SIMD support...

[Marco Leise]

Am 15.01.2012, 11:45 Uhr, schrieb Manu <turkeyman at gmail.com>:

> On 15 January 2012 08:16, Sean Cavanaugh <WorksOnMyMachine at gmail.com>  
> wrote:
>
>> On 1/15/2012 12:09 AM, Walter Bright wrote:
>>
>>> On 1/14/2012 9:58 PM, Sean Cavanaugh wrote:
>>>
>>>> MS has three types, __m128, __m128i and __m128d (float, int, double)
>>>>
>>>> Six if you count AVX's 256 forms.
>>>>
>>>> On 1/7/2012 6:54 PM, Peter Alexander wrote:
>>>>
>>>>> On 7/01/12 9:28 PM, Andrei Alexandrescu wrote:
>>>>> I agree with Manu that we should just have a single type like __m128  
>>>>> in
>>>>> MSVC. The other types and their conversions should be solvable in a
>>>>> library with something like strong typedefs.
>>>>>
>>>>>
>>> The trouble with MS's scheme, is given the following:
>>>
>>> __m128i v;
>>> v += 2;
>>>
>>> Can't tell what to do. With D,
>>>
>>> int4 v;
>>> v += 2;
>>>
>>> it's clear (add 2 to each of the 4 ints).
>>>
>>
>> Working with their intrinsics in their raw form for real code is pure
>> insanity :)  You need to wrap it all with a good math library (even if  
>> 90%
>> of the library is the intrinsics wrapped into __forceinlined  
>> functions), so
>> you can start having sensible operator overloads, and so you can write  
>> code
>> that is readable.
>>
>>
>> if (any4(a > b))
>> {
>>  // do stuff
>> }
>>
>>
>> is way way way better than (pseudocode)
>>
>> if (__movemask_ps(_mm_gt_ps(a, b)) == 0x0F)
>> {
>> }
>>
>>
>>
>> and (if the ternary operator was overrideable in C++)
>>
>> float4 foo = (a > b) ? c : d;
>>
>> would be better than
>>
>> float4 mask = _mm_gt_ps(a, b);
>> float4 foo = _mm_or_ps(_mm_and_ps(mask, c), _mm_nand_ps_(mask, d));
>>
>
> Yep, it's coming... baby steps :)
>
> Walter: I told you games devs would be all over this! :P

And even a compression algorithms. I found one written in C, that uses  
external .asm files to be compiled into object files with NASM for use on  
the linker command line. They contain some MMX/SSE code depending on the  
processor you plan to use. The author claims, that the MMX version of the  
'outsourced' routines run 8x faster. I didn't verify this, but the idea  
that these instructions become part of the language and easy to use for  
regular programmers like me (and not just console game developers) is  
exciting. I bet there are more programs that could benefit from SSE than  
is obvious or code that could be rewritten in way, that multiple data sets  
can be processed simultaneous.