[Bug c/89670] __builtin_ctz(_mm256_movemask_epi8(foo)) assumed to be <31 ?

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89670

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
__builtin_ctz is undefined if the input is 0 as documented.