[Bug rtl-optimization/110202] _mm512_ternarylogic_epi64 generates unnecessary operations

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110202

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|target                      |rtl-optimization
           Severity|normal                      |enhancement

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note you get a warning in your negate1 case


<source>: In function '__m512i negate1(const __m512i*)':
<source>:7:36: warning: 'res' is used uninitialized [-Wuninitialized]
    7 |     res = _mm512_ternarylogic_epi64(res, res, *a, 0x55);
      |           ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
<source>:6:13: note: 'res' was declared here
    6 |     __m512i res;
      |             ^~~


But even doing this:
__m512i negate1(const __m512i *a)
{
    __m512i res = _mm512_undefined_si512 ();
    res = _mm512_ternarylogic_epi64(res, res, *a, 0x55);
    return res;
}


Will cause an extra zeroing.