LLVM: llvm::RegBankSelect Class Reference (original) (raw)

This pass implements the reg bank selector pass used in the GlobalISel pipeline. More...

#include "[llvm/CodeGen/GlobalISel/RegBankSelect.h](RegBankSelect%5F8h%5Fsource.html)"

Classes
class	EdgeInsertPoint
	Insertion point on an edge. More...
class	InsertPoint
	Abstract class used to represent an insertion point in a CFG. More...
class	InstrInsertPoint
	Insertion point before or after an instruction. More...
class	MappingCost
	Helper class used to represent the cost for mapping an instruction. More...
class	MBBInsertPoint
	Insertion point at the beginning or end of a basic block. More...
class	RepairingPlacement
	Struct used to represent the placement of a repairing point for a given operand. More...

Public Types
enum	Mode { Fast, Greedy }
	List of the modes supported by the RegBankSelect pass. More...

Public Member Functions
	RegBankSelect (Mode RunningMode=Fast)
	Create a RegBankSelect pass with the specified RunningMode.
StringRef	getPassName () const override
	getPassName - Return a nice clean name for a pass.
void	getAnalysisUsage (AnalysisUsage &AU) const override
	getAnalysisUsage - Subclasses that override getAnalysisUsage must call this.
MachineFunctionProperties	getRequiredProperties () const override
MachineFunctionProperties	getSetProperties () const override
MachineFunctionProperties	getClearedProperties () const override
bool	checkFunctionIsLegal (MachineFunction &MF) const
	Check that our input is fully legal: we require the function to have the Legalized property, so it should be.
bool	assignRegisterBanks (MachineFunction &MF)
	Walk through MF and assign a register bank to every virtual register that are still mapped to nothing.
bool	runOnMachineFunction (MachineFunction &MF) override
	runOnMachineFunction - This method must be overloaded to perform the desired machine code transformation or analysis.
Public Member Functions inherited from llvm::MachineFunctionPass
bool	doInitialization (Module &) override
	doInitialization - Virtual method overridden by subclasses to do any necessary initialization before any pass is run.
Public Member Functions inherited from llvm::FunctionPass
	FunctionPass (char &pid)
void	assignPassManager (PMStack &PMS, PassManagerType T) override
	Find appropriate Function Pass Manager or Call Graph Pass Manager in the PM Stack and add self into that manager.
PassManagerType	getPotentialPassManagerType () const override
	Return what kind of Pass Manager can manage this pass.
Public Member Functions inherited from llvm::Pass
	Pass (PassKind K, char &pid)
	Pass (const Pass &)=delete
Pass &	operator= (const Pass &)=delete
virtual	~Pass ()
PassKind	getPassKind () const
StringRef	getPassArgument () const
	Return a nice clean name for a pass corresponding to that used to enable the pass in opt.
AnalysisID	getPassID () const
	getPassID - Return the PassID number that corresponds to this pass.
virtual bool	doFinalization (Module &)
	doFinalization - Virtual method overriden by subclasses to do any necessary clean up after all passes have run.
virtual void	print (raw_ostream &OS, const Module *M) const
	print - Print out the internal state of the pass.
void	dump () const
virtual void	preparePassManager (PMStack &)
	Check if available pass managers are suitable for this pass or not.
void	setResolver (AnalysisResolver *AR)
AnalysisResolver *	getResolver () const
virtual void	releaseMemory ()
	releaseMemory() - This member can be implemented by a pass if it wants to be able to release its memory when it is no longer needed.
virtual ImmutablePass *	getAsImmutablePass ()
virtual PMDataManager *	getAsPMDataManager ()
virtual void	verifyAnalysis () const
	verifyAnalysis() - This member can be implemented by a analysis pass to check state of analysis information.
virtual void	dumpPassStructure (unsigned Offset=0)
template
AnalysisType *	getAnalysisIfAvailable () const
	getAnalysisIfAvailable() - Subclasses use this function to get analysis information that might be around, for example to update it.
bool	mustPreserveAnalysisID (char &AID) const
	mustPreserveAnalysisID - This method serves the same function as getAnalysisIfAvailable, but works if you just have an AnalysisID.
template
AnalysisType &	getAnalysis () const
	getAnalysis() - This function is used by subclasses to get to the analysis information that they claim to use by overriding the getAnalysisUsage function.
template
AnalysisType &	getAnalysis (Function &F, bool *Changed=nullptr)
	getAnalysis() - This function is used by subclasses to get to the analysis information that they claim to use by overriding the getAnalysisUsage function.
template
AnalysisType &	getAnalysisID (AnalysisID PI) const
template
AnalysisType &	getAnalysisID (AnalysisID PI, Function &F, bool *Changed=nullptr)

Static Public Attributes
static char	ID = 0

Protected Member Functions
bool	assignInstr (MachineInstr &MI)
	Assign the register bank of each operand of MI.
void	init (MachineFunction &MF)
	Initialize the field members using MF.
bool	assignmentMatch (Register Reg, const RegisterBankInfo::ValueMapping &ValMapping, bool &OnlyAssign) const
	Check if Reg is already assigned what is described by ValMapping.
bool	repairReg (MachineOperand &MO, const RegisterBankInfo::ValueMapping &ValMapping, RegBankSelect::RepairingPlacement &RepairPt, const iterator_range< SmallVectorImpl< Register >::const_iterator > &NewVRegs)
	Insert repairing code for Reg as specified by ValMapping.
uint64_t	getRepairCost (const MachineOperand &MO, const RegisterBankInfo::ValueMapping &ValMapping) const
	Return the cost of the instruction needed to map MO to ValMapping.
const RegisterBankInfo::InstructionMapping &	findBestMapping (MachineInstr &MI, RegisterBankInfo::InstructionMappings &PossibleMappings, SmallVectorImpl< RepairingPlacement > &RepairPts)
	Find the best mapping for MI from PossibleMappings.
MappingCost	computeMapping (MachineInstr &MI, const RegisterBankInfo::InstructionMapping &InstrMapping, SmallVectorImpl< RepairingPlacement > &RepairPts, const MappingCost *BestCost=nullptr)
	Compute the cost of mapping MI with InstrMapping and compute the repairing placement for such mapping in RepairPts.
void	tryAvoidingSplit (RegBankSelect::RepairingPlacement &RepairPt, const MachineOperand &MO, const RegisterBankInfo::ValueMapping &ValMapping) const
	When RepairPt involves splitting to repair MO for the given ValMapping, try to change the way we repair such that the splitting is not required anymore.
bool	applyMapping (MachineInstr &MI, const RegisterBankInfo::InstructionMapping &InstrMapping, SmallVectorImpl< RepairingPlacement > &RepairPts)
	Apply Mapping to MI.
Protected Member Functions inherited from llvm::MachineFunctionPass
	MachineFunctionPass (char &ID)
Protected Member Functions inherited from llvm::FunctionPass
bool	skipFunction (const Function &F) const
	Optional passes call this function to check whether the pass should be skipped.

Protected Attributes
const RegisterBankInfo *	RBI = nullptr
	Interface to the target lowering info related to register banks.
MachineRegisterInfo *	MRI = nullptr
	MRI contains all the register class/bank information that this pass uses and updates.
const TargetRegisterInfo *	TRI = nullptr
	Information on the register classes for the current function.
MachineBlockFrequencyInfo *	MBFI = nullptr
	Get the frequency of blocks.
MachineBranchProbabilityInfo *	MBPI = nullptr
	Get the frequency of the edges.
std::unique_ptr< MachineOptimizationRemarkEmitter >	MORE
	Current optimization remark emitter. Used to report failures.
MachineIRBuilder	MIRBuilder
	Helper class used for every code morphing.
Mode	OptMode
	Optimization mode of the pass.

This pass implements the reg bank selector pass used in the GlobalISel pipeline.

At the end of this pass, all register operands have been assigned

Definition at line 91 of file RegBankSelect.h.

◆ Mode

List of the modes supported by the RegBankSelect pass.

Enumerator
Fast	Assign the register banks as fast as possible (default).
Greedy	Greedily minimize the cost of assigning register banks. This should produce code of greater quality, but will require more compile time.

Definition at line 96 of file RegBankSelect.h.

llvm::RegBankSelect::RegBankSelect	(	Mode	RunningMode = Fast	)

◆ applyMapping()

Apply Mapping to MI.

RepairPts represents the different mapping action that need to happen for the mapping to be applied.

Returns

True if the mapping was applied sucessfully, false otherwise.

Definition at line 589 of file RegBankSelect.cpp.

References assert(), llvm::RegisterBankInfo::ValueMapping::BreakDown, llvm::RegisterBankInfo::OperandsMapper::createVRegs(), llvm::dbgs(), llvm::MachineOperand::getReg(), llvm::RegisterBankInfo::OperandsMapper::getVRegs(), llvm::RegBankSelect::RepairingPlacement::Impossible, llvm::RegBankSelect::RepairingPlacement::Insert, LLVM_DEBUG, llvm_unreachable, MI, MIRBuilder, MRI, llvm::RegBankSelect::RepairingPlacement::None, llvm::RegisterBankInfo::ValueMapping::NumBreakDowns, OpIdx, RBI, llvm::RegBankSelect::RepairingPlacement::Reassign, llvm::RegisterBankInfo::PartialMapping::RegBank, and repairReg().

Referenced by assignInstr().

◆ assignInstr()

Assign the register bank of each operand of MI.

Returns

True on success, false otherwise.

Definition at line 634 of file RegBankSelect.cpp.

References applyMapping(), assert(), computeMapping(), llvm::dbgs(), llvm::SmallVectorTemplateCommon< T, typename >::empty(), Fast, findBestMapping(), llvm::RegBankSelect::MappingCost::ImpossibleCost(), llvm::isPreISelGenericOptimizationHint(), LLVM_DEBUG, MI, MRI, Opc, OptMode, RBI, TRI, and llvm::RegisterBankInfo::InstructionMapping::verify().

Referenced by assignRegisterBanks().

◆ assignmentMatch()

◆ assignRegisterBanks()

Walk through MF and assign a register bank to every virtual register that are still mapped to nothing.

The target needs to provide a RegisterBankInfo and in particular override RegisterBankInfo::getInstrMapping.

Simplified algo:

RBI = MF.subtarget.getRegBankInfo()

MIRBuilder.setMF(MF)

for each bb in MF

for each inst in bb

MIRBuilder.setInstr(inst)

MappingCosts = RBI.getMapping(inst);

Idx = findIdxOfMinCost(MappingCosts)

CurRegBank = MappingCosts[Idx].RegBank

MRI.setRegBank(inst.getOperand(0).getReg(), CurRegBank)

for each argument in inst

if (CurRegBank != argument.RegBank)

ArgReg = argument.getReg()

Tmp = MRI.createNewVirtual(MRI.getSize(ArgReg), CurRegBank)

MIRBuilder.buildInstr(COPY, Tmp, ArgReg)

inst.getOperand(argument.getOperandNo()).setReg(Tmp)

MachineIRBuilder MIRBuilder

Helper class used for every code morphing.

MachineRegisterInfo * MRI

MRI contains all the register class/bank information that this pass uses and updates.

const RegisterBankInfo * RBI

Interface to the target lowering info related to register banks.

Definition at line 682 of file RegBankSelect.cpp.

References assignInstr(), llvm::SmallVectorTemplateCommon< T, typename >::empty(), llvm::isTargetSpecificOpcode(), llvm::make_pointer_range(), MBB, MI, MIRBuilder, MORE, llvm::SmallVectorImpl< T >::pop_back_val(), llvm::reportGISelFailure(), and llvm::reverse().

Referenced by runOnMachineFunction().

◆ checkFunctionIsLegal()

◆ computeMapping()

Compute the cost of mapping MI with InstrMapping and compute the repairing placement for such mapping in RepairPts.

BestCost is used to specify when the cost becomes too high and thus it is not worth computing the RepairPts. Moreover if BestCost == nullptr, the mapping cost is actually not computed.

Definition at line 444 of file RegBankSelect.cpp.

References assert(), assignmentMatch(), llvm::SmallVectorTemplateCommon< T, typename >::back(), llvm::RegBankSelect::RepairingPlacement::canMaterialize(), llvm::SmallVectorImpl< T >::clear(), llvm::dbgs(), llvm::SmallVectorImpl< T >::emplace_back(), llvm::RegisterBankInfo::InstructionMapping::getCost(), llvm::RegisterBankInfo::InstructionMapping::getNumOperands(), llvm::MachineOperand::getReg(), getRepairCost(), llvm::RegBankSelect::RepairingPlacement::hasSplit(), llvm::RegBankSelect::MappingCost::ImpossibleCost(), llvm::RegBankSelect::RepairingPlacement::Insert, llvm::MachineOperand::isReg(), llvm::RegisterBankInfo::InstructionMapping::isValid(), LLVM_DEBUG, MBFI, MBPI, MI, MRI, OpIdx, llvm::RegBankSelect::RepairingPlacement::Reassign, TRI, and tryAvoidingSplit().

Referenced by assignInstr(), and findBestMapping().

◆ findBestMapping()

Find the best mapping for MI from PossibleMappings.

Returns

a reference on the best mapping in PossibleMappings.

Definition at line 289 of file RegBankSelect.cpp.

References assert(), llvm::SmallVectorTemplateCommon< T, typename >::begin(), llvm::SmallVectorImpl< T >::clear(), computeMapping(), llvm::dbgs(), llvm::SmallVectorImpl< T >::emplace_back(), llvm::SmallVectorTemplateCommon< T, typename >::empty(), llvm::Enable, llvm::RegBankSelect::RepairingPlacement::Impossible, llvm::RegBankSelect::MappingCost::ImpossibleCost(), LLVM_DEBUG, MI, and TRI.

Referenced by assignInstr().

◆ getAnalysisUsage()

void RegBankSelect::getAnalysisUsage ( AnalysisUsage & AU) const	overridevirtual

◆ getClearedProperties()

◆ getPassName()

StringRef llvm::RegBankSelect::getPassName ( ) const	inlineoverridevirtual

getPassName - Return a nice clean name for a pass.

This usually implemented in terms of the name that is registered by one of the Registration templates, but can be overloaded directly.

Reimplemented from llvm::Pass.

Definition at line 619 of file RegBankSelect.h.

◆ getRepairCost()

Return the cost of the instruction needed to map MO to ValMapping.

The cost is free of basic block frequencies.

Precondition

MO.isReg()

MO is assigned to a register bank.

ValMapping is a valid mapping for MO.

Definition at line 237 of file RegBankSelect.cpp.

References assert(), llvm::RegisterBankInfo::ValueMapping::BreakDown, llvm::MachineOperand::getReg(), llvm::MachineOperand::isDef(), llvm::MachineOperand::isReg(), MRI, llvm::RegisterBankInfo::ValueMapping::NumBreakDowns, RBI, llvm::RegisterBankInfo::PartialMapping::RegBank, std::swap(), and TRI.

Referenced by computeMapping().

◆ getRequiredProperties()

◆ getSetProperties()

◆ init()

Initialize the field members using MF.

Definition at line 82 of file RegBankSelect.cpp.

References assert(), Fast, llvm::Pass::getAnalysis(), llvm::TargetSubtargetInfo::getRegBankInfo(), llvm::MachineFunction::getRegInfo(), llvm::TargetSubtargetInfo::getRegisterInfo(), llvm::MachineFunction::getSubtarget(), MBFI, MBPI, MIRBuilder, MORE, MRI, OptMode, RBI, and TRI.

Referenced by runOnMachineFunction().

◆ repairReg()

Insert repairing code for Reg as specified by ValMapping.

The repairing placement is specified by RepairPt. NewVRegs contains all the registers required to remap Reg. In other words, the number of registers in NewVRegs must be equal to ValMapping.BreakDown.size().

The transformation could be sketched as:

Becomes

and

Becomes

Reg = COPY or build_sequence

Precondition

NewVRegs.size() == ValMapping.BreakDown.size()

Note

The caller is supposed to do the rewriting of op if need be. I.e., Reg = op ... => = NewOp ...

Returns

True if the repairing worked, false otherwise.

Definition at line 133 of file RegBankSelect.cpp.

References llvm::MachineInstrBuilder::addDef(), llvm::MachineInstrBuilder::addUse(), assert(), llvm::RegisterBankInfo::ValueMapping::BreakDown, llvm::dbgs(), llvm::LLT::getNumElements(), llvm::RegBankSelect::RepairingPlacement::getNumInsertPoints(), llvm::MachineOperand::getReg(), llvm::LLT::getScalarSizeInBits(), llvm::LLT::getSizeInBits(), llvm::MachineOperand::isDef(), llvm::LLT::isVector(), llvm::RegisterBankInfo::PartialMapping::Length, LLVM_DEBUG, MI, MIRBuilder, MRI, llvm::RegisterBankInfo::ValueMapping::NumBreakDowns, llvm::RegisterBankInfo::ValueMapping::partsAllUniform(), llvm::printReg(), llvm::printRegClassOrBank(), llvm::report_fatal_error(), llvm::size(), std::swap(), and TRI.

Referenced by applyMapping().

◆ runOnMachineFunction()

runOnMachineFunction - This method must be overloaded to perform the desired machine code transformation or analysis.

Implements llvm::MachineFunctionPass.

Definition at line 735 of file RegBankSelect.cpp.

References assignRegisterBanks(), checkFunctionIsLegal(), llvm::dbgs(), F, Fast, llvm::MachineFunction::getFunction(), llvm::MachineFunction::getName(), llvm::MachineFunction::getProperties(), init(), LLVM_DEBUG, and OptMode.

◆ tryAvoidingSplit()

When RepairPt involves splitting to repair MO for the given ValMapping, try to change the way we repair such that the splitting is not required anymore.

Precondition

RepairPt.hasSplit()

MO == MO.getParent()->getOperand(RepairPt.getOpIdx())

ValMapping is the mapping of MO for MO.getParent() that implied RepairPt.

Definition at line 324 of file RegBankSelect.cpp.

References assert(), llvm::RegBankSelect::RepairingPlacement::getOpIdx(), llvm::MachineOperand::getParent(), llvm::MachineOperand::getReg(), llvm::RegBankSelect::RepairingPlacement::hasSplit(), llvm::RegBankSelect::RepairingPlacement::Impossible, llvm::MachineOperand::isDef(), MI, llvm::Next, llvm::RegisterBankInfo::ValueMapping::NumBreakDowns, llvm::RegBankSelect::RepairingPlacement::Reassign, and llvm::RegBankSelect::RepairingPlacement::switchTo().