#include "llvm/CodeGen/RegisterScavenging.h"

Public Member Functions
	RegScavenger ()=default

void	assignRegToScavengingIndex (int FI, Register Reg, MachineInstr *Restore=nullptr)
	Record that `Reg` is in use at scavenging index `FI`.

void	enterBasicBlock (MachineBasicBlock &MBB)
	Start tracking liveness from the begin of basic block `MBB`.

void	enterBasicBlockEnd (MachineBasicBlock &MBB)
	Start tracking liveness from the end of basic block `MBB`.

void	backward ()
	Update internal register state and move MBB iterator backwards.

void	backward (MachineBasicBlock::iterator I)
	Call backward() to update internal register state to just before `*I`.

bool	isRegUsed (Register Reg, bool includeReserved=true) const
	Return if a specific register is currently used.

BitVector	getRegsAvailable (const TargetRegisterClass *RC)
	Return all available registers in the register class in Mask.

Register	FindUnusedReg (const TargetRegisterClass *RC) const
	Find an unused register of the specified register class.

void	addScavengingFrameIndex (int FI)
	Add a scavenging frame index.

bool	isScavengingFrameIndex (int FI) const
	Query whether a frame index is a scavenging frame index.

void	getScavengingFrameIndices (SmallVectorImpl< int > &A) const
	Get an array of scavenging frame indices.

Register	scavengeRegisterBackwards (const TargetRegisterClass &RC, MachineBasicBlock::iterator To, bool RestoreAfter, int SPAdj, bool AllowSpill=true)
	Make a register of the specific register class available from the current position backwards to the place before `To`.

void	setRegUsed (Register Reg, LaneBitmask LaneMask=LaneBitmask::getAll())
	Tell the scavenger a register is used.

Detailed Description

Definition at line 34 of file RegisterScavenging.h.

Constructor & Destructor Documentation

◆ RegScavenger()

llvm::RegScavenger::RegScavenger ( )

default

Member Function Documentation

◆ addScavengingFrameIndex()

void llvm::RegScavenger::addScavengingFrameIndex ( int FI )

inline

Add a scavenging frame index.

Definition at line 112 of file RegisterScavenging.h.

References llvm::SmallVectorTemplateBase< T, bool >::push_back().

◆ assignRegToScavengingIndex()

void llvm::RegScavenger::assignRegToScavengingIndex	(	int	FI,
		Register	Reg,
		MachineInstr *	Restore = `nullptr`
	)

inline

Record that Reg is in use at scavenging index FI.

This is for targets which need to directly manage the spilling process, and need to update the scavenger's internal state. It's expected this be called a second time with Restore set to a non-null value, so that the externally inserted restore instruction resets the scavenged slot liveness when encountered.

Definition at line 70 of file RegisterScavenging.h.

References assert(), llvm_unreachable, and Reg.

Referenced by llvm::SGPRSpillBuilder::prepare(), and llvm::SGPRSpillBuilder::restore().

◆ backward() [1/2]

void RegScavenger::backward ( )

Update internal register state and move MBB iterator backwards.

This method gives precise results even in the absence of kill flags.

Definition at line 81 of file RegisterScavenging.cpp.

References I, MI, and llvm::LiveRegUnits::stepBackward().

Referenced by analyzeCompressibleUses(), backward(), indirectCopyToAGPR(), llvm::Mips16InstrInfo::loadImmediate(), llvm::AArch64FrameLowering::processFunctionBeforeFrameFinalized(), llvm::SIFrameLowering::processFunctionBeforeFrameFinalized(), and scavengeFrameVirtualRegsInBlock().

◆ backward() [2/2]

void llvm::RegScavenger::backward ( MachineBasicBlock::iterator I )

inline

Call backward() to update internal register state to just before *I.

Definition at line 96 of file RegisterScavenging.h.

References backward(), I, and MBBI.

◆ enterBasicBlock()

void RegScavenger::enterBasicBlock ( MachineBasicBlock & MBB )

Start tracking liveness from the begin of basic block MBB.

Definition at line 69 of file RegisterScavenging.cpp.

References llvm::LiveRegUnits::addLiveIns(), llvm::MachineBasicBlock::begin(), and MBB.

Referenced by llvm::RISCVFrameLowering::canUseAsPrologue(), and llvm::SIInstrInfo::insertIndirectBranch().

◆ enterBasicBlockEnd()

void RegScavenger::enterBasicBlockEnd ( MachineBasicBlock & MBB )

Start tracking liveness from the end of basic block MBB.

Use backward() to move towards the beginning of the block.

Definition at line 75 of file RegisterScavenging.cpp.

References llvm::LiveRegUnits::addLiveOuts(), llvm::MachineBasicBlock::end(), and MBB.

Referenced by analyzeCompressibleUses(), indirectCopyToAGPR(), llvm::XtensaInstrInfo::insertIndirectBranch(), llvm::AArch64InstrInfo::insertIndirectBranch(), llvm::SIInstrInfo::insertIndirectBranch(), llvm::LoongArchInstrInfo::insertIndirectBranch(), llvm::RISCVInstrInfo::insertIndirectBranch(), llvm::Mips16InstrInfo::loadImmediate(), llvm::AArch64FrameLowering::processFunctionBeforeFrameFinalized(), llvm::SIFrameLowering::processFunctionBeforeFrameFinalized(), and scavengeFrameVirtualRegsInBlock().

◆ FindUnusedReg()

Register RegScavenger::FindUnusedReg ( const TargetRegisterClass * RC ) const

Find an unused register of the specified register class.

Return 0 if none is found.

Definition at line 100 of file RegisterScavenging.cpp.

References llvm::dbgs(), isRegUsed(), LLVM_DEBUG, and llvm::printReg().

Referenced by llvm::LanaiRegisterInfo::eliminateFrameIndex(), llvm::AArch64InstrInfo::insertIndirectBranch(), llvm::AArch64FrameLowering::processFunctionBeforeFrameFinalized(), and replaceFrameIndex().

◆ getRegsAvailable()

BitVector RegScavenger::getRegsAvailable ( const TargetRegisterClass * RC )

Return all available registers in the register class in Mask.

Definition at line 111 of file RegisterScavenging.cpp.

References llvm::MCRegisterInfo::getNumRegs(), and isRegUsed().

Referenced by llvm::PPCRegisterInfo::eliminateFrameIndex(), and llvm::Mips16InstrInfo::loadImmediate().

◆ getScavengingFrameIndices()

void llvm::RegScavenger::getScavengingFrameIndices ( SmallVectorImpl< int > & A ) const

inline

Get an array of scavenging frame indices.

Definition at line 126 of file RegisterScavenging.h.

References A, and I.

◆ isRegUsed()

bool RegScavenger::isRegUsed	(	Register	Reg,
		bool	includeReserved = `true`
	)		const

Return if a specific register is currently used.

Definition at line 94 of file RegisterScavenging.cpp.

References llvm::LiveRegUnits::available().

Referenced by llvm::SIRegisterInfo::buildSpillLoadStore(), llvm::RISCVFrameLowering::canUseAsPrologue(), llvm::SIRegisterInfo::eliminateFrameIndex(), FindUnusedReg(), llvm::SIInstrInfo::getAddNoCarry(), getRegsAvailable(), llvm::AArch64InstrInfo::insertIndirectBranch(), llvm::SGPRSpillBuilder::prepare(), and llvm::SGPRSpillBuilder::readWriteTmpVGPR().

◆ isScavengingFrameIndex()

bool llvm::RegScavenger::isScavengingFrameIndex ( int FI ) const

inline

Query whether a frame index is a scavenging frame index.

Definition at line 117 of file RegisterScavenging.h.

Referenced by llvm::AArch64RegisterInfo::eliminateFrameIndex(), llvm::ARMBaseRegisterInfo::eliminateFrameIndex(), and llvm::ThumbRegisterInfo::eliminateFrameIndex().

◆ scavengeRegisterBackwards()

Register RegScavenger::scavengeRegisterBackwards	(	const TargetRegisterClass &	RC,
		MachineBasicBlock::iterator	To,
		bool	RestoreAfter,
		int	SPAdj,
		bool	AllowSpill = `true`
	)

Make a register of the specific register class available from the current position backwards to the place before To.

If RestoreAfter is true this includes the instruction following the current position. SPAdj is the stack adjustment due to call frame, it's passed along to eliminateFrameIndex(). Returns the scavenged register.

If AllowSpill is false, fail if a spill is required to make the register available, and return NoRegister.

Definition at line 295 of file RegisterScavenging.cpp.

References assert(), llvm::dbgs(), llvm::MachineBasicBlock::end(), findSurvivorBackwards(), llvm::MachineBasicBlock::getParent(), llvm::TargetRegisterClass::getRawAllocationOrder(), LLVM_DEBUG, MBB, P, llvm::printReg(), llvm::LiveRegUnits::removeReg(), and UseMI.