[llvm] [GlobalISel] Combine (X == 0) & (Y == 0) -> (X | Y) == 0 (PR #71949)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> Very recently got merged this #82733, which will insert G_FREEZE before the G_OR (https://godbolt.org/z/dcr83rfM6) causing now the above patterns not to work on cases like in `cmp-chains.ll`, losing those opt opportunities. I am not sure if G_FREEZE should be incorporated into the pattern or not.

You can try the equivalent transform in alive2 on the IR to see if it's valid 

https://github.com/llvm/llvm-project/pull/71949