__simd_sto confusion
Benjamin Thaut via Digitalmars-d-learn
digitalmars-d-learn at puremagic.com
Sun Oct 4 05:23:27 PDT 2015
On Saturday, 3 October 2015 at 14:47:02 UTC, Nachtraaf wrote:
> I'm trying to create some linear algebra functions using simd
> intrinsics. I watched the dconf 2013 presentation by Manu Evans
> but i'm still confused about some aspects and the following
> piece of code doesn't work. I'm trying to copy the result of a
> dot product from the register to memory but dmd fails with an
> overload resolution error, which i guess is due some implicit
> conversion?
>
> dmd error:
>
> simd1.d(34): Error: core.simd.__simd_sto called with argument
> types (XMM, float, __vector(float[4])) matches both:
> /usr/include/dlang/dmd/core/simd.d(434):
> core.simd.__simd_sto(XMM opcode, double op1, __vector(void[16])
> op2)
> and:
> /usr/include/dlang/dmd/core/simd.d(435):
> core.simd.__simd_sto(XMM opcode, float op1, __vector(void[16])
> op2)
>
> from the following piece of code:
>
> float dot_simd1(float4 a, float4 b)
> {
> float4 result = __simd(XMM.DPPS, a, b, 0xFF);
> float value;
> __simd_sto(XMM.STOSS, value, result);
> return value;
> }
>
> What am I doing wrong here?
core.simd is horribly broken. I recommend that you avoid it for
any serious work. If you want to do simd programming with D get
LDC or GDC and use their simd intrinsics instead of core.simd.
If you have to do simd with dmd write inline assembly.
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