[llvm] [LoopInterchange] Make the entries of the Dependency Matrix unique (PR #116195)

[Min-Yih Hsu via llvm-commits]

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@@ -110,6 +110,7 @@ static bool populateDependencyMatrix(CharMatrix &DepMatrix, unsigned Level,
                     << " Loads and Stores to analyze\n");
 
   ValueVector::iterator I, IE, J, JE;
+  SmallDenseSet<size_t> Seen;
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mshockwave wrote:

is there any reason we can't use `SmallDenseSet<StringRef>` here? Manually calculate hashes on common types like std::string / StringRef looks a little unusual to me.

https://github.com/llvm/llvm-project/pull/116195