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[InstCombine] add bitcast+extelt helper function; NFC 

We can handle patterns where the elements have different 
sizes, so refactoring ahead of trying to add another blob
within these clauses.

llvm-svn: 342918
This commit is contained in:
Sanjay Patel 2018-09-24 20:41:22 +00:00
parent dc48c4fff4
commit 4674c7765d
1 changed files with 26 additions and 14 deletions
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40
llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
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@ -166,6 +166,29 @@ Instruction *InstCombiner::scalarizePHI(ExtractElementInst &EI, PHINode *PN) {
return &EI;
}
static Instruction *foldBitcastExtElt(ExtractElementInst &Ext,
InstCombiner::BuilderTy &Builder) {
Value *X;
uint64_t ExtIndexC;
if (!match(Ext.getVectorOperand(), m_BitCast(m_Value(X))) ||
!X->getType()->isVectorTy() ||
!match(Ext.getIndexOperand(), m_ConstantInt(ExtIndexC)))
return nullptr;
// 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), IndexC --> bitcast X[IndexC]
Type *SrcTy = X->getType();
Type *DestTy = Ext.getType();
unsigned NumSrcElts = SrcTy->getVectorNumElements();
unsigned NumElts = Ext.getVectorOperandType()->getNumElements();
if (NumSrcElts == NumElts)
if (Value *Elt = findScalarElement(X, ExtIndexC))
return new BitCastInst(Elt, DestTy);
return nullptr;
}
Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
if (Value *V = SimplifyExtractElementInst(EI.getVectorOperand(),
EI.getIndexOperand(),
@ -187,15 +210,13 @@ Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
if (!IdxC->getValue().ule(NumElts))
return nullptr;
unsigned IndexVal = IdxC->getZExtValue();
// 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() && NumElts != 1) {
APInt UndefElts(NumElts, 0);
APInt DemandedMask(NumElts, 0);
DemandedMask.setBit(IndexVal);
DemandedMask.setBit(IdxC->getZExtValue());
if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0), DemandedMask,
UndefElts)) {
EI.setOperand(0, V);
@ -203,17 +224,8 @@ Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
}
}
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 (Instruction *I = foldBitcastExtElt(EI, Builder))
return I;
// If there's a vector PHI feeding a scalar use through this extractelement
// instruction, try to scalarize the PHI.