable link to
merge the object files resulting from the assembly of the new source
file and the old source file that had the references to the alias
removed.

   The alias itself never makes to the symbol table, and is entirely
handled within the assembler.

7.110 '.word EXPRESSIONS'
=========================

This directive expects zero or more EXPRESSIONS, of any section,
separated by commas.  For each expression, 'as' emits a 32-bit number.

7.111 Deprecated Directives
===========================

One day these directives won't work.  They are included for
compatibility with older assemblers.
.abort
.line

8 ARM Dependent Features
************************

8.1 Options
===========

'-mcpu=PROCESSOR[+EXTENSION...]'
     This option specifies the target processor.  The assembler will
     issue an error message if an attempt is made to assemble an
     instruction which will not execute on the target processor.  The
     following processor names are recognized: 'arm1', 'arm2', 'arm250',
     'arm3', 'arm6', 'arm60', 'arm600', 'arm610', 'arm620', 'arm7',
     'arm7m', 'arm7d', 'arm7dm', 'arm7di', 'arm7dmi', 'arm70', 'arm700',
     'arm700i', 'arm710', 'arm710t', 'arm720', 'arm720t', 'arm740t',
     'arm710c', 'arm7100', 'arm7500', 'arm7500fe', 'arm7t', 'arm7tdmi',
     'arm7tdmi-s', 'arm8', 'arm810', 'strongarm', 'strongarm1',
     'strongarm110', 'strongarm1100', 'strongarm1110', 'arm9', 'arm920',
     'arm920t', 'arm922t', 'arm940t', 'arm9tdmi', 'arm9e', 'arm926e',
     'arm926ej-s', 'arm946e-r0', 'arm946e', 'arm946e-s', 'arm966e-r0',
     'arm966e', 'arm966e-s', 'arm968e-s', 'arm10t', 'arm10tdmi',
     'arm10e', 'arm1020', 'arm1020t', 'arm1020e', 'arm1022e',
     'arm1026ej-s', 'arm1136j-s', 'arm1136jf-s', 'arm1156t2-s',
     'arm1156t2f-s', 'arm1176jz-s', 'arm1176jzf-s', 'mpcore',
     'mpcorenovfp', 'cortex-a8', 'cortex-r4', 'cortex-m3', 'ep9312'
     (ARM920 with Cirrus Maverick coprocessor), 'i80200' (Intel XScale
     processor) 'iwmmxt' (Intel(r) XScale processor with Wireless
     MMX(tm) technology coprocessor) and 'xscale'.  The special name
     'all' may be used to allow the assembler to accept instructions
     valid for any ARM processor.

     In addition to the basic instruction set, the assembler can be told
     to accept various extension mnemonics that extend the processor
     using the co-processor instruction space.  For example,
     '-mcpu=arm920+maverick' is equivalent to specifying '-mcpu=ep9312'.
     The following extensions are currently supported: '+maverick'
     '+iwmmxt' and '+xscale'.

'-march=ARCHITECTURE[+EXTENSION...]'
     This option specifies the target architecture.  The assembler will
     issue an error message if an attempt is made to assemble an
     instruction which will not execute on the target architecture.  The
     following architecture names are recognized: 'armv1', 'armv2',
     'armv2a', 'armv2s', 'armv3', 'armv3m', 'armv4', 'armv4xm',
     'armv4t', 'armv4txm', 'armv5', 'armv5t', 'armv5txm', 'armv5te',
     'armv5texp', 'armv6', 'armv6j', 'armv6k', 'armv6z', 'armv6zk',
     'armv7', 'armv7-a', 'armv7-r', 'armv7-m', 'iwmmxt' and 'xscale'.
     If both '-mcpu' and '-march' are specified, the assembler will use
     the setting for '-mcpu'.

     The architecture option can be extended with the same instruction
     set extension options as the '-mcpu' option.

'-mfpu=FLOATING-POINT-FORMAT'

     This option specifies the floating point format to assemble for.
     The assembler will issue an error message if an attempt is made to
     assemble an instruction which will not execute on the target
     floating point unit.  The following format options are recognized:
     'softfpa', 'fpe', 'fpe2', 'fpe3', 'fpa', 'fpa10', 'fpa11',
     'arm7500fe', 'softvfp', 'softvfp+vfp', 'vfp', 'vfp10', 'vfp10-r0',
     'vfp9', 'vfpxd', 'arm1020t', 'arm1020e', 'arm1136jf-s' and
     'maverick'.

     In addition to determining which instructions are assembled, this
     option also affects the way in which the '.double' assembler
     directive behaves when assembling little-endian code.

     The default is dependent on the processor selected.  For
     Architecture 5 or later, the default is to assembler for VFP
     instructions; for earlier architectures the default is to assemble
     for FPA instructions.

'-mthumb'
     This option specifies that the assembler should start assembling
     Thumb instructions; that is, it should behave as though the file
     starts with a '.code 16' directive.

'-mthumb-interwork'
     This option specifies that the output generated by the assembler
     should be marked as supporting interworking.

'-mapcs [26|32]'
     This option specifies that the output generated by the assembler
     should be marked as supporting the indicated version of the Arm
     Procedure.  Calling Standard.

'-matpcs'
     This option specifies that the output generated by the assembler
     should be marked as supporting the Arm/Thumb Procedure Calling
     Standard.  If enabled this option will cause the assembler to
     create an empty debugging section in the object file called
     .arm.atpcs.  Debuggers can use this to determine the ABI being used
     by.

'-mapcs-float'
     This indicates the floating point variant of the APCS should be
     used.  In this variant floating point arguments are passed in FP
     registers rather than integer registers.

'-mapcs-reentrant'
     This indicates that the reentrant variant of the APCS should be
     used.  This variant supports position independent code.

'-mfloat-abi=ABI'
     This option specifies that the output generated by the assembler
     should be marked as using specified floating point ABI. The
     following values are recognized: 'soft', 'softfp' and 'hard'.

'-meabi=VER'
     This option specifies which EABI version the produced object files
     should conform to.  The following values are recognized: 'gnu', '4'
     and '5'.

'-EB'
     This option specifies that the output generated by the assembler
     should be marked as being encoded for a big-endian processor.

'-EL'
     This option specifies that the output generated by the assembler
     should be marked as being encoded for a little-endian processor.

'-k'
     This option specifies that the output of the assembler should be
     marked as position-independent code (PIC).

8.2 Syntax
==========

8.2.1 Special Characters
------------------------

The presence of a '@' on a line indicates the start of a comment that
extends to the end of the current line.  If a '#' appears as the first
character of a line, the whole line is treated as a comment.

   The ';' character can be used instead of a newline to separate
statements.

   Either '#' or '$' can be used to indicate immediate operands.

   *TODO* Explain about /data modifier on symbols.

8.2.2 Register Names
--------------------

*TODO* Explain about ARM register naming, and the predefined names.

8.2.3 ARM relocation generation
-------------------------------

Specific data relocations can be generated by putting the relocation
name in parentheses after the symbol name.  For example:

             .word foo(TARGET1)

   This will generate an 'R_ARM_TARGET1' relocation against the symbol
FOO.  The following relocations are supported: 'GOT', 'GOTOFF',
'TARGET1', 'TARGET2', 'SBREL', 'TLSGD', 'TLSLDM', 'TLSLDO', 'GOTTPOFF'
and 'TPOFF'.

   For compatibility with older toolchains the assembler also accepts
'(PLT)' after branch targets.  This will generate the deprecated
'R_ARM_PLT32' relocation.

   Relocations for 'MOVW' and 'MOVT' instructions can be generated by
prefixing the value with '#:lower16:' and '#:upper16' respectively.  For
example to load the 32-bit address of foo into r0:

             MOVW r0, #:lower16:foo
             MOVT r0, #:upper16:foo

8.3 Floating Point
==================

The ARM family uses IEEE floating-point numbers.

8.4 ARM Machine Directives
==========================

'.align EXPRESSION [, EXPRESSION]'
     This is the generic .ALIGN directive.  For the ARM however if the
     first argument is zero (ie no alignment is needed) the assembler
     will behave as if the argument had been 2 (ie pad to the next four
     byte boundary).  This is for compatibility with ARM's own
     assembler.

'NAME .req REGISTER NAME'
     This creates an alias for REGISTER NAME called NAME.  For example:

                  foo .req r0

'.unreq ALIAS-NAME'
     This undefines a register alias which was previously defined using
     the 'req', 'dn' or 'qn' directives.  For example:

                  foo .req r0
                  .unreq foo

     An error occurs if the name is undefined.  Note - this pseudo op
     can be used to delete builtin in register name aliases (eg 'r0').
     This should only be done if it is really necessary.

'NAME .dn REGISTER NAME [.TYPE] [[INDEX]]'
'NAME .qn REGISTER NAME [.TYPE] [[INDEX]]'

     The 'dn' and 'qn' directives are used to create typed and/or
     indexed register aliases for use in Advanced SIMD Extension (Neon)
     instructions.  The former should be used to create aliases of
     double-precision registers, and the latter to create aliases of
     quad-precision registers.

     If these directives are used to create typed aliases, those aliases
     can be used in Neon instructions instead of writing types after the
     mnemonic or after each operand.  For example:

                  x .dn d2.f32
                  y .dn d3.f32
                  z .dn d4.f32[1]
                  vmul x,y,z

     This is equivalent to writing the following:

                  vmul.f32 d2,d3,d4[1]

     Aliases created using 'dn' or 'qn' can be destroyed using 'unreq'.

'.code [16|32]'
     This directive selects the instruction set being generated.  The
     value 16 selects Thumb, with the value 32 selecting ARM.

'.thumb'
     This performs the same action as .CODE 16.

'.arm'
     This performs the same action as .CODE 32.

'.force_thumb'
     This directive forces the selection of Thumb instructions, even if
     the target processor does not support those instructions

'.thumb_func'
     This directive specifies that the following symbol is the name of a
     Thumb encoded function.  This information is necessary in order to
     allow the assembler and linker to generate correct code for
     interworking between Arm and Thumb instructions and should be used
     even if interworking is not going to be performed.  The presence of
     this directive also implies '.thumb'

     This directive is not neccessary when generating EABI objects.  On
     these targets the encoding is implicit when generating Thumb code.

'.thumb_set'
     This performs the equivalent of a '.set' directive in that it
     creates a symbol which is an alias for another symbol (possibly not
     yet defined).  This directive also has the added property in that
     it marks the aliased symbol as being a thumb function entry point,
     in the same way that the '.thumb_func' directive does.

'.ltorg'
     This directive causes the current contents of the literal pool to
     be dumped into the current section (which is assumed to be the
     .text section) at the current location (aligned to a word
     boundary).  'GAS' maintains a separate literal pool for each
     section and each sub-section.  The '.ltorg' directive will only
     affect the literal pool of the current section and sub-section.  At
     the end of assembly all remaining, un-empty literal pools will
     automatically be dumped.

     Note - older versions of 'GAS' would dump the current literal pool
     any time a section change occurred.  This is no longer done, since
     it prevents accurate control of the placement of literal pools.

'.pool'
     This is a synonym for .ltorg.

'.unwind_fnstart'
     Marks the start of a function with an unwind table entry.

'.unwind_fnend'
     Marks the end of a function with an unwind table entry.  The unwind
     index table entry is created when this directive is processed.

     If no personality routine has been specified then standard
     personality routine 0 or 1 will be used, depending on the number of
     unwind opcodes required.

'.cantunwind'
     Prevents unwinding through the current function.  No personality
     routine or exception table data is required or permitted.

'.personality NAME'
     Sets the personality routine for the current function to NAME.

'.personalityindex INDEX'
     Sets the personality routine for the current function to the EABI
     standard routine number INDEX

'.handlerdata'
     Marks the end of the current function, and the start of the
     exception table entry for that function.  Anything between this
     directive and the '.fnend' directive will be added to the exception
     table entry.

     Must be preceded by a '.personality' or '.personalityindex'
     directive.

'.save REGLIST'
     Generate unwinder annotations to restore the registers in REGLIST.
     The format of REGLIST is the same as the corresponding
     store-multiple instruction.

     _core registers_
            .save {r4, r5, r6, lr}
            stmfd sp!, {r4, r5, r6, lr}
     _FPA registers_
            .save f4, 2
            sfmfd f4, 2, [sp]!
     _VFP registers_
            .save {d8, d9, d10}
            fstmdx sp!, {d8, d9, d10}
     _iWMMXt registers_
            .save {wr10, wr11}
            wstrd wr11, [sp, #-8]!
            wstrd wr10, [sp, #-8]!
          or
            .save wr11
            wstrd wr11, [sp, #-8]!
            .save wr10
            wstrd wr10, [sp, #-8]!

'.vsave VFP-REGLIST'
     Generate unwinder annotations to restore the VFP registers in
     VFP-REGLIST using FLDMD. Also works for VFPv3 registers that are to
     be restored using VLDM. The format of VFP-REGLIST is the same as
     the corresponding store-multiple instruction.

     _VFP registers_
            .vsave {d8, d9, d10}
            fstmdd sp!, {d8, d9, d10}
     _VFPv3 registers_
            .vsave {d15, d16, d17}
            vstm sp!, {d15, d16, d17}

     Since FLDMX and FSTMX are now deprecated, this directive should be
     used in favour of '.save' for saving VFP registers for ARMv6 and
     above.

'.pad #COUNT'
     Generate unwinder annotations for a stack adjustment of COUNT
     bytes.  A positive value indicates the function prologue allocated
     stack space by decrementing the stack pointer.

'.movsp REG [, #OFFSET]'
     Tell the unwinder that REG contains an offset from the current
     stack pointer.  If OFFSET is not specified then it is assumed to be
     zero.

'.setfp FPREG, SPREG [, #OFFSET]'
     Make all unwinder annotations relaive to a frame pointer.  Without
     this the unwinder will use offsets from the stack pointer.

     The syntax of this directive is the same as the 'sub' or 'mov'
     instruction used to set the frame pointer.  SPREG must be either
     'sp' or mentioned in a previous '.movsp' directive.

          .movsp ip
          mov ip, sp
          ...
          .setfp fp, ip, #4
          sub fp, ip, #4

'.raw OFFSET, BYTE1, ...'
     Insert one of more arbitary unwind opcode bytes, which are known to
     adjust the stack pointer by OFFSET bytes.

     For example '.unwind_raw 4, 0xb1, 0x01' is equivalent to '.save
     {r0}'

'.cpu NAME'
     Select the target processor.  Valid values for NAME are the same as
     for the '-mcpu' commandline option.

'.arch NAME'
     Select the target architecture.  Valid values for NAME are the same
     as for the '-march' commandline option.

'.object_arch NAME'
     Override the architecture recorded in the EABI object attribute
     section.  Valid values for NAME are the same as for the '.arch'
     directive.  Typically this is useful when code uses runtime
     detection of CPU features.

'.fpu NAME'
     Select the floating point unit to assemble for.  Valid values for
     NAME are the same as for the '-mfpu' commandline option.

'.eabi_attribute TAG, VALUE'
     Set the EABI object attribute number TAG to VALUE.  The value is
     either a 'number', '"string"', or 'number, "string"' depending on
     the tag.

8.5 Opcodes
===========

'as' implements all the standard ARM opcodes.  It also implements
several pseudo opcodes, including several synthetic load instructions.

'NOP'
            nop

     This pseudo op will always evaluate to a legal ARM instruction that
     does nothing.  Currently it will evaluate to MOV r0, r0.

'LDR'
            ldr <register> , = <expression>

     If expression evaluates to a numeric constant then a MOV or MVN
     instruction will be used in place of the LDR instruction, if the
     constant can be generated by either of these instructions.
     Otherwise the constant will be placed into the nearest literal pool
     (if it not already there) and a PC relative LDR instruction will be
     generated.

'ADR'
            adr <register> <label>

     This instruction will load the address of LABEL into the indicated
     register.  The instruction will evaluate to a PC relative ADD or
     SUB instruction depending upon where the label is located.  If the
     label is out of range, or if it is not defined in the same file
     (and section) as the ADR instruction, then an error will be
     generated.  This instruction will not make use of the literal pool.

'ADRL'
            adrl <register> <label>

     This instruction will load the address of LABEL into the indicated
     register.  The instruction will evaluate to one or two PC relative
     ADD or SUB instructions depending upon where the label is located.
     If a second instruction is not needed a NOP instruction will be
     generated in its place, so that this instruction is always 8 bytes
     long.

     If the label is out of range, or if it is not defined in the same
     file (and section) as the ADRL instruction, then an error will be
     generated.  This instruction will not make use of the literal pool.

   For information on the ARM or Thumb instruction sets, see 'ARM
Software Development Toolkit Reference Manual', Advanced RISC Machines
Ltd.

8.6 Mapping Symbols
===================

The ARM ELF specification requires that special symbols be inserted into
object files to mark certain features:

'$a'
     At the start of a region of code containing ARM instructions.

'$t'
     At the start of a region of code containing THUMB instructions.

'$d'
     At the start of a region of data.

   The assembler will automatically insert these symbols for you - there
is no need to code them yourself.  Support for tagging symbols ($b, $f,
$p and $m) which is also mentioned in the current ARM ELF specification
is not implemented.  This is because they have been dropped from the new
EABI and so tools cannot rely upon their presence.

9 80386 Dependent Features
**************************

The i386 version 'as' supports both the original Intel 386 architecture
in both 16 and 32-bit mode as well as AMD x86-64 architecture extending
the Intel architecture to 64-bits.

9.1 Options
===========

The i386 version of 'as' has a few machine dependent options:

'--32 | --64'
     Select the word size, either 32 bits or 64 bits.  Selecting 32-bit
     implies Intel i386 architecture, while 64-bit implies AMD x86-64
     architecture.

     These options are only available with the ELF object file format,
     and require that the necessary BFD support has been included (on a
     32-bit platform you have to add -enable-64-bit-bfd to configure
     enable 64-bit usage and use x86-64 as target platform).

'-n'
     By default, x86 GAS replaces multiple nop instructions used for
     alignment within code sections with multi-byte nop instructions
     such as leal 0(%esi,1),%esi.  This switch disables the
     optimization.

'--divide'
     On SVR4-derived platforms, the character '/' is treated as a
     comment character, which means that it cannot be used in
     expressions.  The '--divide' option turns '/' into a normal
     character.  This does not disable '/' at the beginning of a line
     starting a comment, or affect using '#' for starting a comment.

'-march=CPU'
     This option specifies an instruction set architecture for
     generating instructions.  The following architectures are
     recognized: 'i8086', 'i186', 'i286', 'i386', 'i486', 'i586',
     'i686', 'pentium', 'pentiumpro', 'pentiumii', 'pentiumiii',
     'pentium4', 'prescott', 'nocona', 'core', 'core2', 'k6', 'k6_2',
     'athlon', 'sledgehammer', 'opteron', 'k8', 'generic32' and
     'generic64'.

     This option only affects instructions generated by the assembler.
     The '.arch' directive will take precedent.

'-mtune=CPU'
     This option specifies a processor to optimize for.  When used in
     conjunction with the '-march' option, only instructions of the
     processor specified by the '-march' option will be generated.

     Valid CPU values are identical to '-march=CPU'.

9.2 AT&T Syntax versus Intel Syntax
===================================

'as' now supports assembly using Intel assembler syntax.
'.intel_syntax' selects Intel mode, and '.att_syntax' switches back to
the usual AT&T mode for compatibility with the output of 'gcc'.  Either
of these directives may have an optional argument, 'prefix', or
'noprefix' specifying whether registers require a '%' prefix.  AT&T
System V/386 assembler syntax is quite different from Intel syntax.  We
mention these differences because almost all 80386 documents use Intel
syntax.  Notable differences between the two syntaxes are:

   * AT&T immediate operands are preceded by '$'; Intel immediate
     operands are undelimited (Intel 'push 4' is AT&T 'pushl $4').  AT&T
     register operands are preceded by '%'; Intel register operands are
     undelimited.  AT&T absolute (as opposed to PC relative) jump/call
     operands are prefixed by '*'; they are undelimited in Intel syntax.

   * AT&T and Intel syntax use the opposite order for source and
     destination operands.  Intel 'add eax, 4' is 'addl $4, %eax'.  The
     'source, dest' convention is maintained for compatibility with
     previous Unix assemblers.  Note that instructions with more than
     one source operand, such as the 'enter' instruction, do _not_ have
     reversed order.  *note i386-Bugs::.

   * In AT&T syntax the size of memory operands is determined from the
     last character of the instruction mnemonic.  Mnemonic suffixes of
     'b', 'w', 'l' and 'q' specify byte (8-bit), word (16-bit), long
     (32-bit) and quadruple word (64-bit) memory references.  Intel
     syntax accomplishes this by prefixing memory operands (_not_ the
     instruction mnemonics) with 'byte ptr', 'word ptr', 'dword ptr' and
     'qword ptr'.  Thus, Intel 'mov al, byte ptr FOO' is 'movb FOO, %al'
     in AT&T syntax.

   * Immediate form long jumps and calls are 'lcall/ljmp $SECTION,
     $OFFSET' in AT&T syntax; the Intel syntax is 'call/jmp far
     SECTION:OFFSET'.  Also, the far return instruction is 'lret
     $STACK-ADJUST' in AT&T syntax; Intel syntax is 'ret far
     STACK-ADJUST'.

   * The AT&T assembler does not provide support for multiple section
     programs.  Unix style systems expect all programs to be single
     sections.

9.3 Instruction Naming
======================

Instruction mnemonics are suffixed with one character modifiers which
specify the size of operands.  The letters 'b', 'w', 'l' and 'q' specify
byte, word, long and quadruple word operands.  If no suffix is specified
by an instruction then 'as' tries to fill in the missing suffix based on
the destination register operand (the last one by convention).  Thus,
'mov %ax, %bx' is equivalent to 'movw %ax, %bx'; also, 'mov $1, %bx' is
equivalent to 'movw $1, bx'.  Note that this is incompatible with the
AT&T Unix assembler which assumes that a missing mnemonic suffix implies
long operand size.  (This incompatibility does not affect compiler
output since compilers always explicitly specify the mnemonic suffix.)

   Almost all instructions have the same names in AT&T and Intel format.
There are a few exceptions.  The sign extend and zero extend
instructions need two sizes to specify them.  They need a size to
sign/zero extend _from_ and a size to zero extend _to_.  This is
accomplished by using two instruction mnemonic suffixes in AT&T syntax.
Base names for sign extend and zero extend are 'movs...' and 'movz...'
in AT&T syntax ('movsx' and 'movzx' in Intel syntax).  The instruction
mnemonic suffixes are tacked on to this base name, the _from_ suffix
before the _to_ suffix.  Thus, 'movsbl %al, %edx' is AT&T syntax for
"move sign extend _from_ %al _to_ %edx."  Possible suffixes, thus, are
'bl' (from byte to long), 'bw' (from byte to word), 'wl' (from word to
long), 'bq' (from byte to quadruple word), 'wq' (from word to quadruple
word), and 'lq' (from long to quadruple word).

   The Intel-syntax conversion instructions

   * 'cbw' -- sign-extend byte in '%al' to word in '%ax',

   * 'cwde' -- sign-extend word in '%ax' to long in '%eax',

   * 'cwd' -- sign-extend word in '%ax' to long in '%dx:%ax',

   * 'cdq' -- sign-extend dword in '%eax' to quad in '%edx:%eax',

   * 'cdqe' -- sign-extend dword in '%eax' to quad in '%rax' (x86-64
     only),

   * 'cqo' -- sign-extend quad in '%rax' to octuple in '%rdx:%rax'
     (x86-64 only),

are called 'cbtw', 'cwtl', 'cwtd', 'cltd', 'cltq', and 'cqto' in AT&T
naming.  'as' accepts either naming for these instructions.

   Far call/jump instructions are 'lcall' and 'ljmp' in AT&T syntax, but
are 'call far' and 'jump far' in Intel convention.

9.4 Register Naming
===================

Register operands are always prefixed with '%'.  The 80386 registers
consist of

   * the 8 32-bit registers '%eax' (the accumulator), '%ebx', '%ecx',
     '%edx', '%edi', '%esi', '%ebp' (the frame pointer), and '%esp' (the
     stack pointer).

   * the 8 16-bit low-ends of these: '%ax', '%bx', '%cx', '%dx', '%di',
     '%si', '%bp', and '%sp'.

   * the 8 8-bit registers: '%ah', '%al', '%bh', '%bl', '%ch', '%cl',
     '%dh', and '%dl' (These are the high-bytes and low-bytes of '%ax',
     '%bx', '%cx', and '%dx')

   * the 6 section registers '%cs' (code section), '%ds' (data section),
     '%ss' (stack section), '%es', '%fs', and '%gs'.

   * the 3 processor control registers '%cr0', '%cr2', and '%cr3'.

   * the 6 debug registers '%db0', '%db1', '%db2', '%db3', '%db6', and
     '%db7'.

   * the 2 test registers '%tr6' and '%tr7'.

   * the 8 floating point register stack '%st' or equivalently '%st(0)',
     '%st(1)', '%st(2)', '%st(3)', '%st(4)', '%st(5)', '%st(6)', and
     '%st(7)'.  These registers are overloaded by 8 MMX registers
     '%mm0', '%mm1', '%mm2', '%mm3', '%mm4', '%mm5', '%mm6' and '%mm7'.

   * the 8 SSE registers registers '%xmm0', '%xmm1', '%xmm2', '%xmm3',
     '%xmm4', '%xmm5', '%xmm6' and '%xmm7'.

   The AMD x86-64 architecture extends the register set by:

   * enhancing the 8 32-bit registers to 64-bit: '%rax' (the
     accumulator), '%rbx', '%rcx', '%rdx', '%rdi', '%rsi', '%rbp' (the
     frame pointer), '%rsp' (the stack pointer)

   * the 8 extended registers '%r8'-'%r15'.

   * the 8 32-bit low ends of the extended registers: '%r8d'-'%r15d'

   * the 8 16-bit low ends of the extended registers: '%r8w'-'%r15w'

   * the 8 8-bit low ends of the extended registers: '%r8b'-'%r15b'

   * the 4 8-bit registers: '%sil', '%dil', '%bpl', '%spl'.

   * the 8 debug registers: '%db8'-'%db15'.

   * the 8 SSE registers: '%xmm8'-'%xmm15'.

9.5 Instruction Prefixes
========================

Instruction prefixes are used to modify the following instruction.  They
are used to repeat string instructions, to provide section overrides, to
perform bus lock operations, and to change operand and address sizes.
(Most instructions that normally operate on 32-bit operands will use
16-bit operands if the instruction has an "operand size" prefix.)
Instruction prefixes are best written on the same line as the
instruction they act upon.  For example, the 'scas' (scan string)
instruction is repeated with:

             repne scas %es:(%edi),%al

   You may also place prefixes on the lines immediately preceding the
instruction, but this circumvents checks that 'as' does with prefixes,
and will not work with all prefixes.

   Here is a list of instruction prefixes:

   * Section override prefixes 'cs', 'ds', 'ss', 'es', 'fs', 'gs'.
     These are automatically added by specifying using the
     SECTION:MEMORY-OPERAND form for memory references.

   * Operand/Address size prefixes 'data16' and 'addr16' change 32-bit
     operands/addresses into 16-bit operands/addresses, while 'data32'
     and 'addr32' change 16-bit ones (in a '.code16' section) into
     32-bit operands/addresses.  These prefixes _must_ appear on the
     same line of code as the instruction they modify.  For example, in
     a 16-bit '.code16' section, you might write:

                  addr32 jmpl *(%ebx)

   * The bus lock prefix 'lock' inhibits interrupts during execution of
     the instruction it precedes.  (This is only valid with certain
     instructions; see a 80386 manual for details).

   * The wait for coprocessor prefix 'wait' waits for the coprocessor to
     complete the current instruction.  This should never be needed for
     the 80386/80387 combination.

   * The 'rep', 'repe', and 'repne' prefixes are added to string
     instructions to make them repeat '%ecx' times ('%cx' times if the
     current address size is 16-bits).
   * The 'rex' family of prefixes is used by x86-64 to encode extensions
     to i386 instruction set.  The 'rex' prefix has four bits -- an
     operand size overwrite ('64') used to change operand size from
     32-bit to 64-bit and X, Y and Z extensions bits used to extend the
     register set.

     You may write the 'rex' prefixes directly.  The 'rex64xyz'
     instruction emits 'rex' prefix with all the bits set.  By omitting
     the '64', 'x', 'y' or 'z' you may write other prefixes as well.
     Normally, there is no need to write the prefixes explicitly, since
     gas will automatically generate them based on the instruction
     operands.

9.6 Memory References
=====================

An Intel syntax indirect memory reference of the form

     SECTION:[BASE + INDEX*SCALE + DISP]

is translated into the AT&T syntax

     SECTION:DISP(BASE, INDEX, SCALE)

where BASE and INDEX are the optional 32-bit base and index registers,
DISP is the optional displacement, and SCALE, taking the values 1, 2, 4,
and 8, multiplies INDEX to calculate the address of the operand.  If no
SCALE is specified, SCALE is taken to be 1.  SECTION specifies the
optional section register for the memory operand, and may override the
default section register (see a 80386 manual for section register
defaults).  Note that section overrides in AT&T syntax _must_ be
preceded by a '%'.  If you specify a section override which coincides
with the default section register, 'as' does _not_ output any section
register override prefixes to assemble the given instruction.  Thus,
section overrides can be specified to emphasize which section register
is used for a given memory operand.

   Here are some examples of Intel and AT&T style memory references:

AT&T: '-4(%ebp)', Intel: '[ebp - 4]'
     BASE is '%ebp'; DISP is '-4'.  SECTION is missing, and the default
     section is used ('%ss' for addressing with '%ebp' as the base
     register).  INDEX, SCALE are both missing.

AT&T: 'foo(,%eax,4)', Intel: '[foo + eax*4]'
     INDEX is '%eax' (scaled by a SCALE 4); DISP is 'foo'.  All other
     fields are missing.  The section register here defaults to '%ds'.

AT&T: 'foo(,1)'; Intel '[foo]'
     This uses the value pointed to by 'foo' as a memory operand.  Note
     that BASE and INDEX are both missing, but there is only _one_ ','.
     This is a syntactic exception.

AT&T: '%gs:foo'; Intel 'gs:foo'
     This selects the contents of the variable 'foo' with section
     register SECTION being '%gs'.

   Absolute (as opposed to PC relative) call and jump operands must be
prefixed with '*'.  If no '*' is specified, 'as' always chooses PC
relative addressing for jump/call labels.

   Any instruction that has a memory operand, but no register operand,
_must_ specify its size (byte, word, long, or quadruple) with an
instruction mnemonic suffix ('b', 'w', 'l' or 'q', respectively).

   The x86-64 architecture adds an RIP (instruction pointer relative)
addressing.  This addressing mode is specified by using 'rip' as a base
register.  Only constant offsets are valid.  For example:

AT&T: '1234(%rip)', Intel: '[rip + 1234]'
     Points to the address 1234 bytes past the end of the current
     instruction.

AT&T: 'symbol(%rip)', Intel: '[rip + symbol]'
     Points to the 'symbol' in RIP relative way, this is shorter than
     the default absolute addressing.

   Other addressing modes remain unchanged in x86-64 architecture,
except registers used are 64-bit instead of 32-bit.

9.7 Handling of Jump Instructions
=================================

Jump instructions are always optimized to use the smallest possible
displacements.  This is accomplished by using byte (8-bit) displacement
jumps whenever the target is sufficiently close.  If a byte displacement
is insufficient a long displacement is used.  We do not support word
(16-bit) displacement jumps in 32-bit mode (i.e.  prefixing the jump
instruction with the 'data16' instruction prefix), since the 80386
insists upon masking '%eip' to 16 bits after the word displacement is
added.  (See also *note i386-Arch::)

   Note that the 'jcxz', 'jecxz', 'loop', 'loopz', 'loope', 'loopnz' and
'loopne' instructions only come in byte displacements, so that if you
use these instructions ('gcc' does not use them) you may get an error
message (and incorrect code).  The AT&T 80386 assembler tries to get
around this problem by expanding 'jcxz foo' to

              jcxz cx_zero
              jmp cx_nonzero
     cx_zero: jmp foo
     cx_nonzero:

9.8 Floating Point
==================

All 80387 floating point types except packed BCD are supported.  (BCD
support may be added without much difficulty).  These data types are
16-, 32-, and 64- bit integers, and single (32-bit), double (64-bit),
and extended (80-bit) precision floating point.  Each supported type has
an instruction mnemonic suffix and a constructor associated with it.
Instruction mnemonic suffixes specify the operand's data type.
Constructors build these data types into memory.

   * Floating point constructors are '.float' or '.single', '.double',
     and '.tfloat' for 32-, 64-, and 80-bit formats.  These correspond
     to instruction mnemonic suffixes 's', 'l', and 't'.  't' stands for
     80-bit (ten byte) real.  The 80387 only supports this format via
     the 'fldt' (load 80-bit real to stack top) and 'fstpt' (store
     80-bit real and pop stack) instructions.

   * Integer constructors are '.word', '.long' or '.int', and '.quad'
     for the 16-, 32-, and 64-bit integer formats.  The corresponding
     instruction mnemonic suffixes are 's' (single), 'l' (long), and 'q'
     (quad).  As with the 80-bit real format, the 64-bit 'q' format is
     only present in the 'fildq' (load quad integer to stack top) and
     'fistpq' (store quad integer and pop stack) instructions.

   Register to register operations should not use instruction mnemonic
suffixes.  'fstl %st, %st(1)' will give a warning, and be assembled as
if you wrote 'fst %st, %st(1)', since all register to register
operations use 80-bit floating point operands.  (Contrast this with
'fstl %st, mem', which converts '%st' from 80-bit to 64-bit floating
point format, then stores the result in the 4 byte location 'mem')

9.9 Intel's MMX and AMD's 3DNow! SIMD Operations
================================================

'as' supports Intel's MMX instruction set (SIMD instructions for integer
data), available on Intel's Pentium MMX processors and Pentium II
processors, AMD's K6 and K6-2 processors, Cyrix' M2 processor, and
probably others.  It also supports AMD's 3DNow! instruction set (SIMD
instructions for 32-bit floating point data) available on AMD's K6-2
processor and possibly others in the future.

   Currently, 'as' does not support Intel's floating point SIMD, Katmai
(KNI).

   The eight 64-bit MMX operands, also used by 3DNow!, are called
'%mm0', '%mm1', ...  '%mm7'.  They contain eight 8-bit integers, four
16-bit integers, two 32-bit integers, one 64-bit integer, or two 32-bit
floating point values.  The MMX registers cannot be used at the same
time as the floating point stack.

   See Intel and AMD documentation, keeping in mind that the operand
order in instructions is reversed from the Intel syntax.

9.10 Writing 16-bit Code
========================

While 'as' normally writes only "pure" 32-bit i386 code or 64-bit x86-64
code depending on the default configuration, it also supports writing
code to run in real mode or in 16-bit protected mode code segments.  To
do this, put a '.code16' or '.code16gcc' directive before the assembly
language instructions to be run in 16-bit mode.  You can switch 'as'
back to writing normal 32-bit code with the '.code32' directive.

   '.code16gcc' provides experimental support for generating 16-bit code
from gcc, and differs from '.code16' in that 'call', 'ret', 'enter',
'leave', 'push', 'pop', 'pusha', 'popa', 'pushf', and 'popf'
instructions default to 32-bit size.  This is so that the stack pointer
is manipulated in the same way over function calls, allowing access to
function parameters at the same stack offsets as in 32-bit mode.
'.code16gcc' also automatically adds address size prefixes where
necessary to use the 32-bit addressing modes that gcc generates.

   The code which 'as' generates in 16-bit mode will not necessarily run
on a 16-bit pre-80386 processor.  To write code that runs on such a
processor, you must refrain from using _any_ 32-bit constructs which
require 'as' to output address or operand size prefixes.

   Note that writing 16-bit code instructions by explicitly specifying a
prefix or an instruction mnemonic suffix within a 32-bit code section
generates different machine instructions than those generated for a
16-bit code segment.  In a 32-bit code section, the following code
generates the machine opcode bytes '66 6a 04', which pushes the value
'4' onto the stack, decrementing '%esp' by 2.

             pushw $4

   The same code in a 16-bit code section would generate the machine
opcode bytes '6a 04' (i.e., without the operand size prefix), which is
correct since the processor default operand size is assumed to be 16
bits in a 16-bit code section.

9.11 AT&T Syntax bugs
=====================

The UnixWare assembler, and probably other AT&T derived ix86 Unix
assemblers, generate floating point instructions with reversed source
and destination registers in certain cases.  Unfortunately, gcc and
possibly many other programs use this reversed syntax, so we're stuck
with it.

   For example

             fsub %st,%st(3)
results in '%st(3)' being updated to '%st - %st(3)' rather than the
expected '%st(3) - %st'.  This happens with all the non-commutative
arithmetic floating point operations with two register operands where
the source register is '%st' and the destination register is '%st(i)'.

9.12 Specifying CPU Architecture
================================

'as' may be told to assemble for a particular CPU (sub-)architecture
with the '.arch CPU_TYPE' directive.  This directive enables a warning
when gas detects an instruction that is not supported on the CPU
specified.  The choices for CPU_TYPE are:

'i8086'        'i186'         'i286'         'i386'
'i486'         'i586'         'i686'         'pentium'
'pentiumpro'   'pentiumii'    'pentiumiii'   'pentium4'
'prescott'     'nocona'       'core'         'core2'
'amdfam10'
'k6'           'athlon'       'sledgehammer' 'k8'
'.mmx'         '.sse'         '.sse2'        '.sse3'
'.ssse3'       '.sse4.1'      '.sse4.2'      '.sse4'
'.sse4a'       '.3dnow'       '.3dnowa'      '.padlock'
'.pacifica'    '.svme'        '.abm'

   Apart from the warning, there are only two other effects on 'as'
operation; Firstly, if you specify a CPU other than 'i486', then shift
by one instructions such as 'sarl $1, %eax' will automatically use a two
byte opcode sequence.  The larger three byte opcode sequence is used on
the 486 (and when no architecture is specified) because it executes
faster on the 486.  Note that you can explicitly request the two byte
opcode by writing 'sarl %eax'.  Secondly, if you specify 'i8086',
'i186', or 'i286', _and_ '.code16' or '.code16gcc' then byte offset
conditional jumps will be promoted when necessary to a two instruction
sequence consisting of a conditional jump of the opposite sense around
an unconditional jump to the target.

   Following the CPU architecture (but not a sub-architecture, which are
those starting with a dot), you may specify 'jumps' or 'nojumps' to
control automatic promotion of conditional jumps.  'jumps' is the
default, and enables jump promotion; All external jumps will be of the
long variety, and file-local jumps will be promoted as necessary.
(*note i386-Jumps::) 'nojumps' leaves external conditional jumps as byte
offset jumps, and warns about file-local conditional jumps that 'as'
promotes.  Unconditional jumps are treated as for 'jumps'.

   For example

      .arch i8086,nojumps

9.13 Notes
==========

There is some trickery concerning the 'mul' and 'imul' instructions that
deserves mention.  The 16-, 32-, 64- and 128-bit expanding multiplies
(base opcode '0xf6'; extension 4 for 'mul' and 5 for 'imul') can be
output only in the one operand form.  Thus, 'imul %ebx, %eax' does _not_
select the expanding multiply; the expanding multiply would clobber the
'%edx' register, and this would confuse 'gcc' output.  Use 'imul %ebx'
to get the 64-bit product in '%edx:%eax'.

   We have added a two operand form of 'imul' when the first operand is
an immediate mode expression and the second operand is a register.  This
is just a shorthand, so that, multiplying '%eax' by 69, for example, can
be done with 'imul $69, %eax' rather than 'imul $69, %eax, %eax'.

10 IA-64 Dependent Features
***************************

10.1 Options
============

'-mconstant-gp'
     This option instructs the assembler to mark the resulting object
     file as using the "constant GP" model.  With this model, it is
     assumed that the entire program uses a single global pointer (GP)
     value.  Note that this option does not in any fashion affect the
     machine code emitted by the assembler.  All it does is turn on the
     EF_IA_64_CONS_GP flag in the ELF file header.

'-mauto-pic'
     This option instructs the assembler to mark the resulting object
     file as using the "constant GP without function descriptor" data
     model.  This model is like the "constant GP" model, except that it
     additionally does away with function descriptors.  What this means
     is that the address of a function refers directly to the function's
     code entry-point.  Normally, such an address would refer to a
     function descriptor, which contains both the code entry-point and
     the GP-value needed by the function.  Note that this option does
     not in any fashion affect the machine code emitted by the
     assembler.  All it does is turn on the EF_IA_64_NOFUNCDESC_CONS_GP
     flag in the ELF file header.

'-milp32'
'-milp64'
'-mlp64'
'-mp64'
     These options select the data model.  The assembler defaults to
     '-mlp64' (LP64 data model).

'-mle'
'-mbe'
     These options select the byte order.  The '-mle' option selects
     little-endian byte order (default) and '-mbe' selects big-endian
     byte order.  Note that IA-64 machine code always uses little-endian
     byte order.

'-mtune=itanium1'
'-mtune=itanium2'
     Tune for a particular IA-64 CPU, ITANIUM1 or ITANIUM2.  The default
     is ITANIUM2.

'-munwind-check=warning'
'-munwind-check=error'
     These options control what the assembler will do when performing
     consistency checks on unwind directives.  '-munwind-check=warning'
     will make the assembler issue a warning when an unwind directive
     check fails.  This is the default.  '-munwind-check=error' will
     make the assembler issue an error when an unwind directive check
     fails.

'-mhint.b=ok'
'-mhint.b=warning'
'-mhint.b=error'
     These options control what the assembler will do when the 'hint.b'
     instruction is used.  '-mhint.b=ok' will make the assembler accept
     'hint.b'.  '-mint.b=warning' will make the assembler issue a
     warning when 'hint.b' is used.  '-mhint.b=error' will make the
     assembler treat 'hint.b' as an error, which is the default.

'-x'
'-xexplicit'
     These options turn on dependency violation checking.

'-xauto'
     This option instructs the assembler to automatically insert stop
     bits where necessary to remove dependency violations.  This is the
     default mode.

'-xnone'
     This option turns off dependency violation checking.

'-xdebug'
     This turns on debug output intended to help tracking down bugs in
     the dependency violation checker.

'-xdebugn'
     This is a shortcut for -xnone -xdebug.

'-xdebugx'
     This is a shortcut for -xexplicit -xdebug.

10.2 Syntax
===========

The assembler syntax closely follows the IA-64 Assembly Language
Reference Guide.

10.2.1 Special Characters
-------------------------

'//' is the line comment token.

   ';' can be used instead of a newline to separate statements.

10.2.2 Register Names
---------------------

The 128 integer registers are referred to as 'rN'.  The 128
floating-point registers are referred to as 'fN'.  The 128 application
registers are referred to as 'arN'.  The 128 control registers are
referred to as 'crN'.  The 64 one-bit predicate registers are referred
to as 'pN'.  The 8 branch registers are referred to as 'bN'.  In
addition, the assembler defines a number of aliases: 'gp' ('r1'), 'sp'
('r12'), 'rp' ('b0'), 'ret0' ('r8'), 'ret1' ('r9'), 'ret2' ('r10'),
'ret3' ('r9'), 'fargN' ('f8+N'), and 'fretN' ('f8+N').

   For convenience, the assembler also defines aliases for all named
application and control registers.  For example, 'ar.bsp' refers to the
register backing store pointer ('ar17').  Similarly, 'cr.eoi' refers to
the end-of-interrupt register ('cr67').

10.2.3 IA-64 Processor-Status-Register (PSR) Bit Names
------------------------------------------------------

The assembler defines bit masks for each of the bits in the IA-64
processor status register.  For example, 'psr.ic' corresponds to a value
of 0x2000.  These masks are primarily intended for use with the
'ssm'/'sum' and 'rsm'/'rum' instructions, but they can be used anywhere
else where an integer constant is expected.

10.3 Opcodes
============

For detailed information on the IA-64 machine instruction set, see the
IA-64 Architecture Handbook
(http://developer.intel.com/design/itanium/arch_spec.htm).

11 MIPS Dependent Features
**************************

GNU 'as' for MIPS architectures supports several different MIPS
processors, and MIPS ISA levels I through V, MIPS32, and MIPS64.  For
information about the MIPS instruction set, see 'MIPS RISC
Architecture', by Kane and Heindrich (Prentice-Hall).  For an overview
of MIPS assembly conventions, see "Appendix D: Assembly Language
Programming" in the same work.

11.1 Assembler options
======================

The MIPS configurations of GNU 'as' support these special options:

'-G NUM'
     This option sets the largest size of an object that can be
     referenced implicitly with the 'gp' register.  It is only accepted
     for targets that use ECOFF format.  The default value is 8.

'-EB'
'-EL'
     Any MIPS configuration of 'as' can select big-endian or
     little-endian output at run time (unlike the other GNU development
     tools, which must be configured for one or the other).  Use '-EB'
     to select big-endian output, and '-EL' for little-endian.

'-KPIC'
     Generate SVR4-style PIC. This option tells the assembler to
     generate SVR4-style position-independent macro expansions.  It also
     tells the assembler to mark the output file as PIC.

'-mvxworks-pic'
     Generate VxWorks PIC. This option tells the assembler to generate
     VxWorks-style position-independent macro expansions.

'-mips1'
'-mips2'
'-mips3'
'-mips4'
'-mips5'
'-mips32'
'-mips32r2'
'-mips64'
'-mips64r2'
     Generate code for a particular MIPS Instruction Set Architecture
     level.  '-mips1' corresponds to the R2000 and R3000 processors,
     '-mips2' to the R6000 processor, '-mips3' to the R4000 processor,
     and '-mips4' to the R8000 and R10000 processors.  '-mips5',
     '-mips32', '-mips32r2', '-mips64', and '-mips64r2' correspond to
     generic MIPS V, MIPS32, MIPS32 RELEASE 2, MIPS64, and MIPS64
     RELEASE 2 ISA processors, respectively.  You can also switch
     instruction sets during the assembly; see *note Directives to
     override the ISA level: MIPS ISA.

'-mgp32'
'-mfp32'
     Some macros have different expansions for 32-bit and 64-bit
     registers.  The register sizes are normally inferred from the ISA
     and ABI, but these flags force a certain group of registers to be
     treated as 32 bits wide at all times.  '-mgp32' controls the size
     of general-purpose registers and '-mfp32' controls the size of
     floating-point registers.

     The '.set gp=32' and '.set fp=32' directives allow the size of
     registers to be changed for parts of an object.  The default value
     is restored by '.set gp=default' and '.set fp=default'.

     On some MIPS variants there is a 32-bit mode flag; when this flag
     is set, 64-bit instructions generate a trap.  Also, some 32-bit
     OSes only save the 32-bit registers on a context switch, so it is
     essential never to use the 64-bit registers.

'-mgp64'
'-mfp64'
     Assume that 64-bit registers are available.  This is provided in
     the interests of symmetry with '-mgp32' and '-mfp32'.

     The '.set gp=64' and '.set fp=64' directives allow the size of
     registers to be changed for parts of an object.  The default value
     is restored by '.set gp=default' and '.set fp=default'.

'-mips16'
'-no-mips16'
     Generate code for the MIPS 16 processor.  This is equivalent to
     putting '.set mips16' at the start of the assembly file.
     '-no-mips16' turns off this option.

'-msmartmips'
'-mno-smartmips'
     Enables the SmartMIPS extensions to the MIPS32 instruction set,
     which provides a number of new instructions which target smartcard
     and cryptographic applications.  This is equivalent to putting
     '.set smartmips' at the start of the assembly file.
     '-mno-smartmips' turns off this option.

'-mips3d'
'-no-mips3d'
     Generate code for the MIPS-3D Application Specific Extension.  This
     tells the assembler to accept MIPS-3D instructions.  '-no-mips3d'
     turns off this option.

'-mdmx'
'-no-mdmx'
     Generate code for the MDMX Application Specific Extension.  This
     tells the assembler to accept MDMX instructions.  '-no-mdmx' turns
     off this option.

'-mdsp'
'-mno-dsp'
     Generate code for the DSP Release 1 Application Specific Extension.
     This tells the assembler to accept DSP Release 1 instructions.
     '-mno-dsp' turns off this option.

'-mdspr2'
'-mno-dspr2'
     Generate code for the DSP Release 2 Application Specific Extension.
     This option implies -mdsp.  This tells the assembler to accept DSP
     Release 2 instructions.  '-mno-dspr2' turns off this option.

'-mmt'
'-mno-mt'
     Generate code for the MT Application Specific Extension.  This
     tells the assembler to accept MT instructions.  '-mno-mt' turns off
     this option.

'-mfix7000'
'-mno-fix7000'
     Cause nops to be inserted if the read of the destination register
     of an mfhi or mflo instruction occurs in the following two
     instructions.

'-mfix-vr4120'
'-no-mfix-vr4120'
     Insert nops to work around certain VR4120 errata.  This option is
     intended to be used on GCC-generated code: it is not designed to
     catch all problems in hand-written assembler code.

'-mfix-vr4130'
'-no-mfix-vr4130'
     Insert nops to work around the VR4130 'mflo'/'mfhi' errata.

'-m4010'
'-no-m4010'
     Generate code for the LSI R4010 chip.  This tells the assembler to
     accept the R4010 specific instructions ('addciu', 'ffc', etc.), and
     to not schedule 'nop' instructions around accesses to the 'HI' and
     'LO' registers.  '-no-m4010' turns off this option.

'-m4650'
'-no-m4650'
     Generate code for the MIPS R4650 chip.  This tells the assembler to
     accept the 'mad' and 'madu' instruction, and to not schedule 'nop'
     instructions around accesses to the 'HI' and 'LO' registers.
     '-no-m4650' turns off this option.

'-m3900'
'-no-m3900'
'-m4100'
'-no-m4100'
     For each option '-mNNNN', generate code for the MIPS RNNNN chip.
     This tells the assembler to accept instructions specific to that
     chip, and to schedule for that chip's hazards.

'-march=CPU'
     Generate code for a particular MIPS cpu.  It is exactly equivalent
     to '-mCPU', except that there are more value of CPU understood.
     Valid CPU value are:

          2000, 3000, 3900, 4000, 4010, 4100, 4111, vr4120, vr4130,
          vr4181, 4300, 4400, 4600, 4650, 5000, rm5200, rm5230, rm5231,
          rm5261, rm5721, vr5400, vr5500, 6000, rm7000, 8000, rm9000,
          10000, 12000, 4kc, 4km, 4kp, 4ksc, 4kec, 4kem, 4kep, 4ksd,
          m4k, m4kp, 24kc, 24kf, 24kx, 24kec, 24kef, 24kex, 34kc, 34kf,
          34kx, 74kc, 74kf, 74kx, 5kc, 5kf, 20kc, 25kf, sb1, sb1a

'-mtune=CPU'
     Schedule and tune for a particular MIPS cpu.  Valid CPU values are
     identical to '-march=CPU'.

'-mabi=ABI'
     Record which ABI the source code uses.  The recognized arguments
     are: '32', 'n32', 'o64', '64' and 'eabi'.

'-msym32'
'-mno-sym32'
     Equivalent to adding '.set sym32' or '.set nosym32' to the
     beginning of the assembler input.  *Note MIPS symbol sizes::.

'-nocpp'
     This option is ignored.  It is accepted for command-line
     compatibility with other assemblers, which use it to turn off C
     style preprocessing.  With GNU 'as', there is no need for '-nocpp',
     because the GNU assembler itself never runs the C preprocessor.

'--construct-floats'
'--no-construct-floats'
     The '--no-construct-floats' option disables the construction of
     double width floating point constants by loading the two halves of
     the value into the two single width floating point registers that
     make up the double width register.  This feature is useful if the
     processor support the FR bit in its status register, and this bit
     is known (by the programmer) to be set.  This bit prevents the
     aliasing of the double width register by the single width
     registers.

     By default '--construct-floats' is selected, allowing construction
     of these floating point constants.

'--trap'
'--no-break'
     'as' automatically macro expands certain division and
     multiplication instructions to check for overflow and division by
     zero.  This option causes 'as' to generate code to take a trap
     exception rather than a break exception when an error is detected.
     The trap instructions are only supported at Instruction Set
     Architecture level 2 and higher.

'--break'
'--no-trap'
     Generate code to take a break exception rather than a trap
     exception when an error is detected.  This is the default.

'-mpdr'
'-mno-pdr'
     Control generation of '.pdr' sections.  Off by default on IRIX, on
     elsewhere.

'-mshared'
'-mno-shared'
     When generating code using the Unix calling conventions (selected
     by '-KPIC' or '-mcall_shared'), gas will normally generate code
     which can go into a shared library.  The '-mno-shared' option tells
     gas to generate code which uses the calling convention, but can not
     go into a shared library.  The resulting code is slightly more
     efficient.  This option only affects the handling of the '.cpload'
     and '.cpsetup' pseudo-ops.

11.2 MIPS ECOFF object code
===========================

Assembling for a MIPS ECOFF target supports some additional sections
besides the usual '.text', '.data' and '.bss'.  The additional sections
are '.rdata', used for read-only data, '.sdata', used for small data,
and '.sbss', used for small common objects.

   When assembling for ECOFF, the assembler uses the '$gp' ('$28')
register to form the address of a "small object".  Any object in the
'.sdata' or '.sbss' sections is considered "small" in this sense.  For
external objects, or for objects in the '.bss' section, you can use the
'gcc' '-G' option to control the size of objects addressed via '$gp';
the default value is 8, meaning that a reference to any object eight
bytes or smaller uses '$gp'.  Passing '-G 0' to 'as' prevents it from
using the '$gp' register on the basis of object size (but the assembler
uses '$gp' for objects in '.sdata' or 'sbss' in any case).  The size of
an object in the '.bss' section is set by the '.comm' or '.lcomm'
directive that defines it.  The size of an external object may be set
with the '.extern' directive.  For example, '.extern sym,4' declares
that the object at 'sym' is 4 bytes in length, whie leaving 'sym'
otherwise undefined.

   Using small ECOFF objects requires linker support, and assumes that
the '$gp' register is correctly initialized (normally done automatically
by the startup code).  MIPS ECOFF assembly code must not modify the
'$gp' register.

11.3 Directives for debugging information
=========================================

MIPS ECOFF 'as' supports several directives used for generating
debugging information which are not support by traditional MIPS
assemblers.  These are '.def', '.endef', '.dim', '.file', '.scl',
'.size', '.tag', '.type', '.val', '.stabd', '.stabn', and '.stabs'.  The
debugging information generated by the three '.stab' directives can only
be read by GDB, not by traditional MIPS debuggers (this enhancement is
required to fully support C++ debugging).  These directives are
primarily used by compilers, not assembly language programmers!

11.4 Directives to override the size of symbols
===============================================

The n64 ABI allows symbols to have any 64-bit value.  Although this
provides a great deal of flexibility, it means that some macros have
much longer expansions than their 32-bit counterparts.  For example, the
non-PIC expansion of 'dla $4,sym' is usually:

     lui     $4,%highest(sym)
     lui     $1,%hi(sym)
     daddiu  $4,$4,%higher(sym)
     daddiu  $1,$1,%lo(sym)
     dsll32  $4,$4,0
     daddu   $4,$4,$1

   whereas the 32-bit expansion is simply:

     lui     $4,%hi(sym)
     daddiu  $4,$4,%lo(sym)

   n64 code is sometimes constructed in such a way that all symbolic
constants are known to have 32-bit values, and in such cases, it's
preferable to use the 32-bit expansion instead of the 64-bit expansion.

   You can use the '.set sym32' directive to tell the assembler that,
from this point on, all expressions of the form 'SYMBOL' or 'SYMBOL +
OFFSET' have 32-bit values.  For example:

     .set sym32
     dla     $4,sym
     lw      $4,sym+16
     sw      $4,sym+0x8000($4)

   will cause the assembler to treat 'sym', 'sym+16' and 'sym+0x8000' as
32-bit values.  The handling of non-symbolic addresses is not affected.

   The directive '.set nosym32' ends a '.set sym32' block and reverts to
the normal behavior.  It is also possible to change the symbol size
using the command-line options '-msym32' and '-mno-sym32'.

   These options and directives are always accepted, but at present,
they have no effect for anything other than n64.

11.5 Directives to override the ISA level
=========================================

GNU 'as' supports an additional directive to change the MIPS Instruction
Set Architecture level on the fly: '.set mipsN'.  N should be a number
from 0 to 5, or 32, 32r2, 64 or 64r2.  The values other than 0 make the
assembler accept instructions for the corresponding ISA level, from that
point on in the assembly.  '.set mipsN' affects not only which
instructions are permitted, but also how certain macros are expanded.
'.set mips0' restores the ISA level to its original level: either the
level you selected with command line options, or the default for your
configuration.  You can use this feature to permit specific MIPS3
instructions while assembling in 32 bit mode.  Use this directive with
care!

   The '.set arch=CPU' directive provides even finer control.  It
changes the effective CPU target and allows the assembler to use
instructions specific to a particular CPU. All CPUs supported by the
'-march' command line option are also selectable by this directive.  The
original value is restored by '.set arch=default'.

   The directive '.set mips16' puts the assembler into MIPS 16 mode, in
which it will assemble instructions for the MIPS 16 processor.  Use
'.set nomips16' to return to normal 32 bit mode.

   Traditional MIPS assemblers do not support this directive.

11.6 Directives for extending MIPS 16 bit instructions
======================================================

By default, MIPS 16 instructions are automatically extended to 32 bits
when necessary.  The directive '.set noautoextend' will turn this off.
When '.set noautoextend' is in effect, any 32 bit instruction must be
explicitly extended with the '.e' modifier (e.g., 'li.e $4,1000').  The
directive '.set autoextend' may be used to once again automatically
extend instructions when necessary.

   This directive is only meaningful when in MIPS 16 mode.  Traditional
MIPS assemblers do not support this directive.

11.7 Directive to mark data as an instruction
=============================================

The '.insn' directive tells 'as' that the following data is actually
instructions.  This makes a difference in MIPS 16 mode: when loading the
address of a label which precedes instructions, 'as' automatically adds
1 to the value, so that jumping to the loaded address will do the right
thing.

11.8 Directives to save and restore options
===========================================

The directives '.set push' and '.set pop' may be used to save and
restore the current settings for all the options which are controlled by
'.set'.  The '.set push' directive saves the current settings on a
stack.  The '.set pop' directive pops the stack and restores the
settings.

   These directives can be useful inside an macro which must change an
option such as the ISA level or instruction reordering but does not want
to change the state of the code which invoked the macro.

   Traditional MIPS assemblers do not support these directives.

11.9 Directives to control generation of MIPS ASE instructions
==============================================================

The directive '.set mips3d' makes the assembler accept instructions from
the MIPS-3D Application Specific Extension from that point on in the
assembly.  The '.set nomips3d' directive prevents MIPS-3D instructions
from being accepted.

   The directive '.set smartmips' makes the assembler accept
instructions from the SmartMIPS Application Specific Extension to the
MIPS32 ISA from that point on in the assembly.  The '.set nosmartmips'
directive prevents SmartMIPS instructions from being accepted.

   The directive '.set mdmx' makes the assembler accept instructions
from the MDMX Application Specific Extension from that point on in the
assembly.  The '.set nomdmx' directive prevents MDMX instructions from
being accepted.

   The directive '.set dsp' makes the assembler accept instructions from
the DSP Release 1 Application Specific Extension from that point on in
the assembly.  The '.set nodsp' directive prevents DSP Release 1
instructions from being accepted.

   The directive '.set dspr2' makes the assembler accept instructions
from the DSP Release 2 Application Specific Extension from that point on
in the assembly.  This dirctive implies '.set dsp'.  The '.set nodspr2'
directive prevents DSP Release 2 instructions from being accepted.

   The directive '.set mt' makes the assembler accept instructions from
the MT Application Specific Extension from that point on in the
assembly.  The '.set nomt' directive prevents MT instructions from being
accepted.

   Traditional MIPS assemblers do not support these directives.

12 PowerPC Dependent Features
*****************************

12.1 Options
============

The PowerPC chip family includes several successive levels, using the
same core instruction set, but including a few additional instructions
at each level.  There are exceptions to this however.  For details on
what instructions each variant supports, please see the chip's
architecture reference manual.

   The following table lists all available PowerPC options.

'-mpwrx | -mpwr2'
     Generate code for POWER/2 (RIOS2).

'-mpwr'
     Generate code for POWER (RIOS1)

'-m601'
     Generate code for PowerPC 601.

'-mppc, -mppc32, -m603, -m604'
     Generate code for PowerPC 603/604.

'-m403, -m405'
     Generate code for PowerPC 403/405.

'-m440'
     Generate code for PowerPC 440.  BookE and some 405 instructions.

'-m7400, -m7410, -m7450, -m7455'
     Generate code for PowerPC 7400/7410/7450/7455.

'-mppc64, -m620'
     Generate code for PowerPC 620/625/630.

'-me500, -me500x2'
     Generate code for Motorola e500 core complex.

'-mspe'
     Generate code for Motorola SPE instructions.

'-mppc64bridge'
     Generate code for PowerPC 64, including bridge insns.

'-mbooke64'
     Generate code for 64-bit BookE.

'-mbooke, mbooke32'
     Generate code for 32-bit BookE.

'-me300'
     Generate code for PowerPC e300 family.

'-maltivec'
     Generate code for processors with AltiVec instructions.

'-mpower4'
     Generate code for Power4 architecture.

'-mpower5'
     Generate code for Power5 architecture.

'-mpower6'
     Generate code for Power6 architecture.

'-mcell'
     Generate code for Cell Broadband Engine architecture.

'-mcom'
     Generate code Power/PowerPC common instructions.

'-many'
     Generate code for any architecture (PWR/PWRX/PPC).

'-mregnames'
     Allow symbolic names for registers.

'-mno-regnames'
     Do not allow symbolic names for registers.

'-mrelocatable'
     Support for GCC's -mrelocatable option.

'-mrelocatable-lib'
     Support for GCC's -mrelocatable-lib option.

'-memb'
     Set PPC_EMB bit in ELF flags.

'-mlittle, -mlittle-endian'
     Generate code for a little endian machine.

'-mbig, -mbig-endian'
     Generate code for a big endian machine.

'-msolaris'
     Generate code for Solaris.

'-mno-solaris'
     Do not generate code for Solaris.

12.2 PowerPC Assembler Directives
=================================

A number of assembler directives are available for PowerPC. The
following table is far from complete.

'.machine "string"'
     This directive allows you to change the machine for which code is
     generated.  '"string"' may be any of the -m cpu selection options
     (without the -m) enclosed in double quotes, '"push"', or '"pop"'.
     '.machine "push"' saves the currently selected cpu, which may be
     restored with '.machine "pop"'.

13 SPARC Dependent Features
***************************

13.1 Options
============

The SPARC chip family includes several successive levels, using the same
core instruction set, but including a few additional instructions at
each level.  There are exceptions to this however.  For details on what
instructions each variant supports, please see the chip's architecture
reference manual.

   By default, 'as' assumes the core instruction set (SPARC v6), but
"bumps" the architecture level as needed: it switches to successively
higher architectures as it encounters instructions that only exist in
the higher levels.

   If not configured for SPARC v9 ('sparc64-*-*') GAS will not bump
passed sparclite by default, an option must be passed to enable the v9
instructions.

   GAS treats sparclite as being compatible with v8, unless an
architecture is explicitly requested.  SPARC v9 is always incompatible
with sparclite.

'-Av6 | -Av7 | -Av8 | -Asparclet | -Asparclite'
'-Av8plus | -Av8plusa | -Av9 | -Av9a'
     Use one of the '-A' options to select one of the SPARC
     architectures explicitly.  If you select an architecture
     explicitly, 'as' reports a fatal error if it encounters an
     instruction or feature requiring an incompatible or higher level.

     '-Av8plus' and '-Av8plusa' select a 32 bit environment.

     '-Av9' and '-Av9a' select a 64 bit environment and are not
     available unless GAS is explicitly configured with 64 bit
     environment support.

     '-Av8plusa' and '-Av9a' enable the SPARC V9 instruction set with
     UltraSPARC extensions.

'-xarch=v8plus | -xarch=v8plusa'
     For compatibility with the Solaris v9 assembler.  These options are
     equivalent to -Av8plus and -Av8plusa, respectively.

'-bump'
     Warn whenever it is necessary to switch to another level.  If an
     architecture level is explicitly requested, GAS will not issue
     warnings until that level is reached, and will then bump the level
     as required (except between incompatible levels).

'-32 | -64'
     Select the word size, either 32 bits or 64 bits.  These options are
     only available with the ELF object file format, and require that
     the necessary BFD support has been included.

13.2 Enforcing aligned data
===========================

SPARC GAS normally permits data to be misaligned.  For example, it
permits the '.long' pseudo-op to be used on a byte boundary.  However,
the native SunOS and Solaris assemblers issue an error when they see
misaligned data.

   You can use the '--enforce-aligned-data' option to make SPARC GAS
also issue an error about misaligned data, just as the SunOS and Solaris
assemblers do.

   The '--enforce-aligned-data' option is not the default because gcc
issues misaligned data pseudo-ops when it initializes certain packed
data structures (structures defined using the 'packed' attribute).  You
may have to assemble with GAS in order to initialize packed data
structures in your own code.

13.3 Floating Point
===================

The Sparc uses IEEE floating-point numbers.

13.4 Sparc Machine Directives
=============================

The Sparc version of 'as' supports the following additional machine
directives:

'.align'
     This must be followed by the desired alignment in bytes.

'.common'
     This must be followed by a symbol name, a positive number, and
     '"bss"'.  This behaves somewhat like '.comm', but the syntax is
     different.

'.half'
     This is functionally identical to '.short'.

'.nword'
     On the Sparc, the '.nword' directive produces native word sized
     value, ie.  if assembling with -32 it is equivalent to '.word', if
     assembling with -64 it is equivalent to '.xword'.

'.proc'
     This directive is ignored.  Any text following it on the same line
     is also ignored.

'.register'
     This directive declares use of a global application or system
     register.  It must be followed by a register name %g2, %g3, %g6 or
     %g7, comma and the symbol name for that register.  If symbol name
     is '#scratch', it is a scratch register, if it is '#ignore', it
     just suppresses any errors about using undeclared global register,
     but does not emit any information about it into the object file.
     This can be useful e.g.  if you save the register before use and
     restore it after.

'.reserve'
     This must be followed by a symbol name, a positive number, and
     '"bss"'.  This behaves somewhat like '.lcomm', but the syntax is
     different.

'.seg'
     This must be followed by '"text"', '"data"', or '"data1"'.  It
     behaves like '.text', '.data', or '.data 1'.

'.skip'
     This is functionally identical to the '.space' directive.

'.word'
     On the Sparc, the '.word' directive produces 32 bit values, instead
     of the 16 bit values it produces on many other machines.

'.xword'
     On the Sparc V9 processor, the '.xword' directive produces 64 bit
     values.

14 Reporting Bugs
*****************

Your bug reports play an essential role in making 'as' reliable.

   Reporting a bug may help you by bringing a solution to your problem,
or it may not.  But in any case the principal function of a bug report
is to help the entire community by making the next version of 'as' work
better.  Bug reports are your contribution to the maintenance of 'as'.

   In order for a bug report to serve its purpose, you must include the
information that enables us to fix the bug.

14.1 Have You Found a Bug?
==========================

If you are not sure whether you have found a bug, here are some
guidelines:

   * If the assembler gets a fatal signal, for any input whatever, that
     is a 'as' bug.  Reliable assemblers never crash.

   * If 'as' produces an error message for valid input, that is a bug.

   * If 'as' does not produce an error message for invalid input, that
     is a bug.  However, you should note that your idea of "invalid
     input" might be our idea of "an extension" or "support for
     traditional practice".

   * If you are an experienced user of assemblers, your suggestions for
     improvement of 'as' are welcome in any case.

14.2 How to Report Bugs
=======================

A number of companies and individuals offer support for GNU products.
If you obtained 'as' from a support organization, we recommend you
contact that organization first.

   You can find contact information for many support companies and
individuals in the file 'etc/SERVICE' in the GNU Emacs distribution.

   The fundamental principle of reporting bugs usefully is this: *report
all the facts*.  If you are not sure whether to state a fact or leave it
out, state it!

   Often people omit facts because they think they know what causes the
problem and assume that some details do not matter.  Thus, you might
assume that the name of a symbol you use in an example does not matter.
Well, probably it does not, but one cannot be sure.  Perhaps the bug is
a stray memory reference which happens to fetch from the location where
that name is stored in memory; perhaps, if the name were different, the
contents of that location would fool the assembler into doing the right
thing despite the bug.  Play it safe and give a specific, complete
example.  That is the easiest thing for you to do, and the most helpful.

   Keep in mind that the purpose of a bug report is to enable us to fix
the bug if it is new to us.  Therefore, always write your bug reports on
the assumption that the bug has not been reported previously.

   Sometimes people give a few sketchy facts and ask, "Does this ring a
bell?"  This cannot help us fix a bug, so it is basically useless.  We
respond by asking for enough details to enable us to investigate.  You
might as well expedite matters by sending them to begin with.

   To enable us to fix the bug, you should include all these things:

   * The version of 'as'.  'as' announces it if you start it with the
     '--version' argument.

     Without this, we will not know whether there is any point in
     looking for the bug in the current version of 'as'.

   * Any patches you may have applied to the 'as' source.

   * The type of machine you are using, and the operating system name
     and version number.

   * What compiler (and its version) was used to compile 'as'--e.g.
     "'gcc-2.7'".

   * The command arguments you gave the assembler to assemble your
     example and observe the bug.  To guarantee you will not omit
     something important, list them all.  A copy of the Makefile (or the
     output from make) is sufficient.

     If we were to try to guess the arguments, we would probably guess
     wrong and then we might not encounter the bug.

   * A complete input file that will reproduce the bug.  If the bug is
     observed when the assembler is invoked via a compiler, send the
     assembler source, not the high level language source.  Most
     compilers will produce the assembler source when run with the '-S'
     option.  If you are using 'gcc', use the options '-v --save-temps';
     this will save the assembler source in a file with an extension of
     '.s', and also show you exactly how 'as' is being run.

   * A description of what behavior you observe that you believe is
     incorrect.  For example, "It gets a fatal signal."

     Of course, if the bug is that 'as' gets a fatal signal, then we
     will certainly notice it.  But if the bug is incorrect output, we
     might not notice unless it is glaringly wrong.  You might as well
     not give us a chance to make a mistake.

     Even if the problem you experience is a fatal signal, you should
     still say so explicitly.  Suppose something strange is going on,
     such as, your copy of 'as' is out of sync, or you have encountered
     a bug in the C library on your system.  (This has happened!)  Your
     copy might crash and ours would not.  If you told us to expect a
     crash, then when ours fails to crash, we would know that the bug
     was not happening for us.  If you had not told us to expect a
     crash, then we would not be able to draw any conclusion from our
     observations.

   * If you wish to suggest changes to the 'as' source, send us context
     diffs, as generated by 'diff' with the '-u', '-c', or '-p' option.
     Always send diffs from the old file to the new file.  If you even
     discuss something in the 'as' source, refer to it by context, not
     by line number.

     The line numbers in our development sources will not match those in
     your sources.  Your line numbers would convey no useful information
     to us.

   Here are some things that are not necessary:

   * A description of the envelope of the bug.

     Often people who encounter a bug spend a lot of time investigating
     which changes to the input file will make the bug go away and which
     changes will not affect it.

     This is often time consuming and not very useful, because the way
     we will find the bug is by running a single example under the
     debugger with breakpoints, not by pure deduction from a series of
     examples.  We recommend that you save your time for something else.

     Of course, if you can find a simpler example to report _instead_ of
     the original one, that is a convenience for us.  Errors in the
     output will be easier to spot, running under the debugger will take
     less time, and so on.

     However, simplification is not vital; if you do not want to do
     this, report the bug anyway and send us the entire test case you
     used.

   * A patch for the bug.

     A patch for the bug does help us if it is a good one.  But do not
     omit the necessary information, such as the test case, on the
     assumption that a patch is all we need.  We might see problems with
     your patch and decide to fix the problem another way, or we might
     not understand it at all.

     Sometimes with a program as complicated as 'as' it is very hard to
     construct an example that will make the program follow a certain
     path through the code.  If you do not send us the example, we will
     not be able to construct one, so we will not be able to verify that
     the bug is fixed.

     And if we cannot understand what bug you are trying to fix, or why
     your patch should be an improvement, we will not install it.  A
     test case will help us to understand.

   * A guess about what the bug is or what it depends on.

     Such guesses are usually wrong.  Even we cannot guess right about
     such things without first using the debugger to find the facts.

15 Acknowledgements
*******************

If you have contributed to GAS and your name isn't listed here, it is
not meant as a slight.  We just don't know about it.  Send mail to the
maintainer, and we'll correct the situation.  Currently the maintainer
is Ken Raeburn (email address 'raeburn@cygnus.com').

   Dean Elsner wrote the original GNU assembler for the VAX.(1)

   Jay Fenlason maintained GAS for a while, adding support for
GDB-specific debug information and the 68k series machines, most of the
preprocessing pass, and extensive changes in 'messages.c',
'input-file.c', 'write.c'.

   K. Richard Pixley maintained GAS for a while, adding various
enhancements and many bug fixes, including merging support for several
processors, breaking GAS up to handle multiple object file format back
ends (including heavy rewrite, testing, an integration of the coff and
b.out back ends), adding configuration including heavy testing and
verification of cross assemblers and file splits and renaming, converted
GAS to strictly ANSI C including full prototypes, added support for
m680[34]0 and cpu32, did considerable work on i960 including a COFF port
(including considerable amounts of reverse engineering), a SPARC opcode
file rewrite, DECstation, rs6000, and hp300hpux host ports, updated
"know" assertions and made them work, much other reorganization,
cleanup, and lint.

   Ken Raeburn wrote the high-level BFD interface code to replace most
of the code in format-specific I/O modules.

   The original VMS support was contributed by David L. Kashtan.  Eric
Youngdale has done much work with it since.

   The Intel 80386 machine description was written by Eliot Dresselhaus.

   Minh Tran-Le at IntelliCorp contributed some AIX 386 support.

   The Motorola 88k machine description was contributed by Devon Bowen
of Buffalo University and Torbjorn Granlund of the Swedish Institute of
Computer Science.

   Keith Knowles at the Open Software Foundation wrote the original MIPS
back end ('tc-mips.c', 'tc-mips.h'), and contributed Rose format support
(which hasn't been merged in yet).  Ralph Campbell worked with the MIPS
code to support a.out format.

   Support for the Zilog Z8k and Renesas H8/300 processors (tc-z8k,
tc-h8300), and IEEE 695 object file format (obj-ieee), was written by
Steve Chamberlain of Cygnus Support.  Steve also modified the COFF back
end to use BFD for some low-level operations, for use with the H8/300
and AMD 29k targets.

   John Gilmore built the AMD 29000 support, added '.include' support,
and simplified the configuration of which versions accept which
directives.  He updated the 68k machine description so that Motorola's
opcodes always produced fixed-size instructions (e.g., 'jsr'), while
synthetic instructions remained shrinkable ('jbsr').  John fixed many
bugs, including true tested cross-compilation support, and one bug in
relaxation that took a week and required the proverbial one-bit fix.

   Ian Lance Taylor of Cygnus Support merged the Motorola and MIT syntax
for the 68k, completed support for some COFF targets (68k, i386 SVR3,
and SCO Unix), added support for MIPS ECOFF and ELF targets, wrote the
initial RS/6000 and PowerPC assembler, and made a few other minor
patches.

   Steve Chamberlain made GAS able to generate listings.

   Hewlett-Packard contributed support for the HP9000/300.

   Jeff Law wrote GAS and BFD support for the native HPPA object format
(SOM) along with a fairly extensive HPPA testsuite (for both SOM and ELF
object formats).  This work was supported by both the Center for
Software Science at the University of Utah and Cygnus Support.

   Support for ELF format files has been worked on by Mark Eichin of
Cygnus Support (original, incomplete implementation for SPARC), Pete
Hoogenboom and Jeff Law at the University of Utah (HPPA mainly), Michael
Meissner of the Open Software Foundation (i386 mainly), and Ken Raeburn
of Cygnus Support (sparc, and some initial 64-bit support).

   Linas Vepstas added GAS support for the ESA/390 "IBM 370"
architecture.

   Richard Henderson rewrote the Alpha assembler.  Klaus Kaempf wrote
GAS and BFD support for openVMS/Alpha.

   Timothy Wall, Michael Hayes, and Greg Smart contributed to the
various tic* flavors.

   David Heine, Sterling Augustine, Bob Wilson and John Ruttenberg from
Tensilica, Inc. added support for Xtensa processors.

   Several engineers at Cygnus Support have also provided many small bug
fixes and configuration enhancements.

   Many others have contributed large or small bugfixes and
enhancements.  If you have contributed significant work and are not
mentioned on this list, and want to be, let us know.  Some of the
history has been lost; we are not intentionally leaving anyone out.

Appendix A GNU Free Documentation License
*****************************************

                        Version 1.1, March 2000

     Copyright (C) 2000, 2003 Free Software Foundation, Inc.
     51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

     Everyone is permitted to copy and distribute verbatim copies
     of this license document, but changing it is not allowed.

  0. PREAMBLE

     The purpose of this License is to make a manual, textbook, or other
     written document "free" in the sense of freedom: to assure everyone
     the effective freedom to copy and redistribute it, with or without
     modifying it, either commercially or noncommercially.  Secondarily,
     this License preserves for the author and publisher a way to get
     credit for their work, while not being considered responsible for
     modifications made by others.

     This License is a kind of "copyleft", which means that derivative
     works of the document must themselves be free in the same sense.
     It complements the GNU General Public License, which is a copyleft
     license designed for free software.

     We have designed this License in order to use it for manuals for
     free software, because free software needs free documentation: a
     free program should come with manuals providing the same freedoms
     that the software does.  But this License is not limited to
     software manuals; it can be used for any textual work, regardless
     of subject matter or whether it is published as a printed book.  We
     recommend this License principally for works whose purpose is
     instruction or reference.


  1. APPLICABILITY AND DEFINITIONS

     This License applies to any manual or other work that contains a
     notice placed by the copyright holder saying it can be distributed
     under the terms of this License.  The "Document", below, refers to
     any such manual or work.  Any member of the public is a licensee,
     and is addressed as "you."

     A "Modified Version" of the Document means any work containing the
     Document or a portion of it, either copied verbatim, or with
     modifications and/or translated into another language.

     A "Secondary Section" is a named appendix or a front-matter section
     of the Document that deals exclusively with the relationship of the
     publishers or authors of the Document to the Document's overall
     subject (or to related matters) and contains nothing that could
     fall directly within that overall subject.  (For example, if the
     Document is in part a textbook of mathematics, a Secondary Section
     may not explain any mathematics.)  The relationship could be a
     matter of historical connection with the subject or with related
     matters, or of legal, commercial, philosophical, ethical or
     political position regarding them.

     The "Invariant Sections" are certain Secondary Sections whose
     titles are designated, as being those of Invariant Sections, in the
     notice that says that the Document is released under this License.

     The "Cover Texts" are certain short passages of text that are
     listed, as Front-Cover Texts or Back-Cover Texts, in the notice
     that says that the Document is released under this License.

     A "Transparent" copy of the Document means a machine-readable copy,
     represented in a format whose specification is available to the
     general public, whose contents can be viewed and edited directly
     and straightforwardly with generic text editors or (for images
     composed of pixels) generic paint programs or (for drawings) some
     widely available drawing editor, and that is suitable for input to
     text formatters or for automatic translation to a variety of
     formats suitable for input to text formatters.  A copy made in an
     otherwise Transparent file format whose markup has been designed to
     thwart or discourage subsequent modification by readers is not
     Transparent.  A copy that is not "Transparent" is called "Opaque."

     Examples of suitable formats for Transparent copies include plain
     ASCII without markup, Texinfo input format, LaTeX input format,
     SGML or XML using a publicly available DTD, and standard-conforming
     simple HTML designed for human modification.  Opaque formats
     include PostScript, PDF, proprietary formats that can be read and
     edited only by proprietary word processors, SGML or XML for which
     the DTD and/or processing tools are not generally available, and
     the machine-generated HTML produced by some word processors for
     output purposes only.

     The "Title Page" means, for a printed book, the title page itself,
     plus such following pages as are needed to hold, legibly, the
     material this License requires to appear in the title page.  For
     works in formats which do not have any title page as such, "Title
     Page" means the text near the most prominent appearance of the
     work's title, preceding the beginning of the body of the text.

  2. VERBATIM COPYING

     You may copy and distribute the Document in any medium, either
     commercially or noncommercially, provided that this License, the
     copyright notices, and the license notice saying this License
     applies to the Document are reproduced in all copies, and that you
     add no other conditions whatsoever to those of this License.  You
     may not use technical measures to obstruct or control the reading
     or further copying of the copies you make or distribute.  However,
     you may accept compensation in exchange for copies.  If you
     distribute a large enough number of copies you must also follow the
     conditions in section 3.

     You may also lend copies, under the same conditions stated above,
     and you may publicly display copies.

  3. COPYING IN QUANTITY

     If you publish printed copies of the Document numbering more than
     100, and the Document's license notice requires Cover Texts, you
     must enclose the copies in covers that carry, clearly and legibly,
     all these Cover Texts: Front-Cover Texts on the front cover, and
     Back-Cover Texts on the back cover.  Both covers must also clearly
     and legibly identify you as the publisher of these copies.  The
     front cover must present the full title with all words of the title
     equally prominent and visible.  You may add other material on the
     covers in addition.  Copying with changes limited to the covers, as
     long as they preserve the title of the Document and satisfy these
     conditions, can be treated as verbatim copying in other respects.

     If the required texts for either cover are too voluminous to fit
     legibly, you should put the first ones listed (as many as fit
     reasonably) on the actual cover, and continue the rest onto
     adjacent pages.

     If you publish or distribute Opaque copies of the Document
     numbering more than 100, you must either include a machine-readable
     Transparent copy along with each Opaque copy, or state in or with
     each Opaque copy a publicly-accessible computer-network location
     containing a complete Transparent copy of the Document, free of
     added material, which the general network-using public has access
     to download anonymously at no charge using public-standard network
     protocols.  If you use the latter option, you must take reasonably
     prudent steps, when you begin distribution of Opaque copies in
     quantity, to ensure that this Transparent copy will remain thus
     accessible at the stated location until at least one year after the
     last time you distribute an Opaque copy (directly or through your
     agents or retailers) of that edition to the public.

     It is requested, but not required, that you contact the authors of
     the Document well before redistributing any large number of copies,
     to give them a chance to provide you with an updated version of the
     Document.

  4. MODIFICATIONS

     You may copy and distribute a Modified Version of the Document
     under the conditions of sections 2 and 3 above, provided that you
     release the Modified Version under precisely this License, with the
     Modified Version filling the role of the Document, thus licensing
     distribution and modification of the Modified Version to whoever
     possesses a copy of it.  In addition, you must do these things in
     the Modified Version:

     A. Use in the Title Page (and on the covers, if any) a title
     distinct from that of the Document, and from those of previous
     versions (which should, if there were any, be listed in the History
     section of the Document).  You may use the same title as a previous
     version if the original publisher of that version gives permission.
     B. List on the Title Page, as authors, one or more persons or
     entities responsible for authorship of the modifications in the
     Modified Version, together with at least five of the principal
     authors of the Document (all of its principal authors, if it has
     less than five).
     C. State on the Title page the name of the publisher of the
     Modified Version, as the publisher.
     D. Preserve all the copyright notices of the Document.
     E. Add an appropriate copyright notice for your modifications
     adjacent to the other copyright notices.
     F. Include, immediately after the copyright notices, a license
     notice giving the public permission to use the Modified Version
     under the terms of this License, in the form shown in the Addendum
     below.
     G. Preserve in that license notice the full lists of Invariant
     Sections and required Cover Texts given in the Document's license
     notice.
     H. Include an unaltered copy of this License.
     I. Preserve the section entitled "History", and its title, and add
     to it an item stating at least the title, year, new authors, and
     publisher of the Modified Version as given on the Title Page.  If
     there is no section entitled "History" in the Document, create one
     stating the title, year, authors, and publisher of the Document as
     given on its Title Page, then add an item describing the Modified
     Version as stated in the previous sentence.
     J. Preserve the network location, if any, given in the Document for
     public access to a Transparent copy of the Document, and likewise
     the network locations given in the Document for previous versions
     it was based on.  These may be placed in the "History" section.
     You may omit a network location for a work that was published at
     least four years before the Document itself, or if the original
     publisher of the version it refers to gives permission.
     K. In any section entitled "Acknowledgements" or "Dedications",
     preserve the section's title, and preserve in the section all the
     substance and tone of each of the contributor acknowledgements
     and/or dedications given therein.
     L. Preserve all the Invariant Sections of the Document, unaltered
     in their text and in their titles.  Section numbers or the
     equivalent are not considered part of the section titles.
     M. Delete any section entitled "Endorsements."  Such a section may
     not be included in the Modified Version.
     N. Do not retitle any existing section as "Endorsements" or to
     conflict in title with any Invariant Section.

     If the Modified Version includes new front-matter sections or
     appendices that qualify as Secondary Sections and contain no
     material copied from the Document, you may at your option designate
     some or all of these sections as invariant.  To do this, add their
     titles to the list of Invariant Sections in the Modified Version's
     license notice.  These titles must be distinct from any other
     section titles.

     You may add a section entitled "Endorsements", provided it contains
     nothing but endorsements of your Modified Version by various
     parties-for example, statements of peer review or that the text has
     been approved by an organization as the authoritative definition of
     a standard.

     You may add a passage of up to five words as a Front-Cover Text,
     and a passage of up to 25 words as a Back-Cover Text, to the end of
     the list of Cover Texts in the Modified Version.  Only one passage
     of Front-Cover Text and one of Back-Cover Text may be added by (or
     through arrangements made by) any one entity.  If the Document
     already includes a cover text for the same cover, previously added
     by you or by arrangement made by the same entity you are acting on
     behalf of, you may not add another; but you may replace the old
     one, on explicit permission from the previous publisher that added
     the old one.

     The author(s) and publisher(s) of the Document do not by this
     License give permission to use their names for publicity for or to
     assert or imply endorsement of any Modified Version.

  5. COMBINING DOCUMENTS

     You may combine the Document with other documents released under
     this License, under the terms defined in section 4 above for
     modified versions, provided that you include in the combination all
     of the Invariant Sections of all of the original documents,
     unmodified, and list them all as Invariant Sections of your
     combined work in its license notice.

     The combined work need only contain one copy of this License, and
     multiple identical Invariant Sections may be replaced with a single
     copy.  If there are multiple Invariant Sections with the same name
     but different contents, make the title of each such section unique
     by adding at the end of it, in parentheses, the name of the
     original author or publisher of that section if known, or else a
     unique number.  Make the same adjustment to the section titles in
     the list of Invariant Sections in the license notice of the
     combined work.

     In the combination, you must combine any sections entitled
     "History" in the various original documents, forming one section
     entitled "History"; likewise combine any sections entitled
     "Acknowledgements", and any sections entitled "Dedications."  You
     must delete all sections entitled "Endorsements."

  6. COLLECTIONS OF DOCUMENTS

     You may make a collection consisting of the Document and other
     documents released under this License, and replace the individual
     copies of this License in the various documents with a single copy
     that is included in the collection, provided that you follow the
     rules of this License for verbatim copying of each of the documents
     in all other respects.

     You may extract a single document from such a collection, and
     distribute it individually under this License, provided you insert
     a copy of this License into the extracted document, and follow this
     License in all other respects regarding verbatim copying of that
     document.

  7. AGGREGATION WITH INDEPENDENT WORKS

     A compilation of the Document or its derivatives with other
     separate and independent documents or works, in or on a volume of a
     storage or distribution medium, does not as a whole count as a
     Modified Version of the Document, provided no compilation copyright
     is claimed for the compilation.  Such a compilation is called an
     "aggregate", and this License does not apply to the other
     self-contained works thus compiled with the Document, on account of
     their being thus compiled, if they are not themselves derivative
     works of the Document.

     If the Cover Text requirement of section 3 is applicable to these
     copies of the Document, then if the Document is less than one
     quarter of the entire aggregate, the Document's Cover Texts may be
     placed on covers that surround only the Document within the
     aggregate.  Otherwise they must appear on covers around the whole
     aggregate.

  8. TRANSLATION

     Translation is considered a kind of modification, so you may
     distribute translations of the Document under the terms of section
     4.  Replacing Invariant Sections with translations requires special
     permission from their copyright holders, but you may include
     translations of some or all Invariant Sections in addition to the
     original versions of these Invariant Sections.  You may include a
     translation of this License provided that you also include the
     original English version of this License.  In case of a
     disagreement between the translation and the original English
     version of this License, the original English version will prevail.

  9. TERMINATION

     You may not copy, modify, sublicense, or distribute the Document
     except as expressly provided for under this License.  Any other
     attempt to copy, modify, sublicense or distribute the Document is
     void, and will automatically terminate your rights under this
     License.  However, parties who have received copies, or rights,
     from you under this License will not have their licenses terminated
     so long as such parties remain in full compliance.

  10. FUTURE REVISIONS OF THIS LICENSE

     The Free Software Foundation may publish new, revised versions of
     the GNU Free Documentation License from time to time.  Such new
     versions will be similar in spirit to the present version, but may
     differ in detail to address new problems or concerns.  See
     http://www.gnu.org/copyleft/.

     Each version of the License is given a distinguishing version
     number.  If the Document specifies that a particular numbered
     version of this License "or any later version" applies to it, you
     have the option of following the terms and conditions either of
     that specified version or of any later version that has been
     published (not as a draft) by the Free Software Foundation.  If the
     Document does not specify a version number of this License, you may
     choose any version ever published (not as a draft) by the Free
     Software Foundation.

ADDENDUM: How to use this License for your documents
====================================================

To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:

     Copyright (C)  YEAR  YOUR NAME.
     Permission is granted to copy, distribute and/or modify this document
     under the terms of the GNU Free Documentation License, Version 1.1
     or any later version published by the Free Software Foundation;
     with the Invariant Sections being LIST THEIR TITLES, with the
     Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
     A copy of the license is included in the section entitled "GNU
     Free Documentation License."

   If you have no Invariant Sections, write "with no Invariant Sections"
instead of saying which ones are invariant.  If you have no Front-Cover
Texts, write "no Front-Cover Texts" instead of "Front-Cover Texts being
LIST"; likewise for Back-Cover Texts.

   If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of free
software license, such as the GNU General Public License, to permit
their use in free software.

   ---------- Footnotes ----------

   (1) Any more details?

AS Index
********

* Menu:

* #:                                     Comments.           (line 1306)
* #APP:                                  Preprocessing.      (line 1268)
* #NO_APP:                               Preprocessing.      (line 1268)
* '$a':                                  ARM Mapping Symbols.
                                                             (line 4193)
* '$d':                                  ARM Mapping Symbols.
                                                             (line 4199)
* '$t':                                  ARM Mapping Symbols.
                                                             (line 4196)
* --:                                    Command Line.       (line  760)
* '--32' option, i386:                   i386-Options.       (line 4220)
* '--32' option, x86-64:                 i386-Options.       (line 4220)
* '--64' option, i386:                   i386-Options.       (line 4220)
* '--64' option, x86-64:                 i386-Options.       (line 4220)
* --alternate:                           alternate.          (line  929)
* '--divide' option, i386:               i386-Options.       (line 4236)
* --enforce-aligned-data:                Sparc-Aligned-Data. (line 5460)
* --fatal-warnings:                      W.                  (line 1222)
* --hash-size=NUMBER:                    Overview.           (line  459)
* --listing-cont-lines:                  listing.            (line 1015)
* --listing-lhs-width:                   listing.            (line  997)
* --listing-lhs-width2:                  listing.            (line 1002)
* --listing-rhs-width:                   listing.            (line 1009)
* --MD:                                  MD.                 (line 1149)
* --no-warn:                             W.                  (line 1217)
* --statistics:                          statistics.         (line 1188)
* --traditional-format:                  traditional-format. (line 1196)
* --warn:                                W.                  (line 1225)
* -a:                                    a.                  (line  894)
* -ac:                                   a.                  (line  894)
* -ad:                                   a.                  (line  894)
* -ah:                                   a.                  (line  894)
* -al:                                   a.                  (line  894)
* -an:                                   a.                  (line  894)
* -as:                                   a.                  (line  894)
* -Asparclet:                            Sparc-Opts.         (line 5421)
* -Asparclite:                           Sparc-Opts.         (line 5421)
* -Av6:                                  Sparc-Opts.         (line 5421)
* -Av8:                                  Sparc-Opts.         (line 5421)
* -Av9:                                  Sparc-Opts.         (line 5421)
* -Av9a:                                 Sparc-Opts.         (line 5421)
* -construct-floats:                     MIPS Opts.          (line 5056)
* -D:                                    D.                  (line  934)
* '-eabi=' command line option, ARM:     ARM Options.        (line 3844)
* '-EB' command line option, ARM:        ARM Options.        (line 3849)
* '-EB' option (MIPS):                   MIPS Opts.          (line 4879)
* '-EL' command line option, ARM:        ARM Options.        (line 3853)
* '-EL' option (MIPS):                   MIPS Opts.          (line 4879)
* -f:                                    f.                  (line  940)
* '-G' option (MIPS):                    MIPS Opts.          (line 4874)
* -I PATH:                               I.                  (line  952)
* -K:                                    K.                  (line  962)
* '-k' command line option, ARM:         ARM Options.        (line 3857)
* '-KPIC' option, MIPS:                  MIPS Opts.          (line 4887)
* -L:                                    L.                  (line  972)
* -M:                                    M.                  (line 1022)
* '-mapcs' command line option, ARM:     ARM Options.        (line 3817)
* '-mapcs-float' command line option, ARM: ARM Options.      (line 3830)
* '-mapcs-reentrant' command line option, ARM: ARM Options.  (line 3835)
* '-march=' command line option, ARM:    ARM Options.        (line 3773)
* '-march=' option, i386:                i386-Options.       (line 4243)
* '-march=' option, x86-64:              i386-Options.       (line 4243)
* '-matpcs' command line option, ARM:    ARM Options.        (line 3822)
* '-mconstant-gp' command line option, IA-64: IA-64 Options. (line 4733)
* '-mcpu=' command line option, ARM:     ARM Options.        (line 3742)
* '-mfloat-abi=' command line option, ARM: ARM Options.      (line 3839)
* '-mfpu=' command line option, ARM:     ARM Options.        (line 3788)
* -mno-sym32:                            MIPS Opts.          (line 5045)
* -msym32:                               MIPS Opts.          (line 5045)
* '-mthumb' command line option, ARM:    ARM Options.        (line 3808)
* '-mthumb-interwork' command line option, ARM: ARM Options. (line 3813)
* '-mtune=' option, i386:                i386-Options.       (line 4255)
* '-mtune=' option, x86-64:              i386-Options.       (line 4255)
* '-mvxworks-pic' option, MIPS:          MIPS Opts.          (line 4892)
* -no-construct-floats:                  MIPS Opts.          (line 5056)
* '-nocpp' ignored (MIPS):               MIPS Opts.          (line 5048)
* -o:                                    o.                  (line 1160)
* -R:                                    R.                  (line 1170)
* -v:                                    v.                  (line 1206)
* -version:                              v.                  (line 1206)
* -W:                                    W.                  (line 1217)
* '.' (symbol):                          Dot.                (line 1898)
* '.arch' directive, ARM:                ARM Directives.     (line 4118)
* '.cantunwind' directive, ARM:          ARM Directives.     (line 4022)
* '.cpu' directive, ARM:                 ARM Directives.     (line 4114)
* '.eabi_attribute' directive, ARM:      ARM Directives.     (line 4132)
* '.fnend' directive, ARM:               ARM Directives.     (line 4014)
* '.fnstart' directive, ARM:             ARM Directives.     (line 4011)
* '.fpu' directive, ARM:                 ARM Directives.     (line 4128)
* '.handlerdata' directive, ARM:         ARM Directives.     (line 4033)
* '.insn':                               MIPS insn.          (line 5223)
* '.ltorg' directive, ARM:               ARM Directives.     (line 3994)
* '.movsp' directive, ARM:               ARM Directives.     (line 4088)
* .o:                                    Object.             (line  827)
* '.object_arch' directive, ARM:         ARM Directives.     (line 4122)
* '.pad' directive, ARM:                 ARM Directives.     (line 4083)
* '.personality' directive, ARM:         ARM Directives.     (line 4026)
* '.personalityindex' directive, ARM:    ARM Directives.     (line 4029)
* '.pool' directive, ARM:                ARM Directives.     (line 4008)
* '.save' directive, ARM:                ARM Directives.     (line 4042)
* '.set arch=CPU':                       MIPS ISA.           (line 5195)
* '.set autoextend':                     MIPS autoextend.    (line 5210)
* '.set dsp':                            MIPS ASE instruction generation overrides.
                                                             (line 5262)
* '.set dspr2':                          MIPS ASE instruction generation overrides.
                                                             (line 5267)
* '.set mdmx':                           MIPS ASE instruction generation overrides.
                                                             (line 5257)
* '.set mips3d':                         MIPS ASE instruction generation overrides.
                                                             (line 5247)
* '.set mipsN':                          MIPS ISA.           (line 5183)
* '.set mt':                             MIPS ASE instruction generation overrides.
                                                             (line 5272)
* '.set noautoextend':                   MIPS autoextend.    (line 5210)
* '.set nodsp':                          MIPS ASE instruction generation overrides.
                                                             (line 5262)
* '.set nodspr2':                        MIPS ASE instruction generation overrides.
                                                             (line 5267)
* '.set nomdmx':                         MIPS ASE instruction generation overrides.
                                                             (line 5257)
* '.set nomips3d':                       MIPS ASE instruction generation overrides.
                                                             (line 5247)
* '.set nomt':                           MIPS ASE instruction generation overrides.
                                                             (line 5272)
* '.set nosmartmips':                    MIPS ASE instruction generation overrides.
                                                             (line 5252)
* '.set nosym32':                        MIPS symbol sizes.  (line 5140)
* '.set pop':                            MIPS option stack.  (line 5232)
* '.set push':                           MIPS option stack.  (line 5232)
* '.set smartmips':                      MIPS ASE instruction generation overrides.
                                                             (line 5252)
* '.set sym32':                          MIPS symbol sizes.  (line 5140)
* '.setfp' directive, ARM:               ARM Directives.     (line 4093)
* '.unwind_raw' directive, ARM:          ARM Directives.     (line 4107)
* '.vsave' directive, ARM:               ARM Directives.     (line 4066)
* 16-bit code, i386:                     i386-16bit.         (line 4615)
* 3DNow!, i386:                          i386-SIMD.          (line 4593)
* 3DNow!, x86-64:                        i386-SIMD.          (line 4593)
* ':' (label):                           Statements.         (line 1355)
* '\"' (doublequote character):          Strings.            (line 1423)
* '\b' (backspace character):            Strings.            (line 1395)
* '\DDD' (octal character code):         Strings.            (line 1410)
* '\f' (formfeed character):             Strings.            (line 1398)
* '\n' (newline character):              Strings.            (line 1401)
* '\r' (carriage return character):      Strings.            (line 1404)
* '\t' (tab):                            Strings.            (line 1407)
* '\XD...' (hex character code):         Strings.            (line 1416)
* '\\' ('\' character):                  Strings.            (line 1420)
* a.out:                                 Object.             (line  827)
* 'abort' directive:                     Abort.              (line 2114)
* absolute section:                      Ld Sections.        (line 1632)
* addition, permitted arguments:         Infix Ops.          (line 2055)
* addresses:                             Expressions.        (line 1946)
* addresses, format of:                  Secs Background.    (line 1573)
* 'ADR reg,<label>' pseudo op, ARM:      ARM Opcodes.        (line 4159)
* 'ADRL reg,<label>' pseudo op, ARM:     ARM Opcodes.        (line 4169)
* advancing location counter:            Org.                (line 3101)
* 'align' directive:                     Align.              (line 2123)
* 'align' directive, ARM:                ARM Directives.     (line 3915)
* 'align' directive, SPARC:              Sparc-Directives.   (line 5481)
* arch directive, i386:                  i386-Arch.          (line 4670)
* arch directive, x86-64:                i386-Arch.          (line 4670)
* architectures, PowerPC:                PowerPC-Opts.       (line 5285)
* architectures, SPARC:                  Sparc-Opts.         (line 5402)
* arguments for addition:                Infix Ops.          (line 2055)
* arguments for subtraction:             Infix Ops.          (line 2060)
* arguments in expressions:              Arguments.          (line 1973)
* arithmetic functions:                  Operators.          (line 1998)
* arithmetic operands:                   Arguments.          (line 1973)
* ARM data relocations:                  ARM-Relocations.    (line 3886)
* 'arm' directive, ARM:                  ARM Directives.     (line 3969)
* ARM floating point (IEEE):             ARM Floating Point. (line 3910)
* ARM identifiers:                       ARM-Chars.          (line 3876)
* ARM immediate character:               ARM-Chars.          (line 3874)
* ARM line comment character:            ARM-Chars.          (line 3867)
* ARM line separator:                    ARM-Chars.          (line 3871)
* ARM machine directives:                ARM Directives.     (line 3915)
* ARM opcodes:                           ARM Opcodes.        (line 4140)
* ARM options (none):                    ARM Options.        (line 3742)
* ARM register names:                    ARM-Regs.           (line 3881)
* ARM support:                           Machine Dependencies.
                                                             (line 3739)
* 'ascii' directive:                     Ascii.              (line 2165)
* 'asciz' directive:                     Asciz.              (line 2172)
* assembler bugs, reporting:             Bug Reporting.      (line 5566)
* assembler crash:                       Bug Criteria.       (line 5550)
* assembler internal logic error:        As Sections.        (line 1674)
* assembler version:                     v.                  (line 1206)
* assembler, and linker:                 Secs Background.    (line 1535)
* assembly listings, enabling:           a.                  (line  894)
* assigning values to symbols:           Setting Symbols.    (line 1772)
* assigning values to symbols <1>:       Equ.                (line 2471)
* attributes, symbol:                    Symbol Attributes.  (line 1907)
* att_syntax pseudo op, i386:            i386-Syntax.        (line 4265)
* att_syntax pseudo op, x86-64:          i386-Syntax.        (line 4265)
* Av7:                                   Sparc-Opts.         (line 5421)
* backslash ('\\'):                      Strings.            (line 1420)
* backspace ('\b'):                      Strings.            (line 1395)
* 'balign' directive:                    Balign.             (line 2178)
* 'balignl' directive:                   Balign.             (line 2199)
* 'balignw' directive:                   Balign.             (line 2199)
* big endian output, MIPS:               Overview.           (line  560)
* big-endian output, MIPS:               MIPS Opts.          (line 4879)
* bignums:                               Bignums.            (line 1485)
* binary files, including:               Incbin.             (line 2707)
* binary integers:                       Integers.           (line 1466)
* bit names, IA-64:                      IA-64-Bits.         (line 4846)
* bss section:                           Ld Sections.        (line 1623)
* bss section <1>:                       bss.                (line 1739)
* bug criteria:                          Bug Criteria.       (line 5547)
* bug reports:                           Bug Reporting.      (line 5566)
* bugs in assembler:                     Reporting Bugs.     (line 5534)
* bus lock prefixes, i386:               i386-Prefixes.      (line 4444)
* 'byte' directive:                      Byte.               (line 2211)
* call instructions, i386:               i386-Mnemonics.     (line 4353)
* call instructions, x86-64:             i386-Mnemonics.     (line 4353)
* carriage return ('\r'):                Strings.            (line 1404)
* 'cfi_endproc' directive:               CFI directives.     (line 2249)
* 'cfi_startproc' directive:             CFI directives.     (line 2239)
* character constants:                   Characters.         (line 1377)
* character escape codes:                Strings.            (line 1395)
* character, single:                     Chars.              (line 1443)
* characters used in symbols:            Symbol Intro.       (line 1325)
* 'code' directive, ARM:                 ARM Directives.     (line 3962)
* 'code16' directive, i386:              i386-16bit.         (line 4615)
* 'code16gcc' directive, i386:           i386-16bit.         (line 4615)
* 'code32' directive, i386:              i386-16bit.         (line 4615)
* 'code64' directive, i386:              i386-16bit.         (line 4615)
* 'code64' directive, x86-64:            i386-16bit.         (line 4615)
* COMDAT:                                Linkonce.           (line 2831)
* 'comm' directive:                      Comm.               (line 2217)
* command line conventions:              Command Line.       (line  756)
* comments:                              Comments.           (line 1288)
* comments, removed by preprocessor:     Preprocessing.      (line 1253)
* 'common' directive, SPARC:             Sparc-Directives.   (line 5484)
* common sections:                       Linkonce.           (line 2831)
* common variable storage:               bss.                (line 1739)
* comparison expressions:                Infix Ops.          (line 2066)
* conditional assembly:                  If.                 (line 2629)
* constant, single character:            Chars.              (line 1443)
* constants:                             Constants.          (line 1366)
* constants, bignum:                     Bignums.            (line 1485)
* constants, character:                  Characters.         (line 1377)
* constants, converted by preprocessor:  Preprocessing.      (line 1256)
* constants, floating point:             Flonums.            (line 1493)
* constants, integer:                    Integers.           (line 1466)
* constants, number:                     Numbers.            (line 1457)
* constants, string:                     Strings.            (line 1386)
* conversion instructions, i386:         i386-Mnemonics.     (line 4334)
* conversion instructions, x86-64:       i386-Mnemonics.     (line 4334)
* coprocessor wait, i386:                i386-Prefixes.      (line 4448)
* crash of assembler:                    Bug Criteria.       (line 5550)
* current address:                       Dot.                (line 1898)
* current address, advancing:            Org.                (line 3101)
* data alignment on SPARC:               Sparc-Aligned-Data. (line 5455)
* data and text sections, joining:       R.                  (line 1170)
* 'data' directive:                      Data.               (line 2421)
* data relocations, ARM:                 ARM-Relocations.    (line 3886)
* debuggers, and symbol order:           Symbols.            (line 1757)
* decimal integers:                      Integers.           (line 1472)
* dependency tracking:                   MD.                 (line 1149)
* deprecated directives:                 Deprecated.         (line 3731)
* directives and instructions:           Statements.         (line 1347)
* directives for PowerPC:                PowerPC-Pseudo.     (line 5386)
* directives, machine independent:       Pseudo Ops.         (line 2105)
* 'dn' and 'qn' directives, ARM:         ARM Directives.     (line 3938)
* dollar local symbols:                  Symbol Names.       (line 1879)
* dot (symbol):                          Dot.                (line 1898)
* 'double' directive:                    Double.             (line 2428)
* 'double' directive, i386:              i386-Float.         (line 4569)
* 'double' directive, x86-64:            i386-Float.         (line 4569)
* doublequote ('\"'):                    Strings.            (line 1423)
* ECOFF sections:                        MIPS Object.        (line 5100)
* eight-byte integer:                    Quad.               (line 3245)
* 'eject' directive:                     Eject.              (line 2434)
* ELF symbol type:                       Type.               (line 3620)
* 'else' directive:                      Else.               (line 2439)
* 'elseif' directive:                    Elseif.             (line 2446)
* empty expressions:                     Empty Exprs.        (line 1959)
* emulation:                             Overview.           (line  663)
* 'end' directive:                       End.                (line 2453)
* 'endfunc' directive:                   Endfunc.            (line 2459)
* endianness, MIPS:                      Overview.           (line  560)
* 'endif' directive:                     Endif.              (line 2464)
* 'endm' directive:                      Macro.              (line 3025)
* EOF, newline must precede:             Statements.         (line 1341)
* 'equ' directive:                       Equ.                (line 2471)
* 'equiv' directive:                     Equiv.              (line 2477)
* 'eqv' directive:                       Eqv.                (line 2493)
* 'err' directive:                       Err.                (line 2501)
* error directive:                       Error.              (line 2509)
* error messages:                        Errors.             (line  844)
* error on valid input:                  Bug Criteria.       (line 5553)
* errors, caused by warnings:            W.                  (line 1222)
* errors, continuing after:              Z.                  (line 1231)
* escape codes, character:               Strings.            (line 1395)
* 'exitm' directive:                     Macro.              (line 3028)
* expr (internal section):               As Sections.        (line 1678)
* expression arguments:                  Arguments.          (line 1973)
* expressions:                           Expressions.        (line 1946)
* expressions, comparison:               Infix Ops.          (line 2066)
* expressions, empty:                    Empty Exprs.        (line 1959)
* expressions, integer:                  Integer Exprs.      (line 1967)
* 'extern' directive:                    Extern.             (line 2524)
* 'fail' directive:                      Fail.               (line 2531)
* faster processing ('-f'):              f.                  (line  940)
* fatal signal:                          Bug Criteria.       (line 5550)
* 'file' directive:                      LNS directives.     (line 2369)
* 'file' directive <1>:                  File.               (line 2540)
* file name, logical:                    File.               (line 2540)
* files, including:                      Include.            (line 2721)
* files, input:                          Input Files.        (line  780)
* 'fill' directive:                      Fill.               (line 2550)
* filling memory:                        Skip.               (line 3452)
* filling memory <1>:                    Space.              (line 3459)
* 'float' directive:                     Float.              (line 2568)
* 'float' directive, i386:               i386-Float.         (line 4569)
* 'float' directive, x86-64:             i386-Float.         (line 4569)
* floating point numbers:                Flonums.            (line 1493)
* floating point numbers (double):       Double.             (line 2428)
* floating point numbers (single):       Float.              (line 2568)
* floating point numbers (single) <1>:   Single.             (line 3425)
* floating point, ARM (IEEE):            ARM Floating Point. (line 3910)
* floating point, i386:                  i386-Float.         (line 4561)
* floating point, SPARC (IEEE):          Sparc-Float.        (line 5473)
* floating point, x86-64:                i386-Float.         (line 4561)
* flonums:                               Flonums.            (line 1493)
* 'force_thumb' directive, ARM:          ARM Directives.     (line 3972)
* format of error messages:              Errors.             (line  861)
* format of warning messages:            Errors.             (line  850)
* formfeed ('\f'):                       Strings.            (line 1398)
* 'func' directive:                      Func.               (line 2574)
* functions, in expressions:             Operators.          (line 1998)
* 'global' directive:                    Global.             (line 2585)
* 'gp' register, MIPS:                   MIPS Object.        (line 5105)
* grouping data:                         Sub-Sections.       (line 1686)
* 'half' directive, SPARC:               Sparc-Directives.   (line 5489)
* hex character code ('\XD...'):         Strings.            (line 1416)
* hexadecimal integers:                  Integers.           (line 1475)
* 'hidden' directive:                    Hidden.             (line 2597)
* 'hword' directive:                     hword.              (line 2610)
* i386 16-bit code:                      i386-16bit.         (line 4615)
* i386 arch directive:                   i386-Arch.          (line 4670)
* i386 att_syntax pseudo op:             i386-Syntax.        (line 4265)
* i386 conversion instructions:          i386-Mnemonics.     (line 4334)
* i386 floating point:                   i386-Float.         (line 4561)
* i386 immediate operands:               i386-Syntax.        (line 4274)
* i386 instruction naming:               i386-Mnemonics.     (line 4309)
* i386 instruction prefixes:             i386-Prefixes.      (line 4414)
* i386 intel_syntax pseudo op:           i386-Syntax.        (line 4265)
* i386 jump optimization:                i386-Jumps.         (line 4538)
* i386 jump, call, return:               i386-Syntax.        (line 4296)
* i386 jump/call operands:               i386-Syntax.        (line 4274)
* i386 memory references:                i386-Memory.        (line 4471)
* i386 'mul', 'imul' instructions:       i386-Notes.         (line 4714)
* i386 options:                          i386-Options.       (line 4218)
* i386 register operands:                i386-Syntax.        (line 4274)
* i386 registers:                        i386-Regs.          (line 4359)
* i386 sections:                         i386-Syntax.        (line 4302)
* i386 size suffixes:                    i386-Syntax.        (line 4287)
* i386 source, destination operands:     i386-Syntax.        (line 4280)
* i386 support:                          .                   (line 4211)
* i386 syntax compatibility:             i386-Syntax.        (line 4265)
* i80306 support:                        .                   (line 4211)
* IA-64 line comment character:          IA-64-Chars.        (line 4822)
* IA-64 line separator:                  IA-64-Chars.        (line 4824)
* IA-64 options:                         IA-64 Options.      (line 4733)
* IA-64 Processor-status-Register bit names: IA-64-Bits.     (line 4846)
* IA-64 registers:                       IA-64-Regs.         (line 4829)
* IA-64 support:                         .                   (line 4730)
* IA-64 Syntax:                          IA-64 Options.      (line 4812)
* 'ident' directive:                     Ident.              (line 2618)
* identifiers, ARM:                      ARM-Chars.          (line 3876)
* 'if' directive:                        If.                 (line 2629)
* 'ifb' directive:                       If.                 (line 2644)
* 'ifc' directive:                       If.                 (line 2648)
* 'ifdef' directive:                     If.                 (line 2639)
* 'ifeq' directive:                      If.                 (line 2656)
* 'ifeqs' directive:                     If.                 (line 2659)
* 'ifge' directive:                      If.                 (line 2663)
* 'ifgt' directive:                      If.                 (line 2667)
* 'ifle' directive:                      If.                 (line 2671)
* 'iflt' directive:                      If.                 (line 2675)
* 'ifnb' directive:                      If.                 (line 2679)
* 'ifnc' directive:                      If.                 (line 2684)
* 'ifndef' directive:                    If.                 (line 2688)
* 'ifne' directive:                      If.                 (line 2695)
* 'ifnes' directive:                     If.                 (line 2699)
* 'ifnotdef' directive:                  If.                 (line 2688)
* immediate character, ARM:              ARM-Chars.          (line 3874)
* immediate operands, i386:              i386-Syntax.        (line 4274)
* immediate operands, x86-64:            i386-Syntax.        (line 4274)
* 'imul' instruction, i386:              i386-Notes.         (line 4714)
* 'imul' instruction, x86-64:            i386-Notes.         (line 4714)
* 'incbin' directive:                    Incbin.             (line 2707)
* 'include' directive:                   Include.            (line 2721)
* 'include' directive search path:       I.                  (line  952)
* infix operators:                       Infix Ops.          (line 2016)
* inhibiting interrupts, i386:           i386-Prefixes.      (line 4444)
* input:                                 Input Files.        (line  780)
* input file linenumbers:                Input Files.        (line  809)
* instruction naming, i386:              i386-Mnemonics.     (line 4309)
* instruction naming, x86-64:            i386-Mnemonics.     (line 4309)
* instruction prefixes, i386:            i386-Prefixes.      (line 4414)
* instructions and directives:           Statements.         (line 1347)
* 'int' directive:                       Int.                (line 2732)
* 'int' directive, i386:                 i386-Float.         (line 4576)
* 'int' directive, x86-64:               i386-Float.         (line 4576)
* integer expressions:                   Integer Exprs.      (line 1967)
* integer, 16-byte:                      Octa.               (line 3092)
* integer, 8-byte:                       Quad.               (line 3245)
* integers:                              Integers.           (line 1466)
* integers, 16-bit:                      hword.              (line 2610)
* integers, 32-bit:                      Int.                (line 2732)
* integers, binary:                      Integers.           (line 1466)
* integers, decimal:                     Integers.           (line 1472)
* integers, hexadecimal:                 Integers.           (line 1475)
* integers, octal:                       Integers.           (line 1469)
* integers, one byte:                    Byte.               (line 2211)
* intel_syntax pseudo op, i386:          i386-Syntax.        (line 4265)
* intel_syntax pseudo op, x86-64:        i386-Syntax.        (line 4265)
* internal assembler sections:           As Sections.        (line 1667)
* 'internal' directive:                  Internal.           (line 2740)
* invalid input:                         Bug Criteria.       (line 5555)
* invocation summary:                    Overview.           (line  249)
* 'irp' directive:                       Irp.                (line 2754)
* 'irpc' directive:                      Irpc.               (line 2779)
* joining text and data sections:        R.                  (line 1170)
* jump instructions, i386:               i386-Mnemonics.     (line 4353)
* jump instructions, x86-64:             i386-Mnemonics.     (line 4353)
* jump optimization, i386:               i386-Jumps.         (line 4538)
* jump optimization, x86-64:             i386-Jumps.         (line 4538)
* jump/call operands, i386:              i386-Syntax.        (line 4274)
* jump/call operands, x86-64:            i386-Syntax.        (line 4274)
* label (':'):                           Statements.         (line 1355)
* labels:                                Labels.             (line 1763)
* 'lcomm' directive:                     Lcomm.              (line 2805)
* ld:                                    Object.             (line  836)
* 'LDR reg,=<label>' pseudo op, ARM:     ARM Opcodes.        (line 4149)
* length of symbols:                     Symbol Intro.       (line 1331)
* 'lflags' directive (ignored):          Lflags.             (line 2814)
* line comment character:                Comments.           (line 1301)
* line comment character, ARM:           ARM-Chars.          (line 3867)
* line comment character, IA-64:         IA-64-Chars.        (line 4822)
* 'line' directive:                      Line.               (line 2820)
* line numbers, in input files:          Input Files.        (line  809)
* line numbers, in warnings/errors:      Errors.             (line  854)
* line separator character:              Statements.         (line 1336)
* line separator, ARM:                   ARM-Chars.          (line 3871)
* line separator, IA-64:                 IA-64-Chars.        (line 4824)
* lines starting with '#':               Comments.           (line 1306)
* linker:                                Object.             (line  836)
* linker, and assembler:                 Secs Background.    (line 1535)
* 'linkonce' directive:                  Linkonce.           (line 2831)
* 'list' directive:                      List.               (line 2876)
* listing control, turning off:          Nolist.             (line 3083)
* listing control, turning on:           List.               (line 2876)
* listing control: new page:             Eject.              (line 2434)
* listing control: paper size:           Psize.              (line 3208)
* listing control: subtitle:             Sbttl.              (line 3284)
* listing control: title line:           Title.              (line 3609)
* listings, enabling:                    a.                  (line  894)
* little endian output, MIPS:            Overview.           (line  563)
* little-endian output, MIPS:            MIPS Opts.          (line 4879)
* 'ln' directive:                        Ln.                 (line 2863)
* 'loc' directive:                       LNS directives.     (line 2382)
* local common symbols:                  Lcomm.              (line 2805)
* local labels:                          Symbol Names.       (line 1810)
* local symbol names:                    Symbol Names.       (line 1797)
* local symbols, retaining in output:    L.                  (line  972)
* location counter:                      Dot.                (line 1898)
* location counter, advancing:           Org.                (line 3101)
* 'loc_mark_blocks' directive:           LNS directives.     (line 2412)
* logical file name:                     File.               (line 2540)
* logical line number:                   Line.               (line 2820)
* logical line numbers:                  Comments.           (line 1306)
* 'long' directive:                      Long.               (line 2889)
* 'long' directive, i386:                i386-Float.         (line 4576)
* 'long' directive, x86-64:              i386-Float.         (line 4576)
* machine directives, ARM:               ARM Directives.     (line 3915)
* machine directives, SPARC:             Sparc-Directives.   (line 5478)
* machine independent directives:        Pseudo Ops.         (line 2105)
* machine instructions (not covered):    Manual.             (line  716)
* machine-independent syntax:            Syntax.             (line 1241)
* 'macro' directive:                     Macro.              (line 2916)
* macros:                                Macro.              (line 2894)
* macros, count executed:                Macro.              (line 3030)
* make rules:                            MD.                 (line 1149)
* manual, structure and purpose:         Manual.             (line  708)
* Maximum number of continuation lines:  listing.            (line 1015)
* memory references, i386:               i386-Memory.        (line 4471)
* memory references, x86-64:             i386-Memory.        (line 4471)
* merging text and data sections:        R.                  (line 1170)
* messages from assembler:               Errors.             (line  844)
* minus, permitted arguments:            Infix Ops.          (line 2060)
* MIPS architecture options:             MIPS Opts.          (line 4895)
* MIPS big-endian output:                MIPS Opts.          (line 4879)
* MIPS CPU override:                     MIPS ISA.           (line 5195)
* MIPS debugging directives:             MIPS Stabs.         (line 5128)
* MIPS DSP Release 1 instruction generation override: MIPS ASE instruction generation overrides.
                                                             (line 5262)
* MIPS DSP Release 2 instruction generation override: MIPS ASE instruction generation overrides.
                                                             (line 5267)
* MIPS ECOFF sections:                   MIPS Object.        (line 5100)
* MIPS endianness:                       Overview.           (line  560)
* MIPS ISA:                              Overview.           (line  566)
* MIPS ISA override:                     MIPS ISA.           (line 5183)
* MIPS little-endian output:             MIPS Opts.          (line 4879)
* MIPS MDMX instruction generation override: MIPS ASE instruction generation overrides.
                                                             (line 5257)
* MIPS MIPS-3D instruction generation override: MIPS ASE instruction generation overrides.
                                                             (line 5247)
* MIPS MT instruction generation override: MIPS ASE instruction generation overrides.
                                                             (line 5272)
* MIPS option stack:                     MIPS option stack.  (line 5232)
* MIPS processor:                        .                   (line 4862)
* MMX, i386:                             i386-SIMD.          (line 4593)
* MMX, x86-64:                           i386-SIMD.          (line 4593)
* mnemonic suffixes, i386:               i386-Syntax.        (line 4287)
* mnemonic suffixes, x86-64:             i386-Syntax.        (line 4287)
* MOVW and MOVT relocations, ARM:        ARM-Relocations.    (line 3900)
* MRI compatibility mode:                M.                  (line 1022)
* 'mri' directive:                       MRI.                (line 2868)
* MRI mode, temporarily:                 MRI.                (line 2868)
* 'mul' instruction, i386:               i386-Notes.         (line 4714)
* 'mul' instruction, x86-64:             i386-Notes.         (line 4714)
* named section:                         Section.            (line 3293)
* named sections:                        Ld Sections.        (line 1613)
* names, symbol:                         Symbol Names.       (line 1781)
* naming object file:                    o.                  (line 1160)
* new page, in listings:                 Eject.              (line 2434)
* newline ('\n'):                        Strings.            (line 1401)
* newline, required at file end:         Statements.         (line 1341)
* 'nolist' directive:                    Nolist.             (line 3083)
* 'NOP' pseudo op, ARM:                  ARM Opcodes.        (line 4143)
* null-terminated strings:               Asciz.              (line 2172)
* number constants:                      Numbers.            (line 1457)
* number of macros executed:             Macro.              (line 3030)
* numbered subsections:                  Sub-Sections.       (line 1686)
* numbers, 16-bit:                       hword.              (line 2610)
* numeric values:                        Expressions.        (line 1946)
* 'nword' directive, SPARC:              Sparc-Directives.   (line 5492)
* object file:                           Object.             (line  827)
* object file format:                    Object Formats.     (line  746)
* object file name:                      o.                  (line 1160)
* object file, after errors:             Z.                  (line 1231)
* obsolescent directives:                Deprecated.         (line 3731)
* 'octa' directive:                      Octa.               (line 3092)
* octal character code ('\DDD'):         Strings.            (line 1410)
* octal integers:                        Integers.           (line 1469)
* opcodes for ARM:                       ARM Opcodes.        (line 4140)
* operand delimiters, i386:              i386-Syntax.        (line 4274)
* operand delimiters, x86-64:            i386-Syntax.        (line 4274)
* operands in expressions:               Arguments.          (line 1973)
* operator precedence:                   Infix Ops.          (line 2021)
* operators, in expressions:             Operators.          (line 1998)
* operators, permitted arguments:        Infix Ops.          (line 2016)
* option summary:                        Overview.           (line  249)
* options for ARM (none):                ARM Options.        (line 3742)
* options for i386:                      i386-Options.       (line 4218)
* options for IA-64:                     IA-64 Options.      (line 4733)
* options for PowerPC:                   PowerPC-Opts.       (line 5285)
* options for SPARC:                     Sparc-Opts.         (line 5402)
* options for x86-64:                    i386-Options.       (line 4218)
* options, all versions of assembler:    Invoking.           (line  870)
* options, command line:                 Command Line.       (line  763)
* 'org' directive:                       Org.                (line 3101)
* output file:                           Object.             (line  827)
* 'p2align' directive:                   P2align.            (line 3127)
* 'p2alignl' directive:                  P2align.            (line 3149)
* 'p2alignw' directive:                  P2align.            (line 3149)
* padding the location counter:          Align.              (line 2123)
* padding the location counter given a power of two: P2align.
                                                             (line 3127)
* padding the location counter given number of bytes: Balign.
                                                             (line 2178)
* page, in listings:                     Eject.              (line 2434)
* paper size, for listings:              Psize.              (line 3208)
* paths for '.include':                  I.                  (line  952)
* patterns, writing in memory:           Fill.               (line 2550)
* PIC code generation for ARM:           ARM Options.        (line 3857)
* PIC selection, MIPS:                   MIPS Opts.          (line 4887)
* plus, permitted arguments:             Infix Ops.          (line 2055)
* 'popsection' directive:                PopSection.         (line 3177)
* PowerPC architectures:                 PowerPC-Opts.       (line 5285)
* PowerPC directives:                    PowerPC-Pseudo.     (line 5386)
* PowerPC options:                       PowerPC-Opts.       (line 5285)
* PowerPC support:                       .                   (line 5282)
* precedence of operators:               Infix Ops.          (line 2021)
* precision, floating point:             Flonums.            (line 1493)
* prefix operators:                      Prefix Ops.         (line 2005)
* prefixes, i386:                        i386-Prefixes.      (line 4414)
* preprocessing:                         Preprocessing.      (line 1248)
* preprocessing, turning on and off:     Preprocessing.      (line 1268)
* 'previous' directive:                  Previous.           (line 3161)
* 'print' directive:                     Print.              (line 3189)
* 'proc' directive, SPARC:               Sparc-Directives.   (line 5497)
* 'protected' directive:                 Protected.          (line 3195)
* pseudo-ops, machine independent:       Pseudo Ops.         (line 2105)
* 'psize' directive:                     Psize.              (line 3208)
* PSR bits:                              IA-64-Bits.         (line 4846)
* 'purgem' directive:                    Purgem.             (line 3224)
* purpose of GNU assembler:              GNU Assembler.      (line  734)
* 'pushsection' directive:               PushSection.        (line 3230)
* 'quad' directive:                      Quad.               (line 3242)
* 'quad' directive, i386:                i386-Float.         (line 4576)
* 'quad' directive, x86-64:              i386-Float.         (line 4576)
* real-mode code, i386:                  i386-16bit.         (line 4615)
* 'register' directive, SPARC:           Sparc-Directives.   (line 5501)
* register names, ARM:                   ARM-Regs.           (line 3881)
* register names, IA-64:                 IA-64-Regs.         (line 4829)
* register operands, i386:               i386-Syntax.        (line 4274)
* register operands, x86-64:             i386-Syntax.        (line 4274)
* registers, i386:                       i386-Regs.          (line 4359)
* registers, x86-64:                     i386-Regs.          (line 4359)
* 'reloc' directive:                     Reloc.              (line 3253)
* relocation:                            Sections.           (line 1528)
* relocation example:                    Ld Sections.        (line 1643)
* repeat prefixes, i386:                 i386-Prefixes.      (line 4452)
* reporting bugs in assembler:           Reporting Bugs.     (line 5534)
* 'rept' directive:                      Rept.               (line 3266)
* 'req' directive, ARM:                  ARM Directives.     (line 3922)
* 'reserve' directive, SPARC:            Sparc-Directives.   (line 5511)
* return instructions, i386:             i386-Syntax.        (line 4296)
* return instructions, x86-64:           i386-Syntax.        (line 4296)
* REX prefixes, i386:                    i386-Prefixes.      (line 4454)
* 'sbttl' directive:                     Sbttl.              (line 3284)
* search path for '.include':            I.                  (line  952)
* 'section' directive (ELF version):     Section.            (line 3305)
* section override prefixes, i386:       i386-Prefixes.      (line 4431)
* Section Stack:                         Previous.           (line 3161)
* Section Stack <1>:                     PopSection.         (line 3177)
* Section Stack <2>:                     PushSection.        (line 3230)
* Section Stack <3>:                     Section.            (line 3300)
* Section Stack <4>:                     SubSection.         (line 3545)
* section-relative addressing:           Secs Background.    (line 1573)
* sections:                              Sections.           (line 1528)
* sections in messages, internal:        As Sections.        (line 1667)
* sections, i386:                        i386-Syntax.        (line 4302)
* sections, named:                       Ld Sections.        (line 1613)
* sections, x86-64:                      i386-Syntax.        (line 4302)
* 'seg' directive, SPARC:                Sparc-Directives.   (line 5516)
* 'set' directive:                       Set.                (line 3407)
* 'short' directive:                     Short.              (line 3419)
* SIMD, i386:                            i386-SIMD.          (line 4593)
* SIMD, x86-64:                          i386-SIMD.          (line 4593)
* single character constant:             Chars.              (line 1443)
* 'single' directive:                    Single.             (line 3425)
* 'single' directive, i386:              i386-Float.         (line 4569)
* 'single' directive, x86-64:            i386-Float.         (line 4569)
* sixteen bit integers:                  hword.              (line 2610)
* sixteen byte integer:                  Octa.               (line 3092)
* 'size' directive (ELF version):        Size.               (line 3433)
* size prefixes, i386:                   i386-Prefixes.      (line 4435)
* sizes operands, i386:                  i386-Syntax.        (line 4287)
* sizes operands, x86-64:                i386-Syntax.        (line 4287)
* 'skip' directive:                      Skip.               (line 3452)
* 'skip' directive, SPARC:               Sparc-Directives.   (line 5520)
* 'sleb128' directive:                   Sleb128.            (line 3445)
* small objects, MIPS ECOFF:             MIPS Object.        (line 5105)
* SmartMIPS instruction generation override: MIPS ASE instruction generation overrides.
                                                             (line 5252)
* source program:                        Input Files.        (line  780)
* source, destination operands; i386:    i386-Syntax.        (line 4280)
* source, destination operands; x86-64:  i386-Syntax.        (line 4280)
* 'space' directive:                     Space.              (line 3459)
* space used, maximum for assembly:      statistics.         (line 1188)
* SPARC architectures:                   Sparc-Opts.         (line 5402)
* SPARC data alignment:                  Sparc-Aligned-Data. (line 5455)
* SPARC floating point (IEEE):           Sparc-Float.        (line 5473)
* SPARC machine directives:              Sparc-Directives.   (line 5478)
* SPARC options:                         Sparc-Opts.         (line 5402)
* SPARC support:                         .                   (line 5399)
* 'stabd' directive:                     Stab.               (line 3498)
* 'stabn' directive:                     Stab.               (line 3509)
* 'stabs' directive:                     Stab.               (line 3512)
* 'stabX' directives:                    Stab.               (line 3466)
* standard assembler sections:           Secs Background.    (line 1550)
* standard input, as input file:         Command Line.       (line  760)
* statement separator character:         Statements.         (line 1336)
* statement separator, ARM:              ARM-Chars.          (line 3871)
* statement separator, IA-64:            IA-64-Chars.        (line 4824)
* statements, structure of:              Statements.         (line 1336)
* statistics, about assembly:            statistics.         (line 1188)
* stopping the assembly:                 Abort.              (line 2114)
* string constants:                      Strings.            (line 1386)
* 'string' directive:                    String.             (line 3518)
* string literals:                       Ascii.              (line 2165)
* string, copying to object file:        String.             (line 3518)
* 'struct' directive:                    Struct.             (line 3527)
* subexpressions:                        Arguments.          (line 1991)
* 'subsection' directive:                SubSection.         (line 3545)
* subtitles for listings:                Sbttl.              (line 3284)
* subtraction, permitted arguments:      Infix Ops.          (line 2060)
* summary of options:                    Overview.           (line  249)
* supporting files, including:           Include.            (line 2721)
* suppressing warnings:                  W.                  (line 1217)
* symbol attributes:                     Symbol Attributes.  (line 1907)
* symbol names:                          Symbol Names.       (line 1781)
* symbol names, local:                   Symbol Names.       (line 1797)
* symbol names, temporary:               Symbol Names.       (line 1810)
* symbol type:                           Symbol Type.        (line 1938)
* symbol type, ELF:                      Type.               (line 3620)
* symbol value:                          Symbol Value.       (line 1918)
* symbol value, setting:                 Set.                (line 3407)
* symbol values, assigning:              Setting Symbols.    (line 1772)
* symbol versioning:                     Symver.             (line 3557)
* symbol, common:                        Comm.               (line 2217)
* symbol, making visible to linker:      Global.             (line 2585)
* symbolic debuggers, information for:   Stab.               (line 3466)
* symbols:                               Symbols.            (line 1753)
* symbols, assigning values to:          Equ.                (line 2471)
* symbols, local common:                 Lcomm.              (line 2805)
* 'symver' directive:                    Symver.             (line 3557)
* syntax compatibility, i386:            i386-Syntax.        (line 4265)
* syntax compatibility, x86-64:          i386-Syntax.        (line 4265)
* syntax, machine-independent:           Syntax.             (line 1241)
* tab ('\t'):                            Strings.            (line 1407)
* temporary symbol names:                Symbol Names.       (line 1810)
* text and data sections, joining:       R.                  (line 1170)
* 'text' directive:                      Text.               (line 3602)
* 'tfloat' directive, i386:              i386-Float.         (line 4569)
* 'tfloat' directive, x86-64:            i386-Float.         (line 4569)
* 'thumb' directive, ARM:                ARM Directives.     (line 3966)
* Thumb support:                         Machine Dependencies.
                                                             (line 3739)
* 'thumb_func' directive, ARM:           ARM Directives.     (line 3976)
* 'thumb_set' directive, ARM:            ARM Directives.     (line 3987)
* time, total for assembly:              statistics.         (line 1188)
* 'title' directive:                     Title.              (line 3609)
* trusted compiler:                      f.                  (line  940)
* turning preprocessing on and off:      Preprocessing.      (line 1268)
* 'type' directive (ELF version):        Type.               (line 3620)
* type of a symbol:                      Symbol Type.        (line 1938)
* 'uleb128' directive:                   Uleb128.            (line 3656)
* undefined section:                     Ld Sections.        (line 1639)
* 'unreq' directive, ARM:                ARM Directives.     (line 3927)
* value of a symbol:                     Symbol Value.       (line 1918)
* 'version' directive:                   Version.            (line 3663)
* version of assembler:                  v.                  (line 1206)
* versions of symbols:                   Symver.             (line 3557)
* visibility:                            Hidden.             (line 2597)
* visibility <1>:                        Internal.           (line 2740)
* visibility <2>:                        Protected.          (line 3195)
* 'vtable_entry' directive:              VTableEntry.        (line 3669)
* 'vtable_inherit' directive:            VTableInherit.      (line 3675)
* warning directive:                     Warning.            (line 3683)
* warning messages:                      Errors.             (line  844)
* warnings, causing error:               W.                  (line 1222)
* warnings, suppressing:                 W.                  (line 1217)
* warnings, switching on:                W.                  (line 1225)
* 'weak' directive:                      Weak.               (line 3689)
* 'weakref' directive:                   Weakref.            (line 3705)
* whitespace:                            Whitespace.         (line 1280)
* whitespace, removed by preprocessor:   Preprocessing.      (line 1249)
* Width of continuation lines of disassembly output: listing.
                                                             (line 1002)
* Width of first line disassembly output: listing.           (line  997)
* Width of source line output:           listing.            (line 1009)
* 'word' directive:                      Word.               (line 3725)
* 'word' directive, i386:                i386-Float.         (line 4576)
* 'word' directive, SPARC:               Sparc-Directives.   (line 5523)
* 'word' directive, x86-64:              i386-Float.         (line 4576)
* writing patterns in memory:            Fill.               (line 2550)
* x86-64 arch directive:                 i386-Arch.          (line 4670)
* x86-64 att_syntax pseudo op:           i386-Syntax.        (line 4265)
* x86-64 conversion instructions:        i386-Mnemonics.     (line 4334)
* x86-64 floating point:                 i386-Float.         (line 4561)
* x86-64 immediate operands:             i386-Syntax.        (line 4274)
* x86-64 instruction naming:             i386-Mnemonics.     (line 4309)
* x86-64 intel_syntax pseudo op:         i386-Syntax.        (line 4265)
* x86-64 jump optimization:              i386-Jumps.         (line 4538)
* x86-64 jump, call, return:             i386-Syntax.        (line 4296)
* x86-64 jump/call operands:             i386-Syntax.        (line 4274)
* x86-64 memory references:              i386-Memory.        (line 4471)
* x86-64 options:                        i386-Options.       (line 4218)
* x86-64 register operands:              i386-Syntax.        (line 4274)
* x86-64 registers:                      i386-Regs.          (line 4359)
* x86-64 sections:                       i386-Syntax.        (line 4302)
* x86-64 size suffixes:                  i386-Syntax.        (line 4287)
* x86-64 source, destination operands:   i386-Syntax.        (line 4280)
* x86-64 support:                        .                   (line 4211)
* x86-64 syntax compatibility:           i386-Syntax.        (line 4265)
* 'xword' directive, SPARC:              Sparc-Directives.   (line 5527)
* zero-terminated strings:               Asciz.              (line 2172)