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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, 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.

Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
vorlon@debian.org                                   http://www.debian.org/

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