LLVM  4.0.0
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LoopAccessAnalysis.cpp File Reference
#include "llvm/Analysis/LoopAccessAnalysis.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/EquivalenceClasses.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/AliasSetTracker.h"
#include "llvm/Analysis/LoopAnalysisManager.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/MemoryLocation.h"
#include "llvm/Analysis/OptimizationDiagnosticInfo.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/Pass.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <cstdlib>
#include <iterator>
#include <utility>
#include <vector>

Go to the source code of this file.

Namespaces

 llvm
 Compute iterated dominance frontiers using a linear time algorithm.
 

Macros

#define DEBUG_TYPE   "loop-accesses"
 
#define LAA_NAME   "loop-accesses"
 

Functions

static const SCEVgetMinFromExprs (const SCEV *I, const SCEV *J, ScalarEvolution *SE)
 Compare I and J and return the minimum. More...
 
static bool hasComputableBounds (PredicatedScalarEvolution &PSE, const ValueToValueMap &Strides, Value *Ptr, Loop *L)
 Check whether a pointer can participate in a runtime bounds check. More...
 
static bool isNoWrap (PredicatedScalarEvolution &PSE, const ValueToValueMap &Strides, Value *Ptr, Loop *L)
 Check whether a pointer address cannot wrap. More...
 
static bool isInBoundsGep (Value *Ptr)
 
static bool isNoWrapAddRec (Value *Ptr, const SCEVAddRecExpr *AR, PredicatedScalarEvolution &PSE, const Loop *L)
 Return true if an AddRec pointer Ptr is unsigned non-wrapping, i.e. More...
 
static ValuegetPointerOperand (Value *I)
 Take the pointer operand from the Load/Store instruction. More...
 
static unsigned getAddressSpaceOperand (Value *I)
 Take the address space operand from the Load/Store instruction. More...
 
static bool areStridedAccessesIndependent (uint64_t Distance, uint64_t Stride, uint64_t TypeByteSize)
 Check the dependence for two accesses with the same stride Stride. More...
 
static InstructiongetFirstInst (Instruction *FirstInst, Value *V, Instruction *Loc)
 
static PointerBounds expandBounds (const RuntimePointerChecking::CheckingPtrGroup *CG, Loop *TheLoop, Instruction *Loc, SCEVExpander &Exp, ScalarEvolution *SE, const RuntimePointerChecking &PtrRtChecking)
 Expand code for the lower and upper bound of the pointer group CG in TheLoop. More...
 
static SmallVector< std::pair
< PointerBounds, PointerBounds >, 4 > 
expandBounds (const SmallVectorImpl< RuntimePointerChecking::PointerCheck > &PointerChecks, Loop *L, Instruction *Loc, ScalarEvolution *SE, SCEVExpander &Exp, const RuntimePointerChecking &PtrRtChecking)
 Turns a collection of checks into a collection of expanded upper and lower bounds for both pointers in the check. More...
 
Passllvm::createLAAPass ()
 

Variables

static cl::opt< unsigned, trueVectorizationFactor ("force-vector-width", cl::Hidden, cl::desc("Sets the SIMD width. Zero is autoselect."), cl::location(VectorizerParams::VectorizationFactor))
 
static cl::opt< unsigned, trueVectorizationInterleave ("force-vector-interleave", cl::Hidden, cl::desc("Sets the vectorization interleave count. ""Zero is autoselect."), cl::location(VectorizerParams::VectorizationInterleave))
 
static cl::opt< unsigned, trueRuntimeMemoryCheckThreshold ("runtime-memory-check-threshold", cl::Hidden, cl::desc("When performing memory disambiguation checks at runtime do not ""generate more than this number of comparisons (default = 8)."), cl::location(VectorizerParams::RuntimeMemoryCheckThreshold), cl::init(8))
 
static cl::opt< unsignedMemoryCheckMergeThreshold ("memory-check-merge-threshold", cl::Hidden, cl::desc("Maximum number of comparisons done when trying to merge ""runtime memory checks. (default = 100)"), cl::init(100))
 The maximum iterations used to merge memory checks. More...
 
static cl::opt< unsignedMaxDependences ("max-dependences", cl::Hidden, cl::desc("Maximum number of dependences collected by ""loop-access analysis (default = 100)"), cl::init(100))
 We collect dependences up to this threshold. More...
 
static cl::opt< boolEnableMemAccessVersioning ("enable-mem-access-versioning", cl::init(true), cl::Hidden, cl::desc("Enable symbolic stride memory access versioning"))
 This enables versioning on the strides of symbolically striding memory accesses in code like the following. More...
 
static cl::opt< boolEnableForwardingConflictDetection ("store-to-load-forwarding-conflict-detection", cl::Hidden, cl::desc("Enable conflict detection in loop-access analysis"), cl::init(true))
 Enable store-to-load forwarding conflict detection. More...
 
static const char laa_name [] = "Loop Access Analysis"
 

Macro Definition Documentation

#define DEBUG_TYPE   "loop-accesses"

Definition at line 72 of file LoopAccessAnalysis.cpp.

#define LAA_NAME   "loop-accesses"

Definition at line 2112 of file LoopAccessAnalysis.cpp.

Function Documentation

static bool areStridedAccessesIndependent ( uint64_t  Distance,
uint64_t  Stride,
uint64_t  TypeByteSize 
)
static

Check the dependence for two accesses with the same stride Stride.

Distance is the positive distance and TypeByteSize is type size in bytes.

Returns
true if they are independent.

Definition at line 1213 of file LoopAccessAnalysis.cpp.

References assert().

static PointerBounds expandBounds ( const RuntimePointerChecking::CheckingPtrGroup CG,
Loop TheLoop,
Instruction Loc,
SCEVExpander Exp,
ScalarEvolution SE,
const RuntimePointerChecking PtrRtChecking 
)
static
static SmallVector<std::pair<PointerBounds, PointerBounds>, 4> expandBounds ( const SmallVectorImpl< RuntimePointerChecking::PointerCheck > &  PointerChecks,
Loop L,
Instruction Loc,
ScalarEvolution SE,
SCEVExpander Exp,
const RuntimePointerChecking PtrRtChecking 
)
static

Turns a collection of checks into a collection of expanded upper and lower bounds for both pointers in the check.

Definition at line 1901 of file LoopAccessAnalysis.cpp.

References Check(), expandBounds(), and llvm::transform().

static unsigned getAddressSpaceOperand ( Value I)
static

Take the address space operand from the Load/Store instruction.

Returns -1 if this is not a valid Load/Store instruction.

Definition at line 1053 of file LoopAccessAnalysis.cpp.

References L.

Referenced by llvm::isConsecutiveAccess().

static Instruction* getFirstInst ( Instruction FirstInst,
Value V,
Instruction Loc 
)
static
static const SCEV* getMinFromExprs ( const SCEV I,
const SCEV J,
ScalarEvolution SE 
)
static

Compare I and J and return the minimum.

Return nullptr in case we couldn't find an answer.

Definition at line 288 of file LoopAccessAnalysis.cpp.

References C, llvm::dyn_cast(), llvm::ScalarEvolution::getMinusSCEV(), llvm::SCEVConstant::getValue(), I, and llvm::ConstantInt::isNegative().

Referenced by llvm::RuntimePointerChecking::CheckingPtrGroup::addPointer().

static Value* getPointerOperand ( Value I)
static

Take the pointer operand from the Load/Store instruction.

Returns NULL if this is not a valid Load/Store instruction.

Definition at line 1043 of file LoopAccessAnalysis.cpp.

References SI.

Referenced by llvm::isConsecutiveAccess().

static bool hasComputableBounds ( PredicatedScalarEvolution PSE,
const ValueToValueMap Strides,
Value Ptr,
Loop L 
)
static
static bool isInBoundsGep ( Value Ptr)
static

Definition at line 879 of file LoopAccessAnalysis.cpp.

References GEP.

Referenced by llvm::getPtrStride().

static bool isNoWrap ( PredicatedScalarEvolution PSE,
const ValueToValueMap Strides,
Value Ptr,
Loop L 
)
static
static bool isNoWrapAddRec ( Value Ptr,
const SCEVAddRecExpr AR,
PredicatedScalarEvolution PSE,
const Loop L 
)
static

Return true if an AddRec pointer Ptr is unsigned non-wrapping, i.e.

monotonically increasing/decreasing.

Definition at line 887 of file LoopAccessAnalysis.cpp.

References llvm::dyn_cast(), llvm::SCEV::FlagNSW, GEP, llvm::SCEVNAryExpr::getNoWrapFlags(), llvm::PredicatedScalarEvolution::getSCEV(), llvm::make_range(), llvm::SCEV::NoWrapMask, and Ptr.

Referenced by llvm::getPtrStride().

Variable Documentation

cl::opt<bool> EnableForwardingConflictDetection("store-to-load-forwarding-conflict-detection", cl::Hidden, cl::desc("Enable conflict detection in loop-access analysis"), cl::init(true))
static

Enable store-to-load forwarding conflict detection.

This option can be disabled for correctness testing.

cl::opt<bool> EnableMemAccessVersioning("enable-mem-access-versioning", cl::init(true), cl::Hidden, cl::desc("Enable symbolic stride memory access versioning"))
static

This enables versioning on the strides of symbolically striding memory accesses in code like the following.

for (i = 0; i < N; ++i) A[i * Stride1] += B[i * Stride2] ...

Will be roughly translated to if (Stride1 == 1 && Stride2 == 1) { for (i = 0; i < N; i+=4) A[i:i+3] += ... } else ...

const char laa_name[] = "Loop Access Analysis"
static

Definition at line 2111 of file LoopAccessAnalysis.cpp.

cl::opt<unsigned> MaxDependences("max-dependences", cl::Hidden, cl::desc("Maximum number of dependences collected by ""loop-access analysis (default = 100)"), cl::init(100))
static

We collect dependences up to this threshold.

Referenced by llvm::MemoryDepChecker::areDepsSafe().

cl::opt<unsigned> MemoryCheckMergeThreshold("memory-check-merge-threshold", cl::Hidden, cl::desc("Maximum number of comparisons done when trying to merge ""runtime memory checks. (default = 100)"), cl::init(100))
static

The maximum iterations used to merge memory checks.

cl::opt<unsigned, true> RuntimeMemoryCheckThreshold("runtime-memory-check-threshold", cl::Hidden, cl::desc("When performing memory disambiguation checks at runtime do not ""generate more than this number of comparisons (default = 8)."), cl::location(VectorizerParams::RuntimeMemoryCheckThreshold), cl::init(8))
static
cl::opt<unsigned, true> VectorizationFactor("force-vector-width", cl::Hidden, cl::desc("Sets the SIMD width. Zero is autoselect."), cl::location(VectorizerParams::VectorizationFactor))
static
cl::opt<unsigned, true> VectorizationInterleave("force-vector-interleave", cl::Hidden, cl::desc("Sets the vectorization interleave count. ""Zero is autoselect."), cl::location(VectorizerParams::VectorizationInterleave))
static