[Ffmpeg-devel] Problem building ffmpeg on G3 PPC without altivec unit

[Aurelien Jacobs]

On Sun, 26 Feb 2006 22:41:34 +0100
Diego Biurrun <diego at biurrun.de> wrote:

> On Sun, Feb 26, 2006 at 10:12:48PM +0000, Benjamin Larsson wrote:
> > Diego Biurrun wrote:
> > 
> > >On Sun, Feb 26, 2006 at 08:17:56PM +0000, Benjamin Larsson wrote:
> > >  
> > >>http://equinox.campus.luth.se/~banan/2006/02/25/build-gcc-3.4.log
> > >>
> > >> [...]
> > >>
> > >
> > >But configure says
> > >
> > >  AltiVec enabled  yes
> > >
> > >are you passing --enable-altivec or is autodetection failing?
> > >
> > Only, ./configure --enable-gpl.
> 
> Just read through configure, look at lines 866-888 and try to find out
> why it enables AltiVec.  Maybe add

I don't think that autodetection fails. It only check if cpu is a
powerpc, and if gcc is able to build altivec code. Both should be
true even when running on a G3.
So I guess that the altivec code as always been built on G3, and the
current problem is not specific to G3 build.

What fails right now is compiling the following line :
  vector unsigned int v16ui = vec_sl(vec_splat_u16(1),vec_splat_u16(4));
I guess that only some gcc version are able to build this ? (That's
really a wild guess, I know nothing about altivec)
I tested here with gcc 3.3.5 and I can see the same problem.

With the attached patch, altivec support is disabled when gcc is not
able to build this specific initialization (but I guess this could
disable altivec on G4 with certain gcc versions).

Aurel
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