Fixed a couple of optimization with EXTRACT_VECTOR_ELT that assumes the result

type is the same as the element type of the vector.  EXTRACT_VECTOR_ELT can
be used to extended the width of an integer type.  This fixes a bug for
Generic/vector-casts.ll on a ppc750.

llvm-svn: 94990

1 files changed, 11 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 640bdc091ca..6729a93fd71 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -5403,12 +5403,19 @@ SDValue DAGCombiner::visitEXTRACT_VECTOR_ELT(SDNode *N) {
   SDValue InVec = N->getOperand(0);
 
  if (InVec.getOpcode() == ISD::SCALAR_TO_VECTOR) {
-   // If the operand is wider than the vector element type then it is implicitly
-   // truncated.  Make that explicit here.
+   // Check if the result type doesn't match the inserted element type. A
+   // SCALAR_TO_VECTOR may truncate the inserted element and the
+   // EXTRACT_VECTOR_ELT may widen the extracted vector.
    EVT EltVT = InVec.getValueType().getVectorElementType();
    SDValue InOp = InVec.getOperand(0);
-   if (InOp.getValueType() != EltVT)
-     return DAG.getNode(ISD::TRUNCATE, InVec.getDebugLoc(), EltVT, InOp);
+   EVT NVT = N->getValueType(0);
+   if (InOp.getValueType() != NVT) {
+     assert(InOp.getValueType().isInteger() && NVT.isInteger());
+     if (NVT.getSizeInBits() > InOp.getValueType().getSizeInBits())
+       return DAG.getNode(ISD::SIGN_EXTEND, InVec.getDebugLoc(), NVT, InOp);
+     else
+       return DAG.getNode(ISD::TRUNCATE, InVec.getDebugLoc(), NVT, InOp);
+   }
    return InOp;
  }