LoopVectorizationLegality checks if it is legal to vectorize a loop, and to what vectorization factor. More...

#include "llvm/Transforms/Vectorize/LoopVectorizationLegality.h"

Public Types
using	ReductionList = MapVector< PHINode *, RecurrenceDescriptor >
	ReductionList contains the reduction descriptors for all of the reductions that were found in the loop. More...

using	InductionList = MapVector< PHINode *, InductionDescriptor >
	InductionList saves induction variables and maps them to the induction descriptor. More...

using	RecurrenceSet = SmallPtrSet< const PHINode *, 8 >
	RecurrenceSet contains the phi nodes that are recurrences other than inductions and reductions. More...

Public Member Functions
	LoopVectorizationLegality (Loop L, PredicatedScalarEvolution &PSE, DominatorTree DT, TargetTransformInfo TTI, TargetLibraryInfo TLI, AAResults AA, Function F, std::function< const LoopAccessInfo &(Loop &)> GetLAA, LoopInfo LI, OptimizationRemarkEmitter ORE, LoopVectorizationRequirements R, LoopVectorizeHints H, DemandedBits DB, AssumptionCache AC, BlockFrequencyInfo BFI, ProfileSummaryInfo *PSI)

bool	canVectorize (bool UseVPlanNativePath)
	Returns true if it is legal to vectorize this loop. More...

bool	canVectorizeFPMath (bool EnableStrictReductions)
	Returns true if it is legal to vectorize the FP math operations in this loop. More...

bool	prepareToFoldTailByMasking ()
	Return true if we can vectorize this loop while folding its tail by masking, and mark all respective loads/stores for masking. More...

PHINode *	getPrimaryInduction ()
	Returns the primary induction variable. More...

ReductionList &	getReductionVars ()
	Returns the reduction variables found in the loop. More...

InductionList &	getInductionVars ()
	Returns the induction variables found in the loop. More...

RecurrenceSet &	getFirstOrderRecurrences ()
	Return the first-order recurrences found in the loop. More...

MapVector< Instruction , Instruction > &	getSinkAfter ()
	Return the set of instructions to sink to handle first-order recurrences. More...

Type *	getWidestInductionType ()
	Returns the widest induction type. More...

bool	isInductionPhi (const Value *V)
	Returns True if V is a Phi node of an induction variable in this loop. More...

bool	isCastedInductionVariable (const Value *V)
	Returns True if V is a cast that is part of an induction def-use chain, and had been proven to be redundant under a runtime guard (in other words, the cast has the same SCEV expression as the induction phi). More...

bool	isInductionVariable (const Value *V)
	Returns True if V can be considered as an induction variable in this loop. More...

bool	isReductionVariable (PHINode *PN)
	Returns True if PN is a reduction variable in this loop. More...

bool	isFirstOrderRecurrence (const PHINode *Phi)
	Returns True if Phi is a first-order recurrence in this loop. More...

bool	blockNeedsPredication (BasicBlock *BB) const
	Return true if the block BB needs to be predicated in order for the loop to be vectorized. More...

int	isConsecutivePtr (Type AccessTy, Value Ptr) const
	Check if this pointer is consecutive when vectorizing. More...

bool	isUniform (Value *V)
	Returns true if the value V is uniform within the loop. More...

bool	isUniformMemOp (Instruction &I)
	A uniform memory op is a load or store which accesses the same memory location on all lanes. More...

const RuntimePointerChecking *	getRuntimePointerChecking () const
	Returns the information that we collected about runtime memory check. More...

const LoopAccessInfo *	getLAI () const

bool	isSafeForAnyVectorWidth () const

unsigned	getMaxSafeDepDistBytes ()

uint64_t	getMaxSafeVectorWidthInBits () const

bool	hasStride (Value *V)

bool	isMaskRequired (const Instruction *I) const
	Returns true if vector representation of the instruction `I` requires mask. More...

unsigned	getNumStores () const

unsigned	getNumLoads () const

const SmallPtrSetImpl< Instruction * > &	getConditionalAssumes () const
	Returns all assume calls in predicated blocks. More...

Detailed Description

LoopVectorizationLegality checks if it is legal to vectorize a loop, and to what vectorization factor.

This class does not look at the profitability of vectorization, only the legality. This class has two main kinds of checks:

Memory checks - The code in canVectorizeMemory checks if vectorization will change the order of memory accesses in a way that will change the correctness of the program.
Scalars checks - The code in canVectorizeInstrs and canVectorizeMemory checks for a number of different conditions, such as the availability of a single induction variable, that all types are supported and vectorize-able, etc. This code reflects the capabilities of InnerLoopVectorizer. This class is also used by InnerLoopVectorizer for identifying induction variable and the different reduction variables.

Definition at line 248 of file LoopVectorizationLegality.h.

Member Typedef Documentation

◆ InductionList

using llvm::LoopVectorizationLegality::InductionList = MapVector<PHINode *, InductionDescriptor>

InductionList saves induction variables and maps them to the induction descriptor.

Definition at line 267 of file LoopVectorizationLegality.h.

◆ RecurrenceSet

using llvm::LoopVectorizationLegality::RecurrenceSet = SmallPtrSet<const PHINode *, 8>

RecurrenceSet contains the phi nodes that are recurrences other than inductions and reductions.

Definition at line 271 of file LoopVectorizationLegality.h.

◆ ReductionList

using llvm::LoopVectorizationLegality::ReductionList = MapVector<PHINode *, RecurrenceDescriptor>

ReductionList contains the reduction descriptors for all of the reductions that were found in the loop.

Definition at line 263 of file LoopVectorizationLegality.h.

Constructor & Destructor Documentation

◆ LoopVectorizationLegality()

llvm::LoopVectorizationLegality::LoopVectorizationLegality	(	Loop *	L,
		PredicatedScalarEvolution &	PSE,
		DominatorTree *	DT,
		TargetTransformInfo *	TTI,
		TargetLibraryInfo *	TLI,
		AAResults *	AA,
		Function *	F,
		std::function< const LoopAccessInfo &(Loop &)> *	GetLAA,
		LoopInfo *	LI,
		OptimizationRemarkEmitter *	ORE,
		LoopVectorizationRequirements *	R,
		LoopVectorizeHints *	H,
		DemandedBits *	DB,
		AssumptionCache *	AC,
		BlockFrequencyInfo *	BFI,
		ProfileSummaryInfo *	PSI
	)

inline

Definition at line 250 of file LoopVectorizationLegality.h.

Member Function Documentation

◆ blockNeedsPredication()

bool llvm::LoopVectorizationLegality::blockNeedsPredication ( BasicBlock * BB ) const

Return true if the block BB needs to be predicated in order for the loop to be vectorized.

Definition at line 954 of file LoopVectorizationLegality.cpp.

References BB, and llvm::LoopAccessInfo::blockNeedsPredication().

Referenced by llvm::LoopVectorizationCostModel::blockNeedsPredication(), and isUniformMemOp().

◆ canVectorize()

bool llvm::LoopVectorizationLegality::canVectorize ( bool UseVPlanNativePath )

Returns true if it is legal to vectorize this loop.

This does not mean that it is profitable to vectorize this loop, only that it is legal to do so. Temporarily taking UseVPlanNativePath parameter. If true, take the new code path being implemented for outer loop vectorization (should be functional for inner loop vectorization) based on VPlan. If false, good old LV code.

Definition at line 1159 of file LoopVectorizationLegality.cpp.

References llvm::OptimizationRemarkEmitter::allowExtraAnalysis(), assert(), llvm::dbgs(), DEBUG_TYPE, llvm::LoopVectorizeHints::FK_Enabled, llvm::SCEVUnionPredicate::getComplexity(), llvm::LoopAccessInfo::getRuntimePointerChecking(), llvm::PredicatedScalarEvolution::getUnionPredicate(), LLVM_DEBUG, llvm::RuntimePointerChecking::Need, PragmaVectorizeSCEVCheckThreshold, llvm::reportVectorizationFailure(), and VectorizeSCEVCheckThreshold.

Referenced by llvm::LoopVectorizePass::processLoop().

◆ canVectorizeFPMath()

bool llvm::LoopVectorizationLegality::canVectorizeFPMath ( bool EnableStrictReductions )

Returns true if it is legal to vectorize the FP math operations in this loop.

Vectorizing is legal if we allow reordering of FP operations, or if we can use in-order reductions.

Definition at line 906 of file LoopVectorizationLegality.cpp.

References llvm::all_of(), llvm::any_of(), llvm::LoopVectorizationRequirements::getExactFPInst(), llvm::InductionDescriptor::getExactFPMathInst(), getInductionVars(), getReductionVars(), llvm::RecurrenceDescriptor::hasExactFPMath(), llvm::RecurrenceDescriptor::isOrdered(), and Reduction.

Referenced by llvm::LoopVectorizePass::processLoop().

◆ getConditionalAssumes()

const SmallPtrSetImpl<Instruction *>& llvm::LoopVectorizationLegality::getConditionalAssumes ( ) const

inline

Returns all assume calls in predicated blocks.

They need to be dropped when flattening the CFG.

Definition at line 391 of file LoopVectorizationLegality.h.

◆ getFirstOrderRecurrences()

RecurrenceSet& llvm::LoopVectorizationLegality::getFirstOrderRecurrences ( )

inline

Return the first-order recurrences found in the loop.

Definition at line 302 of file LoopVectorizationLegality.h.

◆ getInductionVars()

InductionList& llvm::LoopVectorizationLegality::getInductionVars ( )

inline

Returns the induction variables found in the loop.

Definition at line 299 of file LoopVectorizationLegality.h.

Referenced by canVectorizeFPMath(), llvm::LoopVectorizationPlanner::collectTriviallyDeadInstructions(), llvm::LoopVectorizationCostModel::collectValuesToIgnore(), llvm::InnerLoopVectorizer::createInductionResumeValues(), and llvm::InnerLoopVectorizer::widenPHIInstruction().

◆ getLAI()

const LoopAccessInfo* llvm::LoopVectorizationLegality::getLAI ( ) const

inline

Definition at line 366 of file LoopVectorizationLegality.h.

Referenced by llvm::InnerLoopVectorizer::emitMemRuntimeChecks(), getScalarEpilogueLowering(), llvm::LoopVectorizePass::processLoop(), processLoopInVPlanNativePath(), and llvm::LoopVectorizationCostModel::runtimeChecksRequired().

◆ getMaxSafeDepDistBytes()

unsigned llvm::LoopVectorizationLegality::getMaxSafeDepDistBytes ( )

inline

Definition at line 372 of file LoopVectorizationLegality.h.

References llvm::LoopAccessInfo::getMaxSafeDepDistBytes().

Referenced by llvm::LoopVectorizationCostModel::selectInterleaveCount().

◆ getMaxSafeVectorWidthInBits()

uint64_t llvm::LoopVectorizationLegality::getMaxSafeVectorWidthInBits ( ) const

inline

Definition at line 374 of file LoopVectorizationLegality.h.

References llvm::LoopAccessInfo::getDepChecker(), and llvm::MemoryDepChecker::getMaxSafeVectorWidthInBits().

◆ getNumLoads()

unsigned llvm::LoopVectorizationLegality::getNumLoads ( ) const

inline

Definition at line 387 of file LoopVectorizationLegality.h.

References llvm::LoopAccessInfo::getNumLoads().

Referenced by llvm::LoopVectorizationCostModel::selectInterleaveCount().

◆ getNumStores()

unsigned llvm::LoopVectorizationLegality::getNumStores ( ) const

inline

Definition at line 386 of file LoopVectorizationLegality.h.

References llvm::LoopAccessInfo::getNumStores().

Referenced by llvm::LoopVectorizationCostModel::selectInterleaveCount().

◆ getPrimaryInduction()

PHINode* llvm::LoopVectorizationLegality::getPrimaryInduction ( )

inline

Returns the primary induction variable.

Definition at line 293 of file LoopVectorizationLegality.h.

Referenced by llvm::LoopVectorizationPlanner::collectTriviallyDeadInstructions(), llvm::VPRecipeBuilder::createBlockInMask(), llvm::EpilogueVectorizerMainLoop::createEpilogueVectorizedLoopSkeleton(), llvm::EpilogueVectorizerEpilogueLoop::createEpilogueVectorizedLoopSkeleton(), llvm::InnerLoopVectorizer::createVectorizedLoopSkeleton(), and llvm::LoopVectorizationCostModel::isOptimizableIVTruncate().

◆ getReductionVars()

ReductionList& llvm::LoopVectorizationLegality::getReductionVars ( )

inline

Returns the reduction variables found in the loop.

Definition at line 296 of file LoopVectorizationLegality.h.

Referenced by canVectorizeFPMath(), llvm::LoopVectorizationCostModel::canVectorizeReductions(), llvm::LoopVectorizationCostModel::collectElementTypesForWidening(), llvm::LoopVectorizationCostModel::collectInLoopReductions(), llvm::LoopVectorizationCostModel::collectValuesToIgnore(), prepareToFoldTailByMasking(), llvm::LoopVectorizationCostModel::selectInterleaveCount(), and llvm::VPRecipeBuilder::tryToCreateWidenRecipe().

◆ getRuntimePointerChecking()

const RuntimePointerChecking* llvm::LoopVectorizationLegality::getRuntimePointerChecking ( ) const

inline

Returns the information that we collected about runtime memory check.

Definition at line 362 of file LoopVectorizationLegality.h.

References llvm::LoopAccessInfo::getRuntimePointerChecking().

Referenced by llvm::LoopVectorizationCostModel::computeMaxVF(), llvm::LoopVectorizationCostModel::runtimeChecksRequired(), and llvm::LoopVectorizationCostModel::selectInterleaveCount().

◆ getSinkAfter()

MapVector<Instruction *, Instruction *>& llvm::LoopVectorizationLegality::getSinkAfter ( )

inline

Return the set of instructions to sink to handle first-order recurrences.

Definition at line 305 of file LoopVectorizationLegality.h.

◆ getWidestInductionType()

Type* llvm::LoopVectorizationLegality::getWidestInductionType ( )

inline

Returns the widest induction type.

Definition at line 308 of file LoopVectorizationLegality.h.

Referenced by llvm::EpilogueVectorizerMainLoop::createEpilogueVectorizedLoopSkeleton(), llvm::EpilogueVectorizerEpilogueLoop::createEpilogueVectorizedLoopSkeleton(), llvm::InnerLoopVectorizer::createVectorizedLoopSkeleton(), and llvm::InnerLoopVectorizer::getOrCreateTripCount().

◆ hasStride()

bool llvm::LoopVectorizationLegality::hasStride ( Value * V )

inline

Definition at line 378 of file LoopVectorizationLegality.h.

References llvm::LoopAccessInfo::hasStride().

Referenced by isStrideMul().

◆ isCastedInductionVariable()

bool llvm::LoopVectorizationLegality::isCastedInductionVariable ( const Value * V )

Returns True if V is a cast that is part of an induction def-use chain, and had been proven to be redundant under a runtime guard (in other words, the cast has the same SCEV expression as the induction phi).

Definition at line 941 of file LoopVectorizationLegality.cpp.

References llvm::SmallPtrSetImpl< PtrType >::count().

Referenced by isInductionVariable().

◆ isConsecutivePtr()

int llvm::LoopVectorizationLegality::isConsecutivePtr	(	Type *	AccessTy,
		Value *	Ptr
	)		const

Check if this pointer is consecutive when vectorizing.

This happens when the last index of the GEP is the induction variable, or that the pointer itself is an induction variable. This check allows us to vectorize A[idx] into a wide load/store. Returns: 0 - Stride is unknown or non-consecutive. 1 - Address is consecutive. -1 - Address is consecutive, and decreasing. NOTE: This method must only be used before modifying the original scalar loop. Do not use after invoking 'createVectorizedLoopSkeleton' (PR34965).

Definition at line 422 of file LoopVectorizationLegality.cpp.

References F, llvm::LoopBase< BlockT, LoopT >::getHeader(), llvm::BasicBlock::getParent(), llvm::getPtrStride(), llvm::IRPass, and llvm::shouldOptimizeForSize().

Referenced by llvm::LoopVectorizationCostModel::isLegalMaskedLoad(), llvm::LoopVectorizationCostModel::isLegalMaskedStore(), llvm::LoopVectorizationCostModel::memoryInstructionCanBeWidened(), and llvm::LoopVectorizationCostModel::setCostBasedWideningDecision().