From: Sascha Hlusiak <saschahlusiak@arcor.de>
To: gentoo-user@lists.gentoo.org
Cc: maxim wexler <blissfix@yahoo.com>
Subject: Re: [gentoo-user] CFLAGS "...-O3 -pipe" vs "...O2 <no pipe>"
Date: Sun, 8 Apr 2007 21:57:03 -0400 [thread overview]
Message-ID: <200704082157.09565.saschahlusiak@arcor.de> (raw)
In-Reply-To: <739325.15429.qm@web31706.mail.mud.yahoo.com>
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> One suggests using -O3 -pipe, the other, -O2 without
> the pipe.
>
> How much difference does this make? Is the extra level
> of optimization with pipe the equivalent of the lower
> level without?
From the gcc manpage:
-pipe
Use pipes rather than temporary files for communication between the various
stages of compilation. This fails to work on some systems where the
assembler is unable to read from a pipe; but the GNU assembler has no
trouble.
The pipe is only for speeding up the compiling process. It does not speed up
binaries.
The -O3 contains some more optimizations than -O2, which can result in much
bigger applications and may be contraproductive. The -O2 is widely
recommended, but I guess you won't feel a big difference anyway. See man gcc
for a more detailled description.
- Sascha
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next prev parent reply other threads:[~2007-04-09 2:03 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-09 1:48 [gentoo-user] CFLAGS "...-O3 -pipe" vs "...O2 <no pipe>" maxim wexler
2007-04-09 1:57 ` Sascha Hlusiak [this message]
2007-04-09 5:47 ` Andrey Gerasimenko
2007-04-09 8:28 ` Neil Bothwick
2007-04-09 12:40 ` [gentoo-user] " Alexander Skwar
2007-04-09 13:43 ` Francisco Rivas
2007-04-10 14:29 ` maxim wexler
2007-04-10 14:58 ` Uwe Thiem
2007-04-10 15:17 ` Bo Ørsted Andresen
2007-04-10 15:29 ` Francisco Rivas
2007-04-10 15:55 ` Tony Stohne
2007-04-10 16:40 ` Andrey Vul
2007-04-10 18:48 ` maxim wexler
2007-04-10 19:01 ` Francisco Rivas
2007-04-10 19:10 ` Davi
2007-04-10 19:45 ` Uwe Thiem
2007-04-10 19:50 ` Bo Ørsted Andresen
2007-04-10 19:56 ` Jesús Guerrero
2007-04-10 20:08 ` Davi
2007-04-10 20:15 ` Jesús Guerrero
2007-04-10 20:24 ` Davi
2007-04-10 22:03 ` Ryan Sims
2007-04-11 0:34 ` Davi
2007-04-11 10:02 ` [gentoo-user] " Alexander Skwar
2007-04-10 21:22 ` [gentoo-user] " Uwe Thiem
2007-04-10 21:08 ` Dan Farrell
2007-04-10 19:52 ` Renat Golubchyk
2007-04-10 19:39 ` Uwe Thiem
2007-04-11 9:39 ` Daniel Iliev
2007-04-11 10:08 ` Bo Ørsted Andresen
2007-04-11 10:56 ` Daniel Iliev
2007-04-11 11:05 ` Davi
2007-04-11 11:44 ` Bo Ørsted Andresen
2007-04-11 12:37 ` Francisco Rivas
2007-04-11 12:45 ` Daniel Iliev
2007-04-10 15:29 ` Jesús Guerrero
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