[Ffmpeg-devel] [PATCH] fix x86 asm compilation

[Aurelien Jacobs]

On Mon, 30 May 2005 09:57:48 +0200
Michel Bardiaux <mbardiaux at peaktime.be> wrote:

> Rich Felker wrote:
> > On Mon, May 30, 2005 at 12:39:23AM +0200, Aurelien Jacobs wrote:
> > 
> >>Hi,
> >>
> >>Currently i386/dsputil_mmx.c fails to compiles on x86 when
> >configured >with --disable-opts. (At least for me with gcc 3.3.4)
> > 
> > 
> > Why does this option to configure exist? It's known that disabling
> > optimizations is not supported for asm...
> > 
> > 
> >>I've written a small patch which fixes this. I don't like it very
> >much, >but I've no better idea right now.
> > 
> > 
> > If you insist on disabling optimizations (there is no good reason
> > for this), then disable asm while you're at it too...
> 
> There *is* one good reason to disable optimisations: when you need 
> debugging (which of course never happens with ffmpeg :-) ), gdb is
> often  very confused by optimisations. Being unable to have asm and
> no-opt  simultaneously makes debugging of code containing asm a real
> PITA.

That was exactly my purpose. I only used --disable-opts for debugging.
I never use it for any other purpose.
The fact is that --disable-opts used to work and was broken some times
ago (it still works on amd64 thanks to it's 8 new general purpose
registers).
The transpose4x4 is the only asm code which breaks compilation with
--disable-opts so I think it should really be fixed.

Aurel