[PATCH] D118877: [DagCombine] Increase depth by number of operands to avoid a pathological compile time.

[Alina Sbirlea via Phabricator via llvm-commits]

asbirlea created this revision.
asbirlea added reviewers: niravd, RKSimon, bjope, spatel, craig.topper.
Herald added subscribers: ecnelises, steven.zhang, hiraditya.
asbirlea requested review of this revision.
Herald added a project: LLVM.

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.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D118877

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


Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -23928,7 +23928,7 @@
       }
       for (unsigned n = Chain.getNumOperands(); n;)
         Chains.push_back(Chain.getOperand(--n));
-      ++Depth;
+      Depth += Chain.getNumOperands();
       continue;
     }
     // Everything else


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