//===- AliasAnalysis.cpp - Generic Alias Analysis Interface Implementation -==//
//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
// This file implements the generic AliasAnalysis interface which is used as the
// common interface used by all clients and implementations of alias analysis.
//
//
//===----------------------------------------------------------------------===//
-#include "llvm/Analysis/BasicAliasAnalysis.h"
-#include "llvm/BasicBlock.h"
-#include "llvm/Support/InstVisitor.h"
-#include "llvm/iMemory.h"
-#include "llvm/Constants.h"
-#include "llvm/GlobalValue.h"
+#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Pass.h"
+#include "llvm/BasicBlock.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/Type.h"
+#include "llvm/Target/TargetData.h"
+using namespace llvm;
// Register the AliasAnalysis interface, providing a nice name to refer to.
-static RegisterAnalysisGroup<AliasAnalysis> X("Alias Analysis");
-
-// CanModify - Define a little visitor class that is used to check to see if
-// arbitrary chunks of code can modify a specified pointer.
-//
namespace {
- struct CanModify : public InstVisitor<CanModify, bool> {
- const AliasAnalysis &AA;
- const Value *Ptr;
-
- CanModify(const AliasAnalysis *aa, const Value *ptr)
- : AA(*aa), Ptr(ptr) {}
+ RegisterAnalysisGroup<AliasAnalysis> Z("Alias Analysis");
+}
+char AliasAnalysis::ID = 0;
- bool visitInvokeInst(InvokeInst &II) {
- return AA.canInvokeModify(II, Ptr);
- }
- bool visitCallInst(CallInst &CI) {
- return AA.canCallModify(CI, Ptr);
- }
- bool visitStoreInst(StoreInst &SI) {
- assert(!SI.hasIndices() && "Only support stores without indexing!");
- return AA.alias(Ptr, SI.getOperand(1));
- }
+//===----------------------------------------------------------------------===//
+// Default chaining methods
+//===----------------------------------------------------------------------===//
- // Other instructions do not alias anything.
- bool visitInstruction(Instruction &I) { return false; }
- };
+AliasAnalysis::AliasResult
+AliasAnalysis::alias(const Value *V1, unsigned V1Size,
+ const Value *V2, unsigned V2Size) {
+ assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
+ return AA->alias(V1, V1Size, V2, V2Size);
}
-// AliasAnalysis destructor: DO NOT move this to the header file for
-// AliasAnalysis or else clients of the AliasAnalysis class may not depend on
-// the AliasAnalysis.o file in the current .a file, causing alias analysis
-// support to not be included in the tool correctly!
-//
-AliasAnalysis::~AliasAnalysis() {}
+void AliasAnalysis::getMustAliases(Value *P, std::vector<Value*> &RetVals) {
+ assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
+ return AA->getMustAliases(P, RetVals);
+}
-// canBasicBlockModify - Return true if it is possible for execution of the
-// specified basic block to modify the value pointed to by Ptr.
-//
-bool AliasAnalysis::canBasicBlockModify(const BasicBlock &bb,
- const Value *Ptr) const {
- CanModify CM(this, Ptr);
- BasicBlock &BB = const_cast<BasicBlock&>(bb);
+bool AliasAnalysis::pointsToConstantMemory(const Value *P) {
+ assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
+ return AA->pointsToConstantMemory(P);
+}
- for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
- if (CM.visit(I)) // Check every instruction in the basic block...
- return true;
+AliasAnalysis::ModRefBehavior
+AliasAnalysis::getModRefBehavior(Function *F, CallSite CS,
+ std::vector<PointerAccessInfo> *Info) {
+ assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
+ return AA->getModRefBehavior(F, CS, Info);
+}
- return false;
+bool AliasAnalysis::hasNoModRefInfoForCalls() const {
+ assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
+ return AA->hasNoModRefInfoForCalls();
}
-// canInstructionRangeModify - Return true if it is possible for the execution
-// of the specified instructions to modify the value pointed to by Ptr. The
-// instructions to consider are all of the instructions in the range of [I1,I2]
-// INCLUSIVE. I1 and I2 must be in the same basic block.
-//
-bool AliasAnalysis::canInstructionRangeModify(const Instruction &I1,
- const Instruction &I2,
- const Value *Ptr) const {
- assert(I1.getParent() == I2.getParent() &&
- "Instructions not in same basic block!");
- CanModify CM(this, Ptr);
- BasicBlock::iterator I = const_cast<Instruction*>(&I1);
- BasicBlock::iterator E = const_cast<Instruction*>(&I2);
- ++E; // Convert from inclusive to exclusive range.
+void AliasAnalysis::deleteValue(Value *V) {
+ assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
+ AA->deleteValue(V);
+}
- for (; I != E; ++I)
- if (CM.visit(I)) // Check every instruction in the basic block...
- return true;
+void AliasAnalysis::copyValue(Value *From, Value *To) {
+ assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
+ AA->copyValue(From, To);
+}
- return false;
+AliasAnalysis::ModRefResult
+AliasAnalysis::getModRefInfo(CallSite CS1, CallSite CS2) {
+ // FIXME: we can do better.
+ assert(AA && "AA didn't call InitializeAliasAnalysis in its run method!");
+ return AA->getModRefInfo(CS1, CS2);
}
+
//===----------------------------------------------------------------------===//
-// BasicAliasAnalysis Pass Implementation
+// AliasAnalysis non-virtual helper method implementation
//===----------------------------------------------------------------------===//
-//
-// Because of the way .a files work, the implementation of the
-// BasicAliasAnalysis class MUST be in the AliasAnalysis file itself, or else we
-// run the risk of AliasAnalysis being used, but the default implementation not
-// being linked into the tool that uses it. As such, we register and implement
-// the class here.
-//
-namespace {
- // Register this pass...
- RegisterOpt<BasicAliasAnalysis>
- X("basicaa", "Basic Alias Analysis (default AA impl)");
- // Declare that we implement the AliasAnalysis interface
- RegisterAnalysisGroup<AliasAnalysis, BasicAliasAnalysis, true> Y;
-} // End of anonymous namespace
+AliasAnalysis::ModRefResult
+AliasAnalysis::getModRefInfo(LoadInst *L, Value *P, unsigned Size) {
+ return alias(L->getOperand(0), TD->getTypeStoreSize(L->getType()),
+ P, Size) ? Ref : NoModRef;
+}
+AliasAnalysis::ModRefResult
+AliasAnalysis::getModRefInfo(StoreInst *S, Value *P, unsigned Size) {
+ // If the stored address cannot alias the pointer in question, then the
+ // pointer cannot be modified by the store.
+ if (!alias(S->getOperand(1),
+ TD->getTypeStoreSize(S->getOperand(0)->getType()), P, Size))
+ return NoModRef;
+
+ // If the pointer is a pointer to constant memory, then it could not have been
+ // modified by this store.
+ return pointsToConstantMemory(P) ? NoModRef : Mod;
+}
+AliasAnalysis::ModRefBehavior
+AliasAnalysis::getModRefBehavior(CallSite CS,
+ std::vector<PointerAccessInfo> *Info) {
+ if (CS.doesNotAccessMemory() &&
+ // FIXME: workaround gcc bootstrap breakage
+ CS.getCalledFunction() && CS.getCalledFunction()->isDeclaration())
+ // Can't do better than this.
+ return DoesNotAccessMemory;
+ ModRefBehavior MRB = UnknownModRefBehavior;
+ if (Function *F = CS.getCalledFunction())
+ MRB = getModRefBehavior(F, CS, Info);
+ if (MRB != DoesNotAccessMemory && CS.onlyReadsMemory() &&
+ // FIXME: workaround gcc bootstrap breakage
+ CS.getCalledFunction() && CS.getCalledFunction()->isDeclaration())
+ return OnlyReadsMemory;
+ return MRB;
+}
-// hasUniqueAddress - Return true if the
-static inline bool hasUniqueAddress(const Value *V) {
- return isa<GlobalValue>(V) || isa<MallocInst>(V) || isa<AllocaInst>(V);
+AliasAnalysis::ModRefBehavior
+AliasAnalysis::getModRefBehavior(Function *F,
+ std::vector<PointerAccessInfo> *Info) {
+ if (F->doesNotAccessMemory() &&
+ // FIXME: workaround gcc bootstrap breakage
+ F->isDeclaration())
+ // Can't do better than this.
+ return DoesNotAccessMemory;
+ ModRefBehavior MRB = getModRefBehavior(F, CallSite(), Info);
+ if (MRB != DoesNotAccessMemory && F->onlyReadsMemory() &&
+ // FIXME: workaround gcc bootstrap breakage
+ F->isDeclaration())
+ return OnlyReadsMemory;
+ return MRB;
}
-AliasAnalysis::Result BasicAliasAnalysis::alias(const Value *V1,
- const Value *V2) const {
- // Strip off constant pointer refs if they exist
- if (const ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(V1))
- V1 = CPR->getValue();
- if (const ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(V2))
- V2 = CPR->getValue();
+AliasAnalysis::ModRefResult
+AliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
+ ModRefResult Mask = ModRef;
+ ModRefBehavior MRB = getModRefBehavior(CS);
+ if (MRB == OnlyReadsMemory)
+ Mask = Ref;
+ else if (MRB == DoesNotAccessMemory)
+ return NoModRef;
+
+ if (!AA) return Mask;
+
+ // If P points to a constant memory location, the call definitely could not
+ // modify the memory location.
+ if ((Mask & Mod) && AA->pointsToConstantMemory(P))
+ Mask = ModRefResult(Mask & ~Mod);
- // Are we checking for alias of the same value?
- if (V1 == V2) return MustAlias;
+ return ModRefResult(Mask & AA->getModRefInfo(CS, P, Size));
+}
- if (!isa<PointerType>(V1->getType()) || !isa<PointerType>(V2->getType()))
- return NoAlias; // Scalars cannot alias each other
+// AliasAnalysis destructor: DO NOT move this to the header file for
+// AliasAnalysis or else clients of the AliasAnalysis class may not depend on
+// the AliasAnalysis.o file in the current .a file, causing alias analysis
+// support to not be included in the tool correctly!
+//
+AliasAnalysis::~AliasAnalysis() {}
- bool V1Unique = hasUniqueAddress(V1);
- bool V2Unique = hasUniqueAddress(V2);
+/// setTargetData - Subclasses must call this method to initialize the
+/// AliasAnalysis interface before any other methods are called.
+///
+void AliasAnalysis::InitializeAliasAnalysis(Pass *P) {
+ TD = &P->getAnalysis<TargetData>();
+ AA = &P->getAnalysis<AliasAnalysis>();
+}
- if (V1Unique && V2Unique)
- return NoAlias; // Can't alias if they are different unique values
+// getAnalysisUsage - All alias analysis implementations should invoke this
+// directly (using AliasAnalysis::getAnalysisUsage(AU)) to make sure that
+// TargetData is required by the pass.
+void AliasAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<TargetData>(); // All AA's need TargetData.
+ AU.addRequired<AliasAnalysis>(); // All AA's chain
+}
- if ((V1Unique && isa<ConstantPointerNull>(V2)) ||
- (V2Unique && isa<ConstantPointerNull>(V1)))
- return NoAlias; // Unique values don't alias null
+/// canBasicBlockModify - Return true if it is possible for execution of the
+/// specified basic block to modify the value pointed to by Ptr.
+///
+bool AliasAnalysis::canBasicBlockModify(const BasicBlock &BB,
+ const Value *Ptr, unsigned Size) {
+ return canInstructionRangeModify(BB.front(), BB.back(), Ptr, Size);
+}
- // TODO: Handle getelementptr with nonzero offset
+/// canInstructionRangeModify - Return true if it is possible for the execution
+/// of the specified instructions to modify the value pointed to by Ptr. The
+/// instructions to consider are all of the instructions in the range of [I1,I2]
+/// INCLUSIVE. I1 and I2 must be in the same basic block.
+///
+bool AliasAnalysis::canInstructionRangeModify(const Instruction &I1,
+ const Instruction &I2,
+ const Value *Ptr, unsigned Size) {
+ assert(I1.getParent() == I2.getParent() &&
+ "Instructions not in same basic block!");
+ BasicBlock::iterator I = const_cast<Instruction*>(&I1);
+ BasicBlock::iterator E = const_cast<Instruction*>(&I2);
+ ++E; // Convert from inclusive to exclusive range.
- return MayAlias;
+ for (; I != E; ++I) // Check every instruction in range
+ if (getModRefInfo(I, const_cast<Value*>(Ptr), Size) & Mod)
+ return true;
+ return false;
}
+
+// Because of the way .a files work, we must force the BasicAA implementation to
+// be pulled in if the AliasAnalysis classes are pulled in. Otherwise we run
+// the risk of AliasAnalysis being used, but the default implementation not
+// being linked into the tool that uses it.
+DEFINING_FILE_FOR(AliasAnalysis)