[X86] Fix assertion failure caused by a wrong folding of vector shifts by immediate count.

This fixes a regression intruced by r198113.

Revision r198113 introduced an algorithm that tries to fold a vector shift
by immediate count into a build_vector if the input vector is a known vector
of constants.

However the algorithm only worked under the assumption that the input vector
type and the shift type are exactly the same.

This patch disables the folding of vector shift by immediate count if the
input vector type and the shift value type are not the same.

llvm-svn: 199213

1 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index a41faab73b4..ef1bd7fd301 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -11118,8 +11118,9 @@ static SDValue getTargetVShiftByConstNode(unsigned Opc, SDLoc dl, MVT VT,
          && "Unknown target vector shift-by-constant node");
 
   // Fold this packed vector shift into a build vector if SrcOp is a
-  // vector of ConstantSDNodes or UNDEFs.
-  if (ISD::isBuildVectorOfConstantSDNodes(SrcOp.getNode())) {
+  // vector of Constants or UNDEFs, and SrcOp valuetype is the same as VT.
+  if (VT == SrcOp.getSimpleValueType() &&
+      ISD::isBuildVectorOfConstantSDNodes(SrcOp.getNode())) {
     SmallVector<SDValue, 8> Elts;
     unsigned NumElts = SrcOp->getNumOperands();
     ConstantSDNode *ND;