https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110214
Bug ID: 110214
Summary: x86 backend lacks support for vec_pack_ssat_m and
vec_pack_usat_m
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: crazylht at gmail dot com
Target Milestone: ---
This is from PR108410:
> 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.
AVX512 support vpmov{u,}sqd, vpmov{u,}sdw, vpmov{u,}swb for demotion with
signed/unsigned saturation.
