| //===-- llvm/MC/MCAsmBackend.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; |
| |
| /// Generic interface to target specific assembler backends. |
| class MCAsmBackend { |
| MCAsmBackend(const MCAsmBackend &) = delete; |
| void operator=(const MCAsmBackend &) = delete; |
| |
| protected: // Can only create subclasses. |
| MCAsmBackend(); |
| |
| unsigned HasDataInCodeSupport : 1; |
| |
| public: |
| virtual ~MCAsmBackend(); |
| |
| /// lifetime management |
| virtual void reset() {} |
| |
| /// Create a new MCObjectWriter instance for use by the assembler backend to |
| /// emit the final object file. |
| virtual MCObjectWriter *createObjectWriter(raw_pwrite_stream &OS) const = 0; |
| |
| /// Create a new ELFObjectTargetWriter to enable non-standard |
| /// ELFObjectWriters. |
| virtual MCELFObjectTargetWriter *createELFObjectTargetWriter() const { |
| llvm_unreachable("createELFObjectTargetWriter is not supported by asm " |
| "backend"); |
| } |
| |
| /// Check whether this target implements data-in-code markers. If not, data |
| /// region directives will be ignored. |
| bool hasDataInCodeSupport() const { return HasDataInCodeSupport; } |
| |
| /// \name Target Fixup Interfaces |
| /// @{ |
| |
| /// Get the number of target specific fixup kinds. |
| virtual unsigned getNumFixupKinds() const = 0; |
| |
| /// Map a relocation name used in .reloc to a fixup kind. |
| /// Returns true and sets MappedKind if Name is successfully mapped. |
| /// Otherwise returns false and leaves MappedKind unchanged. |
| virtual bool getFixupKind(StringRef Name, MCFixupKind &MappedKind) const; |
| |
| /// Get information on a fixup kind. |
| virtual const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const; |
| |
| /// 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) {} |
| |
| /// 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 |
| /// @{ |
| |
| /// Check whether the given instruction may need relaxation. |
| /// |
| /// \param Inst - The instruction to test. |
| virtual bool mayNeedRelaxation(const MCInst &Inst) const = 0; |
| |
| /// Target specific predicate for whether a given fixup requires the |
| /// associated instruction to be relaxed. |
| virtual bool fixupNeedsRelaxationAdvanced(const MCFixup &Fixup, bool Resolved, |
| uint64_t Value, |
| const MCRelaxableFragment *DF, |
| const MCAsmLayout &Layout) const; |
| |
| /// Simple predicate for targets where !Resolved implies requiring relaxation |
| virtual bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value, |
| const MCRelaxableFragment *DF, |
| const MCAsmLayout &Layout) const = 0; |
| |
| /// 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; |
| |
| /// @} |
| |
| /// 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; } |
| |
| /// 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; |
| |
| /// 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 |