As I understand it (... haven't tested recently) you're right that it's not usually a win on modern architectures, and the compiler could do it wherever there's

As I understand it (... haven't tested recently) you're right that it's not usually a win on modern architectures, and the compiler could do it wherever there's enough register pressure that it might actually help (if anywhere). It's still neat, but I don't think there's any reason to be writing it unless you are on a particularly constrained system with a limited compiler. I assume you're being downvoted for your slightly incorrect caveat.