[llvm] [InstCombine] Canonicalize `(gep <not i8> p, (div exact X, C))` (PR #96898)

[Nikita Popov via llvm-commits]

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

LGTM

I think we should consolidate all the ptradd canonicalizations via EmitGEPOffset (i.e. only check profitability, and let everything else fold), but landing this as-is for now is fine.

https://github.com/llvm/llvm-project/pull/96898