[llvm] [DA] Cache delinearization results. NFCI. (PR #164379)

[Ryotaro Kasuga via llvm-commits]

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@@ -420,6 +420,12 @@ class DependenceInfo {
   Function *F;
   SmallVector<const SCEVPredicate *, 4> Assumptions;
 
+  /// Cache for delinearized subscripts to avoid recomputation.
+  /// Maps (Instruction, Loop, AccessFn) -> Subscripts
+  DenseMap<std::tuple<Instruction *, Loop *, const SCEV *>,
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kasuga-fj wrote:

Does the key need to be a tuple? Wouldn't `Instruction *` or `const SCEV *` be sufficient?

https://github.com/llvm/llvm-project/pull/164379