[llvm] [GVN] Don't coerce forwarded byte values through integers (PR #226583)

[Antonio Frighetto via llvm-commits]

https://github.com/antoniofrighetto commented:

This looks fine to me. I think it would also make it a bit easier to extend to address https://github.com/llvm/llvm-project/issues/99268 and friends.

Were you also considering adding support in ConstantFolding? Might make sense to address this contextually before employing the new instructions (given, also, that we still don't emit byte-typed IR), as GVN wouldn't otherwise perform simple store to load forwards here (https://llvm.godbolt.org/z/zn6o7Mcca).

https://github.com/llvm/llvm-project/pull/226583