[eigen] limiting executable code size with debug info

[Benoît Jacob <jacob@xxxxxxxxxxxxxxx>]

Hi List,

I'm currently worried about the following problem. Eigen now compiles to 
excellent code with just the following gcc options,
-O2 -g,

i.e. we get near-optimal speed while retaining all the debug info. Good! But, 
the executable code is then huge: about 30 times what it is with just -O2, 
that is, the debug info takes 30x the space of the actual code!

Since -g means -g2, we can get a lighter debug mode with -g1. Then the code 
size is very good: about 1.5x the size of the code produced with just -O2.

But we do *not* want to force our users to use only -g1 when compiling their 
apps.

According to 'man gcc' the difference between -g1 and -g2 is that -g2 adds 
source code line number info and local variables info.

Here I uploaded the generated assembly file with -O2 -g2:
http://download.tuxfamily.org/eigen/benchmark-g2.s.gz

And here is the file generated by -O2 -g1:
http://download.tuxfamily.org/eigen/benchmark-g1.s.gz

So, does anybody have an idea what to do to make Eigen usable with -g2 ?

Cheers,

Benoit

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