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Factorize code: remove variants of "strip off
pointer bitcasts and GEP's", and centralize the logic in Value::getUnderlyingObject. The difference with stripPointerCasts is that stripPointerCasts only strips GEPs if all indices are zero, while getUnderlyingObject strips GEPs no matter what the indices are. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56922 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -228,11 +228,20 @@ public:
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/// stripPointerCasts - This method strips off any unneeded pointer
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/// casts from the specified value, returning the original uncasted value.
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/// Note that the returned value is guaranteed to have pointer type.
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/// Note that the returned value has pointer type if the specified value does.
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Value *stripPointerCasts();
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const Value *stripPointerCasts() const {
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return const_cast<Value*>(this)->stripPointerCasts();
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}
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/// getUnderlyingObject - This method strips off any GEP address adjustments
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/// and pointer casts from the specified value, returning the original object
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/// being addressed. Note that the returned value has pointer type if the
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/// specified value does.
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Value *getUnderlyingObject();
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const Value *getUnderlyingObject() const {
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return const_cast<Value*>(this)->getUnderlyingObject();
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}
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};
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inline std::ostream &operator<<(std::ostream &OS, const Value &V) {
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@ -76,30 +76,6 @@ static bool AddressMightEscape(const Value *V) {
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return false;
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}
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/// getUnderlyingObject - This traverses the use chain to figure out what object
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/// the specified value points to. If the value points to, or is derived from,
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/// a unique object or an argument, return it. This returns:
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/// Arguments, GlobalVariables, Functions, Allocas, Mallocs.
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static const Value *getUnderlyingObject(const Value *V) {
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if (!isa<PointerType>(V->getType())) return V;
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// If we are at some type of object, return it. GlobalValues and Allocations
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// have unique addresses.
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if (isa<GlobalValue>(V) || isa<AllocationInst>(V) || isa<Argument>(V))
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return V;
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// Traverse through different addressing mechanisms...
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if (const Instruction *I = dyn_cast<Instruction>(V)) {
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if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I))
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return getUnderlyingObject(I->getOperand(0));
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} else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
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if (CE->getOpcode() == Instruction::BitCast ||
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CE->getOpcode() == Instruction::GetElementPtr)
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return getUnderlyingObject(CE->getOperand(0));
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}
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return V;
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}
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static const User *isGEP(const Value *V) {
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if (isa<GetElementPtrInst>(V) ||
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(isa<ConstantExpr>(V) &&
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@ -314,7 +290,7 @@ ImmutablePass *llvm::createBasicAliasAnalysisPass() {
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/// global) or not.
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bool BasicAliasAnalysis::pointsToConstantMemory(const Value *P) {
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if (const GlobalVariable *GV =
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dyn_cast<GlobalVariable>(getUnderlyingObject(P)))
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dyn_cast<GlobalVariable>(P->getUnderlyingObject()))
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return GV->isConstant();
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return false;
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}
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@ -327,7 +303,7 @@ bool BasicAliasAnalysis::pointsToConstantMemory(const Value *P) {
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AliasAnalysis::ModRefResult
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BasicAliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
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if (!isa<Constant>(P)) {
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const Value *Object = getUnderlyingObject(P);
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const Value *Object = P->getUnderlyingObject();
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// If this is a tail call and P points to a stack location, we know that
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// the tail call cannot access or modify the local stack.
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@ -390,8 +366,8 @@ BasicAliasAnalysis::alias(const Value *V1, unsigned V1Size,
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return alias(V1, V1Size, I->getOperand(0), V2Size);
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// Figure out what objects these things are pointing to if we can...
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const Value *O1 = getUnderlyingObject(V1);
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const Value *O2 = getUnderlyingObject(V2);
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const Value *O1 = V1->getUnderlyingObject();
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const Value *O2 = V2->getUnderlyingObject();
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if (O1 != O2) {
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// If V1/V2 point to two different objects we know that we have no alias.
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@ -157,29 +157,6 @@ static RegisterAnalysisGroup<AliasAnalysis> Y(X);
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Pass *llvm::createGlobalsModRefPass() { return new GlobalsModRef(); }
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/// getUnderlyingObject - This traverses the use chain to figure out what object
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/// the specified value points to. If the value points to, or is derived from,
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/// a global object, return it.
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static Value *getUnderlyingObject(Value *V) {
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if (!isa<PointerType>(V->getType())) return V;
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// If we are at some type of object... return it.
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if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) return GV;
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// Traverse through different addressing mechanisms.
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if (Instruction *I = dyn_cast<Instruction>(V)) {
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if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I))
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return getUnderlyingObject(I->getOperand(0));
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} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
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if (CE->getOpcode() == Instruction::BitCast ||
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CE->getOpcode() == Instruction::GetElementPtr)
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return getUnderlyingObject(CE->getOperand(0));
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}
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// Otherwise, we don't know what this is, return it as the base pointer.
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return V;
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}
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/// AnalyzeGlobals - Scan through the users of all of the internal
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/// GlobalValue's in the program. If none of them have their "address taken"
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/// (really, their address passed to something nontrivial), record this fact,
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@ -304,7 +281,7 @@ bool GlobalsModRef::AnalyzeIndirectGlobalMemory(GlobalValue *GV) {
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continue;
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// Check the value being stored.
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Value *Ptr = getUnderlyingObject(SI->getOperand(0));
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Value *Ptr = SI->getOperand(0)->getUnderlyingObject();
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if (isa<MallocInst>(Ptr)) {
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// Okay, easy case.
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@ -468,8 +445,8 @@ AliasAnalysis::AliasResult
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GlobalsModRef::alias(const Value *V1, unsigned V1Size,
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const Value *V2, unsigned V2Size) {
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// Get the base object these pointers point to.
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Value *UV1 = getUnderlyingObject(const_cast<Value*>(V1));
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Value *UV2 = getUnderlyingObject(const_cast<Value*>(V2));
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Value *UV1 = const_cast<Value*>(V1->getUnderlyingObject());
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Value *UV2 = const_cast<Value*>(V2->getUnderlyingObject());
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// If either of the underlying values is a global, they may be non-addr-taken
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// globals, which we can answer queries about.
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@ -526,7 +503,7 @@ GlobalsModRef::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
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// If we are asking for mod/ref info of a direct call with a pointer to a
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// global we are tracking, return information if we have it.
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if (GlobalValue *GV = dyn_cast<GlobalValue>(getUnderlyingObject(P)))
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if (GlobalValue *GV = dyn_cast<GlobalValue>(P->getUnderlyingObject()))
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if (GV->hasInternalLinkage())
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if (Function *F = CS.getCalledFunction())
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if (NonAddressTakenGlobals.count(GV))
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@ -59,28 +59,7 @@ namespace {
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SetVector<Instruction*>& possiblyDead);
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void DeleteDeadInstructionChains(Instruction *I,
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SetVector<Instruction*> &DeadInsts);
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/// Find the base pointer that a pointer came from
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/// Because this is used to find pointers that originate
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/// from allocas, it is safe to ignore GEP indices, since
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/// either the store will be in the alloca, and thus dead,
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/// or beyond the end of the alloca, and thus undefined.
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void TranslatePointerBitCasts(Value*& v, bool zeroGepsOnly = false) {
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assert(isa<PointerType>(v->getType()) &&
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"Translating a non-pointer type?");
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while (true) {
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if (BitCastInst* C = dyn_cast<BitCastInst>(v))
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v = C->getOperand(0);
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else if (GetElementPtrInst* G = dyn_cast<GetElementPtrInst>(v))
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if (!zeroGepsOnly || G->hasAllZeroIndices()) {
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v = G->getOperand(0);
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} else {
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break;
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}
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else
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break;
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}
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}
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// getAnalysisUsage - We require post dominance frontiers (aka Control
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// Dependence Graph)
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@ -119,20 +98,20 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
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// If we find a store or a free...
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if (!isa<StoreInst>(BBI) && !isa<FreeInst>(BBI))
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continue;
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Value* pointer = 0;
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if (StoreInst* S = dyn_cast<StoreInst>(BBI)) {
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if (!S->isVolatile())
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pointer = S->getPointerOperand();
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else
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if (S->isVolatile())
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continue;
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} else
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pointer = S->getPointerOperand();
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} else {
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pointer = cast<FreeInst>(BBI)->getPointerOperand();
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TranslatePointerBitCasts(pointer, true);
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}
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pointer = pointer->stripPointerCasts();
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StoreInst*& last = lastStore[pointer];
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bool deletedStore = false;
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// ... to a pointer that has been stored to before...
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if (last) {
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Instruction* dep = MD.getDependency(BBI);
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@ -302,10 +281,9 @@ bool DSE::handleEndBlock(BasicBlock& BB,
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// If we find a store whose pointer is dead...
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if (StoreInst* S = dyn_cast<StoreInst>(BBI)) {
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if (!S->isVolatile()) {
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Value* pointerOperand = S->getPointerOperand();
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// See through pointer-to-pointer bitcasts
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TranslatePointerBitCasts(pointerOperand);
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Value* pointerOperand = S->getPointerOperand()->getUnderlyingObject();
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// Alloca'd pointers or byval arguments (which are functionally like
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// alloca's) are valid candidates for removal.
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if (deadPointers.count(pointerOperand)) {
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@ -330,9 +308,8 @@ bool DSE::handleEndBlock(BasicBlock& BB,
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// We can also remove memcpy's to local variables at the end of a function
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} else if (MemCpyInst* M = dyn_cast<MemCpyInst>(BBI)) {
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Value* dest = M->getDest();
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TranslatePointerBitCasts(dest);
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Value* dest = M->getDest()->getUnderlyingObject();
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if (deadPointers.count(dest)) {
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MD.removeInstruction(M);
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@ -480,9 +457,9 @@ bool DSE::handleEndBlock(BasicBlock& BB,
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if (!killPointer)
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continue;
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TranslatePointerBitCasts(killPointer);
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killPointer = killPointer->getUnderlyingObject();
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// Deal with undead pointers
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MadeChange |= RemoveUndeadPointers(killPointer, killPointerSize, BBI,
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deadPointers, possiblyDead);
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@ -992,16 +992,7 @@ bool GVN::processLoad(LoadInst *L, DenseMap<Value*, LoadInst*> &lastLoad,
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isa<AllocationInst>(dep)) {
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// Check that this load is actually from the
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// allocation we found
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Value* v = L->getOperand(0);
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while (true) {
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if (BitCastInst *BC = dyn_cast<BitCastInst>(v))
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v = BC->getOperand(0);
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else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(v))
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v = GEP->getOperand(0);
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else
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break;
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}
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if (v == dep) {
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if (L->getOperand(0)->getUnderlyingObject() == dep) {
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// If this load depends directly on an allocation, there isn't
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// anything stored there; therefore, we can optimize this load
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// to undef.
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@ -10367,28 +10367,6 @@ static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
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return false;
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}
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/// GetUnderlyingObject - Trace through a series of getelementptrs and bitcasts
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/// until we find the underlying object a pointer is referring to or something
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/// we don't understand. Note that the returned pointer may be offset from the
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/// input, because we ignore GEP indices.
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static Value *GetUnderlyingObject(Value *Ptr) {
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while (1) {
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if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) {
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if (CE->getOpcode() == Instruction::BitCast ||
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CE->getOpcode() == Instruction::GetElementPtr)
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Ptr = CE->getOperand(0);
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else
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return Ptr;
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} else if (BitCastInst *BCI = dyn_cast<BitCastInst>(Ptr)) {
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Ptr = BCI->getOperand(0);
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} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
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Ptr = GEP->getOperand(0);
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} else {
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return Ptr;
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}
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}
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}
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Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
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Value *Op = LI.getOperand(0);
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@ -10479,7 +10457,7 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
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// If this load comes from anywhere in a constant global, and if the global
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// is all undef or zero, we know what it loads.
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if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GetUnderlyingObject(Op))) {
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if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op->getUnderlyingObject())){
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if (GV->isConstant() && GV->hasInitializer()) {
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if (GV->getInitializer()->isNullValue())
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return ReplaceInstUsesWith(LI, Constant::getNullValue(LI.getType()));
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@ -322,22 +322,20 @@ void Value::replaceAllUsesWith(Value *New) {
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}
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Value *Value::stripPointerCasts() {
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if (!isa<PointerType>(getType()))
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return this;
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if (ConstantExpr *CE = dyn_cast<ConstantExpr>(this)) {
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if (CE->getOpcode() == Instruction::BitCast) {
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if (isa<PointerType>(CE->getOperand(0)->getType()))
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return CE->getOperand(0)->stripPointerCasts();
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return CE->getOperand(0)->stripPointerCasts();
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} else if (CE->getOpcode() == Instruction::GetElementPtr) {
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for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
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if (!CE->getOperand(i)->isNullValue())
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return this;
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return CE->getOperand(0)->stripPointerCasts();
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}
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return this;
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}
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if (BitCastInst *CI = dyn_cast<BitCastInst>(this)) {
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if (isa<PointerType>(CI->getOperand(0)->getType()))
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return CI->getOperand(0)->stripPointerCasts();
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} else if (BitCastInst *CI = dyn_cast<BitCastInst>(this)) {
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return CI->getOperand(0)->stripPointerCasts();
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} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(this)) {
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if (GEP->hasAllZeroIndices())
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return GEP->getOperand(0)->stripPointerCasts();
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@ -345,6 +343,21 @@ Value *Value::stripPointerCasts() {
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return this;
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}
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Value *Value::getUnderlyingObject() {
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if (!isa<PointerType>(getType()))
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return this;
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if (Instruction *I = dyn_cast<Instruction>(this)) {
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if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I))
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return I->getOperand(0)->getUnderlyingObject();
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} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(this)) {
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if (CE->getOpcode() == Instruction::BitCast ||
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CE->getOpcode() == Instruction::GetElementPtr)
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return CE->getOperand(0)->getUnderlyingObject();
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}
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return this;
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}
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//===----------------------------------------------------------------------===//
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// User Class
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//===----------------------------------------------------------------------===//
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