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Fix 9173.

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Add more folding patterns to constant expressions of vector selects and vector
bitcasts.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125393 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem
2011-02-11 19:37:55 +00:00
parent 5a4552ca42
commit d2f27ead2d
3 changed files with 67 additions and 0 deletions
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40
lib/VMCore/ConstantFold.cpp
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@@ -42,6 +42,10 @@ using namespace llvm;
/// input vector constant are all simple integer or FP values.
static Constant *BitCastConstantVector(ConstantVector *CV,
const VectorType *DstTy) {
if (CV->isAllOnesValue()) return Constant::getAllOnesValue(DstTy);
if (CV->isNullValue()) return Constant::getNullValue(DstTy);
// If this cast changes element count then we can't handle it here:
// doing so requires endianness information. This should be handled by
// Analysis/ConstantFolding.cpp
@@ -689,6 +693,42 @@ Constant *llvm::ConstantFoldSelectInstruction(Constant *Cond,
if (ConstantInt *CB = dyn_cast<ConstantInt>(Cond))
return CB->getZExtValue() ? V1 : V2;
// Check for zero aggregate and ConstantVector of zeros
if (Cond->isNullValue()) return V2;
if (ConstantVector* CondV = dyn_cast<ConstantVector>(Cond)) {
if (CondV->isAllOnesValue()) return V1;
const VectorType *VTy = cast<VectorType>(V1->getType());
ConstantVector *CP1 = dyn_cast<ConstantVector>(V1);
ConstantVector *CP2 = dyn_cast<ConstantVector>(V2);
if ((CP1 || isa<ConstantAggregateZero>(V1)) &&
(CP2 || isa<ConstantAggregateZero>(V2))) {
// Find the element type of the returned vector
const Type *EltTy = VTy->getElementType();
unsigned NumElem = VTy->getNumElements();
std::vector<Constant*> Res(NumElem);
bool Valid = true;
for (unsigned i = 0; i < NumElem; ++i) {
ConstantInt* c = dyn_cast<ConstantInt>(CondV->getOperand(i));
if (!c) {
Valid = false;
break;
}
Constant *C1 = CP1 ? CP1->getOperand(i) : Constant::getNullValue(EltTy);
Constant *C2 = CP2 ? CP2->getOperand(i) : Constant::getNullValue(EltTy);
Res[i] = c->getZExtValue() ? C1 : C2;
}
// If we were able to build the vector, return it
if (Valid) return ConstantVector::get(Res);
}
}
if (isa<UndefValue>(V1)) return V2;
if (isa<UndefValue>(V2)) return V1;
if (isa<UndefValue>(Cond)) return V1;