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132 lines
4.4 KiB
C++
132 lines
4.4 KiB
C++
//===-- llvm/MC/MCAsmBack.h - MC Asm Backend --------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_MC_MCASMBACKEND_H
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#define LLVM_MC_MCASMBACKEND_H
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#include "llvm/MC/MCDirectives.h"
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#include "llvm/MC/MCFixup.h"
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#include "llvm/MC/MCFixupKindInfo.h"
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#include "llvm/Support/DataTypes.h"
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namespace llvm {
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class MCELFObjectTargetWriter;
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class MCFixup;
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class MCInst;
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class MCObjectWriter;
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class MCSection;
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template<typename T>
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class SmallVectorImpl;
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class raw_ostream;
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/// MCAsmBackend - Generic interface to target specific assembler backends.
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class MCAsmBackend {
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MCAsmBackend(const MCAsmBackend &); // DO NOT IMPLEMENT
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void operator=(const MCAsmBackend &); // DO NOT IMPLEMENT
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protected: // Can only create subclasses.
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MCAsmBackend();
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unsigned HasReliableSymbolDifference : 1;
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public:
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virtual ~MCAsmBackend();
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/// createObjectWriter - Create a new MCObjectWriter instance for use by the
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/// assembler backend to emit the final object file.
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virtual MCObjectWriter *createObjectWriter(raw_ostream &OS) const = 0;
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/// createELFObjectTargetWriter - Create a new ELFObjectTargetWriter to enable
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/// non-standard ELFObjectWriters.
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virtual MCELFObjectTargetWriter *createELFObjectTargetWriter() const {
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assert(0 && "createELFObjectTargetWriter is not supported by asm backend");
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return 0;
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}
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/// hasReliableSymbolDifference - Check whether this target implements
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/// accurate relocations for differences between symbols. If not, differences
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/// between symbols will always be relocatable expressions and any references
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/// to temporary symbols will be assumed to be in the same atom, unless they
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/// reside in a different section.
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///
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/// This should always be true (since it results in fewer relocations with no
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/// loss of functionality), but is currently supported as a way to maintain
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/// exact object compatibility with Darwin 'as' (on non-x86_64). It should
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/// eventually should be eliminated.
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bool hasReliableSymbolDifference() const {
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return HasReliableSymbolDifference;
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}
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/// doesSectionRequireSymbols - Check whether the given section requires that
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/// all symbols (even temporaries) have symbol table entries.
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virtual bool doesSectionRequireSymbols(const MCSection &Section) const {
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return false;
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}
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/// isSectionAtomizable - Check whether the given section can be split into
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/// atoms.
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///
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/// \see MCAssembler::isSymbolLinkerVisible().
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virtual bool isSectionAtomizable(const MCSection &Section) const {
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return true;
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}
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/// @name Target Fixup Interfaces
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/// @{
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/// getNumFixupKinds - Get the number of target specific fixup kinds.
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virtual unsigned getNumFixupKinds() const = 0;
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/// getFixupKindInfo - Get information on a fixup kind.
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virtual const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const;
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/// @}
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/// ApplyFixup - Apply the \arg Value for given \arg Fixup into the provided
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/// data fragment, at the offset specified by the fixup and following the
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/// fixup kind as appropriate.
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virtual void ApplyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
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uint64_t Value) const = 0;
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/// @}
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/// @name Target Relaxation Interfaces
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/// @{
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/// MayNeedRelaxation - Check whether the given instruction may need
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/// relaxation.
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///
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/// \param Inst - The instruction to test.
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virtual bool MayNeedRelaxation(const MCInst &Inst) const = 0;
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/// RelaxInstruction - Relax the instruction in the given fragment to the next
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/// wider instruction.
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///
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/// \param Inst - The instruction to relax, which may be the same as the
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/// output.
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/// \parm Res [output] - On return, the relaxed instruction.
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virtual void RelaxInstruction(const MCInst &Inst, MCInst &Res) const = 0;
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/// @}
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/// WriteNopData - Write an (optimal) nop sequence of Count bytes to the given
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/// output. If the target cannot generate such a sequence, it should return an
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/// error.
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///
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/// \return - True on success.
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virtual bool WriteNopData(uint64_t Count, MCObjectWriter *OW) const = 0;
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/// HandleAssemblerFlag - Handle any target-specific assembler flags.
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/// By default, do nothing.
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virtual void HandleAssemblerFlag(MCAssemblerFlag Flag) {}
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};
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} // End llvm namespace
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#endif
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