[scottlamb]

> Don't know how exactly it interacts with aliasing rules; maybe you'd have to explicitly pass the mutable reference to the asm as an input, otherwise it'd be illegal for the asm to change it and so the compiler can still assume it isn't? or, I guess, not have any references live during the asm call is the proper thing.

I don't know either, but really it's the opposite half of the buffer you want to tell it may have changed, so I imagine it doesn't matter even if you still have the `&mut [T]` live.

Maybe the extra guard I described isn't necessary either; the DerefMut could directly return `&mut [T]` but set a `barrier_before_next_access` on the ring, or you could just always have the barrier, whatever performs best I guess.