[FFmpeg-devel] r9017 breaks WMA decoding on Intel Macs

[Guillaume Poirier]

Hi,

Le 27 mai 07 ? 14:52, Guillaume POIRIER a ?crit :

> On 5/27/07, Guillaume POIRIER <poirierg at gmail.com> wrote:
>> Any vorbis should do the trick. I'll try to narrow down the  
>> problem to
>> see which part of the patch broke it.
>
> This hunk is what causes the regression:

Off course this should read: "applying this hunk fixes the regression".


> Index: fft_sse.c
> ===================================================================
> --- fft_sse.c	(revision 9017)
> +++ fft_sse.c	(revision 6577)
> @@ -100,33 +100,20 @@
>              i = nloops*8;
>              asm volatile(
>                  "1: \n\t"
> -                "sub $32, %0 \n\t"
> +                "sub $16, %0 \n\t"
>                  "movaps    (%2,%0), %%xmm1 \n\t"
>                  "movaps    (%1,%0), %%xmm0 \n\t"
> -                "movaps  16(%2,%0), %%xmm5 \n\t"
> -                "movaps  16(%1,%0), %%xmm4 \n\t"
>                  "movaps     %%xmm1, %%xmm2 \n\t"
> -                "movaps     %%xmm5, %%xmm6 \n\t"
>                  "shufps      $0xA0, %%xmm1, %%xmm1 \n\t"
>                  "shufps      $0xF5, %%xmm2, %%xmm2 \n\t"
> -                "shufps      $0xA0, %%xmm5, %%xmm5 \n\t"
> -                "shufps      $0xF5, %%xmm6, %%xmm6 \n\t"
>                  "mulps   (%3,%0,2), %%xmm1 \n\t" //  cre*re cim*re
>                  "mulps 16(%3,%0,2), %%xmm2 \n\t" // -cim*im cre*im
> -                "mulps 32(%3,%0,2), %%xmm5 \n\t" //  cre*re cim*re
> -                "mulps 48(%3,%0,2), %%xmm6 \n\t" // -cim*im cre*im
>                  "addps      %%xmm2, %%xmm1 \n\t"
> -                "addps      %%xmm6, %%xmm5 \n\t"
>                  "movaps     %%xmm0, %%xmm3 \n\t"
> -                "movaps     %%xmm4, %%xmm7 \n\t"
>                  "addps      %%xmm1, %%xmm0 \n\t"
>                  "subps      %%xmm1, %%xmm3 \n\t"
> -                "addps      %%xmm5, %%xmm4 \n\t"
> -                "subps      %%xmm5, %%xmm7 \n\t"
>                  "movaps     %%xmm0, (%1,%0) \n\t"
>                  "movaps     %%xmm3, (%2,%0) \n\t"
> -                "movaps     %%xmm4, 16(%1,%0) \n\t"
> -                "movaps     %%xmm7, 16(%2,%0) \n\t"
>                  "jg 1b \n\t"
>                  :"+r"(i)
>                  :"r"(p), "r"(p + nloops), "r"(cptr)
>
>
> We're quite lucky, it's the shortest of the 2 hunks.
>
> Now I need to figure out what's wrong in that hunk.

There's nothing wrong to this hunk!
It just duplicates the original code and uses "original register  
number" + 4.
Why on earth would it break on OSX and not on Linux?

Is there's some qualified guru out there who could could enlighten me  
here?

Guillaume