[llvm] AMDGPU: Undo atomicrmw add/sub/xor 0 -> atomicrmw or canonicalization (PR #87533)

[Stanislav Mekhanoshin via llvm-commits]

rampitec wrote:

> > should we do this for other synch scopes? Or revisit it after we add metadata for no-fine-grained and no-remote?
> 
> I wanted to stay as targeted as possible. There will be an interaction with the new metadata, but it shouldn't be necessary outside of system scope

I believe scope does not necessarily point to a specific bus. Most of the uses probably would not request a device scope on an atomic in remote memory, but this is not necessary. Why not to do it for any scope?

https://github.com/llvm/llvm-project/pull/87533