[llvm] [InstCombine] fold `(a == c && b != c) || (a != c && b == c))` to `(a == c) == (b != c)` (PR #94915)

[Zain Jaffal via llvm-commits]

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@@ -3476,7 +3469,7 @@ Instruction *InstCombinerImpl::visitOr(BinaryOperator &I) {
   if (Instruction *X = foldComplexAndOrPatterns(I, Builder))
     return X;
 
-  // (A == c & B != d) | (A != c & B == d)) -> (A == c) | (B == d)
+  // (A == c & B != d) | (A != c & B == d)) -> (A == c) ^ (B == d)
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zjaffal wrote:

to be able to do that we need to generalise `isKnownInversion` to handle the case of a  and ~a being inversions of each other. I will change that once we land this 

https://github.com/llvm/llvm-project/pull/94915