[llvm] 49ab760 - [DagCombine] Increase depth by number of operands to avoid a pathological compile time.

[Alina Sbirlea via llvm-commits]

Author: Alina Sbirlea
Date: 2022-02-09T13:31:28-08:00
New Revision: 49ab760090514dcbf84bd9dc7429146c4ca578ef

URL: https://github.com/llvm/llvm-project/commit/49ab760090514dcbf84bd9dc7429146c4ca578ef
DIFF: https://github.com/llvm/llvm-project/commit/49ab760090514dcbf84bd9dc7429146c4ca578ef.diff

LOG: [DagCombine] Increase depth by number of operands to avoid a pathological compile time.

We're hitting a pathological compile-time case, profiled to be in
DagCombiner::visitTokenFactor and many inserts into a SmallPtrSet.
It looks like one of the paths around findBetterNeighborChains is not
capped and leads to this.

This patch resolves the issue. Looking for feedback if this solution
looks reasonable.

Differential Revision: https://reviews.llvm.org/D118877

Added: 
    

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

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 8fd0001b4eb3f..954f30d4df4e7 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -24037,7 +24037,7 @@ void DAGCombiner::GatherAllAliases(SDNode *N, SDValue OriginalChain,
       }
       for (unsigned n = Chain.getNumOperands(); n;)
         Chains.push_back(Chain.getOperand(--n));
-      ++Depth;
+      Depth += Chain.getNumOperands();
       continue;
     }
     // Everything else