From: Andi Kleen <ak@suse.de>
To: Toon Moene <moene@knmi.nl>
Cc: gcc@gcc.gnu.org, starlex@eng.sun.com
Subject: Re: contribution
Date: Fri, 12 Apr 2002 05:54:00 -0000 [thread overview]
Message-ID: <p73ads9axvo.fsf@oldwotan.suse.de> (raw)
In-Reply-To: Toon Moene's message of "12 Apr 2002 14:35:57 +0200"
Toon Moene <moene@knmi.nl> writes:
> Andi Kleen wrote:
>
> > Alexey Starovoytov <starlex@eng.sun.com> writes:
>
> >> For example SPECfp benchmark 172.mgrid showed 48% improvement
> >> compiled with "-O2 -Ws,-O2,-fno-strict-aliasing" vs plain GCC
> >> with "-O2"
>
> > You could compiled 172.mgrid with gcc twice this way and it showed
> > 48% improvement ? Or did you use a different compiler as backend?
> > If you used gcc - is it known where that huge difference comes
> > from?
>
> A more important aspect of such a compiler would be idempotency.
>
> I.e., is
>
> gcc(gcc(x.c)) = gcc(x.c)
>
> ?
To be honest I don't believe that he got that result with multiple runs
of gcc. If yes that would be a very bad bug in the optimizer. More likely
it was reached with the proprietary Sun compiler as backend (that would
make the patch more a porting tool for GNU C programs to Sun C)
-Andi
next parent reply other threads:[~2002-04-12 12:45 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <3CB6D448.45A4FE3E@knmi.nl.suse.lists.egcs>
2002-04-12 5:54 ` Andi Kleen [this message]
2002-04-12 5:58 ` contribution Toon Moene
2022-12-14 15:32 Contribution Mohamed Atef
2022-12-15 14:47 ` Contribution Jason Merrill
2022-12-15 16:42 ` Contribution Paul Smith
[not found] <CAOw3FZBzjtxEmbSMJDviD-td4bDM_mCMs9BQpk0SvK4EpR8N5g@mail.gmail.com>
2022-03-14 8:35 ` Fwd: Contribution farhad
2022-03-14 16:51 ` Contribution David Edelsohn
-- strict thread matches above, loose matches on Subject: below --
2002-04-12 5:45 contribution Toon Moene
[not found] <Pine.GSO.4.31.0204112030350.15026-101000@boojum.suse.lists.egcs-patches>
2002-04-12 1:28 ` contribution Andi Kleen
2002-04-12 11:42 ` contribution Alexey Starovoytov
2002-04-12 15:15 ` contribution Toon Moene
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