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From: "martin at mpa-garching dot mpg dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/42376] [4.5 Regression] Performance regression of generated code
Date: Thu, 17 Dec 2009 14:12:00 -0000 [thread overview]
Message-ID: <20091217141228.16450.qmail@sourceware.org> (raw)
In-Reply-To: <bug-42376-2736@http.gcc.gnu.org/bugzilla/>
------- Comment #5 from martin at mpa-garching dot mpg dot de 2009-12-17 14:12 -------
> GCC with -std=c99 makes sure to properly handle the i387 FPU excess precision.
> With -fexcess-precision=fast the code is as fast (and non-conforming) like
> with GCC 4.4. Using -std=gnu99 is also an option.
Thanks a lot for pointing this out! I was aware of the floating-point change
but simply had not realized it would be switched on by -std=c99.
I imagine that this might catch many people by surprise once 4.5.0 is released,
and it might be politically advisable to mention it (and the "fix") in a place
where users can't miss it.
Is there a plan to mention this (in a prominent place) in the release notes?
Or in the FAQ or the "non-bugs" section of bugs.html? I can prepare a
documentation patch if this is desirable.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42376
next prev parent reply other threads:[~2009-12-17 14:12 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-15 8:41 [Bug tree-optimization/42376] New: [4.5] " martin at mpa-garching dot mpg dot de
2009-12-15 8:42 ` [Bug tree-optimization/42376] " martin at mpa-garching dot mpg dot de
2009-12-15 8:42 ` martin at mpa-garching dot mpg dot de
2009-12-15 8:43 ` martin at mpa-garching dot mpg dot de
2009-12-15 13:16 ` [Bug tree-optimization/42376] [4.5 Regression] " rguenth at gcc dot gnu dot org
2009-12-17 14:12 ` martin at mpa-garching dot mpg dot de [this message]
2009-12-17 16:23 ` rguenth at gcc dot gnu dot org
2010-01-07 15:17 ` martin at mpa-garching dot mpg dot de
2010-01-07 15:27 ` rguenth at gcc dot gnu dot org
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