https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104901
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
It's a way to say a == b == c, no? Not sure if that was intended of course,
but it seems so since we follow with
if (__alignment < __vec_align)
__alignment = __vec_align;
