[Bug target/107563] __builtin_shufflevector fails to pshufd instructions under default x86_64 compilation toggle which is the sse2 one

[unlvsur at live dot com]

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

--- Comment #9 from cqwrteur <unlvsur at live dot com> ---
(In reply to cqwrteur from comment #8)
> for sse2 to do the __builtin_convertvector job yeah

https://godbolt.org/z/dsf3WK58E

using temp_vec_type [[__gnu__::__vector_size__ (16)]] = char;
void foo4(temp_vec_type& v) noexcept
{
        v=__builtin_shufflevector(v,v,1,0,3,2,5,4,7,6,9,8,11,10,13,12,15,14);
}

This is even more interesting.

foo4(char __vector(16)&): # @foo4(char __vector(16)&)
  movdqa (%rdi), %xmm0
  movdqa %xmm0, %xmm1
  psrlw $8, %xmm1
  psllw $8, %xmm0
  por %xmm1, %xmm0
  movdqa %xmm0, (%rdi)
  retq

clang generates this. by using ror and or