Re: [PATCH v2 3/3] msvcrt: Add an SSE2 memset_aligned_32 implementation.

[Piotr Caban]

On 9/14/21 1:01 PM, Rémi Bernon wrote:
> And what about using intel intrinsics? Like for instance:
> > #ifdef __SSE2__
> > #ifdef __i386__
> >     if (sse2_supported)
> > #endif
> >     {
> >         __m128i x = _mm_set1_epi64x(v);
> >         while (n >= 64)
> >         {
> >             _mm_store_si128((__m128i *)(d + n - 64), x);
> >             _mm_store_si128((__m128i *)(d + n - 48), x);
> >             _mm_store_si128((__m128i *)(d + n - 32), x);
> >             _mm_store_si128((__m128i *)(d + n - 16), x);
> >             n -= 64;
> >         }
> >         if (n >= 32)
> >         {
> >             _mm_store_si128((__m128i *)(d + n - 32), x);
> >             _mm_store_si128((__m128i *)(d + n - 16), x);
> >         }
> >         return;
> >     }
> > #endif
>
> In all cases, if SSE is disabled at compile-time it will not be able to 
> use SSE2 path at runtime, even if supported. Which was possible with the 
> assembly function.
>
> Is this something we would like to have?

I don't think this is portable. I quick test shows that it doesn't 
compile with x86_64-w64-mingw on my machine.

Thanks,
Piotr