Re: inline asm mmx: how to movq from memory to %mmX

["Jack Andrews" <effbiae at gmail dot com>]

<fwd from ian taylor's response>

"Jack Andrews" <effbiae@gmail.com> writes:
> simd_mmintrin(n, is)
> I *is;
> {   __v2si q,r;
>     I i;
>     _m_empty();
>     q=_m_from_int(0);
>     for (i=0; i < n; i+=W) {
>         memcpy(&r,is+i,IZ*W);
>         q=_m_paddd(q,r);
>     }
>     I*qq=(I*)&q;
>     return qq[0]+qq[1];
> }

For mmintrin.h functions, use __m64, not __v2si.

Why the memcpy?  Use _mm_set_pi32(is[i], is[i + 1]).

Don't extract the values by taking the address of q.  Instead do
something like this:
  union { long ai[2]; __m64 m } u;
  u.m = q;
  return u.ai[0] + u.ai[1];

Ian