Fix slightly too aggressive conact_vector optimization.

(Would sometimes optimize away conacts used to extend a vector with undef values)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181186 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 0 deletions

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 85f5df9..2e09ec0 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -9145,6 +9145,12 @@ SDValue DAGCombiner::visitCONCAT_VECTORS(SDNode *N) {
         return SDValue();
     } else {
       SingleSource = Op.getOperand(0);
+
+      // Check the source type is the same as the type of the result.
+      // If not, this concat may extend the vector, so we can not
+      // optimize it away.
+      if (SingleSource.getValueType() != N->getValueType(0))
+        return SDValue();
     }
 
     unsigned IdentityIndex = i * PartNumElem;