Simplify extract element of a scalar to vector.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62383 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 13 insertions, 5 deletions

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index f8b9142..230079b 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -4878,16 +4878,24 @@ SDValue DAGCombiner::visitINSERT_VECTOR_ELT(SDNode *N) {
 }
 
 SDValue DAGCombiner::visitEXTRACT_VECTOR_ELT(SDNode *N) {
-  // (vextract (v4f32 load $addr), c) -> (f32 load $addr+c*size)
-  // (vextract (v4f32 s2v (f32 load $addr)), c) -> (f32 load $addr+c*size)
-  // (vextract (v4f32 shuffle (load $addr), <1,u,u,u>), 0) -> (f32 load $addr)
+  // (vextract (scalar_to_vector val, 0) -> val
+  SDValue InVec = N->getOperand(0);
+  SDValue EltNo = N->getOperand(1);
+
+  if (isa<ConstantSDNode>(EltNo)) {
+    unsigned Elt = cast<ConstantSDNode>(EltNo)->getZExtValue();
+    if (InVec.getOpcode() == ISD::SCALAR_TO_VECTOR && Elt == 0) {
+      return InVec.getOperand(0);
+    }
+  }
 
   // Perform only after legalization to ensure build_vector / vector_shuffle
   // optimizations have already been done.
   if (!LegalOperations) return SDValue();
 
-  SDValue InVec = N->getOperand(0);
-  SDValue EltNo = N->getOperand(1);
+  // (vextract (v4f32 load $addr), c) -> (f32 load $addr+c*size)
+  // (vextract (v4f32 s2v (f32 load $addr)), c) -> (f32 load $addr+c*size)
+  // (vextract (v4f32 shuffle (load $addr), <1,u,u,u>), 0) -> (f32 load $addr)
 
   if (isa<ConstantSDNode>(EltNo)) {
     unsigned Elt = cast<ConstantSDNode>(EltNo)->getZExtValue();