[PATCH] D40892: Add early out to O(n^2) switch analysis in switch-to-select conversion

[Andrew Scheidecker via Phabricator via llvm-commits]

AndrewScheidecker updated this revision to Diff 125717.
AndrewScheidecker added a comment.

Include full context in diff, as suggested on IRC


Repository:
  rL LLVM

https://reviews.llvm.org/D40892

Files:
  lib/Transforms/Utils/SimplifyCFG.cpp


Index: lib/Transforms/Utils/SimplifyCFG.cpp
===================================================================
--- lib/Transforms/Utils/SimplifyCFG.cpp
+++ lib/Transforms/Utils/SimplifyCFG.cpp
@@ -4720,6 +4720,15 @@
       return false;
     MapCaseToResult(CaseVal, UniqueResults, Results.begin()->second);
 
+    // No more than two unique results can be selected between.
+    if (UniqueResults.size() > 2)
+      return false;
+
+    // No result may have more than one case that selects it.
+    for(const auto &RI : UniqueResults)
+      if (RI.second.size() > 1)
+        return false;
+
     // Check the PHI consistency.
     if (!PHI)
       PHI = Results[0].first;


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