From: Jakub Jelinek <jakub@redhat.com>
To: Thomas Kunert <kunert@physik.tu-dresden.de>
Cc: Roger Sayle <roger@eyesopen.com>, gcc@gcc.gnu.org
Subject: Re: x87 float truncation/accuracy (gcc vs. icc/msvc)
Date: Fri, 19 Mar 2004 12:28:00 -0000 [thread overview]
Message-ID: <20040319061651.GH6393@sunsite.ms.mff.cuni.cz> (raw)
In-Reply-To: <405AAC97.60308@physik.tu-dresden.de>
On Fri, Mar 19, 2004 at 09:17:27AM +0100, Thomas Kunert wrote:
> Roger Sayle wrote:
>
> >interesting is that both the Microsoft Visual C/C++ compiler and Intel's
> >icc both *by default* completely optimized away this "float_truncate",
> >producing incorrectly rounded results.
> >
>
> Could you please explain what's wrong with incorrectly rounded results?
> I was under the impression accuracy and performance is more important to
> most people. And for the ones who actually care about rounding
> there is -ffloat-store. What is this option for, if the truncation happens
> anyway?
OTOH ISO C99 requires certain handling of float/double which
GCC on IA-32 doesn't meet even with -ffloat-store.
Jakub
next prev parent reply other threads:[~2004-03-19 8:26 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-18 17:49 Roger Sayle
2004-03-18 18:40 ` Jan Hubicka
2004-03-18 19:18 ` Roger Sayle
2004-03-20 22:07 ` Jan Hubicka
2004-03-19 11:30 ` Thomas Kunert
2004-03-19 12:28 ` Jakub Jelinek [this message]
2004-03-21 2:04 ` Robert Dewar
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