[Bug target/47949] Missed optimization for -Os using xchg instead of mov.

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47949

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This might have been fixed already via the commit referenced in PR92549