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.

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

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

Public Member Functions
	LoopVectorizationLegality (Loop L, PredicatedScalarEvolution &PSE, DominatorTree DT, TargetTransformInfo TTI, TargetLibraryInfo TLI, Function F, LoopAccessInfoManager &LAIs, 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.

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

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

PHINode *	getPrimaryInduction ()
	Returns the primary induction variable.

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

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

RecurrenceSet &	getFixedOrderRecurrences ()
	Return the fixed-order recurrences found in the loop.

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

Type *	getWidestInductionType ()
	Returns the widest induction type.

bool	isInvariantStoreOfReduction (StoreInst *SI)
	Returns True if given store is a final invariant store of one of the reductions found in the loop.

bool	isInvariantAddressOfReduction (Value *V)
	Returns True if given address is invariant and is used to store recurrent expression.

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

const InductionDescriptor *	getIntOrFpInductionDescriptor (PHINode *Phi) const
	Returns a pointer to the induction descriptor, if `Phi` is an integer or floating point induction.

const InductionDescriptor *	getPointerInductionDescriptor (PHINode *Phi) const
	Returns a pointer to the induction descriptor, if `Phi` is pointer induction.

bool	isCastedInductionVariable (const Value *V) const
	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).

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

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

bool	isFixedOrderRecurrence (const PHINode *Phi) const
	Returns True if Phi is a fixed-order recurrence in this loop.

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

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

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

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

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

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.

unsigned	getNumStores () const

unsigned	getNumLoads () const

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

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 241 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 259 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 263 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 255 of file LoopVectorizationLegality.h.

Constructor & Destructor Documentation

◆ LoopVectorizationLegality()

llvm::LoopVectorizationLegality::LoopVectorizationLegality	(	Loop *	L,
		PredicatedScalarEvolution &	PSE,
		DominatorTree *	DT,
		TargetTransformInfo *	TTI,
		TargetLibraryInfo *	TLI,
		Function *	F,
		LoopAccessInfoManager &	LAIs,
		LoopInfo *	LI,
		OptimizationRemarkEmitter *	ORE,
		LoopVectorizationRequirements *	R,
		LoopVectorizeHints *	H,
		DemandedBits *	DB,
		AssumptionCache *	AC,
		BlockFrequencyInfo *	BFI,
		ProfileSummaryInfo *	PSI
	)

inline

Definition at line 243 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 1105 of file LoopVectorizationLegality.cpp.

References llvm::LoopAccessInfo::blockNeedsPredication().

Referenced by 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 1289 of file LoopVectorizationLegality.cpp.

References llvm::OptimizationRemarkEmitter::allowExtraAnalysis(), assert(), llvm::dbgs(), DEBUG_TYPE, llvm::LoopVectorizeHints::FK_Enabled, llvm::SCEVPredicate::getComplexity(), llvm::LoopBase< BlockT, LoopT >::getHeader(), llvm::Value::getName(), llvm::LoopBase< BlockT, LoopT >::getNumBlocks(), llvm::PredicatedScalarEvolution::getPredicate(), llvm::LoopAccessInfo::getRuntimePointerChecking(), llvm::LoopBase< BlockT, LoopT >::isInnermost(), 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 1014 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 390 of file LoopVectorizationLegality.h.

◆ getFixedOrderRecurrences()

RecurrenceSet & llvm::LoopVectorizationLegality::getFixedOrderRecurrences ( )

inline

Return the fixed-order recurrences found in the loop.

Definition at line 294 of file LoopVectorizationLegality.h.

Referenced by llvm::AArch64TTIImpl::preferPredicateOverEpilogue().

◆ getInductionVars()

const InductionList & llvm::LoopVectorizationLegality::getInductionVars ( ) const

inline

Returns the induction variables found in the loop.

Definition at line 291 of file LoopVectorizationLegality.h.

Referenced by canVectorizeFPMath(), getIntOrFpInductionDescriptor(), and getPointerInductionDescriptor().

◆ getIntOrFpInductionDescriptor()

const InductionDescriptor * llvm::LoopVectorizationLegality::getIntOrFpInductionDescriptor ( PHINode * Phi ) const

Returns a pointer to the induction descriptor, if Phi is an integer or floating point induction.

Definition at line 1070 of file LoopVectorizationLegality.cpp.

References llvm::MapVector< KeyT, ValueT, MapType, VectorType >::find(), getInductionVars(), llvm::InductionDescriptor::IK_FpInduction, llvm::InductionDescriptor::IK_IntInduction, and isInductionPhi().

◆ getLAI()

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

inline

Definition at line 365 of file LoopVectorizationLegality.h.

Referenced by llvm::LoopVectorizationPlanner::executePlan(), llvm::ARMTTIImpl::preferPredicateOverEpilogue(), llvm::LoopVectorizePass::processLoop(), and processLoopInVPlanNativePath().

◆ getMaxSafeDepDistBytes()

unsigned llvm::LoopVectorizationLegality::getMaxSafeDepDistBytes ( )

inline

Definition at line 371 of file LoopVectorizationLegality.h.

References llvm::LoopAccessInfo::getMaxSafeDepDistBytes().

◆ getMaxSafeVectorWidthInBits()

uint64_t llvm::LoopVectorizationLegality::getMaxSafeVectorWidthInBits ( ) const

inline

Definition at line 373 of file LoopVectorizationLegality.h.

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

◆ getNumLoads()

unsigned llvm::LoopVectorizationLegality::getNumLoads ( ) const

inline

Definition at line 386 of file LoopVectorizationLegality.h.

References llvm::LoopAccessInfo::getNumLoads().

◆ getNumStores()

unsigned llvm::LoopVectorizationLegality::getNumStores ( ) const

inline

Definition at line 385 of file LoopVectorizationLegality.h.

References llvm::LoopAccessInfo::getNumStores().

◆ getPointerInductionDescriptor()

const InductionDescriptor * llvm::LoopVectorizationLegality::getPointerInductionDescriptor ( PHINode * Phi ) const

Returns a pointer to the induction descriptor, if Phi is pointer induction.

Definition at line 1081 of file LoopVectorizationLegality.cpp.

References llvm::MapVector< KeyT, ValueT, MapType, VectorType >::find(), getInductionVars(), llvm::InductionDescriptor::IK_PtrInduction, and isInductionPhi().

◆ getPrimaryInduction()

PHINode * llvm::LoopVectorizationLegality::getPrimaryInduction ( )

inline

Returns the primary induction variable.

Definition at line 285 of file LoopVectorizationLegality.h.

◆ getReductionVars()

const ReductionList & llvm::LoopVectorizationLegality::getReductionVars ( ) const

inline

Returns the reduction variables found in the loop.

Definition at line 288 of file LoopVectorizationLegality.h.

Referenced by canVectorizeFPMath(), isInvariantAddressOfReduction(), isInvariantStoreOfReduction(), llvm::AArch64TTIImpl::preferPredicateOverEpilogue(), and prepareToFoldTailByMasking().

◆ getRuntimePointerChecking()

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

inline

Returns the information that we collected about runtime memory check.

Definition at line 361 of file LoopVectorizationLegality.h.

References llvm::LoopAccessInfo::getRuntimePointerChecking().

◆ getSinkAfter()

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

inline

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

Definition at line 297 of file LoopVectorizationLegality.h.

◆ getWidestInductionType()

Type * llvm::LoopVectorizationLegality::getWidestInductionType ( )

inline

Returns the widest induction type.

Definition at line 300 of file LoopVectorizationLegality.h.

◆ hasStride()

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

inline

Definition at line 377 of file LoopVectorizationLegality.h.

References llvm::LoopAccessInfo::hasStride().

◆ isCastedInductionVariable()

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

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 1090 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 448 of file LoopVectorizationLegality.cpp.

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