[llvm] 4180e2b - [UniformityAnalysis] Make divergent-exit cycle print order deterministic (#210107)

[via llvm-commits]

Author: Fangrui Song
Date: 2026-07-16T10:15:59-07:00
New Revision: 4180e2bb885271956e80344354b046a9b4cf3031

URL: https://github.com/llvm/llvm-project/commit/4180e2bb885271956e80344354b046a9b4cf3031
DIFF: https://github.com/llvm/llvm-project/commit/4180e2bb885271956e80344354b046a9b4cf3031.diff

LOG: [UniformityAnalysis] Make divergent-exit cycle print order deterministic (#210107)

Once the set spills to the heap its iteration order follows allocation
addresses, so the printed order is nondeterministic.

Fix https://reviews.llvm.org/D130746 ("RFC: Uniformity Analysis for
Irreducible Control Flow")

Added: 
    

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

Removed: 
    


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diff  --git a/llvm/include/llvm/ADT/GenericUniformityImpl.h b/llvm/include/llvm/ADT/GenericUniformityImpl.h
index 528fe11d8579e..3f78b21edd8a9 100644
--- a/llvm/include/llvm/ADT/GenericUniformityImpl.h
+++ b/llvm/include/llvm/ADT/GenericUniformityImpl.h
@@ -48,6 +48,7 @@
 
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SparseBitVector.h"
 #include "llvm/ADT/StringExtras.h"
@@ -462,7 +463,7 @@ template <typename ContextT> class GenericUniformityAnalysisImpl {
   const DominatorTreeT &DT;
 
   // Recognized cycles with divergent exits.
-  SmallPtrSet<const CycleT *, 16> DivergentExitCycles;
+  SmallSetVector<const CycleT *, 8> DivergentExitCycles;
 
   // Cycles assumed to be divergent.
   //
@@ -919,7 +920,7 @@ void GenericUniformityAnalysisImpl<ContextT>::propagateCycleExitDivergence(
   LLVM_DEBUG(dbgs() << "\tOuter-most exiting cycle: "
                     << Context.print(CI.getHeader(*OuterDivCycle)) << "\n");
 
-  if (!DivergentExitCycles.insert(OuterDivCycle).second)
+  if (!DivergentExitCycles.insert(OuterDivCycle))
     return;
 
   // Exit divergence does not matter if the cycle itself is assumed to