[llvm] [InstCombine] Improve `(icmp pred (and X, Y), ...)` fold. (PR #66787)

[Nikita Popov via llvm-commits]

nikic wrote:

Only looked at the first three commits, which imho could be a separate PR (maybe drop the rest from this one for now).

I think after adding getFreeInverted() it would be good to also go through existing users of isFreeToInvert() and replace them with getFreeInverted() where this is easy, e.g. in foldICmpOrXX(). Directly creating the inverted op instead of letting it get inverted separately does seem a lot more robust to me. 

https://github.com/llvm/llvm-project/pull/66787