Generic interface to target specific assembler backends. More...

#include "llvm/MC/MCAsmBackend.h"

Inheritance diagram for llvm::MCAsmBackend:

Public Member Functions
	MCAsmBackend (const MCAsmBackend &)=delete

MCAsmBackend &	operator= (const MCAsmBackend &)=delete

virtual	~MCAsmBackend ()

void	setAssembler (MCAssembler *A)

MCContext &	getContext () const

bool	allowAutoPadding () const
	Return true if this target might automatically pad instructions and thus need to emit padding enable/disable directives around sensative code.

bool	allowEnhancedRelaxation () const
	Return true if this target allows an unrelaxable instruction to be emitted into RelaxableFragment and then we can increase its size in a tricky way for optimization.

virtual void	reset ()
	lifetime management

std::unique_ptr< MCObjectWriter >	createObjectWriter (raw_pwrite_stream &OS) const
	Create a new MCObjectWriter instance for use by the assembler backend to emit the final object file.

std::unique_ptr< MCObjectWriter >	createDwoObjectWriter (raw_pwrite_stream &OS, raw_pwrite_stream &DwoOS) const
	Create an MCObjectWriter that writes two object files: a .o file which is linked into the final program and a .dwo file which is used by debuggers.

virtual std::unique_ptr< MCObjectTargetWriter >	createObjectTargetWriter () const =0

virtual unsigned	getMinimumNopSize () const
	Returns the minimum size of a nop in bytes on this target.

virtual unsigned	getMaximumNopSize (const MCSubtargetInfo &STI) const
	Returns the maximum size of a nop in bytes on this target.

virtual bool	writeNopData (raw_ostream &OS, uint64_t Count, const MCSubtargetInfo *STI) const =0
	Write an (optimal) nop sequence of Count bytes to the given output.

virtual bool	finishLayout (const MCAssembler &Asm) const

virtual uint64_t	generateCompactUnwindEncoding (const MCDwarfFrameInfo FI, const MCContext Ctxt) const
	Generate the compact unwind encoding for the CFI instructions.

bool	isDarwinCanonicalPersonality (const MCSymbol *Sym) const

Target Fixup Interfaces
virtual std::optional< MCFixupKind >	getFixupKind (StringRef Name) const
	Map a relocation name used in .reloc to a fixup kind.

virtual MCFixupKindInfo	getFixupKindInfo (MCFixupKind Kind) const
	Get information on a fixup kind.

virtual std::optional< bool >	evaluateFixup (const MCFragment &, MCFixup &, MCValue &, uint64_t &)

void	maybeAddReloc (const MCFragment &, const MCFixup &, const MCValue &, uint64_t &Value, bool IsResolved)

virtual void	applyFixup (const MCFragment &, const MCFixup &, const MCValue &Target, uint8_t *Data, uint64_t Value, bool IsResolved)=0

Target Relaxation Interfaces
virtual bool	mayNeedRelaxation (unsigned Opcode, ArrayRef< MCOperand > Operands, const MCSubtargetInfo &STI) const
	Check whether the given instruction (encoded as Opcode+Operands) may need relaxation.

virtual bool	fixupNeedsRelaxationAdvanced (const MCFragment &, const MCFixup &, const MCValue &, uint64_t, bool Resolved) const
	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
	Simple predicate for targets where !Resolved implies requiring relaxation.

virtual void	relaxInstruction (MCInst &Inst, const MCSubtargetInfo &STI) const
	Relax the instruction in the given fragment to the next wider instruction.

virtual bool	relaxAlign (MCFragment &F, unsigned &Size)

virtual bool	relaxDwarfLineAddr (MCFragment &) const

virtual bool	relaxDwarfCFA (MCFragment &) const

virtual std::pair< bool, bool >	relaxLEB128 (MCFragment &, int64_t &Value) const

Static Public Member Functions
static const MCSubtargetInfo *	getSubtargetInfo (const MCFragment &F)

Public Attributes
const llvm::endianness	Endian

Protected Member Functions
	MCAsmBackend (llvm::endianness Endian)

Protected Attributes
MCAssembler *	Asm = nullptr

bool	AllowAutoPadding = false

bool	AllowEnhancedRelaxation = false

Detailed Description

Generic interface to target specific assembler backends.

Definition at line 55 of file MCAsmBackend.h.

Constructor & Destructor Documentation

◆ MCAsmBackend() [1/2]

llvm::MCAsmBackend::MCAsmBackend ( llvm::endianness Endian )

inlineprotected

Definition at line 57 of file MCAsmBackend.h.

◆ MCAsmBackend() [2/2]

llvm::MCAsmBackend::MCAsmBackend ( const MCAsmBackend & )

delete

◆ ~MCAsmBackend()

MCAsmBackend::~MCAsmBackend ( )

virtualdefault

Member Function Documentation

◆ allowAutoPadding()

bool llvm::MCAsmBackend::allowAutoPadding ( ) const

inline

Return true if this target might automatically pad instructions and thus need to emit padding enable/disable directives around sensative code.

Definition at line 77 of file MCAsmBackend.h.

◆ allowEnhancedRelaxation()

bool llvm::MCAsmBackend::allowEnhancedRelaxation ( ) const

inline

Return true if this target allows an unrelaxable instruction to be emitted into RelaxableFragment and then we can increase its size in a tricky way for optimization.

Definition at line 81 of file MCAsmBackend.h.

Referenced by llvm::MCObjectStreamer::emitInstruction().

◆ applyFixup()

virtual void llvm::MCAsmBackend::applyFixup	(	const MCFragment &	,
		const MCFixup &	,
		const MCValue &	Target,
		uint8_t *	Data,
		uint64_t	Value,
		bool	IsResolved
	)

pure virtual

Implemented in llvm::ARMAsmBackend, llvm::AVRAsmBackend, llvm::CSKYAsmBackend, llvm::LoongArchAsmBackend, llvm::MipsAsmBackend, and llvm::RISCVAsmBackend.

◆ createDwoObjectWriter()

std::unique_ptr< MCObjectWriter > MCAsmBackend::createDwoObjectWriter	(	raw_pwrite_stream &	OS,
		raw_pwrite_stream &	DwoOS
	)		const

Create an MCObjectWriter that writes two object files: a .o file which is linked into the final program and a .dwo file which is used by debuggers.

This function is only supported with ELF targets.

Definition at line 66 of file MCAsmBackend.cpp.

References llvm::Triple::COFF, createObjectTargetWriter(), llvm::createWasmDwoObjectWriter(), llvm::createWinCOFFDwoObjectWriter(), llvm::Triple::ELF, Endian, llvm::little, OS, llvm::report_fatal_error(), and llvm::Triple::Wasm.

Referenced by llvm::CodeGenTargetMachineImpl::createMCStreamer().

◆ createObjectTargetWriter()

virtual std::unique_ptr< MCObjectTargetWriter > llvm::MCAsmBackend::createObjectTargetWriter ( ) const

pure virtual

Implemented in llvm::ARMAsmBackendDarwin, llvm::ARMAsmBackendELF, llvm::ARMAsmBackendWinCOFF, llvm::AVRAsmBackend, llvm::CSKYAsmBackend, llvm::LoongArchAsmBackend, llvm::MipsAsmBackend, and llvm::RISCVAsmBackend.

Referenced by createDwoObjectWriter(), and createObjectWriter().

◆ createObjectWriter()

std::unique_ptr< MCObjectWriter > MCAsmBackend::createObjectWriter ( raw_pwrite_stream & OS ) const

Create a new MCObjectWriter instance for use by the assembler backend to emit the final object file.

Definition at line 32 of file MCAsmBackend.cpp.

References llvm::Triple::COFF, llvm::createGOFFObjectWriter(), createObjectTargetWriter(), llvm::createSPIRVObjectWriter(), llvm::createWasmObjectWriter(), llvm::createWinCOFFObjectWriter(), llvm::createXCOFFObjectWriter(), llvm::Triple::DXContainer, llvm::Triple::ELF, Endian, llvm::Triple::GOFF, llvm::little, llvm_unreachable, llvm::Triple::MachO, OS, llvm::Triple::SPIRV, llvm::Triple::Wasm, and llvm::Triple::XCOFF.

Referenced by llvm::CodeGenTargetMachineImpl::addPassesToEmitMC(), llvm::CodeGenTargetMachineImpl::createMCStreamer(), llvm::dwarf_linker::classic::DwarfStreamer::init(), and llvm::dwarf_linker::parallel::DwarfEmitterImpl::init().

◆ evaluateFixup()

virtual std::optional< bool > llvm::MCAsmBackend::evaluateFixup	(	const MCFragment &	,
		MCFixup &	,
		MCValue &	,
		uint64_t &
	)

inlinevirtual

Reimplemented in llvm::ARMAsmBackend, llvm::CSKYAsmBackend, and llvm::RISCVAsmBackend.

Definition at line 112 of file MCAsmBackend.h.

◆ finishLayout()

virtual bool llvm::MCAsmBackend::finishLayout ( const MCAssembler & Asm ) const

inlinevirtual

Definition at line 202 of file MCAsmBackend.h.

◆ fixupNeedsRelaxation()

virtual bool llvm::MCAsmBackend::fixupNeedsRelaxation	(	const MCFixup &	Fixup,
		uint64_t	Value
	)		const

inlinevirtual

Simple predicate for targets where !Resolved implies requiring relaxation.

Reimplemented in llvm::CSKYAsmBackend.

Definition at line 147 of file MCAsmBackend.h.

References llvm_unreachable.

Referenced by fixupNeedsRelaxationAdvanced().

◆ fixupNeedsRelaxationAdvanced()

bool MCAsmBackend::fixupNeedsRelaxationAdvanced	(	const MCFragment &	,
		const MCFixup &	Fixup,
		const MCValue &	,
		uint64_t	Value,
		bool	Resolved
	)		const

virtual

Target specific predicate for whether a given fixup requires the associated instruction to be relaxed.

Reimplemented in llvm::ARMAsmBackend, llvm::CSKYAsmBackend, and llvm::RISCVAsmBackend.

Definition at line 109 of file MCAsmBackend.cpp.

References Fixup, and fixupNeedsRelaxation().

◆ generateCompactUnwindEncoding()

virtual uint64_t llvm::MCAsmBackend::generateCompactUnwindEncoding	(	const MCDwarfFrameInfo *	FI,
		const MCContext *	Ctxt
	)		const

inlinevirtual

Generate the compact unwind encoding for the CFI instructions.

Reimplemented in llvm::ARMAsmBackendDarwin.

Definition at line 205 of file MCAsmBackend.h.

Referenced by llvm::MCStreamer::generateCompactUnwindEncodings().

◆ getContext()

MCContext & MCAsmBackend::getContext ( ) const

Definition at line 29 of file MCAsmBackend.cpp.

References Asm, and llvm::MCAssembler::getContext().

Referenced by llvm::ARMAsmBackend::adjustFixupValue(), llvm::ARMAsmBackend::applyFixup(), llvm::AVRAsmBackend::applyFixup(), llvm::CSKYAsmBackend::applyFixup(), llvm::LoongArchAsmBackend::applyFixup(), llvm::MipsAsmBackend::applyFixup(), llvm::RISCVAsmBackend::applyFixup(), llvm::RISCVAsmBackend::evaluateFixup(), isDarwinCanonicalPersonality(), llvm::LoongArchAsmBackend::relaxAlign(), llvm::RISCVAsmBackend::relaxAlign(), llvm::LoongArchAsmBackend::relaxDwarfCFA(), llvm::RISCVAsmBackend::relaxDwarfCFA(), llvm::LoongArchAsmBackend::relaxDwarfLineAddr(), and llvm::RISCVAsmBackend::relaxDwarfLineAddr().

◆ getFixupKind()

std::optional< MCFixupKind > MCAsmBackend::getFixupKind ( StringRef Name ) const

virtual

Map a relocation name used in .reloc to a fixup kind.

Reimplemented in llvm::ARMAsmBackend, llvm::ARMAsmBackendELF, llvm::AVRAsmBackend, llvm::LoongArchAsmBackend, llvm::MipsAsmBackend, and llvm::RISCVAsmBackend.

Definition at line 85 of file MCAsmBackend.cpp.

Referenced by llvm::MipsAsmBackend::getFixupKind().

◆ getFixupKindInfo()

MCFixupKindInfo MCAsmBackend::getFixupKindInfo ( MCFixupKind Kind ) const

virtual

Get information on a fixup kind.

Reimplemented in llvm::ARMAsmBackend, llvm::AVRAsmBackend, llvm::CSKYAsmBackend, llvm::LoongArchAsmBackend, llvm::MipsAsmBackend, and llvm::RISCVAsmBackend.

Definition at line 89 of file MCAsmBackend.cpp.

References assert(), and llvm::FK_NONE.

Referenced by llvm::ARMAsmBackend::getFixupKindInfo(), llvm::AVRAsmBackend::getFixupKindInfo(), llvm::CSKYAsmBackend::getFixupKindInfo(), llvm::LoongArchAsmBackend::getFixupKindInfo(), llvm::MipsAsmBackend::getFixupKindInfo(), and llvm::RISCVAsmBackend::getFixupKindInfo().

◆ getMaximumNopSize()

virtual unsigned llvm::MCAsmBackend::getMaximumNopSize ( const MCSubtargetInfo & STI ) const

inlinevirtual

Returns the maximum size of a nop in bytes on this target.

Definition at line 189 of file MCAsmBackend.h.

◆ getMinimumNopSize()

virtual unsigned llvm::MCAsmBackend::getMinimumNopSize ( ) const

inlinevirtual

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.

Definition at line 185 of file MCAsmBackend.h.

◆ getSubtargetInfo()

const MCSubtargetInfo * MCAsmBackend::getSubtargetInfo ( const MCFragment & F )

static

Definition at line 139 of file MCAsmBackend.cpp.

References assert(), and F.

Referenced by llvm::ARMAsmBackend::applyFixup().

◆ isDarwinCanonicalPersonality()

bool MCAsmBackend::isDarwinCanonicalPersonality ( const MCSymbol * Sym ) const

Definition at line 125 of file MCAsmBackend.cpp.

References assert(), getContext(), name, and Sym.

Referenced by llvm::ARMAsmBackendDarwin::generateCompactUnwindEncoding().

◆ maybeAddReloc()

void MCAsmBackend::maybeAddReloc	(	const MCFragment &	F,
		const MCFixup &	Fixup,
		const MCValue &	Target,
		uint64_t &	Value,
		bool	IsResolved
	)

Definition at line 118 of file MCAsmBackend.cpp.

References Asm, F, Fixup, llvm::MCAssembler::getWriter(), and llvm::MCObjectWriter::recordRelocation().

Referenced by llvm::LoongArchAsmBackend::addReloc(), llvm::ARMAsmBackend::applyFixup(), llvm::CSKYAsmBackend::applyFixup(), and llvm::MipsAsmBackend::applyFixup().

◆ mayNeedRelaxation()

virtual bool llvm::MCAsmBackend::mayNeedRelaxation	(	unsigned	Opcode,
		ArrayRef< MCOperand >	Operands,
		const MCSubtargetInfo &	STI
	)		const

inlinevirtual

Check whether the given instruction (encoded as Opcode+Operands) may need relaxation.

Reimplemented in llvm::ARMAsmBackend, llvm::CSKYAsmBackend, and llvm::RISCVAsmBackend.

Definition at line 135 of file MCAsmBackend.h.

Referenced by llvm::MCObjectStreamer::emitInstruction().

◆ operator=()

MCAsmBackend & llvm::MCAsmBackend::operator= ( const MCAsmBackend & )

delete

◆ relaxAlign()

virtual bool llvm::MCAsmBackend::relaxAlign	(	MCFragment &	F,
		unsigned &	Size
	)

inlinevirtual

Reimplemented in llvm::LoongArchAsmBackend, and llvm::RISCVAsmBackend.

Definition at line 168 of file MCAsmBackend.h.

◆ relaxDwarfCFA()

virtual bool llvm::MCAsmBackend::relaxDwarfCFA ( MCFragment & ) const

inlinevirtual

Reimplemented in llvm::LoongArchAsmBackend, and llvm::RISCVAsmBackend.

Definition at line 170 of file MCAsmBackend.h.

◆ relaxDwarfLineAddr()

virtual bool llvm::MCAsmBackend::relaxDwarfLineAddr ( MCFragment & ) const

inlinevirtual

Reimplemented in llvm::LoongArchAsmBackend, and llvm::RISCVAsmBackend.

Definition at line 169 of file MCAsmBackend.h.

◆ relaxInstruction()

virtual void llvm::MCAsmBackend::relaxInstruction	(	MCInst &	Inst,
		const MCSubtargetInfo &	STI
	)		const

inlinevirtual

Relax the instruction in the given fragment to the next wider instruction.

Parameters

[out]	Inst	The instruction to relax, which is also the relaxed instruction.
	STI	the subtarget information for the associated instruction.

Reimplemented in llvm::ARMAsmBackend, llvm::CSKYAsmBackend, and llvm::RISCVAsmBackend.

Definition at line 157 of file MCAsmBackend.h.

References llvm_unreachable.

Referenced by llvm::MCObjectStreamer::emitInstruction().

◆ relaxLEB128()

virtual std::pair< bool, bool > llvm::MCAsmBackend::relaxLEB128	(	MCFragment &	,
		int64_t &	Value
	)		const

inlinevirtual

Reimplemented in llvm::LoongArchAsmBackend, and llvm::RISCVAsmBackend.

Definition at line 174 of file MCAsmBackend.h.

◆ reset()

virtual void llvm::MCAsmBackend::reset ( )

inlinevirtual

lifetime management

Definition at line 84 of file MCAsmBackend.h.

Referenced by llvm::MCAssembler::reset().

◆ setAssembler()

void llvm::MCAsmBackend::setAssembler ( MCAssembler * A )

inline

Definition at line 71 of file MCAsmBackend.h.

References A.

◆ writeNopData()

virtual bool llvm::MCAsmBackend::writeNopData	(	raw_ostream &	OS,
		uint64_t	Count,
		const MCSubtargetInfo *	STI
	)		const

pure virtual

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.

Returns: - True on success.

Implemented in llvm::ARMAsmBackend, llvm::AVRAsmBackend, llvm::CSKYAsmBackend, llvm::LoongArchAsmBackend, llvm::MipsAsmBackend, and llvm::RISCVAsmBackend.

Member Data Documentation

◆ AllowAutoPadding

bool llvm::MCAsmBackend::AllowAutoPadding = false

protected

Definition at line 61 of file MCAsmBackend.h.

◆ AllowEnhancedRelaxation

bool llvm::MCAsmBackend::AllowEnhancedRelaxation = false

protected

Definition at line 62 of file MCAsmBackend.h.

◆ Asm

MCAssembler* llvm::MCAsmBackend::Asm = nullptr

protected

Definition at line 59 of file MCAsmBackend.h.

Referenced by llvm::LoongArchAsmBackend::addReloc(), llvm::RISCVAsmBackend::addReloc(), llvm::ARMAsmBackend::adjustFixupValue(), llvm::ARMAsmBackend::applyFixup(), llvm::AVRAsmBackend::applyFixup(), llvm::ARMAsmBackend::evaluateFixup(), llvm::CSKYAsmBackend::evaluateFixup(), llvm::RISCVAsmBackend::evaluateFixup(), llvm::ARMAsmBackend::fixupNeedsRelaxationAdvanced(), getContext(), maybeAddReloc(), llvm::RISCVAsmBackend::maybeAddVendorReloc(), llvm::LoongArchAsmBackend::relaxAlign(), llvm::LoongArchAsmBackend::relaxDwarfCFA(), llvm::RISCVAsmBackend::relaxDwarfCFA(), llvm::LoongArchAsmBackend::relaxDwarfLineAddr(), llvm::RISCVAsmBackend::relaxDwarfLineAddr(), llvm::LoongArchAsmBackend::relaxLEB128(), llvm::RISCVAsmBackend::relaxLEB128(), and llvm::ARMAsmBackend::shouldForceRelocation().

◆ Endian

const llvm::endianness llvm::MCAsmBackend::Endian

Definition at line 69 of file MCAsmBackend.h.

Referenced by llvm::ARMAsmBackend::adjustFixupValue(), llvm::ARMAsmBackend::applyFixup(), llvm::CSKYAsmBackend::applyFixup(), llvm::MipsAsmBackend::applyFixup(), llvm::RISCVAsmBackend::applyFixup(), createDwoObjectWriter(), createObjectWriter(), llvm::ARMAsmBackend::getFixupKindInfo(), llvm::MipsAsmBackend::getFixupKindInfo(), llvm::RISCVAsmBackend::relaxDwarfCFA(), llvm::RISCVAsmBackend::relaxDwarfLineAddr(), and llvm::ARMAsmBackend::writeNopData().

The documentation for this class was generated from the following files:

include/llvm/MC/MCAsmBackend.h
lib/MC/MCAsmBackend.cpp

Public Member Functions

Static Public Member Functions

Public Attributes

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ MCAsmBackend() [1/2]

◆ MCAsmBackend() [2/2]

◆ ~MCAsmBackend()

Member Function Documentation

◆ allowAutoPadding()

◆ allowEnhancedRelaxation()

◆ applyFixup()

◆ createDwoObjectWriter()

◆ createObjectTargetWriter()

◆ createObjectWriter()

◆ evaluateFixup()

◆ finishLayout()

◆ fixupNeedsRelaxation()

◆ fixupNeedsRelaxationAdvanced()

◆ generateCompactUnwindEncoding()

◆ getContext()

◆ getFixupKind()

◆ getFixupKindInfo()

◆ getMaximumNopSize()

◆ getMinimumNopSize()

◆ getSubtargetInfo()

◆ isDarwinCanonicalPersonality()

◆ maybeAddReloc()

◆ mayNeedRelaxation()

◆ operator=()

◆ relaxAlign()

◆ relaxDwarfCFA()

◆ relaxDwarfLineAddr()

◆ relaxInstruction()

◆ relaxLEB128()

◆ reset()

◆ setAssembler()

◆ writeNopData()

Member Data Documentation

◆ AllowAutoPadding

◆ AllowEnhancedRelaxation

◆ Asm

◆ Endian