https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108410
--- Comment #6 from Hongtao.liu <crazylht at gmail dot com> ---
> and the key thing to optimize is
>
> ivtmp_78 = ivtmp_77 + 4294967232; // -64
> _79 = MIN_EXPR <ivtmp_78, 255>;
> _80 = (unsigned char) _79;
> _81 = {_80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80,
> _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80,
> _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80,
> _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80, _80,
> _80, _80, _80, _80, _80, _80};
>
> that is we want to broadcast a saturated (to vector element precision) value.
Yes, backend needs to support vec_pack_ssat_m, vec_pack_usat_m.
But I didn't find optab for ss_truncate or us_truncate which might be used by
BB vectorizer.
