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Re: GCC 4.1: Buildable on GHz machines only?
Ian Lance Taylor writes:
> Andrew Haley <aph@redhat.com> writes:
>
> > > >> OK, I know nothing about libtool so this might not be possible, but
> > > >> IMO the easiest way of making a dramatic difference is to cease to
> > > >> compile every file twice, once with PIC and once without. There would
> > > >> be a small performance regression for statically linked Java apps, but
> > > >> in practice Java is very hard to use with static linkage.
> > > >
> > > > Try putting
> > > >
> > > > enable_shared=no
> > > >
> > > > in configure.ac somewhere before AC_PROG_LIBTOOL.
> > >
> > > I think you rather want AC_DISABLE_STATIC.
> >
> > Won't that disable static libraries? I don't want to do that.
>
> Sorry, my misunderstanding.
>
> I don't know of a way to tell libtool to not do duplicate compiles.
> You can use -prefer-pic, but at least from looking at the script it
> will still compile twice, albeit with -fPIC both times.
>
> Incidentally, at least on my system I don't think this will make a
> dramatic difference. The incredibly slow parts of building libjava
> all seem to have to do with building the .a and .so files, both of
> which tend to cause my system to start swapping.
IME the biggest thing there is the libtool shell script.
> While it would obviously help to not build the objects twice, that
> doesn't seem to be the major time sink, at least not for me.
That's not the problem I have: the link is slow, but it's not the
dominant thing. Maybe it depends how much RAM you have? I have 1 Gbyte.
Andrew.