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Diffstat (limited to 'contrib/gcc/caller-save.c')
| -rw-r--r-- | contrib/gcc/caller-save.c | 757 |
1 files changed, 0 insertions, 757 deletions
diff --git a/contrib/gcc/caller-save.c b/contrib/gcc/caller-save.c deleted file mode 100644 index 7c390a5955ee..000000000000 --- a/contrib/gcc/caller-save.c +++ /dev/null @@ -1,757 +0,0 @@ -/* Save and restore call-clobbered registers which are live across a call. - Copyright (C) 1989, 1992, 94-95, 97, 98, 1999 Free Software Foundation, Inc. - -This file is part of GNU CC. - -GNU CC is free software; you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation; either version 2, or (at your option) -any later version. - -GNU CC is distributed in the hope that it will be useful, -but WITHOUT ANY WARRANTY; without even the implied warranty of -MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -GNU General Public License for more details. - -You should have received a copy of the GNU General Public License -along with GNU CC; see the file COPYING. If not, write to -the Free Software Foundation, 59 Temple Place - Suite 330, -Boston, MA 02111-1307, USA. */ - -#include "config.h" -#include "system.h" -#include "rtl.h" -#include "insn-config.h" -#include "flags.h" -#include "regs.h" -#include "hard-reg-set.h" -#include "recog.h" -#include "basic-block.h" -#include "reload.h" -#include "expr.h" -#include "toplev.h" - -#ifndef MAX_MOVE_MAX -#define MAX_MOVE_MAX MOVE_MAX -#endif - -#ifndef MIN_UNITS_PER_WORD -#define MIN_UNITS_PER_WORD UNITS_PER_WORD -#endif - -#define MOVE_MAX_WORDS (MOVE_MAX / UNITS_PER_WORD) - -/* Modes for each hard register that we can save. The smallest mode is wide - enough to save the entire contents of the register. When saving the - register because it is live we first try to save in multi-register modes. - If that is not possible the save is done one register at a time. */ - -static enum machine_mode - regno_save_mode[FIRST_PSEUDO_REGISTER][MAX_MOVE_MAX / MIN_UNITS_PER_WORD + 1]; - -/* For each hard register, a place on the stack where it can be saved, - if needed. */ - -static rtx - regno_save_mem[FIRST_PSEUDO_REGISTER][MAX_MOVE_MAX / MIN_UNITS_PER_WORD + 1]; - -/* We will only make a register eligible for caller-save if it can be - saved in its widest mode with a simple SET insn as long as the memory - address is valid. We record the INSN_CODE is those insns here since - when we emit them, the addresses might not be valid, so they might not - be recognized. */ - -static enum insn_code - reg_save_code[FIRST_PSEUDO_REGISTER][MAX_MOVE_MAX / MIN_UNITS_PER_WORD + 1]; -static enum insn_code - reg_restore_code[FIRST_PSEUDO_REGISTER][MAX_MOVE_MAX / MIN_UNITS_PER_WORD + 1]; - -/* Set of hard regs currently residing in save area (during insn scan). */ - -static HARD_REG_SET hard_regs_saved; - -/* Number of registers currently in hard_regs_saved. */ - -static int n_regs_saved; - -/* Computed by mark_referenced_regs, all regs referenced in a given - insn. */ -static HARD_REG_SET referenced_regs; - -/* Computed in mark_set_regs, holds all registers set by the current - instruction. */ -static HARD_REG_SET this_insn_sets; - - -static void mark_set_regs PROTO((rtx, rtx)); -static void mark_referenced_regs PROTO((rtx)); -static int insert_save PROTO((struct insn_chain *, int, int, - HARD_REG_SET *)); -static int insert_restore PROTO((struct insn_chain *, int, int, - int)); -static void insert_one_insn PROTO((struct insn_chain *, int, - enum insn_code, rtx)); - -/* Initialize for caller-save. - - Look at all the hard registers that are used by a call and for which - regclass.c has not already excluded from being used across a call. - - Ensure that we can find a mode to save the register and that there is a - simple insn to save and restore the register. This latter check avoids - problems that would occur if we tried to save the MQ register of some - machines directly into memory. */ - -void -init_caller_save () -{ - char *first_obj = (char *) oballoc (0); - rtx addr_reg; - int offset; - rtx address; - int i, j; - - /* First find all the registers that we need to deal with and all - the modes that they can have. If we can't find a mode to use, - we can't have the register live over calls. */ - - for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) - { - if (call_used_regs[i] && ! call_fixed_regs[i]) - { - for (j = 1; j <= MOVE_MAX_WORDS; j++) - { - regno_save_mode[i][j] = HARD_REGNO_CALLER_SAVE_MODE (i, j); - if (regno_save_mode[i][j] == VOIDmode && j == 1) - { - call_fixed_regs[i] = 1; - SET_HARD_REG_BIT (call_fixed_reg_set, i); - } - } - } - else - regno_save_mode[i][1] = VOIDmode; - } - - /* The following code tries to approximate the conditions under which - we can easily save and restore a register without scratch registers or - other complexities. It will usually work, except under conditions where - the validity of an insn operand is dependent on the address offset. - No such cases are currently known. - - We first find a typical offset from some BASE_REG_CLASS register. - This address is chosen by finding the first register in the class - and by finding the smallest power of two that is a valid offset from - that register in every mode we will use to save registers. */ - - for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) - if (TEST_HARD_REG_BIT (reg_class_contents[(int) BASE_REG_CLASS], i)) - break; - - if (i == FIRST_PSEUDO_REGISTER) - abort (); - - addr_reg = gen_rtx_REG (Pmode, i); - - for (offset = 1 << (HOST_BITS_PER_INT / 2); offset; offset >>= 1) - { - address = gen_rtx_PLUS (Pmode, addr_reg, GEN_INT (offset)); - - for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) - if (regno_save_mode[i][1] != VOIDmode - && ! strict_memory_address_p (regno_save_mode[i][1], address)) - break; - - if (i == FIRST_PSEUDO_REGISTER) - break; - } - - /* If we didn't find a valid address, we must use register indirect. */ - if (offset == 0) - address = addr_reg; - - /* Next we try to form an insn to save and restore the register. We - see if such an insn is recognized and meets its constraints. */ - - start_sequence (); - - for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) - for (j = 1; j <= MOVE_MAX_WORDS; j++) - if (regno_save_mode[i][j] != VOIDmode) - { - rtx mem = gen_rtx_MEM (regno_save_mode[i][j], address); - rtx reg = gen_rtx_REG (regno_save_mode[i][j], i); - rtx savepat = gen_rtx_SET (VOIDmode, mem, reg); - rtx restpat = gen_rtx_SET (VOIDmode, reg, mem); - rtx saveinsn = emit_insn (savepat); - rtx restinsn = emit_insn (restpat); - int ok; - - reg_save_code[i][j] = recog_memoized (saveinsn); - reg_restore_code[i][j] = recog_memoized (restinsn); - - /* Now extract both insns and see if we can meet their - constraints. */ - ok = (reg_save_code[i][j] != (enum insn_code)-1 - && reg_restore_code[i][j] != (enum insn_code)-1); - if (ok) - { - extract_insn (saveinsn); - ok = constrain_operands (1); - extract_insn (restinsn); - ok &= constrain_operands (1); - } - - if (! ok) - { - regno_save_mode[i][j] = VOIDmode; - if (j == 1) - { - call_fixed_regs[i] = 1; - SET_HARD_REG_BIT (call_fixed_reg_set, i); - } - } - } - - end_sequence (); - - obfree (first_obj); -} - -/* Initialize save areas by showing that we haven't allocated any yet. */ - -void -init_save_areas () -{ - int i, j; - - for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) - for (j = 1; j <= MOVE_MAX_WORDS; j++) - regno_save_mem[i][j] = 0; -} - -/* Allocate save areas for any hard registers that might need saving. - We take a conservative approach here and look for call-clobbered hard - registers that are assigned to pseudos that cross calls. This may - overestimate slightly (especially if some of these registers are later - used as spill registers), but it should not be significant. - - Future work: - - In the fallback case we should iterate backwards across all possible - modes for the save, choosing the largest available one instead of - falling back to the smallest mode immediately. (eg TF -> DF -> SF). - - We do not try to use "move multiple" instructions that exist - on some machines (such as the 68k moveml). It could be a win to try - and use them when possible. The hard part is doing it in a way that is - machine independent since they might be saving non-consecutive - registers. (imagine caller-saving d0,d1,a0,a1 on the 68k) */ - -void -setup_save_areas () -{ - int i, j, k; - HARD_REG_SET hard_regs_used; - - /* Allocate space in the save area for the largest multi-register - pseudos first, then work backwards to single register - pseudos. */ - - /* Find and record all call-used hard-registers in this function. */ - CLEAR_HARD_REG_SET (hard_regs_used); - for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++) - if (reg_renumber[i] >= 0 && REG_N_CALLS_CROSSED (i) > 0) - { - int regno = reg_renumber[i]; - int endregno - = regno + HARD_REGNO_NREGS (regno, GET_MODE (regno_reg_rtx[i])); - int nregs = endregno - regno; - - for (j = 0; j < nregs; j++) - { - if (call_used_regs[regno+j]) - SET_HARD_REG_BIT (hard_regs_used, regno+j); - } - } - - /* Now run through all the call-used hard-registers and allocate - space for them in the caller-save area. Try to allocate space - in a manner which allows multi-register saves/restores to be done. */ - - for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) - for (j = MOVE_MAX_WORDS; j > 0; j--) - { - int do_save = 1; - - /* If no mode exists for this size, try another. Also break out - if we have already saved this hard register. */ - if (regno_save_mode[i][j] == VOIDmode || regno_save_mem[i][1] != 0) - continue; - - /* See if any register in this group has been saved. */ - for (k = 0; k < j; k++) - if (regno_save_mem[i + k][1]) - { - do_save = 0; - break; - } - if (! do_save) - continue; - - for (k = 0; k < j; k++) - if (! TEST_HARD_REG_BIT (hard_regs_used, i + k)) - { - do_save = 0; - break; - } - if (! do_save) - continue; - - /* We have found an acceptable mode to store in. */ - regno_save_mem[i][j] - = assign_stack_local (regno_save_mode[i][j], - GET_MODE_SIZE (regno_save_mode[i][j]), 0); - - /* Setup single word save area just in case... */ - for (k = 0; k < j; k++) - { - /* This should not depend on WORDS_BIG_ENDIAN. - The order of words in regs is the same as in memory. */ - rtx temp = gen_rtx_MEM (regno_save_mode[i+k][1], - XEXP (regno_save_mem[i][j], 0)); - - regno_save_mem[i+k][1] - = adj_offsettable_operand (temp, k * UNITS_PER_WORD); - } - } -} - -/* Find the places where hard regs are live across calls and save them. */ -void -save_call_clobbered_regs () -{ - struct insn_chain *chain, *next; - - CLEAR_HARD_REG_SET (hard_regs_saved); - n_regs_saved = 0; - - for (chain = reload_insn_chain; chain != 0; chain = next) - { - rtx insn = chain->insn; - enum rtx_code code = GET_CODE (insn); - - next = chain->next; - - if (chain->is_caller_save_insn) - abort (); - - if (GET_RTX_CLASS (code) == 'i') - { - /* If some registers have been saved, see if INSN references - any of them. We must restore them before the insn if so. */ - - if (n_regs_saved) - { - int regno; - - if (code == JUMP_INSN) - /* Restore all registers if this is a JUMP_INSN. */ - COPY_HARD_REG_SET (referenced_regs, hard_regs_saved); - else - { - CLEAR_HARD_REG_SET (referenced_regs); - mark_referenced_regs (PATTERN (insn)); - AND_HARD_REG_SET (referenced_regs, hard_regs_saved); - } - - for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) - if (TEST_HARD_REG_BIT (referenced_regs, regno)) - regno += insert_restore (chain, 1, regno, MOVE_MAX_WORDS); - } - - if (code == CALL_INSN) - { - rtx x; - int regno, nregs; - HARD_REG_SET hard_regs_to_save; - - /* Use the register life information in CHAIN to compute which - regs are live before the call. */ - REG_SET_TO_HARD_REG_SET (hard_regs_to_save, chain->live_before); - compute_use_by_pseudos (&hard_regs_to_save, chain->live_before); - - /* Record all registers set in this call insn. These don't need - to be saved. */ - CLEAR_HARD_REG_SET (this_insn_sets); - note_stores (PATTERN (insn), mark_set_regs); - - /* Compute which hard regs must be saved before this call. */ - AND_COMPL_HARD_REG_SET (hard_regs_to_save, call_fixed_reg_set); - AND_COMPL_HARD_REG_SET (hard_regs_to_save, this_insn_sets); - AND_COMPL_HARD_REG_SET (hard_regs_to_save, hard_regs_saved); - AND_HARD_REG_SET (hard_regs_to_save, call_used_reg_set); - - /* Registers used for function parameters need not be saved. */ - for (x = CALL_INSN_FUNCTION_USAGE (insn); x != 0; - x = XEXP (x, 1)) - { - rtx y; - - if (GET_CODE (XEXP (x, 0)) != USE) - continue; - y = XEXP (XEXP (x, 0), 0); - if (GET_CODE (y) != REG) - abort (); - regno = REGNO (y); - if (REGNO (y) >= FIRST_PSEUDO_REGISTER) - abort (); - nregs = HARD_REGNO_NREGS (regno, GET_MODE (y)); - while (nregs-- > 0) - CLEAR_HARD_REG_BIT (hard_regs_to_save, regno + nregs); - } - - /* Neither do registers for which we find a death note. */ - for (x = REG_NOTES (insn); x != 0; x = XEXP (x, 1)) - { - rtx y = XEXP (x, 0); - - if (REG_NOTE_KIND (x) != REG_DEAD) - continue; - if (GET_CODE (y) != REG) - abort (); - regno = REGNO (y); - - if (regno >= FIRST_PSEUDO_REGISTER) - regno = reg_renumber[regno]; - if (regno < 0) - continue; - nregs = HARD_REGNO_NREGS (regno, GET_MODE (y)); - while (nregs-- > 0) - CLEAR_HARD_REG_BIT (hard_regs_to_save, regno + nregs); - } - - for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) - if (TEST_HARD_REG_BIT (hard_regs_to_save, regno)) - regno += insert_save (chain, 1, regno, &hard_regs_to_save); - - /* Must recompute n_regs_saved. */ - n_regs_saved = 0; - for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) - if (TEST_HARD_REG_BIT (hard_regs_saved, regno)) - n_regs_saved++; - } - } - - if (chain->next == 0 || chain->next->block > chain->block) - { - int regno; - /* At the end of the basic block, we must restore any registers that - remain saved. If the last insn in the block is a JUMP_INSN, put - the restore before the insn, otherwise, put it after the insn. */ - - if (n_regs_saved) - for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) - if (TEST_HARD_REG_BIT (hard_regs_saved, regno)) - regno += insert_restore (chain, GET_CODE (insn) == JUMP_INSN, - regno, MOVE_MAX_WORDS); - } - } -} - -/* Here from note_stores when an insn stores a value in a register. - Set the proper bit or bits in this_insn_sets. All pseudos that have - been assigned hard regs have had their register number changed already, - so we can ignore pseudos. */ -static void -mark_set_regs (reg, setter) - rtx reg; - rtx setter ATTRIBUTE_UNUSED; -{ - register int regno, endregno, i; - enum machine_mode mode = GET_MODE (reg); - int word = 0; - - if (GET_CODE (reg) == SUBREG) - { - word = SUBREG_WORD (reg); - reg = SUBREG_REG (reg); - } - - if (GET_CODE (reg) != REG || REGNO (reg) >= FIRST_PSEUDO_REGISTER) - return; - - regno = REGNO (reg) + word; - endregno = regno + HARD_REGNO_NREGS (regno, mode); - - for (i = regno; i < endregno; i++) - SET_HARD_REG_BIT (this_insn_sets, i); -} - -/* Walk X and record all referenced registers in REFERENCED_REGS. */ -static void -mark_referenced_regs (x) - rtx x; -{ - enum rtx_code code = GET_CODE (x); - char *fmt; - int i, j; - - if (code == SET) - mark_referenced_regs (SET_SRC (x)); - if (code == SET || code == CLOBBER) - { - x = SET_DEST (x); - code = GET_CODE (x); - if (code == REG || code == PC || code == CC0 - || (code == SUBREG && GET_CODE (SUBREG_REG (x)) == REG)) - return; - } - if (code == MEM || code == SUBREG) - { - x = XEXP (x, 0); - code = GET_CODE (x); - } - - if (code == REG) - { - int regno = REGNO (x); - int hardregno = (regno < FIRST_PSEUDO_REGISTER ? regno - : reg_renumber[regno]); - - if (hardregno >= 0) - { - int nregs = HARD_REGNO_NREGS (hardregno, GET_MODE (x)); - while (nregs-- > 0) - SET_HARD_REG_BIT (referenced_regs, hardregno + nregs); - } - /* If this is a pseudo that did not get a hard register, scan its - memory location, since it might involve the use of another - register, which might be saved. */ - else if (reg_equiv_mem[regno] != 0) - mark_referenced_regs (XEXP (reg_equiv_mem[regno], 0)); - else if (reg_equiv_address[regno] != 0) - mark_referenced_regs (reg_equiv_address[regno]); - return; - } - - fmt = GET_RTX_FORMAT (code); - for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) - { - if (fmt[i] == 'e') - mark_referenced_regs (XEXP (x, i)); - else if (fmt[i] == 'E') - for (j = XVECLEN (x, i) - 1; j >= 0; j--) - mark_referenced_regs (XVECEXP (x, i, j)); - } -} - -/* Insert a sequence of insns to restore. Place these insns in front of - CHAIN if BEFORE_P is nonzero, behind the insn otherwise. MAXRESTORE is - the maximum number of registers which should be restored during this call. - It should never be less than 1 since we only work with entire registers. - - Note that we have verified in init_caller_save that we can do this - with a simple SET, so use it. Set INSN_CODE to what we save there - since the address might not be valid so the insn might not be recognized. - These insns will be reloaded and have register elimination done by - find_reload, so we need not worry about that here. - - Return the extra number of registers saved. */ - -static int -insert_restore (chain, before_p, regno, maxrestore) - struct insn_chain *chain; - int before_p; - int regno; - int maxrestore; -{ - int i; - rtx pat = NULL_RTX; - enum insn_code code = CODE_FOR_nothing; - int numregs = 0; - - /* A common failure mode if register status is not correct in the RTL - is for this routine to be called with a REGNO we didn't expect to - save. That will cause us to write an insn with a (nil) SET_DEST - or SET_SRC. Instead of doing so and causing a crash later, check - for this common case and abort here instead. This will remove one - step in debugging such problems. */ - - if (regno_save_mem[regno][1] == 0) - abort (); - - /* Get the pattern to emit and update our status. - - See if we can restore `maxrestore' registers at once. Work - backwards to the single register case. */ - for (i = maxrestore; i > 0; i--) - { - int j, k; - int ok = 1; - - if (regno_save_mem[regno][i] == 0) - continue; - - for (j = 0; j < i; j++) - if (! TEST_HARD_REG_BIT (hard_regs_saved, regno + j)) - { - ok = 0; - break; - } - /* Must do this one restore at a time */ - if (! ok) - continue; - - pat = gen_rtx_SET (VOIDmode, - gen_rtx_REG (GET_MODE (regno_save_mem[regno][i]), - regno), - regno_save_mem[regno][i]); - code = reg_restore_code[regno][i]; - - /* Clear status for all registers we restored. */ - for (k = 0; k < i; k++) - { - CLEAR_HARD_REG_BIT (hard_regs_saved, regno + k); - n_regs_saved--; - } - - numregs = i; - break; - } - - insert_one_insn (chain, before_p, code, pat); - - /* Tell our callers how many extra registers we saved/restored */ - return numregs - 1; -} - -/* Like insert_restore above, but save registers instead. */ -static int -insert_save (chain, before_p, regno, to_save) - struct insn_chain *chain; - int before_p; - int regno; - HARD_REG_SET *to_save; -{ - int i; - rtx pat = NULL_RTX; - enum insn_code code = CODE_FOR_nothing; - int numregs = 0; - - /* A common failure mode if register status is not correct in the RTL - is for this routine to be called with a REGNO we didn't expect to - save. That will cause us to write an insn with a (nil) SET_DEST - or SET_SRC. Instead of doing so and causing a crash later, check - for this common case and abort here instead. This will remove one - step in debugging such problems. */ - - if (regno_save_mem[regno][1] == 0) - abort (); - - /* Get the pattern to emit and update our status. - - See if we can save several registers with a single instruction. - Work backwards to the single register case. */ - for (i = MOVE_MAX_WORDS; i > 0; i--) - { - int j, k; - int ok = 1; - if (regno_save_mem[regno][i] == 0) - continue; - - for (j = 0; j < i; j++) - if (! TEST_HARD_REG_BIT (*to_save, regno + j)) - { - ok = 0; - break; - } - /* Must do this one save at a time */ - if (! ok) - continue; - - pat = gen_rtx_SET (VOIDmode, regno_save_mem[regno][i], - gen_rtx_REG (GET_MODE (regno_save_mem[regno][i]), - regno)); - code = reg_save_code[regno][i]; - - /* Set hard_regs_saved for all the registers we saved. */ - for (k = 0; k < i; k++) - { - SET_HARD_REG_BIT (hard_regs_saved, regno + k); - n_regs_saved++; - } - - numregs = i; - break; - } - - insert_one_insn (chain, before_p, code, pat); - - /* Tell our callers how many extra registers we saved/restored */ - return numregs - 1; -} - -/* Emit a new caller-save insn and set the code. */ -static void -insert_one_insn (chain, before_p, code, pat) - struct insn_chain *chain; - int before_p; - enum insn_code code; - rtx pat; -{ - rtx insn = chain->insn; - struct insn_chain *new; - -#ifdef HAVE_cc0 - /* If INSN references CC0, put our insns in front of the insn that sets - CC0. This is always safe, since the only way we could be passed an - insn that references CC0 is for a restore, and doing a restore earlier - isn't a problem. We do, however, assume here that CALL_INSNs don't - reference CC0. Guard against non-INSN's like CODE_LABEL. */ - - if ((GET_CODE (insn) == INSN || GET_CODE (insn) == JUMP_INSN) - && before_p - && reg_referenced_p (cc0_rtx, PATTERN (insn))) - chain = chain->prev, insn = chain->insn; -#endif - - new = new_insn_chain (); - if (before_p) - { - new->prev = chain->prev; - if (new->prev != 0) - new->prev->next = new; - else - reload_insn_chain = new; - - chain->prev = new; - new->next = chain; - new->insn = emit_insn_before (pat, insn); - /* ??? It would be nice if we could exclude the already / still saved - registers from the live sets. */ - COPY_REG_SET (new->live_before, chain->live_before); - COPY_REG_SET (new->live_after, chain->live_before); - if (chain->insn == BLOCK_HEAD (chain->block)) - BLOCK_HEAD (chain->block) = new->insn; - } - else - { - new->next = chain->next; - if (new->next != 0) - new->next->prev = new; - chain->next = new; - new->prev = chain; - new->insn = emit_insn_after (pat, insn); - /* ??? It would be nice if we could exclude the already / still saved - registers from the live sets, and observe REG_UNUSED notes. */ - COPY_REG_SET (new->live_before, chain->live_after); - COPY_REG_SET (new->live_after, chain->live_after); - if (chain->insn == BLOCK_END (chain->block)) - BLOCK_END (chain->block) = new->insn; - } - new->block = chain->block; - new->is_caller_save_insn = 1; - - INSN_CODE (new->insn) = code; -} |