[llvm] [InstSimplify] Fold xor using implied conditions (PR #75609)

[Nikita Popov via llvm-commits]

nikic wrote:

In terms of high-level approach for the motivating case, I wonder whether it may make sense to implement an exact set-xor operation on ConstantRange and then handle this in foldAndOrOfICmpsUsingRanges. This would allow handling cases where the xor can be folded into a new icmp, rather than just folded to true.

https://github.com/llvm/llvm-project/pull/75609