primitive vector types

[Denis Koroskin]

On Fri, 20 Feb 2009 06:22:40 +0300, Andrei Alexandrescu <SeeWebsiteForEmail at erdani.org> wrote:

> Denis Koroskin wrote:
>> On Thu, 19 Feb 2009 23:05:34 +0300, Andrei Alexandrescu  
>> <SeeWebsiteForEmail at erdani.org> 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?
>>>>>
>>>>> Yes, the array operations are nice (and one of the main reasons for  
>>>>> why I like D :) ), but have the problem that an array of floats must  
>>>>> be aligned on float boundaries and not vector boundaries. In my mind  
>>>>> vectors are a primitive data type that should be exposed by the  
>>>>> programming language.
>>>>>
>>>>> Something OpenCL-like:
>>>>>
>>>>>     float4 vec;
>>>>>     vec.xyzw = {1.0,1.0, 1.0, 1.0}; // assignment
>>>>>     vec.xyzw = vec.wyxz; // permutation
>>>>>     vec[i] = 1.0; // indexing
>>>>>
>>>>> And then we can easily immagine some extra nice features to have  
>>>>> with respect to operators:
>>>>>
>>>>>     vec ^ vec2; // 3d cross product for float vectors, for int  
>>>>> vectors xor
>>>>>
>>>>> Has this been discussed before?
>>>>>
>>>>> / Mattias
>>>>>
>>>>  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
>>  That would be great. If float4 gets its way into D, I'll share our  
>> blazing fast math code with community (most common operations on  
>> vectors, matrices, quaternions etc). It is written entirely in SSE  
>> (intrinsics, not asm; there is a problem with inlining asm in D, IIRC.  
>> Can anyone elaborate on this?) and *very* fast. According to our  
>> benchmarks, that's the best we get squeeze out of hardware.
>>  I know LLVM have support for *very* wide range of intrinsics:
>> http://www.cs.ucla.edu/classes/spring08/cs259/llvm-2.2/include/llvm/Intrinsics.gen  
>>   Hopefully they will get into LDC (and DMD *hint* Walter *hint*) very  
>> soon.
>>
>
> Put me down for that. What do I need to do?
>
> Andrei

Convince Walter to add float4 type and some intrinsics to DMD (I'll post a list of those we use later), LDC will follow, I believe.
There should be some type that would be treated specially. After all, intrinsics have function signatures and those should specify some concrete types.