[FFmpeg-devel] [PATCH 02/10] x86: dcadsp: implement SSE lfe_dir

[Hendrik Leppkes]

On Fri, Feb 14, 2014 at 5:00 PM, Christophe Gisquet
<christophe.gisquet at gmail.com> wrote:
> Results for Arrandale/Windows:
> 32: 1670 -> 316
> 64:  728 -> 298
> ---
>  libavcodec/x86/dcadsp.asm    | 87 ++++++++++++++++++++++++++++++++++++++++++++
>  libavcodec/x86/dcadsp_init.c |  4 ++
>  2 files changed, 91 insertions(+)
>
> diff --git a/libavcodec/x86/dcadsp.asm b/libavcodec/x86/dcadsp.asm
> index a0995c9..f4149d2 100644
> --- a/libavcodec/x86/dcadsp.asm
> +++ b/libavcodec/x86/dcadsp.asm
> @@ -88,3 +88,90 @@ INT8X8_FMUL_INT32
>
>  INIT_XMM sse4
>  INT8X8_FMUL_INT32
> +
> +; %1=v0/v1  %2=in1  %3=in2
> +%macro FIR_LOOP 2-3
> +.loop%1:
> +%define va          m1
> +%define vb          m2
> +%if %1
> +%define OFFSET      0
> +%else
> +%define OFFSET      NUM_COEF*count
> +%endif
> +; for v0, incrementint and for v1, decrementing
> +    mova        va, [cf0q + OFFSET]
> +    mova        vb, [cf0q + OFFSET + 4*NUM_COEF]
> +%if %0 == 3
> +    mova        m4, [cf0q + OFFSET + mmsize]
> +    mova        m0, [cf0q + OFFSET + 4*NUM_COEF + mmsize]
> +%endif
> +    mulps       va, %2
> +    mulps       vb, %2
> +%if %0 == 3
> +    mulps       m4, %3
> +    mulps       m0, %3
> +    addps       va, m4
> +    addps       vb, m0
> +%endif
> +    ; va = va1 va2 va3 va4
> +    ; vb = vb1 vb2 vb3 vb4
> +%if %1
> +    SWAP        va, vb
> +%endif
> +    mova        m4, va
> +    unpcklps    va, vb ; va3 vb3 va4 vb4
> +    unpckhps    m4, vb ; va1 vb1 va2 vb2
> +    addps       m4, va ; va1+3 vb1+3 va2+4 vb2+4
> +    movhlps     vb, m4 ; va1+3  vb1+3
> +    addps       vb, m4 ; va0..4 vb0..4
> +    movh    [outq + count], vb

I got a complaint about a crash on a SSE-only system, and the disasm I
got from the user was pointing at this exact line:

......
6A2F283F  movaps      xmm4,xmm1
6A2F2842  unpcklps    xmm1,xmm2
6A2F2845  unpckhps    xmm4,xmm2
6A2F2848  addps       xmm4,xmm1
6A2F284B  movhlps     xmm2,xmm4
6A2F284E  addps       xmm2,xmm4
6A2F2851  movq        mmword ptr [eax+ecx],xmm2  <<<

The "movh" generates a movq, which according to my quick research
seems to be SSE2-only, and causes an illegal instruction on the users
CPU.

- Hendrik