Re: Large, modular C++ application performance ...

["H. J. Lu" <hjl@lucon.org>]

On Mon, Aug 01, 2005 at 10:38:46AM +0100, michael meeks wrote:
> Hi Giovanni,
> 
> On Sat, 2005-07-30 at 15:36 +0200, Giovanni Bajo wrote:
> > I'm slow, but I can't understand why a careful design of the interfaces of
> > the dynamic libraries
> 
> 	Well - sure, depends how 'careful' you are ;-) clearly if no C++
> classes with virtual methods form the interface of any library, then
> there is no problem ;-) unfortunately, mandating that would rather
> cripple C++.
> 
> >  together with the new -fvisibility flags, should not
> > be sufficient. It worked well in other scenarios
> 
> 	-fvisibility is helpful - as the paper says, not as helpful as the old
> -Bsymbolic (or link maps exposing only 3 or so functions) were. However
> - -fvisibility can only help so much - if you have:
> 

Since you were comparing Windows vs. ELF, doesn't Windows need a file
to define which symbols to export for a shared library? Why can't you
you do it with ELF using a linker map? Libstdc++.so is built with
a linker map. Any C++ shared library should use one if the startup
time is a big concern. Of coursee, if gcc can generate a list of
symbols suitable for linker map, which needs to be exported, it will
be very helpful. I don't think it will be too hard to implement.


H.J.