[FFmpeg-devel] ASM support for MACOSX 10.5: really?

Michael Niedermayer michaelni
Tue Mar 25 20:18:57 CET 2008


On Tue, Mar 25, 2008 at 07:04:10PM +0000, Robert Swain wrote:
> On 25/03/2008, vmrsss <vmrsss at gmail.com> wrote:
> > On 25 Mar 2008, at 14:53, ?smail D?nmez wrote:
> >  > First of all try with gcc not gcc-4.2, static build works fine with
> >  > gcc which is 4.0.1, if you want gcc 4.2 you'll have to do a 64bit
> >  > build due to flac error you encountered. And to do 64bit build on
> >  > MacOSX you need a patch that I posted to this list many times, a
> >  > little search will find it.
> >
> > Thanks a lot Ismail! This helped. Indeed, using gcc the static build
> >  goes through smoothly. With --enable-shared however, I still have
> >  can't compile cavdsp_mmx and flacdsp_mmx:
> 
> These two are known. As I recall, for flac Loren said that it could be
> done using less regs but it's faster the way it is and the issue isn't
> the code, it's GCC's register allocation. Maybe this works in gcc 4.4?
> I've just been disabling them at configure time for the moment.

As i have a dozen gccs installed

(all with -fPIC -DPIC)
2.95        works
3.3         works
3.4         works
4.0         works
4.1         works
4.2         5 "error: 'asm' operand has impossible constraints" nonsense
4.3         3 "error: 'asm' operand has impossible constraints" nonsense
4.4         3 "error: 'asm' operand has impossible constraints" nonsense

so, if someone wants to use latestest and "greatest" gcc go report it.

Also if someone wants to workaround it in ffmpeg, no problem, the code
though must not be slower!
The whole loop of that code should be written in a asm( ) anyway, no
stincky for(){asm()}.

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Those who are too smart to engage in politics are punished by being
governed by those who are dumber. -- Plato 
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