[llvm-branch-commits] [llvm] AtomicExpand: Copy metadata from atomicrmw to cmpxchg (PR #109409)

[Eli Friedman via llvm-branch-commits]

efriedma-quic wrote:

> (which for some reason is not emitted as an atomic).

In terms of the generated code, I think we're fine; we don't rely on the load producing a value that's consistent with atomic ordering, I think.

That said, it probably should be atomic, because strictly speaking a race is UB if we use a non-atomic load.

https://github.com/llvm/llvm-project/pull/109409