[SelectionDAG] More Aggressibly prune nodes in AddChains. NFCI.

Travel all chains paths to first non-tokenfactor node can be
exponential work. Add simple redundency check to avoid this.
Fixes PR36264.

llvm-svn: 324491

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 53e8b2ee5b5..ef307400d97 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -2396,13 +2396,15 @@ HandleMergeInputChains(SmallVectorImpl<SDNode*> &ChainNodesMatched,
       return;
     if (V->getOpcode() == ISD::EntryToken)
       return;
+    if (!Visited.insert(V.getNode()).second)
+      return;
     // Newly selected nodes (-1) are always added directly.
     if (V->getNodeId() == -1)
       InputChains.push_back(V);
     else if (V->getOpcode() == ISD::TokenFactor) {
       for (int i = 0, e = V->getNumOperands(); i != e; ++i)
         AddChains(V->getOperand(i));
-    } else if (!Visited.count(V.getNode()))
+    } else
       InputChains.push_back(V);
   };