[DAG] Aggressively cleanup dangling node in CombineZExtLogicopShiftLoad.

While dangling nodes will eventually be pruned when they are
considered, leaving them disables combines requiring single-use.

Reviewers: Carrot, spatel, craig.topper, RKSimon, efriedma

Subscribers: hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D57520

llvm-svn: 352784

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index d2e235189ec..1f05a435bbe 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -8465,6 +8465,10 @@ SDValue DAGCombiner::CombineZExtLogicopShiftLoad(SDNode *N) {
                                 Load->getValueType(0), ExtLoad);
     CombineTo(Load, Trunc, ExtLoad.getValue(1));
   }
+
+  // N0 is dead at this point.
+  recursivelyDeleteUnusedNodes(N0.getNode());
+
   return SDValue(N,0); // Return N so it doesn't get rechecked!
 }