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Back out 76300; apparently the preference is to canonicalize the other

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way (bitcast -> insert/extractelement).

llvm-svn: 76325
This commit is contained in:
Eli Friedman 2009-07-18 19:04:16 +00:00
parent ffd009f039
commit debc43cb11
2 changed files with 6 additions and 28 deletions
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22
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -12374,18 +12374,13 @@ Instruction *InstCombiner::visitExtractElementInst(ExtractElementInst &EI) {
if (op0)
return ReplaceInstUsesWith(EI, op0);
}
unsigned VectorWidth =
cast<VectorType>(EI.getOperand(0)->getType())->getNumElements();
// Canonicalize extractelement from a vector of width 1 to a bitcast
if (VectorWidth == 1)
return new BitCastInst(EI.getOperand(0), EI.getType());
// 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 IndexVal = IdxC->getZExtValue();
unsigned VectorWidth =
cast<VectorType>(EI.getOperand(0)->getType())->getNumElements();
// If this is extracting an invalid index, turn this into undef, to avoid
// crashing the code below.
@ -12395,7 +12390,7 @@ 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()) {
if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) {
APInt UndefElts(VectorWidth, 0);
APInt DemandedMask(VectorWidth, 1 << IndexVal);
if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0),
@ -12632,18 +12627,13 @@ Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
// Inserting an undef or into an undefined place, remove this.
if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
ReplaceInstUsesWith(IE, VecOp);
unsigned NumVectorElts = IE.getType()->getNumElements();
// Canonicalize insertelement into vector of width 1 to a bitcast
if (NumVectorElts == 1)
return new BitCastInst(IE.getOperand(1), IE.getType());
// If the inserted element was extracted from some other vector, and if the
// indexes are constant, try to turn this into a shufflevector operation.
if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
EI->getOperand(0)->getType() == IE.getType()) {
unsigned NumVectorElts = IE.getType()->getNumElements();
unsigned ExtractedIdx =
cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();

12
test/Transforms/InstCombine/vec-single-elt.ll
View File

@ -1,12 +0,0 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep element
; insert/extractelement should canonicalize to bitcast
define i64 @a(<1 x i64> %x) {
%r = extractelement <1 x i64> %x, i32 0
ret i64 %r
}
define <1 x i64> @b(i64 %x) {
%r = insertelement <1 x i64> undef, i64 %x, i32 0
ret <1 x i64> %r
}