LLVM 20.0.0git
Public Member Functions | Static Public Member Functions | List of all members
llvm::LoopAccessInfo Class Reference

Drive the analysis of memory accesses in the loop. More...

#include "llvm/Analysis/LoopAccessAnalysis.h"

Public Member Functions

 LoopAccessInfo (Loop *L, ScalarEvolution *SE, const TargetTransformInfo *TTI, const TargetLibraryInfo *TLI, AAResults *AA, DominatorTree *DT, LoopInfo *LI)
 
bool canVectorizeMemory () const
 Return true we can analyze the memory accesses in the loop and there are no memory dependence cycles.
 
bool hasConvergentOp () const
 Return true if there is a convergent operation in the loop.
 
const RuntimePointerCheckinggetRuntimePointerChecking () const
 
unsigned getNumRuntimePointerChecks () const
 Number of memchecks required to prove independence of otherwise may-alias pointers.
 
bool isInvariant (Value *V) const
 Returns true if value V is loop invariant.
 
unsigned getNumStores () const
 
unsigned getNumLoads () const
 
const OptimizationRemarkAnalysisgetReport () const
 The diagnostics report generated for the analysis.
 
const MemoryDepCheckergetDepChecker () const
 the Memory Dependence Checker which can determine the loop-independent and loop-carried dependences between memory accesses.
 
SmallVector< Instruction *, 4 > getInstructionsForAccess (Value *Ptr, bool isWrite) const
 Return the list of instructions that use Ptr to read or write memory.
 
const DenseMap< Value *, const SCEV * > & getSymbolicStrides () const
 If an access has a symbolic strides, this maps the pointer value to the stride symbol.
 
void print (raw_ostream &OS, unsigned Depth=0) const
 Print the information about the memory accesses in the loop.
 
bool hasStoreStoreDependenceInvolvingLoopInvariantAddress () const
 Return true if the loop has memory dependence involving two stores to an invariant address, else return false.
 
bool hasLoadStoreDependenceInvolvingLoopInvariantAddress () const
 Return true if the loop has memory dependence involving a load and a store to an invariant address, else return false.
 
ArrayRef< StoreInst * > getStoresToInvariantAddresses () const
 Return the list of stores to invariant addresses.
 
const PredicatedScalarEvolutiongetPSE () const
 Used to add runtime SCEV checks.
 

Static Public Member Functions

static bool blockNeedsPredication (BasicBlock *BB, Loop *TheLoop, DominatorTree *DT)
 Return true if the block BB needs to be predicated in order for the loop to be vectorized.
 

Detailed Description

Drive the analysis of memory accesses in the loop.

This class is responsible for analyzing the memory accesses of a loop. It collects the accesses and then its main helper the AccessAnalysis class finds and categorizes the dependences in buildDependenceSets.

For memory dependences that can be analyzed at compile time, it determines whether the dependence is part of cycle inhibiting vectorization. This work is delegated to the MemoryDepChecker class.

For memory dependences that cannot be determined at compile time, it generates run-time checks to prove independence. This is done by AccessAnalysis::canCheckPtrAtRT and the checks are maintained by the RuntimePointerCheck class.

If pointers can wrap or can't be expressed as affine AddRec expressions by ScalarEvolution, we will generate run-time checks by emitting a SCEVUnionPredicate.

Checks for both memory dependences and the SCEV predicates contained in the PSE must be emitted in order for the results of this analysis to be valid.

Definition at line 625 of file LoopAccessAnalysis.h.

Constructor & Destructor Documentation

◆ LoopAccessInfo()

LoopAccessInfo::LoopAccessInfo ( Loop L,
ScalarEvolution SE,
const TargetTransformInfo TTI,
const TargetLibraryInfo TLI,
AAResults AA,
DominatorTree DT,
LoopInfo LI 
)

Member Function Documentation

◆ blockNeedsPredication()

bool LoopAccessInfo::blockNeedsPredication ( BasicBlock BB,
Loop TheLoop,
DominatorTree DT 
)
static

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

Definition at line 2764 of file LoopAccessAnalysis.cpp.

References assert(), llvm::LoopBase< BlockT, LoopT >::contains(), llvm::DominatorTree::dominates(), and llvm::LoopBase< BlockT, LoopT >::getLoopLatch().

Referenced by llvm::LoopVectorizationLegality::blockNeedsPredication().

◆ canVectorizeMemory()

bool llvm::LoopAccessInfo::canVectorizeMemory ( ) const
inline

Return true we can analyze the memory accesses in the loop and there are no memory dependence cycles.

Note that for dependences between loads & stores with uniform addresses, hasStoreStoreDependenceInvolvingLoopInvariantAddress and hasLoadStoreDependenceInvolvingLoopInvariantAddress also need to be checked.

Definition at line 637 of file LoopAccessAnalysis.h.

◆ getDepChecker()

const MemoryDepChecker & llvm::LoopAccessInfo::getDepChecker ( ) const
inline

the Memory Dependence Checker which can determine the loop-independent and loop-carried dependences between memory accesses.

Definition at line 671 of file LoopAccessAnalysis.h.

Referenced by llvm::LoopVersioning::annotateLoopWithNoAlias(), llvm::LoopVectorizationLegality::getMaxSafeVectorWidthInBits(), llvm::LoopVectorizationLegality::isSafeForAnyVectorWidth(), and print().

◆ getInstructionsForAccess()

SmallVector< Instruction *, 4 > llvm::LoopAccessInfo::getInstructionsForAccess ( Value Ptr,
bool  isWrite 
) const
inline

Return the list of instructions that use Ptr to read or write memory.

Definition at line 675 of file LoopAccessAnalysis.h.

References Ptr.

◆ getNumLoads()

unsigned llvm::LoopAccessInfo::getNumLoads ( ) const
inline

Definition at line 663 of file LoopAccessAnalysis.h.

Referenced by llvm::LoopVectorizationLegality::getNumLoads().

◆ getNumRuntimePointerChecks()

unsigned llvm::LoopAccessInfo::getNumRuntimePointerChecks ( ) const
inline

Number of memchecks required to prove independence of otherwise may-alias pointers.

Definition at line 650 of file LoopAccessAnalysis.h.

◆ getNumStores()

unsigned llvm::LoopAccessInfo::getNumStores ( ) const
inline

Definition at line 662 of file LoopAccessAnalysis.h.

Referenced by llvm::LoopVectorizationLegality::getNumStores().

◆ getPSE()

const PredicatedScalarEvolution & llvm::LoopAccessInfo::getPSE ( ) const
inline

Used to add runtime SCEV checks.

Simplifies SCEV expressions and converts them to a more usable form. All SCEV expressions during the analysis should be re-written (and therefore simplified) according to PSE. A user of LoopAccessAnalysis will need to emit the runtime checks associated with this predicate.

Definition at line 711 of file LoopAccessAnalysis.h.

Referenced by canTailPredicateLoop().

◆ getReport()

const OptimizationRemarkAnalysis * llvm::LoopAccessInfo::getReport ( ) const
inline

The diagnostics report generated for the analysis.

E.g. why we couldn't analyze the loop.

Definition at line 667 of file LoopAccessAnalysis.h.

◆ getRuntimePointerChecking()

const RuntimePointerChecking * llvm::LoopAccessInfo::getRuntimePointerChecking ( ) const
inline

◆ getStoresToInvariantAddresses()

ArrayRef< StoreInst * > llvm::LoopAccessInfo::getStoresToInvariantAddresses ( ) const
inline

Return the list of stores to invariant addresses.

Definition at line 702 of file LoopAccessAnalysis.h.

◆ getSymbolicStrides()

const DenseMap< Value *, const SCEV * > & llvm::LoopAccessInfo::getSymbolicStrides ( ) const
inline

If an access has a symbolic strides, this maps the pointer value to the stride symbol.

Definition at line 682 of file LoopAccessAnalysis.h.

Referenced by llvm::InterleavedAccessInfo::analyzeInterleaving(), llvm::LoopVectorizationLegality::isConsecutivePtr(), and llvm::LoopVectorizationCostModel::runtimeChecksRequired().

◆ hasConvergentOp()

bool llvm::LoopAccessInfo::hasConvergentOp ( ) const
inline

Return true if there is a convergent operation in the loop.

There may still be reported runtime pointer checks that would be required, but it is not legal to insert them.

Definition at line 642 of file LoopAccessAnalysis.h.

◆ hasLoadStoreDependenceInvolvingLoopInvariantAddress()

bool llvm::LoopAccessInfo::hasLoadStoreDependenceInvolvingLoopInvariantAddress ( ) const
inline

Return true if the loop has memory dependence involving a load and a store to an invariant address, else return false.

Definition at line 697 of file LoopAccessAnalysis.h.

◆ hasStoreStoreDependenceInvolvingLoopInvariantAddress()

bool llvm::LoopAccessInfo::hasStoreStoreDependenceInvolvingLoopInvariantAddress ( ) const
inline

Return true if the loop has memory dependence involving two stores to an invariant address, else return false.

Definition at line 691 of file LoopAccessAnalysis.h.

◆ isInvariant()

bool LoopAccessInfo::isInvariant ( Value V) const

◆ print()

void LoopAccessInfo::print ( raw_ostream OS,
unsigned  Depth = 0 
) const

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