[llvm] [AMDGPU][NPM] Port AMDGPUArgumentUsageInfo to NPM (PR #170886)

[Dark Steve via llvm-commits]

PrasoonMishra wrote:

> LGTM but we should probably eliminate this pass

I looked into eliminating this pass. It doesn't seem straightforward as I can't use MMI to look up the callee's MF (i.e. passSpecialInputs fn needs the callee's ArgInfo during the caller's ISel) as FreeMachineFunction deletes each function's MF from MMI after its codegen completes. So by the time the caller is being lowered, the callee's MF may already be destroyed (or not yet created). I also thought of reconstructing ArgInfo from IR which is not quite trivial for entry functions.

I feel the current way of having scratchpad that stores ArgInfo is not too bad or expensive. What are your thoughts on this @arsenm?

https://github.com/llvm/llvm-project/pull/170886