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Diffstat (limited to 'contrib/llvm-project/llvm/lib/CodeGen/AsmPrinter/EHStreamer.h')
-rw-r--r-- | contrib/llvm-project/llvm/lib/CodeGen/AsmPrinter/EHStreamer.h | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/contrib/llvm-project/llvm/lib/CodeGen/AsmPrinter/EHStreamer.h b/contrib/llvm-project/llvm/lib/CodeGen/AsmPrinter/EHStreamer.h new file mode 100644 index 000000000000..234e62506a56 --- /dev/null +++ b/contrib/llvm-project/llvm/lib/CodeGen/AsmPrinter/EHStreamer.h @@ -0,0 +1,165 @@ +//===- EHStreamer.h - Exception Handling Directive Streamer -----*- C++ -*-===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file contains support for writing exception info into assembly files. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_EHSTREAMER_H +#define LLVM_LIB_CODEGEN_ASMPRINTER_EHSTREAMER_H + +#include "llvm/ADT/DenseMap.h" +#include "llvm/CodeGen/AsmPrinterHandler.h" +#include "llvm/Support/Compiler.h" + +namespace llvm { + +class AsmPrinter; +struct LandingPadInfo; +class MachineInstr; +class MachineModuleInfo; +class MCSymbol; +template <typename T> class SmallVectorImpl; + +/// Emits exception handling directives. +class LLVM_LIBRARY_VISIBILITY EHStreamer : public AsmPrinterHandler { +protected: + /// Target of directive emission. + AsmPrinter *Asm; + + /// Collected machine module information. + MachineModuleInfo *MMI; + + /// How many leading type ids two landing pads have in common. + static unsigned sharedTypeIDs(const LandingPadInfo *L, + const LandingPadInfo *R); + + /// Structure holding a try-range and the associated landing pad. + struct PadRange { + // The index of the landing pad. + unsigned PadIndex; + + // The index of the begin and end labels in the landing pad's label lists. + unsigned RangeIndex; + }; + + using RangeMapType = DenseMap<MCSymbol *, PadRange>; + + /// Structure describing an entry in the actions table. + struct ActionEntry { + int ValueForTypeID; // The value to write - may not be equal to the type id. + int NextAction; + unsigned Previous; + }; + + /// Structure describing an entry in the call-site table. + struct CallSiteEntry { + // The 'try-range' is BeginLabel .. EndLabel. + MCSymbol *BeginLabel; // Null indicates the start of the function. + MCSymbol *EndLabel; // Null indicates the end of the function. + + // LPad contains the landing pad start labels. + const LandingPadInfo *LPad; // Null indicates that there is no landing pad. + + unsigned Action; + }; + + /// Structure describing a contiguous range of call-sites which reside + /// in the same procedure fragment. With -fbasic-block-sections, there will + /// be one call site range per basic block section. Otherwise, we will have + /// one call site range containing all the call sites in the function. + struct CallSiteRange { + // Symbol marking the beginning of the precedure fragment. + MCSymbol *FragmentBeginLabel = nullptr; + // Symbol marking the end of the procedure fragment. + MCSymbol *FragmentEndLabel = nullptr; + // LSDA symbol for this call-site range. + MCSymbol *ExceptionLabel = nullptr; + // Index of the first call-site entry in the call-site table which + // belongs to this range. + size_t CallSiteBeginIdx = 0; + // Index just after the last call-site entry in the call-site table which + // belongs to this range. + size_t CallSiteEndIdx = 0; + // Whether this is the call-site range containing all the landing pads. + bool IsLPRange = false; + }; + + /// Compute the actions table and gather the first action index for each + /// landing pad site. + void computeActionsTable( + const SmallVectorImpl<const LandingPadInfo *> &LandingPads, + SmallVectorImpl<ActionEntry> &Actions, + SmallVectorImpl<unsigned> &FirstActions); + + void computePadMap(const SmallVectorImpl<const LandingPadInfo *> &LandingPads, + RangeMapType &PadMap); + + /// Compute the call-site table and the call-site ranges. The entry for an + /// invoke has a try-range containing the call, a non-zero landing pad and an + /// appropriate action. The entry for an ordinary call has a try-range + /// containing the call and zero for the landing pad and the action. Calls + /// marked 'nounwind' have no entry and must not be contained in the try-range + /// of any entry - they form gaps in the table. Entries must be ordered by + /// try-range address. CallSiteRanges vector is only populated for Itanium + /// exception handling. + virtual void computeCallSiteTable( + SmallVectorImpl<CallSiteEntry> &CallSites, + SmallVectorImpl<CallSiteRange> &CallSiteRanges, + const SmallVectorImpl<const LandingPadInfo *> &LandingPads, + const SmallVectorImpl<unsigned> &FirstActions); + + /// Emit landing pads and actions. + /// + /// The general organization of the table is complex, but the basic concepts + /// are easy. First there is a header which describes the location and + /// organization of the three components that follow. + /// 1. The landing pad site information describes the range of code covered + /// by the try. In our case it's an accumulation of the ranges covered + /// by the invokes in the try. There is also a reference to the landing + /// pad that handles the exception once processed. Finally an index into + /// the actions table. + /// 2. The action table, in our case, is composed of pairs of type ids + /// and next action offset. Starting with the action index from the + /// landing pad site, each type Id is checked for a match to the current + /// exception. If it matches then the exception and type id are passed + /// on to the landing pad. Otherwise the next action is looked up. This + /// chain is terminated with a next action of zero. If no type id is + /// found the frame is unwound and handling continues. + /// 3. Type id table contains references to all the C++ typeinfo for all + /// catches in the function. This tables is reversed indexed base 1. + /// + /// Returns the starting symbol of an exception table. + MCSymbol *emitExceptionTable(); + + virtual void emitTypeInfos(unsigned TTypeEncoding, MCSymbol *TTBaseLabel); + + // Helpers for identifying what kind of clause an EH typeid or selector + // corresponds to. Negative selectors are for filter clauses, the zero + // selector is for cleanups, and positive selectors are for catch clauses. + static bool isFilterEHSelector(int Selector) { return Selector < 0; } + static bool isCleanupEHSelector(int Selector) { return Selector == 0; } + static bool isCatchEHSelector(int Selector) { return Selector > 0; } + +public: + EHStreamer(AsmPrinter *A); + ~EHStreamer() override; + + // Unused. + void setSymbolSize(const MCSymbol *Sym, uint64_t Size) override {} + void beginInstruction(const MachineInstr *MI) override {} + void endInstruction() override {} + + /// Return `true' if this is a call to a function marked `nounwind'. Return + /// `false' otherwise. + static bool callToNoUnwindFunction(const MachineInstr *MI); +}; + +} // end namespace llvm + +#endif // LLVM_LIB_CODEGEN_ASMPRINTER_EHSTREAMER_H |