Fix a bug in DAGCombine for the optimization of BUILD_VECTOR. We cant generate a shuffle node from two vectors of different types.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150383 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 9fa5572..f51e721 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -7385,9 +7385,13 @@
     // If VecIn2 is unused then change it to undef.
     VecIn2 = VecIn2.getNode() ? VecIn2 : DAG.getUNDEF(VT);
 
+    // Check that we were able to transform all incoming values to the same type.
+    if (VecIn2.getValueType() != VecIn1.getValueType() ||
+        VecIn1.getValueType() != VT)
+          return SDValue();
+
     // Only type-legal BUILD_VECTOR nodes are converted to shuffle nodes.
-    if (!isTypeLegal(VT) || !isTypeLegal(VecIn1.getValueType()) ||
-        !isTypeLegal(VecIn2.getValueType()))
+    if (!isTypeLegal(VT))
       return SDValue();
 
     // Return the new VECTOR_SHUFFLE node.