[FFmpeg-devel] [PATCH] split-radix FFT

[Uoti Urpala]

On Tue, 2008-07-29 at 16:46 +0200, Michael Niedermayer wrote:
> On Tue, Jul 29, 2008 at 05:32:44PM +0300, Uoti Urpala wrote:
> > On Tue, 2008-07-29 at 16:18 +0200, Michael Niedermayer wrote:
> > > On Tue, Jul 29, 2008 at 07:36:06AM -0600, Loren Merritt wrote:
> > > > On Tue, 29 Jul 2008, Michael Niedermayer wrote:
> > > > >
> > > > > Also if i use MANGLE to access the 2 root2 globals things clear up a bit in
> > > > > the code generated, so i would suggest that to be done at least, even if
> > > > > the asm stays split up.
> > > > 
> > > > If we don't actually require the output to be position independent, isn't 
> > > > the simpler solution to not compile with -fPIC? Or are we doing some sort 
> > > > of informed trade-off where only the most cpu-intensive functions get 
> > > > textrels?
> > > 
> > > Thats a good argument as well.
> > 
> > Funny how you didn't find the argument good at all when I mentioned it
> > while talking about MANGLE earlier... :)
> 
> You argued in favor of using MANGLE ?

Against using it. The argument being that if you don't want PIC, don't
compile with -fPIC (the asm files at least) instead of using -fPIC and
then uglifying the code with MANGLE to negate it.

What do you refer to as "good argument" then if not the "better to not
use -fPIC than to add MANGLE" first part? The question (doesn't look
like an argument to me)?

> > >  Though i was more thinking of distributions
> > > that have a policy that says -fPIC must be added to the flags.
> > > 
> > > http://www.debian.org/doc/debian-policy/ch-files.html:
> > > 10.2 Libraries
> > 
> > Currently FFmpeg in Debian is built without -fPIC on x86.
> 
> Iam happy to hear this, still the point stands, distributions have such
> requirements. And it takes the package maintainer quite a bit of work (or
> rulebreaking) to not compile with -fpic.

And how does using MANGLE improve things? By increasing the changes that
someone fails to realize it's still creating textrels even though the
flags seem to say otherwise? I think that counts at most as "helps
breaking the rules without anyone noticing". Where such rules exist
they're meant to forbid textrels in the generated binaries. Changing the
command line while still generating textrels by some other mechanism
does not achieve anything meaningful.