From: Robert Dewar <dewar@adacore.com>
To: Steven Bosscher <stevenb@suse.de>
Cc: Daniel Berlin <dberlin@dberlin.org>,
Ulrich Weigand <uweigand@de.ibm.com>,
gcc@gcc.gnu.org, Mark Mitchell <mark@codesourcery.com>,
Michael Veksler <VEKSLER@il.ibm.com>,
Paul Koning <pkoning@equallogic.com>,
gdr@integrable-solutions.net, nathan@codesourcery.com
Subject: Re: Do C++ signed types have modulo semantics?
Date: Wed, 29 Jun 2005 18:45:00 -0000 [thread overview]
Message-ID: <42C2EC27.3010602@adacore.com> (raw)
In-Reply-To: <200506292032.16423.stevenb@suse.de>
Steven Bosscher wrote:
> On Wednesday 29 June 2005 20:01, Daniel Berlin wrote:
>
>>So i would advise anyone arguing against turning on -fwrapv simply
>>because it doesn't seem to hurt us at O2.
>
>
> wtf, "doesn't seem to hurt us at -O2". Look again at the 64 bits
> numbers! Losing 5% on the fp benchmarks is a serious regression.
> Even without exercising the heavy-ammo loop optimizers, -fwrapv is
> a serious performance-hurter.
Still these figures are very interesting for Ada, where I am afraid
the kludge we do in the front end for required overflow checking is
much more expensive than these figures indicate. Of course this will
be *highly* target dependent.
next prev parent reply other threads:[~2005-06-29 18:45 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-06-27 5:09 Michael Veksler
2005-06-27 13:02 ` Nathan Sidwell
2005-06-27 14:10 ` Gabriel Dos Reis
2005-06-27 14:36 ` Nathan Sidwell
2005-06-27 14:47 ` Paul Koning
2005-06-27 15:21 ` Michael Veksler
2005-06-28 3:06 ` Mark Mitchell
2005-06-28 3:49 ` Gabriel Dos Reis
2005-06-28 10:08 ` Robert Dewar
2005-06-28 11:19 ` Steven Bosscher
2005-06-28 12:03 ` Ulrich Weigand
2005-06-28 12:09 ` Steven Bosscher
2005-06-29 16:46 ` Steven Bosscher
2005-06-29 18:01 ` Daniel Berlin
2005-06-29 18:32 ` Steven Bosscher
2005-06-29 18:45 ` Robert Dewar [this message]
2005-06-29 19:13 ` Nicholas Nethercote
2005-06-28 12:16 ` Paul Koning
2005-06-28 12:30 ` Steven Bosscher
2005-06-28 12:35 ` Michael Veksler
2005-06-28 12:38 ` Steven Bosscher
2005-06-28 16:54 ` Joe Buck
2005-06-28 17:02 ` Mark Mitchell
2005-06-28 17:08 ` Daniel Berlin
2005-06-28 18:12 ` Mark Mitchell
2005-06-28 17:46 ` Theodore Papadopoulo
2005-06-27 15:17 ` Gabriel Dos Reis
2005-06-30 20:53 ` Kai Henningsen
2005-06-27 14:39 Morten Welinder
2005-06-27 15:21 ` Gabriel Dos Reis
[not found] <OF0E4366CA.5D54868B-ON4325702E.0036D351-4325702E.003973C5@il.ibm.com>
[not found] ` <m3k6keeibo.fsf@uniton.integrable-solutions.net>
2005-06-28 13:29 ` Nathan Sidwell
2005-06-28 13:59 ` Gabriel Dos Reis
2005-06-28 14:05 ` Andrew Pinski
2005-06-28 14:13 ` Gabriel Dos Reis
2005-06-28 15:30 ` Michael Veksler
2005-06-28 15:49 ` Nathan Sidwell
2005-06-28 15:58 ` Michael Veksler
2005-06-28 16:07 ` Andrew Pinski
2005-06-28 16:39 ` Gabriel Dos Reis
2005-06-28 15:55 ` Gabriel Dos Reis
2005-06-28 16:47 ` Joseph S. Myers
2005-06-28 17:58 ` Gabriel Dos Reis
2005-06-28 14:05 ` Nathan Sidwell
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