[llvm] [InstCombine] Fold comparison of adding two z/sext booleans (PR #67895)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

This looks basically good to me. Only one suggestion to relax the one-use checks.

Can you please squash the changes such that all the test additions are in the first commit and the implementation (and test diffs) are in the second one?

https://github.com/llvm/llvm-project/pull/67895