primitive vector types

[downs]

Daniel Keep wrote:
> Andrei Alexandrescu wrote:
>> Denis Koroskin wrote:
>>> On Thu, 19 Feb 2009 22:25:04 +0300, Mattias Holm
>>> <hannibal.holm at gmail.com> wrote:
>>>
>>>> Since (SIMD) vectors are so common and every reasonabe system support
>>>> them in one way or the other (and scalar emulation of this is rather
>>>> simple), why not have support for this in D directly?
>>>>
>>>> [snip]
>>> I don't see any reason why float4 can't be made a library type.
>> Yah, I was thinking the same:
>>
>> struct float4
>> {
>>     __align(16) float[4] data; // right syntax and value?
>>     alias data this;
>> }
>>
>> This looks like something that should go into std.matrix pronto. It even
>> has value semantics even though fixed arrays don't :o/.
>>
>>
>> Andrei
> 
> I remember implementing a vector struct [1] quite some time ago that had
> an SSE-accelerated path.

We have that in dglut too :) It's optimized for the float[3]/float[4] case - all float[3]s add a hidden bogus member, then the arithmetic operations generate for loops which are very easy for a properly patched gdc to autovectorize :)

No loss of inlining, which means no ref VS. val issues. Alignment is still a problem, but movups in the aligned case is just as fast as movaps, so I figure it doesn't matter that much.

Autovec is sweet.