[FFmpeg-devel] Fix VP3 IDCT on Win64

[Reimar Döffinger]

On Wed, Aug 25, 2010 at 09:04:33PM +0100, M?ns Rullg?rd wrote:
> Reimar D?ffinger <Reimar.Doeffinger at gmx.de> writes:
> 
> > On Wed, Aug 25, 2010 at 07:46:35PM +0100, M?ns Rullg?rd wrote:
> >> "Ronald S. Bultje" <rsbultje at gmail.com> writes:
> >> 
> >> > Hi,
> >> >
> >> > After this patch, it's still broken, because of put_h264_chroma_mc8
> >> > ssse3 not properly marking clobbers, but this patch 1/3rd-fixes
> >> > VP6/Win64/FATE failures (similar to how my previous patch fixed a
> >> > third of it).
> >> >
> >> > I can't fix put_h264_chroma_mc8_ssse3 because it's split over multiple
> >> > asm() statements which rely on maintaining register values between, so
> >> > I will likely rewrite that (also for VC-1/H.264/RV40) in yasm, but
> >> > that'll take a little longer... After that, fate-ea-vp60 passes
> >> > (haven't tested the others yet, because Win64 hates me).
> >> >
> >> > Ronald
> >> >
> >> > Index: libavcodec/x86/vp3dsp_sse2.c
> >> > ===================================================================
> >> > --- libavcodec/x86/vp3dsp_sse2.c	(revision 24909)
> >> > +++ libavcodec/x86/vp3dsp_sse2.c	(working copy)
> >> > @@ -171,6 +171,7 @@
> >> >          VP3_1D_IDCT_SSE2(ADD8, SHIFT4)
> >> >          PUT_BLOCK(%%xmm0, %%xmm1, %%xmm2, %%xmm3, %%xmm4, %%xmm5, %%xmm6, %%xmm7)
> >> >          :: "r"(input_data), "r"(ff_vp3_idct_data), "m"(ff_pw_8)
> >> > +        : "%xmm6", "%xmm7"
> >> >      );
> >> >  }
> >> 
> >> Looks good to my untrained eye.
> >
> > Assuming it works with all compilers, which would simplify the patch
> > I proposed some time ago (though listing all XMM registers 0-7 IMO
> > would be better).
> 
> Why wouldn't it work?  The problem was, IIRC, with the high,
> amd64-only xmm registers in 32-bit builds.

Because some compilers might refuse to compile with xmm clobbers because
they don't know anything about a xmm register?