llvm::IndexedReference Class Reference

Represents a memory reference as a base pointer and a set of indexing operations. More...

#include "llvm/Analysis/LoopCacheAnalysis.h"

Public Member Functions
	IndexedReference (Instruction &StoreOrLoadInst, const LoopInfo &LI, ScalarEvolution &SE)
	Construct an indexed reference given a StoreOrLoadInst instruction.
bool	isValid () const
const SCEV *	getBasePointer () const
size_t	getNumSubscripts () const
const SCEV *	getSubscript (unsigned SubNum) const
const SCEV *	getFirstSubscript () const
const SCEV *	getLastSubscript () const
std::optional< bool >	hasSpacialReuse (const IndexedReference &Other, unsigned CLS, AAResults &AA) const
	Return true/false if the current object and the indexed reference Other are/aren't in the same cache line of size CLS.
std::optional< bool >	hasTemporalReuse (const IndexedReference &Other, unsigned MaxDistance, const Loop &L, DependenceInfo &DI, AAResults &AA) const
	Return true if the current object and the indexed reference Other have distance smaller than MaxDistance in the dimension associated with the given loop L.
CacheCostTy	computeRefCost (const Loop &L, unsigned CLS) const
	Compute the cost of the reference w.r.t.

Friends
raw_ostream &	operator<< (raw_ostream &OS, const IndexedReference &R)

Detailed Description

Represents a memory reference as a base pointer and a set of indexing operations.

For example given the array reference A[i][2j+1][3k+2] in a 3-dim loop nest: for(i=0;i<n;++i) for(j=0;j<m;++j) for(k=0;k<o;++k) ... A[i][2j+1][3k+2] ... We expect: BasePointer -> A Subscripts -> [{0,+,1}<for.i>][{1,+,2}<for.j>][{2,+,3}<for.k>] Sizes -> [m][o][4]

Definition at line 48 of file LoopCacheAnalysis.h.

Constructor & Destructor Documentation

IndexedReference()

IndexedReference::IndexedReference	(	Instruction &	StoreOrLoadInst,
		const LoopInfo &	LI,
		ScalarEvolution &	SE
	)

Construct an indexed reference given a StoreOrLoadInst instruction.

Definition at line 147 of file LoopCacheAnalysis.cpp.

References assert(), llvm::dbgs(), and LLVM_DEBUG.

Member Function Documentation

computeRefCost()

CacheCostTy IndexedReference::computeRefCost	(	const Loop &	L,
		unsigned	CLS
	)		const

Compute the cost of the reference w.r.t.

the given loop L when it is considered in the innermost position in the loop nest. The cost is defined as:

• equal to one if the reference is loop invariant, or
• equal to '(TripCount * stride) / cache_line_size' if:
  • the reference stride is less than the cache line size, and
  • the coefficient of this loop's index variable used in all other subscripts is zero
• or otherwise equal to 'TripCount'.

Definition at line 272 of file LoopCacheAnalysis.cpp.

References assert(), CacheLineSize, computeTripCount(), llvm::dbgs(), llvm::ScalarEvolution::getConstant(), llvm::SCEVAddRecExpr::getLoop(), llvm::ScalarEvolution::getMulExpr(), llvm::ScalarEvolution::getNoopOrAnyExtend(), llvm::ScalarEvolution::getNoopOrZeroExtend(), getNumSubscripts(), getSubscript(), llvm::SCEV::getType(), llvm::ScalarEvolution::getUDivCeilSCEV(), llvm::ScalarEvolution::getWiderType(), I, llvm::raw_ostream::indent(), llvm::CacheCost::InvalidCost, and LLVM_DEBUG.

getBasePointer()

const SCEV * llvm::IndexedReference::getBasePointer ( ) const

inline

Definition at line 57 of file LoopCacheAnalysis.h.

getFirstSubscript()

const SCEV * llvm::IndexedReference::getFirstSubscript ( ) const

inline

Definition at line 63 of file LoopCacheAnalysis.h.

References assert().

getLastSubscript()

const SCEV * llvm::IndexedReference::getLastSubscript ( ) const

inline

Definition at line 67 of file LoopCacheAnalysis.h.

References assert().

Referenced by hasSpacialReuse().

getNumSubscripts()

size_t llvm::IndexedReference::getNumSubscripts ( ) const

inline

Definition at line 58 of file LoopCacheAnalysis.h.

Referenced by computeRefCost(), getSubscript(), and hasSpacialReuse().

getSubscript()

const SCEV * llvm::IndexedReference::getSubscript ( unsigned  SubNum ) const

inline

Definition at line 59 of file LoopCacheAnalysis.h.

References assert(), and getNumSubscripts().

Referenced by computeRefCost(), and hasSpacialReuse().

hasSpacialReuse()

std::optional< bool > IndexedReference::hasSpacialReuse	(	const IndexedReference &	Other,
		unsigned	CLS,
		AAResults &	AA
	)		const

Return true/false if the current object and the indexed reference Other are/aren't in the same cache line of size CLS.

Two references are in the same chace line iff the distance between them in the innermost dimension is less than the cache line size. Return std::nullopt if unsure.

Definition at line 160 of file LoopCacheAnalysis.cpp.

References assert(), llvm::dbgs(), getLastSubscript(), llvm::ScalarEvolution::getMinusSCEV(), getNumSubscripts(), llvm::ConstantInt::getSExtValue(), getSubscript(), llvm::SCEVConstant::getValue(), llvm::raw_ostream::indent(), LLVM_DEBUG, and llvm::Other.

hasTemporalReuse()

std::optional< bool > IndexedReference::hasTemporalReuse	(	const IndexedReference &	Other,
		unsigned	MaxDistance,
		const Loop &	L,
		DependenceInfo &	DI,
		AAResults &	AA
	)		const

Return true if the current object and the indexed reference Other have distance smaller than MaxDistance in the dimension associated with the given loop L.

Return false if the distance is not smaller than MaxDistance and std::nullopt if unsure.

Definition at line 215 of file LoopCacheAnalysis.cpp.

References assert(), D, llvm::dbgs(), llvm::DependenceInfo::depends(), llvm::ConstantInt::getSExtValue(), llvm::SCEVConstant::getValue(), llvm::ConstantInt::isZero(), LLVM_DEBUG, and llvm::Other.

isValid()

bool llvm::IndexedReference::isValid ( ) const

inline

Definition at line 56 of file LoopCacheAnalysis.h.

Friends And Related Function Documentation

operator<<

raw_ostream & operator<< ( raw_ostream &  OS, const IndexedReference &  R  )

friend

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The documentation for this class was generated from the following files:

• include/llvm/Analysis/LoopCacheAnalysis.h
• lib/Analysis/LoopCacheAnalysis.cpp