Re: gcc 2.7.1

=?us-ascii?Q?Bernard_S=E9bastien?= (sbernard@suresnes.marben.fr)
Mon, 10 Aug 1998 10:55:29 +0200


De : Etienne Lorrain <lorrain@fb.sony.de>
À : Linus Torvalds <torvalds@transmeta.com>
Cc : linux-kernel@vger.rutgers.edu <linux-kernel@vger.rutgers.edu>
Date : vendredi 7 août 1998 17:19
Objet : Re: gcc 2.7.1

On Wed, 5 Aug 1998, Linus Torvalds wrote:
> On Wed, 5 Aug 1998, Etienne Lorrain wrote:
> > Maybe it is time to upgrade to gcc-2.7.3, so that this patch could
> > be applied in the main stream :
>
> Do you have numbers for the effect of "-fno-strength-reduce"? Back
when I
> added it I couldn't see any difference at all to any benchmarks, so
I've
> had no real incentive to even try to remove it.
>
> Does anybody have any numbers that show that it actually matters for
the
> kernel (I know it matters a lot for some other things, but I'm looking
for
> something that really makes a difference in kernel-land)?

Hi,

I have done some benchmarking of the kernel (and not benchmarking
of gcc), and you are _again_ right...

The 2.7.3.2 version of the gcc could be used without
the -fno-strength-reduce because the feature has been disabled internaly for
the i386 architecture. The compilation is always done with that flag set,
even if you do not put it in the CFLAGS. So, with or without, it is the
same. If you want to benchmark the results, try the 2.8.x version of some of
the pgcc equivalent version.

Seb

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