https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121392
--- Comment #1 from Andrew Stubbs <ams at gcc dot gnu.org> --- The i386 host platform was avoiding the amdgcn backend bug by basically disabling vectorization on arrays known to be smaller than 64 elements. Now that the option pass-through is removed, we're seeing previously hidden bugs (and also improved performance where its not broken). I'll take a look soon.