[llvm] [PreISelIntrinsicLowering] Look through ptrtoint for a constant (e.g. global ptr) when trying to produce memset_pattern16 (PR #129220)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

> This continues along the path of leaving memset.pattern as taking an integer type for now, and potentially allowing overloads of other types in future work.

I feel like it would make more sense to lift that restriction right away. It seem like both this PR and #129220 have to do unnecessary work to force the use of integers, while (I think?) non-integer types should "just work" if we allow them.

https://github.com/llvm/llvm-project/pull/129220