Use movaps / movd to extract vector element 0 even with sse4.1. It's still cheaper than pextrw especially if the value is in memory.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61555 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 43a7bb5..5ed6342 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -4215,6 +4215,14 @@
DAG.getValueType(VT));
return DAG.getNode(ISD::TRUNCATE, VT, Assert);
} else if (VT.getSizeInBits() == 16) {
+ unsigned Idx = cast<ConstantSDNode>(Op.getOperand(1))->getZExtValue();
+ // If Idx is 0, it's cheaper to do a move instead of a pextrw.
+ if (Idx == 0)
+ return DAG.getNode(ISD::TRUNCATE, MVT::i16,
+ DAG.getNode(ISD::EXTRACT_VECTOR_ELT, MVT::i32,
+ DAG.getNode(ISD::BIT_CONVERT, MVT::v4i32,
+ Op.getOperand(0)),
+ Op.getOperand(1)));
SDValue Extract = DAG.getNode(X86ISD::PEXTRW, MVT::i32,
Op.getOperand(0), Op.getOperand(1));
SDValue Assert = DAG.getNode(ISD::AssertZext, MVT::i32, Extract,