[PATCH] D145216: [llvm][Uniformity] correctly use a vector as a set by uniqifying elements

[Sameer Sahasrabuddhe via Phabricator via llvm-commits]

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The search for temporal divergence needs to determine a dominance frontier
defined for a cycle. The implementation uses a temporary vector to store a set
of newly discovered successors. Failing to uniqify the elements in this vector
causes a very large regression in compile time due to an exponential number of
redundant visits.

This fixes github issue #61123


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D145216

Files:
  llvm/include/llvm/ADT/GenericUniformityImpl.h


Index: llvm/include/llvm/ADT/GenericUniformityImpl.h
===================================================================
--- llvm/include/llvm/ADT/GenericUniformityImpl.h
+++ llvm/include/llvm/ADT/GenericUniformityImpl.h
@@ -876,6 +876,11 @@
     }
     if (!Promoted)
       break;
+
+    // Restore the set property for the temporary vector
+    llvm::sort(Temp);
+    Temp.erase(std::unique(Temp.begin(), Temp.end()), Temp.end());
+
     DomFrontier = Temp;
   }
 


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