Re: [Gcl-devel] Re: gcc-3.2 problems in compiling GCL

[Richard Zidlicky]

On Mon, Feb 24, 2003 at 11:26:39AM -0500, Camm Maguire wrote:
> Greetings!
> 
> Richard Zidlicky <address@hidden> writes:
> 
> > On Tue, Feb 18, 2003 at 04:46:46PM -0500, Camm Maguire wrote:
> > > Greetings, and thanks for the insight.  GCL does a subbuild of part of
> > > GMP.  With the default configure script canonical host of
> > > m68k-unknown-linux-gnu, gmp3 adds -m68000 to the command line.
> > 
> > this is slightly broken - there has never been 68000 support
> > in Linux.
> > 
> > > Perhaps the autobuilders should use m68020-unknown-linux-gnu as the
> > > lowest common denominator?
> > 
> > this would work but not very well on 68060 models though.. here
> > are the options:
> >   a) use m68k-*linux WITHOUT -m68000 flag. Will loose some
> >      performance on 68020-40 models, nearly optimal for 68060
> >   b) m68020-linux will loose *lots* of performance on 68060 models.
> >   c) compile 2 versions of the library/program for 20-40 or 60
> >      models.
> > 
> > (a) is pretty acceptable, (b) would be probably the worst alternative. 
> > (c) would be nice and I think it is time to use multilibs for m68k-linux.
> > 
> 
> OK, this won't get done before the next release, but what I'd like to
> do is 1) benchmark the bignum code and see if these issues make a big
> difference, and 2) assuming yes to 1), implement a dynamic library
> alternative system as is done in atlas/lapack/blas on Debian
> GNU/Linux, say by building a libgcl_gmp.so.  I don't know if you are
> familiar with how this works, but I'd like your feedback if you are
> interested.  Basically, one can install several binary-compatible
> versions of the same library, and have the running cpu select the best
> one for its capabilities at run time via ld.so.conf. I've made a
> policy proposal, but thus far it has not received much interest:
> 
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=120418

I agree that something like this is necessary, on m68k most 
if not all applications that use gmp, ssl and similar are in
desperate need to come in 68020-40 and 68060 flavours.

Incidentally glibc itself includes the gmp "muladd" code that
would require a similar treatment.

Richard