[llvm] [AMDGPU] Add alignment attr & propagate alignment through make.buffer.rsrc inst (PR #145278)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm commented:

Description should be more clear about what this is. This isn't adding anything to the intrinsic itself.

I think the only thing special about this case is it's an intrinsic that propagates a pointer operand, similar to llvm.ptrmask. It looks like AAAlign also fails to propagate the alignment (which may have been improved by the ptrmask). Can you start by adding support for llvm.ptrmask, and then generalizing the support to other pointer intrinsics?

https://github.com/llvm/llvm-project/pull/145278