[llvm] [SelectionDAG] Add space-optimized forms of OPC_CheckComplexPat (PR #73310)

[Paul Kirth via llvm-commits]

https://github.com/ilovepi approved this pull request.

This seems fine to me, and in line with the earlier patches. Would you mind adding some documentation about the change somewhere though? I feel like we should at least have a meta comment somewhere noting that the first 8 numbers are special.

You probably want to wait for one of the code owners to give the LGTM before landing, though.

https://github.com/llvm/llvm-project/pull/73310