Utility class for getting and setting loop vectorizer hints in the form of loop metadata. More...

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

Public Types
enum	ForceKind { FK_Undefined = -1 , FK_Disabled = 0 , FK_Enabled = 1 }

enum	ScalableForceKind { SK_Unspecified = -1 , SK_FixedWidthOnly = 0 , SK_PreferScalable = 1 }

Public Member Functions
	LoopVectorizeHints (const Loop L, bool InterleaveOnlyWhenForced, OptimizationRemarkEmitter &ORE, const TargetTransformInfo TTI=nullptr)

void	setAlreadyVectorized ()
	Mark the loop L as already vectorized by setting the width to 1.

bool	allowVectorization (Function F, Loop L, bool VectorizeOnlyWhenForced) const

void	emitRemarkWithHints () const
	Dumps all the hint information.

ElementCount	getWidth () const

unsigned	getInterleave () const

unsigned	getIsVectorized () const

unsigned	getPredicate () const

enum ForceKind	getForce () const

bool	isScalableVectorizationDisabled () const

const char *	vectorizeAnalysisPassName () const
	If hints are provided that force vectorization, use the AlwaysPrint pass name to force the frontend to print the diagnostic.

bool	allowReordering () const
	When enabling loop hints are provided we allow the vectorizer to change the order of operations that is given by the scalar loop.

bool	isPotentiallyUnsafe () const

void	setPotentiallyUnsafe ()

Detailed Description

Utility class for getting and setting loop vectorizer hints in the form of loop metadata.

This class keeps a number of loop annotations locally (as member variables) and can, upon request, write them back as metadata on the loop. It will initially scan the loop for existing metadata, and will update the local values based on information in the loop. We cannot write all values to metadata, as the mere presence of some info, for example 'force', means a decision has been made. So, we need to be careful NOT to add them if the user hasn't specifically asked so.

Definition at line 60 of file LoopVectorizationLegality.h.

Member Enumeration Documentation

◆ ForceKind

enum llvm::LoopVectorizeHints::ForceKind

Enumerator
FK_Undefined	Not selected.
FK_Disabled	Forcing disabled.
FK_Enabled	Forcing enabled.

Definition at line 107 of file LoopVectorizationLegality.h.

◆ ScalableForceKind

enum llvm::LoopVectorizeHints::ScalableForceKind

Enumerator

SK_Unspecified

Not selected.

SK_FixedWidthOnly

Disables vectorization with scalable vectors.

SK_PreferScalable

Vectorize loops using scalable vectors or fixed-width vectors, but favor scalable vectors when the cost-model is inconclusive.

This is the default when the scalable.enable hint is enabled through a pragma.

Definition at line 113 of file LoopVectorizationLegality.h.

Constructor & Destructor Documentation

◆ LoopVectorizeHints()

llvm::LoopVectorizeHints::LoopVectorizeHints	(	const Loop *	L,
		bool	InterleaveOnlyWhenForced,
		OptimizationRemarkEmitter &	ORE,
		const TargetTransformInfo *	TTI = `nullptr`
	)

Definition at line 103 of file LoopVectorizationLegality.cpp.

References llvm::dbgs(), llvm::TargetTransformInfo::enableScalableVectorization(), ForceScalableVectorization, llvm::ElementCount::getFixed(), getInterleave(), getWidth(), llvm::VectorizerParams::isInterleaveForced(), LLVM_DEBUG, SK_FixedWidthOnly, SK_PreferScalable, SK_Unspecified, and llvm::VectorizerParams::VectorizationInterleave.

Member Function Documentation

◆ allowReordering()

bool llvm::LoopVectorizeHints::allowReordering ( ) const

When enabling loop hints are provided we allow the vectorizer to change the order of operations that is given by the scalar loop.

This is not enabled by default because can be unsafe or inefficient. For example, reordering floating-point operations will change the way round-off error accumulates in the loop.

Definition at line 246 of file LoopVectorizationLegality.cpp.

References FK_Enabled, getForce(), getWidth(), and llvm::HintsAllowReordering.

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