From: Paolo Carlini <pcarlini@suse.de>
To: Andrew Pinski <pinskia@physics.uc.edu>
Cc: Scott Robert Ladd <coyote@coyotegulch.com>,
gcc@gcc.gnu.org, Zdenek Dvorak <rakdver@atrey.karlin.mff.cuni.cz>
Subject: Re: GCC beaten by ICC in stupid trig test!
Date: Mon, 15 Mar 2004 11:25:00 -0000 [thread overview]
Message-ID: <405592D6.3060200@suse.de> (raw)
In-Reply-To: <64F82240-7615-11D8-8086-000393A6D2F2@physics.uc.edu>
Andrew Pinski wrote:
> The reason why still is that ICC will just unroll the loop to be "r =
> doit(a)*100000000.0" so that is the reasons why
> ICC is better than GCC at doing this stupid trig test (note this is
> transformation
> is only valid if fast-math is on as you loose precision).
In the meanwhile we have learned that the real reason why Icc performs
better then mainline gcc is the use of an iterative SSE instruction
(see Dan Nicolaescu message).
On the other hand, gcc-lno "appear" to perform as well as Icc because of
the unrolling trick (just checked that gcc-lno transforms the loop to
the trivial:
8048470: 40 inc %eax
8048471: d8 c1 fadd %st(1),%st
8048473: 3d 00 e1 f5 05 cmp $0x5f5e100,%eax
8048478: 75 f6 jne 8048470 <main+0x20>)
Now, my question is: why gcc-lno is doing that also when -ffast-math is
*not* passed???
Paolo.
next prev parent reply other threads:[~2004-03-15 11:25 UTC|newest]
Thread overview: 116+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-14 23:40 GCC viciously beaten by ICC in " Scott Robert Ladd
2004-03-14 23:49 ` Gabriel Dos Reis
2004-03-15 1:47 ` Scott Robert Ladd
2004-03-15 0:11 ` Paolo Carlini
2004-03-15 1:47 ` Scott Robert Ladd
2004-03-15 2:07 ` Daniel Berlin
2004-03-15 2:30 ` Scott Robert Ladd
2004-03-15 2:31 ` Daniel Berlin
2004-03-15 2:38 ` Scott Robert Ladd
2004-03-15 10:00 ` Sebastian Pop
2004-03-15 0:12 ` GCC beaten by ICC in stupid " Andrew Pinski
2004-03-15 0:32 ` Paolo Carlini
2004-03-15 1:31 ` Scott Robert Ladd
2004-03-15 2:36 ` Scott Robert Ladd
2004-03-15 11:25 ` Paolo Carlini [this message]
2004-03-15 11:31 ` Paolo Carlini
2004-03-15 13:29 ` Zdenek Dvorak
2004-03-15 13:42 ` Paolo Carlini
2004-03-15 13:51 ` Zdenek Dvorak
2004-03-15 13:55 ` Paolo Carlini
2004-03-15 14:00 ` Zdenek Dvorak
2004-03-15 14:05 ` Joseph S. Myers
2004-03-15 14:13 ` Paolo Carlini
2004-03-15 14:18 ` Zdenek Dvorak
2004-03-15 14:29 ` Segher Boessenkool
2004-03-15 14:28 ` Joseph S. Myers
2004-03-15 1:55 ` GCC viciously beaten by ICC in " Roger Sayle
2004-03-15 2:22 ` Dan Nicolaescu
2004-03-15 12:05 ` Stelios Xanthakis
2004-03-15 18:22 ` Dan Nicolaescu
2004-03-15 2:41 ` Scott Robert Ladd
2004-03-15 3:05 ` Gabriel Dos Reis
2004-03-15 14:47 ` Segher Boessenkool
2004-03-15 17:44 ` Geert Bosch
2004-03-15 17:46 ` Geert Bosch
2004-03-15 2:41 ` Kaveh R. Ghazi
2004-03-15 6:06 ` Andreas Jaeger
2004-03-15 8:57 ` Gabriel Dos Reis
2004-03-15 3:01 ` Gabriel Dos Reis
2004-03-15 4:06 ` Scott Robert Ladd
2004-03-15 5:15 ` James Morrison
2004-03-15 8:20 ` Jakub Jelinek
2004-03-15 18:13 ` Joe Buck
2004-03-16 13:31 ` Jakub Jelinek
2004-03-15 7:42 ` Ranjit Mathew
2004-03-15 19:00 ` Toon Moene
2004-03-15 19:44 ` Laurent GUERBY
2004-03-15 16:06 GCC beaten by ICC in stupid " Robert Dewar
2004-03-16 8:45 ` Per Abrahamsen
2004-03-17 0:09 ` Robert Dewar
2004-03-17 0:36 ` Scott Robert Ladd
2004-03-17 5:53 ` Gabriel Dos Reis
2004-03-17 7:21 ` Robert Dewar
2004-03-17 9:10 ` Gabriel Dos Reis
2004-03-21 16:55 ` Robert Dewar
2004-03-23 19:38 ` Joe Buck
2004-03-23 19:58 ` Gabriel Dos Reis
2004-03-23 20:49 ` Laurent GUERBY
2004-03-24 8:17 ` Toon Moene
2004-03-24 13:50 ` Robert Dewar
2004-03-24 18:25 ` Paul Koning
2004-03-24 18:51 ` Robert Dewar
2004-03-25 18:18 ` Per Abrahamsen
2004-03-27 1:26 ` Robert Dewar
2004-03-24 18:56 ` Joe Buck
2004-03-24 19:10 ` Robert Dewar
2004-03-24 19:14 ` Richard Guenther
2004-03-24 19:39 ` Paul Brook
2004-03-24 19:45 ` Dave Korn
2004-03-24 20:57 ` Paul Brook
2004-03-25 6:14 ` Robert Dewar
2004-03-25 18:32 ` Scott Robert Ladd
2004-03-27 1:28 ` Robert Dewar
2004-03-17 14:51 ` Per Abrahamsen
2004-03-17 15:18 ` Gabriel Dos Reis
2004-03-17 16:05 ` Per Abrahamsen
2004-03-16 12:14 ` Scott Robert Ladd
2004-03-17 0:19 ` Robert Dewar
2004-03-24 19:04 Bradley Lucier
2004-03-24 19:29 ` Joe Buck
2004-03-24 19:43 ` Bradley Lucier
2004-03-24 19:50 ` Joe Buck
2004-03-24 23:48 ` Toon Moene
2004-03-25 0:02 ` Toon Moene
2004-03-25 0:11 ` Roger Sayle
2004-03-25 5:56 ` Scott Robert Ladd
2004-03-25 6:07 ` Bradley Lucier
2004-03-25 8:18 ` Robert Dewar
2004-03-25 16:15 ` Roger Sayle
2004-03-25 16:36 ` David Edelsohn
2004-03-25 17:09 ` Scott Robert Ladd
2004-03-25 17:47 ` David Edelsohn
2004-03-25 18:03 ` Scott Robert Ladd
2004-03-26 1:29 ` Toon Moene
2004-03-27 0:23 ` Daniel Egger
2004-03-27 0:50 ` Laurent GUERBY
2004-03-27 0:55 ` Joe Buck
2004-03-27 0:58 ` Laurent GUERBY
2004-03-27 1:16 ` Joe Buck
2004-03-25 5:36 ` Gabriel Dos Reis
2004-03-25 8:46 ` Robert Dewar
2004-03-25 5:34 ` Gabriel Dos Reis
2004-03-25 7:24 ` Robert Dewar
2004-03-25 8:28 ` Gabriel Dos Reis
2004-03-25 18:19 ` Per Abrahamsen
2004-03-24 20:14 ` Paul Koning
2004-03-24 21:00 ` Joe Buck
2004-03-24 22:20 ` Dale Johannesen
2004-03-24 21:07 ` Joseph S. Myers
2004-03-24 21:38 ` Joe Buck
2004-03-24 21:44 ` Joe Buck
2004-03-24 22:49 ` Joseph S. Myers
2004-03-24 22:19 ` Richard Guenther
2004-03-24 22:21 ` Dale Johannesen
2004-03-25 7:29 ` Robert Dewar
2004-03-25 16:51 Wolfgang Bangerth
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