[DAGCombiner] Added CTPOP vector constant folding support.

Added tests to the existing SSE/AVX test files.

llvm-svn: 239252
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index d5b2f36..307bfa5 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -4809,7 +4809,7 @@
   EVT VT = N->getValueType(0);
 
   // fold (ctpop c1) -> c2
-  if (isa<ConstantSDNode>(N0))
+  if (isConstantIntBuildVectorOrConstantInt(N0))
     return DAG.getNode(ISD::CTPOP, SDLoc(N), VT, N0);
   return SDValue();
 }