https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127382
--- Comment #4 from Hongtao Liu <liuhongt at gcc dot gnu.org> ---
> >
> > So TYPE_SIZE equal of @2 and @3 is not enough for _BitInt, need
> > TYPE_PRECISION
> > for that, I'm working on a patch.
>
> Also for other INTEGER_TYPEs.
regarding conversion, GCC currently vectorizes below testcase directly with
padded mode, but for scalar code, there's normalization like (b[i] << 15) >>
15, so the vectorized code looks incorrect and should be restrict to
type_has_mode_precision_p?
void
foo (long *a, _BitInt(17) *b)
{
for (int i = 0; i != 100; i++)
a[i] = b[i];
}