[UniformityAnalysis] Use DenseSet for DivergentValues

[Pierre-vh]

Values are small, and std::set is just unnecessarily expensive. It stood out in some quick performance profiling. DenseSet is a better alternative in this case.

[llvmbot]

@llvm/pr-subscribers-llvm-adt

Author: Pierre van Houtryve (Pierre-vh)

Changes

Values are small, and std::set is just unnecessarily expensive. It stood out in some quick performance profiling. DenseSet is a better alternative in this case.

---

Full diff: https://github.com/llvm/llvm-project/pull/93455.diff

1 Files Affected:

• (modified) llvm/include/llvm/ADT/GenericUniformityImpl.h (+2-3)

diff --git a/llvm/include/llvm/ADT/GenericUniformityImpl.h b/llvm/include/llvm/ADT/GenericUniformityImpl.h
index 6b744384051b5..e170b10441bbb 100644
--- a/llvm/include/llvm/ADT/GenericUniformityImpl.h
+++ b/llvm/include/llvm/ADT/GenericUniformityImpl.h
@@ -48,12 +48,11 @@
 
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/SparseBitVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/raw_ostream.h"
 
-#include <set>
-
 #define DEBUG_TYPE "uniformity"
 
 namespace llvm {
@@ -413,7 +412,7 @@ template <typename ContextT> class GenericUniformityAnalysisImpl {
   const TargetTransformInfo *TTI = nullptr;
 
   // Detected/marked divergent values.
-  std::set<ConstValueRefT> DivergentValues;
+  DenseSet<ConstValueRefT> DivergentValues;
   SmallPtrSet<const BlockT *, 32> DivergentTermBlocks;
 
   // Internal worklist for divergence propagation.

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[ssahasra]

LGTM!