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Re: GCC 4.1: Buildable on GHz machines only?
Dan Nicolaescu <dann@ics.uci.edu> writes:
> Matt Thomas <matt@3am-software.com> writes:
>
> > Richard Henderson wrote:
> > > On Tue, Apr 26, 2005 at 10:57:07PM -0400, Daniel Jacobowitz wrote:
> > >
> > >>I would expect it to be drastically faster. However this won't show up
> > >>clearly in the bootstrap. The, bar none, longest bit of the bootstrap
> > >>is building stage2; and stage1 is always built with optimization off and
> > >>(IIRC) checking on.
> > >
> > >
> > > Which is why I essentially always supply STAGE1_CFLAGS='-O -g' when
> > > building on risc machines.
> >
> > Alas, the --disable-checking and STAGE1_CFLAGS="-O2 -g" (which I was
>
> I don't think that is enough, also edit gcc/Makefile.in and change the line:
> STAGE1_CHECKING = -DENABLE_CHECKING -DENABLE_ASSERT_CHECKING
> to be
> STAGE1_CHECKING =
>
> Is there a better way to do this? STAGE1_CHECKING is not passed from
> the toplevel make, so one cannot put it on the make bootstrap command
> line...
Following up on this to show some numbers.
On a 2.8GHz P4, 1MB cache, 512MB RAM, Fedora Core 3
gcc HEAD configured with --enable-languages=c --disable-checking --disable-nls
time make bootstrap > & out
1227.861u 53.623s 21:26.53 99.6% 0+0k 0+0io 18pf+0w
If gcc/Makefile.in is first edited as shown above, then the bootstrap
time is:
983.769u 53.241s 17:33.12 98.4% 0+0k 0+0io 3573pf+0w
A significant difference!
Given that with --enable-languages=c the amount of stuff built with
the slow stage1 compiler is minimal, the impact might be even higher
when more languages are enabled (I haven't tried).
It would be nice to have some way to disable STAGE1_CHECKING other
than by editing gcc/Makefile.in (Sorry, I can't help with this, I
don't know much about how the gcc configuration process).