[llvm] r339688 - [DAG] Avoid redundant chain transversal in store merge cycle check. NFCI.

[Nirav Dave via llvm-commits]

Author: niravd
Date: Tue Aug 14 09:20:43 2018
New Revision: 339688

URL: http://llvm.org/viewvc/llvm-project?rev=339688&view=rev
Log:
[DAG] Avoid redundant chain transversal in store merge cycle check. NFCI.

Patch by Henric Karlsson.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=339688&r1=339687&r2=339688&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Tue Aug 14 09:20:43 2018
@@ -13971,11 +13971,12 @@ bool DAGCombiner::checkMergeStoreCandida
   Worklist.push_back(RootNode);
   while (!Worklist.empty()) {
     auto N = Worklist.pop_back_val();
+    if (!Visited.insert(N).second)
+      continue; // Already present in Visited.
     if (N->getOpcode() == ISD::TokenFactor) {
       for (SDValue Op : N->ops())
         Worklist.push_back(Op.getNode());
     }
-    Visited.insert(N);
   }
 
   // Don't count pruning nodes towards max.