[llvm] Introduce CounterExpressionBuilder::replace(C, Map) (PR #112698)

[NAKAMURA Takumi via llvm-commits]

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@@ -213,6 +214,11 @@ class CounterExpressionBuilder {
   /// Return a counter that represents the expression that subtracts RHS from
   /// LHS.
   Counter subtract(Counter LHS, Counter RHS, bool Simplify = true);
+
+  using ReplaceMap = std::map<Counter, Counter>;
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chapuni wrote:

I am so lazy to add hash helper into `llvm::Counter`. I have taken `std::map` since `Counter` has provided enough operators.

The map may grow up to hundreds of keys. Could we make `Counter` ready for hash maps?

https://github.com/llvm/llvm-project/pull/112698