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Re: downgrading optimization for m68k [was: Bug#328453: pbzip2_0.9.4-1(m68k/unstable/zeus): FTBFS on m68k]

On Thu, 2005-09-15 at 19:47 -0700, Steve Langasek wrote:
> On Thu, Sep 15, 2005 at 07:15:16PM -0700, tony mancill wrote:
> > Stephen R Marenka wrote:
> > > On Fri, Sep 16, 2005 at 10:40:50AM +1000, Anibal Monsalve Salazar wrote:
> > >>>to bug #317475 on gcc-4.0. As a workaround, you might try compiling with
> > >>>less optimization or gcc-3.3/gcc-3.4.
> > >>+ifneq (,$(findstring m68k,$(DEB_HOST_ARCH)))
> > >>+	CFLAGS = -Wall -O0
> > >>+endif
> > > For the record, -O2 seems to work fine. The segfaults only seem to 
> > > apply to -O3 and better (at least in my experience).
> > This seems to affect one of the packages I sponsor as well:
> >    http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=325557
> > If gcc-4.0 is going to puke on lots of packages that use -O3, doesn't it
> > make more sense to upload a patched gcc-4.0 for m68k that silently
> > changes the optimization level back to 2 untile the problem with the
> > compiler can be fixed rather than upload and recompile a large number of
> > packages for every architecture?
> If you have a patch that fixes the ICEs on m68k, by all means please forward
> it to the BTS.
> But a larger question is, why are so many packages being built entirely with
> -O3 when policy recommends -O2?  Policy does say it's ok to use other
> compiler flags if appropriate, but I'd be surprised if all of these packages
> have been benchmarked to confirm that -O3 actually gives measurable
> performance benefits.

I don't know if it gives measurable benefits, but all Python extensions
use -O3 by default (from /usr/lib/python2.3/config/Makefile). Personally
I think it's dumb, but maybe the Python maintainers know better? This is
what triggered the bug in python-flac for me. Overriding distutils isn't
something I've figured out yet (doing so is a task for the weekend).
Joe Wreschnig <piman@debian.org>

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