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[InstCombine] improve variable name and use 'match'; NFC

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'width' of a vector usually refers to the bit-width.

https://bugs.llvm.org/show_bug.cgi?id=39016
shows a case where we could extend this fold to handle
a case where the number of elements in the bitcasted
vector is not equal to the resulting value.

llvm-svn: 342902
This commit is contained in:
Sanjay Patel 2018-09-24 16:39:03 +00:00
parent a69b45a477
commit bfdf7bad58
1 changed files with 15 additions and 13 deletions
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28
lib/Transforms/InstCombine/InstCombineVectorOps.cpp
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@ -181,10 +181,10 @@ Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
// If extracting a specified index from the vector, see if we can recursively
// find a previously computed scalar that was inserted into the vector.
if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) {
unsigned VectorWidth = EI.getVectorOperandType()->getNumElements();
unsigned NumElts = EI.getVectorOperandType()->getNumElements();
// InstSimplify should handle cases where the index is invalid.
if (!IdxC->getValue().ule(VectorWidth))
if (!IdxC->getValue().ule(NumElts))
return nullptr;
unsigned IndexVal = IdxC->getZExtValue();
@ -192,9 +192,9 @@ Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
// This instruction only demands the single element from the input vector.
// If the input vector has a single use, simplify it based on this use
// property.
if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) {
APInt UndefElts(VectorWidth, 0);
APInt DemandedMask(VectorWidth, 0);
if (EI.getOperand(0)->hasOneUse() && NumElts != 1) {
APInt UndefElts(NumElts, 0);
APInt DemandedMask(NumElts, 0);
DemandedMask.setBit(IndexVal);
if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0), DemandedMask,
UndefElts)) {
@ -203,14 +203,16 @@ Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
}
}
// If this extractelement is directly using a bitcast from a vector of
// the same number of elements, see if we can find the source element from
// it. In this case, we will end up needing to bitcast the scalars.
if (BitCastInst *BCI = dyn_cast<BitCastInst>(EI.getOperand(0))) {
if (VectorType *VT = dyn_cast<VectorType>(BCI->getOperand(0)->getType()))
if (VT->getNumElements() == VectorWidth)
if (Value *Elt = findScalarElement(BCI->getOperand(0), IndexVal))
return new BitCastInst(Elt, EI.getType());
Value *X;
if (match(EI.getVectorOperand(), m_BitCast(m_Value(X))) &&
X->getType()->isVectorTy()) {
// If this extractelement is using a bitcast from a vector of the same
// number of elements, see if we can find the source element from the
// source vector:
// extelt (bitcast VecX), IdxC --> bitcast X[IdxC]
if (X->getType()->getVectorNumElements() == NumElts)
if (Value *Elt = findScalarElement(X, IndexVal))
return new BitCastInst(Elt, EI.getType());
}
// If there's a vector PHI feeding a scalar use through this extractelement