[FFmpeg-devel] [PATCH] split-radix FFT
Tue Jul 29 19:38:00 CEST 2008
On Tue, Jul 29, 2008 at 06:57:21PM +0300, Uoti Urpala wrote:
> On Tue, 2008-07-29 at 17:41 +0200, Michael Niedermayer wrote:
> > On Tue, Jul 29, 2008 at 06:26:49PM +0300, Uoti Urpala wrote:
> > > On Tue, 2008-07-29 at 17:10 +0200, Michael Niedermayer wrote:
> > > > And just to clarify, yes what i considered a good argument was the sentance
> > > > above where my reply is. That is to use MANGLE in speed critical code.
> > > > That way most textrels are avoided while minimizing the speed impact.
> > > >
> > > > I do not think you ever argued for that.
> > >
> > > IIRC I did mention the possibility of omitting -fPIC for a subset of
> > > files.
> > >
> > > > I remember you strongly arguing
> > > > toward replacing all MANGLE by "m" knowing that it would break gcc 2.95
> > > > and not really caring that it would slow down code compiled with -fPIC.
> > >
> > > Of course the code would be slower on x86. If you want it to be as fast
> > > as possible then compile it with -fPIC on x86. I don't think it's
> > > worthwhile to pick only the globals used inside asm for such special
> > > treatment.
> > x86-64 shared libs require -fPIC, unless that has been fixed.
> > so the user does not always have the option to omit -fPIC
> I didn't mean to include AMD64 in x86. -fPIC does not cause that much
> slowdown on it. And anyway what shared libs on AMD64 require is *no
> textrels* - generating them by some other method wouldn't work any
> better. So you don't need MANGLE to force creating textrels, and if it
> did that the result in fact wouldn't work. You can avoid GOT lookup by
> adding visibility information (and then the compiler will avoid it for
> ALL uses, not just those inside asm).
We dont have visibility attributes in svn,
they are a gcc only feature and
I think noone came up with a clean way to add visibility attributes,
that is a way that does not require adding them to a significant
portion of the globals one by one.
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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