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Optimize away insertelement of an undef value. This shows up in

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test/Codegen/ARM/reg_sequence.ll but it doesn't affect the generated code
because the coalescer cleans it up.  Radar 7998853.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104185 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bob Wilson 2010-05-19 23:42:58 +00:00
parent a7f1354eb5
commit 492fd454ca
1 changed files with 4 additions and 0 deletions
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4
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -6024,6 +6024,10 @@ SDValue DAGCombiner::visitINSERT_VECTOR_ELT(SDNode *N) {
SDValue InVal = N->getOperand(1);
SDValue EltNo = N->getOperand(2);
// If the inserted element is an UNDEF, just use the input vector.
if (InVal.getOpcode() == ISD::UNDEF)
return InVec;
// If the invec is a BUILD_VECTOR and if EltNo is a constant, build a new
// vector with the inserted element.
if (InVec.getOpcode() == ISD::BUILD_VECTOR && isa<ConstantSDNode>(EltNo)) {