[llvm] IR: introduce CmpInst::is{Eq,Ne}Equivalence (PR #111979)

[Nikita Popov via llvm-commits]

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@@ -912,6 +912,16 @@ class CmpInst : public Instruction {
   /// Determine if this is an equals/not equals predicate.
   bool isEquality() const { return isEquality(getPredicate()); }
 
+  /// Determine if this is an equals predicate that is also an equivalence. This
+  /// is useful in GVN-like transformations, where we can replace RHS by LHS in
+  /// the true branch of the CmpInst.
+  bool isEqEquivalence() const;
+
+  /// Determine if this is a not-equals predicate that is also an equivalence.
+  /// This is useful in GVN-like transformations, where we can replace RHS by
+  /// LHS in the false branch of the CmpInst.
+  bool isNeEquivalence() const;
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nikic wrote:

Instead of two methods, pass an invert flag.

https://github.com/llvm/llvm-project/pull/111979