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Don't eliminate bitcast instructions that change the type of a pointer 

llvm-svn: 48971
This commit is contained in:
Nate Begeman 2008-03-31 00:22:16 +00:00
parent c00c35a857
commit f2b0b0eb17
2 changed files with 26 additions and 19 deletions
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5
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -7575,6 +7575,11 @@ Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
const Type *DstElTy = DstPTy->getElementType();
const Type *SrcElTy = SrcPTy->getElementType();
// If the address spaces don't match, don't eliminate the bitcast, which is
// required for changing types.
if (SrcPTy->getAddressSpace() != DstPTy->getAddressSpace())
return 0;
// If we are casting a malloc or alloca to a pointer to a type of the same
// size, rewrite the allocation instruction to allocate the "right" type.
if (AllocationInst *AI = dyn_cast<AllocationInst>(Src))

40
llvm/lib/VMCore/ConstantFold.cpp
View File

@ -96,27 +96,29 @@ static Constant *FoldBitCast(Constant *V, const Type *DestTy) {
// Check to see if we are casting a pointer to an aggregate to a pointer to
// the first element. If so, return the appropriate GEP instruction.
if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) {
SmallVector<Value*, 8> IdxList;
IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
const Type *ElTy = PTy->getElementType();
while (ElTy != DPTy->getElementType()) {
if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
if (STy->getNumElements() == 0) break;
ElTy = STy->getElementType(0);
IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
} else if (const SequentialType *STy = dyn_cast<SequentialType>(ElTy)) {
if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
ElTy = STy->getElementType();
IdxList.push_back(IdxList[0]);
} else {
break;
if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy))
if (PTy->getAddressSpace() == DPTy->getAddressSpace()) {
SmallVector<Value*, 8> IdxList;
IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
const Type *ElTy = PTy->getElementType();
while (ElTy != DPTy->getElementType()) {
if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
if (STy->getNumElements() == 0) break;
ElTy = STy->getElementType(0);
IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
} else if (const SequentialType *STy =
dyn_cast<SequentialType>(ElTy)) {
if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
ElTy = STy->getElementType();
IdxList.push_back(IdxList[0]);
} else {
break;
}
}
if (ElTy == DPTy->getElementType())
return ConstantExpr::getGetElementPtr(V, &IdxList[0], IdxList.size());
}
if (ElTy == DPTy->getElementType())
return ConstantExpr::getGetElementPtr(V, &IdxList[0], IdxList.size());
}
// Handle casts from one vector constant to another. We know that the src
// and dest type have the same size (otherwise its an illegal cast).