//
// This differs from traditional loop dependence analysis in that it tests
// for dependencies within a single iteration of a loop, rather than
-// dependences between different iterations.
+// dependencies between different iterations.
//
// ScalarEvolution has a more complete understanding of pointer arithmetic
// than BasicAliasAnalysis' collection of ad-hoc analyses.
//
//===----------------------------------------------------------------------===//
+#include "llvm/Analysis/Passes.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
-#include "llvm/Analysis/Passes.h"
+#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
using namespace llvm;
public:
static char ID; // Class identification, replacement for typeinfo
- ScalarEvolutionAliasAnalysis() : FunctionPass(&ID), SE(0) {}
+ ScalarEvolutionAliasAnalysis() : FunctionPass(ID), SE(nullptr) {
+ initializeScalarEvolutionAliasAnalysisPass(
+ *PassRegistry::getPassRegistry());
+ }
/// getAdjustedAnalysisPointer - This method is used when a pass implements
/// an analysis interface through multiple inheritance. If needed, it
/// should override this to adjust the this pointer as needed for the
/// specified pass info.
- virtual void *getAdjustedAnalysisPointer(const PassInfo *PI) {
- if (PI->isPassID(&AliasAnalysis::ID))
+ void *getAdjustedAnalysisPointer(AnalysisID PI) override {
+ if (PI == &AliasAnalysis::ID)
return (AliasAnalysis*)this;
return this;
}
private:
- virtual void getAnalysisUsage(AnalysisUsage &AU) const;
- virtual bool runOnFunction(Function &F);
- virtual AliasResult alias(const Value *V1, unsigned V1Size,
- const Value *V2, unsigned V2Size);
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+ bool runOnFunction(Function &F) override;
+ AliasResult alias(const MemoryLocation &LocA,
+ const MemoryLocation &LocB) override;
Value *GetBaseValue(const SCEV *S);
};
// Register this pass...
char ScalarEvolutionAliasAnalysis::ID = 0;
-static RegisterPass<ScalarEvolutionAliasAnalysis>
-X("scev-aa", "ScalarEvolution-based Alias Analysis", false, true);
-
-// Declare that we implement the AliasAnalysis interface
-static RegisterAnalysisGroup<AliasAnalysis> Y(X);
+INITIALIZE_AG_PASS_BEGIN(ScalarEvolutionAliasAnalysis, AliasAnalysis, "scev-aa",
+ "ScalarEvolution-based Alias Analysis", false, true, false)
+INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
+INITIALIZE_AG_PASS_END(ScalarEvolutionAliasAnalysis, AliasAnalysis, "scev-aa",
+ "ScalarEvolution-based Alias Analysis", false, true, false)
FunctionPass *llvm::createScalarEvolutionAliasAnalysisPass() {
return new ScalarEvolutionAliasAnalysis();
bool
ScalarEvolutionAliasAnalysis::runOnFunction(Function &F) {
- InitializeAliasAnalysis(this);
+ InitializeAliasAnalysis(this, &F.getParent()->getDataLayout());
SE = &getAnalysis<ScalarEvolution>();
return false;
}
return U->getValue();
}
// No Identified object found.
- return 0;
+ return nullptr;
}
AliasAnalysis::AliasResult
-ScalarEvolutionAliasAnalysis::alias(const Value *A, unsigned ASize,
- const Value *B, unsigned BSize) {
+ScalarEvolutionAliasAnalysis::alias(const MemoryLocation &LocA,
+ const MemoryLocation &LocB) {
+ // If either of the memory references is empty, it doesn't matter what the
+ // pointer values are. This allows the code below to ignore this special
+ // case.
+ if (LocA.Size == 0 || LocB.Size == 0)
+ return NoAlias;
+
// This is ScalarEvolutionAliasAnalysis. Get the SCEVs!
- const SCEV *AS = SE->getSCEV(const_cast<Value *>(A));
- const SCEV *BS = SE->getSCEV(const_cast<Value *>(B));
+ const SCEV *AS = SE->getSCEV(const_cast<Value *>(LocA.Ptr));
+ const SCEV *BS = SE->getSCEV(const_cast<Value *>(LocB.Ptr));
// If they evaluate to the same expression, it's a MustAlias.
if (AS == BS) return MustAlias;
if (SE->getEffectiveSCEVType(AS->getType()) ==
SE->getEffectiveSCEVType(BS->getType())) {
unsigned BitWidth = SE->getTypeSizeInBits(AS->getType());
- APInt AI(BitWidth, ASize);
+ APInt ASizeInt(BitWidth, LocA.Size);
+ APInt BSizeInt(BitWidth, LocB.Size);
+
+ // Compute the difference between the two pointers.
const SCEV *BA = SE->getMinusSCEV(BS, AS);
- if (AI.ule(SE->getUnsignedRange(BA).getUnsignedMin())) {
- APInt BI(BitWidth, BSize);
- const SCEV *AB = SE->getMinusSCEV(AS, BS);
- if (BI.ule(SE->getUnsignedRange(AB).getUnsignedMin()))
- return NoAlias;
- }
+
+ // Test whether the difference is known to be great enough that memory of
+ // the given sizes don't overlap. This assumes that ASizeInt and BSizeInt
+ // are non-zero, which is special-cased above.
+ if (ASizeInt.ule(SE->getUnsignedRange(BA).getUnsignedMin()) &&
+ (-BSizeInt).uge(SE->getUnsignedRange(BA).getUnsignedMax()))
+ return NoAlias;
+
+ // Folding the subtraction while preserving range information can be tricky
+ // (because of INT_MIN, etc.); if the prior test failed, swap AS and BS
+ // and try again to see if things fold better that way.
+
+ // Compute the difference between the two pointers.
+ const SCEV *AB = SE->getMinusSCEV(AS, BS);
+
+ // Test whether the difference is known to be great enough that memory of
+ // the given sizes don't overlap. This assumes that ASizeInt and BSizeInt
+ // are non-zero, which is special-cased above.
+ if (BSizeInt.ule(SE->getUnsignedRange(AB).getUnsignedMin()) &&
+ (-ASizeInt).uge(SE->getUnsignedRange(AB).getUnsignedMax()))
+ return NoAlias;
}
// If ScalarEvolution can find an underlying object, form a new query.
// inttoptr and ptrtoint operators.
Value *AO = GetBaseValue(AS);
Value *BO = GetBaseValue(BS);
- if ((AO && AO != A) || (BO && BO != B))
- if (alias(AO ? AO : A, AO ? ~0u : ASize,
- BO ? BO : B, BO ? ~0u : BSize) == NoAlias)
+ if ((AO && AO != LocA.Ptr) || (BO && BO != LocB.Ptr))
+ if (alias(MemoryLocation(AO ? AO : LocA.Ptr, AO ? +UnknownSize : LocA.Size,
+ AO ? AAMDNodes() : LocA.AATags),
+ MemoryLocation(BO ? BO : LocB.Ptr, BO ? +UnknownSize : LocB.Size,
+ BO ? AAMDNodes() : LocB.AATags)) == NoAlias)
return NoAlias;
// Forward the query to the next analysis.
- return AliasAnalysis::alias(A, ASize, B, BSize);
+ return AliasAnalysis::alias(LocA, LocB);
}
projects / oota-llvm.git / blobdiff