[llvm] [InstCombine] Simplify and/or of icmp eq with op replacement (PR #70335)

[via llvm-commits]

mikaelholmen wrote:

> I reverted this because I'm seeing segfaults in stage2 llvm-tblgen on a build server, but for some reason I can't reproduce this in local stage2 builds :/ Not sure what the difference is, my best guess is the libstdc++ version.

@nikic 
We saw miscompiles with this patch when testing our out-of-tree target. I don't have any reproducer to share at the moment but if you're struggling to reproduce yourself I can try to see if I might be able to extract something that shows the problem on trunk as well. Should I try?

https://github.com/llvm/llvm-project/pull/70335