[llvm] [InstCombine][AMDGPU] Disable PtrReplacer when select has mismatch AS. (PR #98456)

[via llvm-commits]

jofrn wrote:

> Checking specifically for select x, cast, cast seems too specific of a pattern to defend against an assertion. What happens if there are arbitrary indexing separating them?

If there is arbitrary indexing to separate them, then HasASC can be used with the scanning version of hasConflictingAS in order to prevent scanning through indices each time; so we would have to go back to the prior version if we cannot assume the casts are adjacent to the select.

https://github.com/llvm/llvm-project/pull/98456