[llvm] [RFC][BPF] Do atomic_fetch_*() pattern matching with memory ordering (PR #107343)

[via llvm-commits]

yonghong-song wrote:

@anakryiko @eddyz87 Yes, we can implement other memory ordering (acquire, release, act_rel) to be the same as seq_cst initially. Later on, we can invent new instructions in llvm to actually support acquire, release, act_rel properly. It is very likely that when we are able to land llvm/kernel change, we may already figure out the new insn format and we will just implement them at that time.

https://github.com/llvm/llvm-project/pull/107343