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-rw-r--r--llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp5
1 files changed, 4 insertions, 1 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 6e106bb869a..df38ef423fa 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -8863,12 +8863,15 @@ SDValue DAGCombiner::visitBITCAST(SDNode *N) {
if (Op.getOpcode() == ISD::BITCAST &&
Op.getOperand(0).getValueType() == VT)
return SDValue(Op.getOperand(0));
- if (ISD::isBuildVectorOfConstantSDNodes(Op.getNode()) ||
+ if (Op.isUndef() || ISD::isBuildVectorOfConstantSDNodes(Op.getNode()) ||
ISD::isBuildVectorOfConstantFPSDNodes(Op.getNode()))
return DAG.getBitcast(VT, Op);
return SDValue();
};
+ // FIXME: If either input vector is bitcast, try to convert the shuffle to
+ // the result type of this bitcast. This would eliminate at least one
+ // bitcast. See the transform in InstCombine.
SDValue SV0 = PeekThroughBitcast(N0->getOperand(0));
SDValue SV1 = PeekThroughBitcast(N0->getOperand(1));
if (!(SV0 && SV1))
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