forked from OSchip/llvm-project
[DAGCombine] Skip re-visiting EntryToken to avoid compile time explosion
During the main DAGCombine loop, whenever a node gets replaced, the new node and all its users are pushed onto the worklist. Omit this if the new node is the EntryToken (e.g. if a store managed to get optimized out), because re-visiting the EntryToken and its users will not uncover any additional opportunities, but there may be a large number of such users, potentially causing compile time explosion. This compile time explosion showed up in particular when building the SingleSource/UnitTests/matrix-types-spec.cpp test-suite case on any platform without SIMD vector support. Reviewed By: arsenm Differential Revision: https://reviews.llvm.org/D86963
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@ -1558,9 +1558,15 @@ void DAGCombiner::Run(CombineLevel AtLevel) {
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DAG.ReplaceAllUsesWith(N, &RV);
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DAG.ReplaceAllUsesWith(N, &RV);
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}
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}
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// Push the new node and any users onto the worklist
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// Push the new node and any users onto the worklist. Omit this if the
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AddToWorklist(RV.getNode());
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// new node is the EntryToken (e.g. if a store managed to get optimized
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AddUsersToWorklist(RV.getNode());
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// out), because re-visiting the EntryToken and its users will not uncover
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// any additional opportunities, but there may be a large number of such
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// users, potentially causing compile time explosion.
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if (RV.getOpcode() != ISD::EntryToken) {
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AddToWorklist(RV.getNode());
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AddUsersToWorklist(RV.getNode());
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}
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// Finally, if the node is now dead, remove it from the graph. The node
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// Finally, if the node is now dead, remove it from the graph. The node
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// may not be dead if the replacement process recursively simplified to
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// may not be dead if the replacement process recursively simplified to
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