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InstCombine: Canonicalize addrspacecast between different element types

Browse Source 
addrspacecast X addrspace(M)* to Y addrspace(N)*

-->

bitcast X addrspace(M)* to Y addrspace(M)*
addrspacecast Y addrspace(M)* to Y addrspace(N)*

Updat all affected tests and add several new tests in addrspacecast.ll.

This patch is based on http://reviews.llvm.org/D2186 (authored by Matt
Arsenault) with fixes and more tests.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210375 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jingyue Wu
2014-06-06 21:52:55 +00:00
parent a51acc7631
commit c77dec905a
5 changed files with 125 additions and 17 deletions
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24
lib/Transforms/InstCombine/InstCombineCasts.cpp
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@ -1434,7 +1434,12 @@ Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) {
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Src)) {
// If casting the result of a getelementptr instruction with no offset, turn
// this into a cast of the original pointer!
if (GEP->hasAllZeroIndices()) {
if (GEP->hasAllZeroIndices() &&
// If CI is an addrspacecast and GEP changes the poiner type, merging
// GEP into CI would undo canonicalizing addrspacecast with different
// pointer types, causing infinite loops.
(!isa<AddrSpaceCastInst>(CI) ||
GEP->getType() == GEP->getPointerOperand()->getType())) {
// Changing the cast operand is usually not a good idea but it is safe
// here because the pointer operand is being replaced with another
// pointer operand so the opcode doesn't need to change.
@ -1904,5 +1909,22 @@ Instruction *InstCombiner::visitBitCast(BitCastInst &CI) {
}
Instruction *InstCombiner::visitAddrSpaceCast(AddrSpaceCastInst &CI) {
// If the destination pointer element type is not the the same as the source's
// do the addrspacecast to the same type, and then the bitcast in the new
// address space. This allows the cast to be exposed to other transforms.
Value *Src = CI.getOperand(0);
PointerType *SrcTy = cast<PointerType>(Src->getType()->getScalarType());
PointerType *DestTy = cast<PointerType>(CI.getType()->getScalarType());
Type *DestElemTy = DestTy->getElementType();
if (SrcTy->getElementType() != DestElemTy) {
Type *MidTy = PointerType::get(DestElemTy, SrcTy->getAddressSpace());
if (CI.getType()->isVectorTy()) // Handle vectors of pointers.
MidTy = VectorType::get(MidTy, CI.getType()->getVectorNumElements());
Value *NewBitCast = Builder->CreateBitCast(Src, MidTy);
return new AddrSpaceCastInst(NewBitCast, CI.getType());
}
return commonPointerCastTransforms(CI);
}