https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117266
--- Comment #10 from H. Peter Anvin <hpa at zytor dot com> --- Well sizeof() ought to be sufficient to represent something with enough bits. Even if x86 is the only architecture that has that specific instruction, I would be extremely surprised if gcc couldn't use that knowledge to optimize the code sequences involved, including libgcc, significantly.
