Re: [eigen] limiting executable code size with debug info

[Benoît Jacob <jacob@xxxxxxxxxxxxxxx>]

Updating the list:

http://bjacob.livejournal.com/5447.html

Comment from Thiago (KDE, Qt guru) who believes that the size of debug symbols 
doesn't matter as anyway they're split into separate files and packaged 
separately by distros.

Also IRC conversation with Gael, the ratio g2/g1 for kdelibs is already x5, 
and in his own project heavily using eigen2 (probably more than any kde 
module ever will) the ratio is x8 so it looks like at the scale of a whole 
project the impact of eigen2 on the size of debugging symbols is not so 
dramatic. So far I had only tested very little examples but they were not so 
representative.

Cheers,
Benoit

On Monday 09 June 2008 17:26:48 Gael Guennebaud wrote:
> On Mon, Jun 9, 2008 at 5:17 PM, Benoît Jacob <jacob@xxxxxxxxxxxxxxx> wrote:
> > On Monday 09 June 2008 16:57:37 Gael Guennebaud wrote:
> > > but my project also has its own template mess so the overhead is not
> > > 100% due to eigen2. It would be interesting to grab such statistics on
> > > kdelibs for instance...
> >
> > Just FYI kdelibs is not using eigen and, as far as I can see, doesn't
> > have a
> > use for it.
>
> I know, this is why it is interesting to try on it to see the overhead of
> -g2 compared to -g1 on "normal" code. But it seems KDE cmake files
> overwrite user settings... so I cannot try with -g1....
>
>
> 57M code sounds huge... is it a really big project you're working on, or is
>
> > it
> > something really special that justifies having many template
> > instantiations,
> > or is it just that eigen and/or your other template stuff is generating
> > far too much executable code?
>
> 57M is not that huge, my project is quite large indeed with large templated
> classes instanciated twice for 2D and 3D...
>
> Gael.
>
> > Cheers,
> > Benoit
> >
> > > Gael.
> > >
> > > On Mon, Jun 9, 2008 at 4:26 PM, Gael Guennebaud <
> >
> > gael.guennebaud@xxxxxxxxx>
> >
> > > wrote:
> > > > Hi,
> > > >
> > > > On Mon, Jun 9, 2008 at 9:06 AM, Benoît Jacob <jacob@xxxxxxxxxxxxxxx>
> > > > wrote: <http://download.tuxfamily.org/eigen/benchmark-g1.s.gz>
> > > >
> > > >> So, does anybody have an idea what to do to make Eigen usable with
> > > >> -g2
> >
> > ?
> >
> > > > yes of course, that's easy:
> > > >
> > > > let's rewrite eigen using QVariant to store the coefficients and
> >
> > virtual
> >
> > > > members ;)
> > > >
> > > > no, seriously I have no idea how to deal with that issue :(  I know
> > > > several template libraries which generate GB of .o in debug mode and
> > > > I hate that... Maybe it'd be worth asking on GCC mailing list since
> > > > the answer to this issue probably requires to know very well how GCC
> >
> > behaves
> >
> > > > internally.
> > > >
> > > > Gael.

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