[UniformityAnalysis] Use DenseSet for DivergentValues (llvm#93455)

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.

Author: Pierre-vh

llvm/include/llvm/ADT/GenericUniformityImpl.h

@@ -46,14 +46,13 @@
 
 #include "llvm/ADT/GenericUniformityInfo.h"
 
+#include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallPtrSet.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.