[Bug rtl-optimization/107563] New: __builtin_shufflevector fails to use pshufb and pshufd instructions under default x86_64 compilation toggle which is the sse2 one

[unlvsur at live dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107563

            Bug ID: 107563
           Summary: __builtin_shufflevector fails to use pshufb and pshufd
                    instructions under default x86_64 compilation toggle
                    which is the sse2 one
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: unlvsur at live dot com
  Target Milestone: ---

#if defined(__SSE2__)

using temp_vec_type [[__gnu__::__vector_size__ (16)]] = char;
void foo(temp_vec_type& v) noexcept
{
        v=__builtin_shufflevector(v,v,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0);
}

#endif

g++ -S pq.cc -Ofast
proves sse2 is enabled by default, but it does not call
https://www.felixcloutier.com/x86/pshufb
neither
https://www.felixcloutier.com/x86/pshufd

while g++ -S pq.cc -Ofast -msse4.2 will generate them correctly. Which is buggy