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

[Hendrik Leppkes]

On Sun, Apr 6, 2014 at 5:34 PM, Timothy Gu <timothygu99 at gmail.com> wrote:
> On Apr 6, 2014 8:24 AM, "Hendrik Leppkes" <h.leppkes at gmail.com> wrote:
>>
>> 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.
>
> That should probably be movlps. See
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b5161908e06b4497bf663510fb495ba97a6fd2b5
> .
>

I sent a patch based on that, thanks for remembering the earlier case. :)

- Hendrik