core.simd woes

Iain Buclaw ibuclaw at ubuntu.com
Mon Oct 8 14:29:48 PDT 2012


On 8 October 2012 22:18, Manu <turkeyman at gmail.com> wrote:
> On 8 October 2012 23:05, Iain Buclaw <ibuclaw at ubuntu.com> wrote:
>>
>> On 7 October 2012 13:12, Manu <turkeyman at gmail.com> wrote:
>> > On 5 October 2012 14:46, Iain Buclaw <ibuclaw at ubuntu.com> wrote:
>> >>
>> >> On 5 October 2012 11:28, Manu <turkeyman at gmail.com> wrote:
>> >> > On 3 October 2012 16:40, Iain Buclaw <ibuclaw at ubuntu.com> wrote:
>> >> >>
>> >> >> On 3 October 2012 02:31, jerro <a at a.com> wrote:
>> >> >> >> import core.simd, std.stdio;
>> >> >> >>
>> >> >> >> void main()
>> >> >> >> {
>> >> >> >>   float4 a = 1, b = 2;
>> >> >> >>   writeln((a + b).array); // WORKS: [3, 3, 3, 3]
>> >> >> >>
>> >> >> >>   float4 c = [1, 2, 3, 4]; // ERROR: "Stored value type does
>> >> >> >>                            // not match pointer operand type!"
>> >> >> >>                            // [..a bunch of LLVM error code..]
>> >> >> >>
>> >> >> >>   float4 c = 0, d = 1;
>> >> >> >>   c.array[0] = 4;
>> >> >> >>   c.ptr[1] = 4;
>> >> >> >>   writeln((c + d).array); // WRONG: [1, 1, 1, 1]
>> >> >> >> }
>> >> >> >
>> >> >> >
>> >> >> > Oh, that doesn't work for me either. I never tried to use those,
>> >> >> > so I
>> >> >> > didn't
>> >> >> > notice that before. This code gives me internal compiler errors
>> >> >> > with
>> >> >> > GDC
>> >> >> > and
>> >> >> > DMD too (with "float4 c = [1, 2, 3, 4]" commented out). I'm using
>> >> >> > DMD
>> >> >> > 2.060
>> >> >> > and a recent versions of GDC and LDC on 64 bit Linux.
>> >> >>
>> >> >> Then don't just talk about it, raise a bug - otherwise how do you
>> >> >> expect it to get fixed!  ( http://www.gdcproject.org/bugzilla )
>> >> >>
>> >> >> I've made a note of the error you get with `__vector(float[4]) c =
>> >> >> [1,2,3,4];' - That is because vector expressions implementation is
>> >> >> very basic at the moment.  Look forward to hear from all your
>> >> >> experiences so we can make vector support rock solid in GDC. ;-)
>> >> >
>> >> >
>> >> > I didn't realise vector literals like that were supported properly in
>> >> > the
>> >> > front end yet?
>> >> > Do they work at all? What does the code generated look like?
>> >>
>> >> They get passed to the backend as of 2.060 - so looks like the
>> >> semantic passes now allow them.
>> >>
>> >> I've just recently added backend support in GDC -
>> >>
>> >>
>> >> https://github.com/D-Programming-GDC/GDC/commit/7ada3d95b8af1b271d82f1ec5208f0b689eb143c#L1R1194
>> >>
>> >> The codegen looks like so:
>> >>
>> >> float4 a = 2;
>> >> float4 b = [1,2,3,4];
>> >>
>> >> ==>
>> >> vector(4) float a = { 2.0e+0, 2.0e+0, 2.0e+0, 2.0e+0 };
>> >> vector(4) float b = { 1.0e+0, 2.0e+0, 3.0e+0, 4.0e+0 };
>> >>
>> >> ==>
>> >>         movaps  .LC0, %xmm0
>> >>         movaps  %xmm0, -24(%ebp)
>> >>         movaps  .LC1, %xmm0
>> >>         movaps  %xmm0, -40(%ebp)
>> >>
>> >>         .align 16
>> >> .LC0:
>> >>         .long   1073741824
>> >>         .long   1073741824
>> >>         .long   1073741824
>> >>         .long   1073741824
>> >>         .align 16
>> >> .LC1:
>> >>         .long   1065353216
>> >>         .long   1073741824
>> >>         .long   1077936128
>> >>         .long   1082130432
>> >
>> >
>> > Perfect!
>> > I can get on with my unittests :P
>>
>> I fixed them again.
>>
>>
>> https://github.com/D-Programming-GDC/GDC/commit/9402516e0b07031e841a15849f5dc94ae81dccdc#L4R1201
>>
>>
>> float a = 1, b = 2, c = 3, d = 4;
>> float4 f = [a,b,c,d];
>>
>> ===>
>>         movss   -16(%rbp), %xmm0
>>         movss   -12(%rbp), %xmm1
>
>
> Errr, that's not fixed...?
> movss is not the opcode you're looking for.
> Surely that should produce a single movaps...

I didn't say I compiled with optimisations - only -march=native.  =)


-- 
Iain Buclaw

*(p < e ? p++ : p) = (c & 0x0f) + '0';


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