64-bit and SSE

[Don]

retard wrote:
> Tue, 02 Mar 2010 14:17:12 -0500, Nick Sabalausky wrote:
> 
>> "retard" <re at tard.com.invalid> wrote in message
>> news:hmjmjd$15uj$1 at digitalmars.com...
>>> Tue, 02 Mar 2010 15:49:02 +0000, dsimcha wrote:
>>>
>>>> Given that Walter has indicated that 64-bit support is on the agenda
>>>> for after D2 is finished and x87 is deprecated in 64-bit mode, will we
>>>> also see SSE(2) support in DMD in the relatively near future?  If so,
>>>> will it be exposed as a compiler option even when compiling in 32-bit
>>>> mode?
>>>>
>>>> I've realized that this is kind of important for me since Intel
>>>> deprecated x87 on its Core 2 and Pentium 4 chips, meaning any old
>>>> school floating point code runs painfully slow compared to, say, an
>>>> AMD chip that still has a decent x87.
>>> SSE(2) ? Don't people already use SSE 4.2 and prepare for AVX?
>> Yes. The ones who enjoy arbitrarily shrinking their potential user base.
> 
> Why not dynamic code path selection:
> 
> if (cpu_capabilities && SSE4_2)
>   run_fast_method();
> else if (cpu_capabilities && SSE2)
>   run_medium_fast_method();
> else
>   run_slow_method();
> 
> One could also use higher level design patterns like abstract factories 
> here.

The method needs to be fairly large for that to be beneficial. For 
fine-grained stuff, like basic operations on 3D vectors, it doesn't work 
at all. And that's one of the primary use cases for SSE.