From: Horst von Brand <vonbrand@inf.utfsm.cl>
To: Andrea Arcangeli <andrea@suse.de>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] removal of "static foo = 0"
Date: Tue, 28 Nov 2000 08:25:36 -0300 [thread overview]
Message-ID: <200011281125.eASBPaC13521@pincoya.inf.utfsm.cl> (raw)
In-Reply-To: Message from Andrea Arcangeli <andrea@suse.de> of "Tue, 28 Nov 2000 01:28:36 BST." <20001128012836.B25166@athlon.random>
Andrea Arcangeli <andrea@suse.de> said:
> On Mon, Nov 27, 2000 at 02:34:45PM -0500, Richard B. Johnson wrote:
> > The following shell-script shows that gcc-2.8.1 produces code with
> > data allocations adjacent. However, they are reversed!
> same with 2.95.* :).
The point was if gcc did use the fact that variables are adyacent in memory
to generate better code, and this degenerated into the current discussion
about where they are from the programmers perspective.
- If gcc is going to use the fact that some variables are nearby for some
optimization purposes, I do trust the gcc hackers to set stuff up so that
they use it for variables that are nearby in VM, not just where defined
together. If variables defined together end up adyacent or not is
completely irrelevant. The compiler might even rearrange them to
optimize for the access pattern observed.
- As a C programmer, you are only entitled to assume that pieces of the
same object (array or struct) are laid out in memory in the order
given. With segmented VM different objects would probably end up in
different segments anyway.
--
Dr. Horst H. von Brand mailto:vonbrand@inf.utfsm.cl
Departamento de Informatica Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria +56 32 654239
Casilla 110-V, Valparaiso, Chile Fax: +56 32 797513
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next prev parent reply other threads:[~2000-11-28 11:56 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-11-27 8:41 [PATCH] removal of "static foo = 0" Werner Almesberger
2000-11-27 5:56 ` Adam J. Richter
2000-11-27 8:39 ` David S. Miller
2000-11-27 9:08 ` Werner Almesberger
2000-11-27 17:21 ` Andrea Arcangeli
2000-11-27 17:36 ` Michael Meissner
2000-11-27 19:06 ` Andrea Arcangeli
2000-11-27 19:34 ` Richard B. Johnson
2000-11-28 0:28 ` Andrea Arcangeli
2000-11-28 11:25 ` Horst von Brand [this message]
2000-11-27 21:27 ` Marcus Sundberg
2000-11-28 0:49 ` real_root_dev Andries Brouwer
2000-11-28 3:10 ` [PATCH] removal of "static foo = 0" kumon
2000-11-28 3:28 ` Andrea Arcangeli
2000-11-28 3:35 ` Alexander Viro
2000-11-28 4:15 ` Michael Meissner
2000-11-28 9:55 ` Andreas Schwab
2000-11-28 15:16 ` Andrea Arcangeli
2000-11-28 16:09 ` Andreas Schwab
2000-11-28 19:29 ` Andrea Arcangeli
2000-11-28 16:44 ` Michael Meissner
2000-11-27 18:11 ` Richard B. Johnson
2000-11-27 18:01 ` Michael Meissner
-- strict thread matches above, loose matches on Subject: below --
2000-11-26 17:53 Elmer Joandi
2000-11-26 18:36 ` Alexander Viro
2000-11-26 19:11 ` Elmer Joandi
2000-11-26 22:49 ` Rogier Wolff
2000-11-26 15:15 Adam J. Richter
2000-11-25 20:19 Andries Brouwer
2000-11-25 21:07 ` Russell King
2000-11-25 21:29 ` Andries Brouwer
2000-11-26 1:19 ` Russell King
2000-11-25 22:11 ` Herbert Xu
2000-11-25 22:46 ` Andries Brouwer
2000-11-25 22:53 ` James A Sutherland
2000-11-25 23:55 ` Tim Waugh
2000-11-26 3:10 ` James A Sutherland
2000-11-26 10:37 ` Tigran Aivazian
2000-11-26 14:52 ` Philipp Rumpf
2000-11-28 0:01 ` Peter Samuelson
2000-11-27 4:00 ` Michael Meissner
2000-11-25 23:02 ` Jeff Garzik
2000-11-26 2:08 ` Andries Brouwer
2000-11-26 9:22 ` Martin Mares
2000-11-25 23:33 ` Herbert Xu
2000-11-27 10:03 ` Helge Hafting
2000-11-27 20:33 ` Albert D. Cahalan
2000-11-27 22:57 ` Russell King
2000-11-29 1:46 ` Albert D. Cahalan
2000-11-29 3:21 ` Peter Samuelson
2000-11-29 7:25 ` Russell King
2000-11-25 22:27 ` Tigran Aivazian
2000-11-26 1:32 ` Andries Brouwer
2000-11-26 6:21 ` Werner Almesberger
2000-11-26 2:11 ` Georg Nikodym
2000-11-26 4:25 ` Alan Cox
2000-11-26 5:01 ` John Alvord
2000-11-26 5:10 ` Andre Hedrick
2000-11-26 6:22 ` Keith Owens
2000-11-26 6:28 ` Andre Hedrick
2000-11-26 10:43 ` Tigran Aivazian
2000-11-26 10:52 ` Tigran Aivazian
2000-11-24 7:47 ` Pavel Machek
2000-11-26 14:32 ` bert hubert
2000-11-26 10:52 ` Rogier Wolff
2000-11-26 14:13 ` Philipp Rumpf
2000-11-26 20:47 ` H. Peter Anvin
2000-11-27 21:12 ` Kai Henningsen
2000-11-26 15:19 ` Georg Nikodym
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