Don't do all the lowering stuff for 2-wide build_vector's. Also, minor optimization for shuffle of undef.
llvm-svn: 27946
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 248393b..db2b5dd 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -2977,8 +2977,8 @@
ShouldXformToMOVLP(V1.Val, PermMask.Val))
return CommuteVectorShuffle(Op, DAG);
- bool V1IsSplat = isSplatVector(V1.Val);
- bool V2IsSplat = isSplatVector(V2.Val);
+ bool V1IsSplat = isSplatVector(V1.Val) || V1.getOpcode() == ISD::UNDEF;
+ bool V2IsSplat = isSplatVector(V2.Val) || V2.getOpcode() == ISD::UNDEF;
if (V1IsSplat && !V2IsSplat) {
Op = CommuteVectorShuffle(Op, DAG);
V1 = Op.getOperand(0);
@@ -3137,6 +3137,9 @@
return Op;
unsigned NumElems = Op.getNumOperands();
+ if (NumElems == 2)
+ return SDOperand();
+
unsigned Half = NumElems/2;
MVT::ValueType VT = Op.getValueType();
MVT::ValueType EVT = MVT::getVectorBaseType(VT);