| //===-- llvm/MC/MCAsmBack.h - MC Asm Backend --------------------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_MC_MCASMBACKEND_H |
| #define LLVM_MC_MCASMBACKEND_H |
| |
| #include "llvm/ADT/ArrayRef.h" |
| #include "llvm/MC/MCDirectives.h" |
| #include "llvm/MC/MCDwarf.h" |
| #include "llvm/MC/MCFixup.h" |
| #include "llvm/Support/DataTypes.h" |
| #include "llvm/Support/ErrorHandling.h" |
| |
| namespace llvm { |
| class MCAsmLayout; |
| class MCAssembler; |
| class MCELFObjectTargetWriter; |
| struct MCFixupKindInfo; |
| class MCFragment; |
| class MCInst; |
| class MCRelaxableFragment; |
| class MCObjectWriter; |
| class MCSection; |
| class MCValue; |
| class raw_ostream; |
| |
| /// MCAsmBackend - Generic interface to target specific assembler backends. |
| class MCAsmBackend { |
| MCAsmBackend(const MCAsmBackend &) LLVM_DELETED_FUNCTION; |
| void operator=(const MCAsmBackend &) LLVM_DELETED_FUNCTION; |
| |
| protected: // Can only create subclasses. |
| MCAsmBackend(); |
| |
| unsigned HasDataInCodeSupport : 1; |
| |
| public: |
| virtual ~MCAsmBackend(); |
| |
| /// lifetime management |
| virtual void reset() {} |
| |
| /// createObjectWriter - Create a new MCObjectWriter instance for use by the |
| /// assembler backend to emit the final object file. |
| virtual MCObjectWriter *createObjectWriter(raw_ostream &OS) const = 0; |
| |
| /// createELFObjectTargetWriter - Create a new ELFObjectTargetWriter to enable |
| /// non-standard ELFObjectWriters. |
| virtual MCELFObjectTargetWriter *createELFObjectTargetWriter() const { |
| llvm_unreachable("createELFObjectTargetWriter is not supported by asm " |
| "backend"); |
| } |
| |
| /// hasDataInCodeSupport - Check whether this target implements data-in-code |
| /// markers. If not, data region directives will be ignored. |
| bool hasDataInCodeSupport() const { return HasDataInCodeSupport; } |
| |
| /// doesSectionRequireSymbols - Check whether the given section requires that |
| /// all symbols (even temporaries) have symbol table entries. |
| virtual bool doesSectionRequireSymbols(const MCSection &Section) const { |
| return false; |
| } |
| |
| /// isSectionAtomizable - Check whether the given section can be split into |
| /// atoms. |
| /// |
| /// \see MCAssembler::isSymbolLinkerVisible(). |
| virtual bool isSectionAtomizable(const MCSection &Section) const { |
| return true; |
| } |
| |
| /// @name Target Fixup Interfaces |
| /// @{ |
| |
| /// getNumFixupKinds - Get the number of target specific fixup kinds. |
| virtual unsigned getNumFixupKinds() const = 0; |
| |
| /// getFixupKindInfo - Get information on a fixup kind. |
| virtual const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const; |
| |
| /// processFixupValue - Target hook to adjust the literal value of a fixup |
| /// if necessary. IsResolved signals whether the caller believes a relocation |
| /// is needed; the target can modify the value. The default does nothing. |
| virtual void processFixupValue(const MCAssembler &Asm, |
| const MCAsmLayout &Layout, |
| const MCFixup &Fixup, const MCFragment *DF, |
| const MCValue &Target, uint64_t &Value, |
| bool &IsResolved) {} |
| |
| /// applyFixup - Apply the \p Value for given \p Fixup into the provided |
| /// data fragment, at the offset specified by the fixup and following the |
| /// fixup kind as appropriate. |
| virtual void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize, |
| uint64_t Value, bool IsPCRel) const = 0; |
| |
| /// @} |
| |
| /// @name Target Relaxation Interfaces |
| /// @{ |
| |
| /// mayNeedRelaxation - Check whether the given instruction may need |
| /// relaxation. |
| /// |
| /// \param Inst - The instruction to test. |
| virtual bool mayNeedRelaxation(const MCInst &Inst) const = 0; |
| |
| /// fixupNeedsRelaxation - Target specific predicate for whether a given |
| /// fixup requires the associated instruction to be relaxed. |
| virtual bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value, |
| const MCRelaxableFragment *DF, |
| const MCAsmLayout &Layout) const = 0; |
| |
| /// RelaxInstruction - Relax the instruction in the given fragment to the next |
| /// wider instruction. |
| /// |
| /// \param Inst The instruction to relax, which may be the same as the |
| /// output. |
| /// \param [out] Res On return, the relaxed instruction. |
| virtual void relaxInstruction(const MCInst &Inst, MCInst &Res) const = 0; |
| |
| /// @} |
| |
| /// getMinimumNopSize - Returns the minimum size of a nop in bytes on this |
| /// target. The assembler will use this to emit excess padding in situations |
| /// where the padding required for simple alignment would be less than the |
| /// minimum nop size. |
| /// |
| virtual unsigned getMinimumNopSize() const { return 1; } |
| |
| /// writeNopData - Write an (optimal) nop sequence of Count bytes to the given |
| /// output. If the target cannot generate such a sequence, it should return an |
| /// error. |
| /// |
| /// \return - True on success. |
| virtual bool writeNopData(uint64_t Count, MCObjectWriter *OW) const = 0; |
| |
| /// handleAssemblerFlag - Handle any target-specific assembler flags. |
| /// By default, do nothing. |
| virtual void handleAssemblerFlag(MCAssemblerFlag Flag) {} |
| |
| /// \brief Generate the compact unwind encoding for the CFI instructions. |
| virtual uint32_t |
| generateCompactUnwindEncoding(ArrayRef<MCCFIInstruction>) const { |
| return 0; |
| } |
| }; |
| |
| } // End llvm namespace |
| |
| #endif |