From: "Stephen J. Turnbull" <stephen@xemacs.org>
To: Ken Raeburn <raeburn@raeburn.org>
Cc: dann@gnu.org, Eli Zaretskii <eliz@gnu.org>, emacs-devel@gnu.org
Subject: Re: stop using P_, __P in header files
Date: Tue, 06 Jul 2010 13:32:44 +0900 [thread overview]
Message-ID: <87vd8t9qmr.fsf@uwakimon.sk.tsukuba.ac.jp> (raw)
In-Reply-To: <EFA28558-0540-405D-ABD7-10B4C964E41B@raeburn.org>
Ken Raeburn writes:
> Do the non-GCC compilers (those that have halfway decent
> optimizers) still need "register" these days to indicate what
> variables belong in registers, or do the optimizers do a reasonable
> job of working it out for themselves?
In principle, "register" is still occasionally useful. If you have a
large number of variables in a loop which has two long branches, then
which variables belong in registers depend on which branch is taken
more often, something that the compiler cannot know.
OTOH, without profiling typically the programmer won't know, either.
Also, "large" depends on the number of registers available, of course.
In the case of x86, "large" is pretty small, about 8-10 IIRC.
next prev parent reply other threads:[~2010-07-06 4:32 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-01 21:16 stop using P_, __P in header files Dan Nicolaescu
2010-07-02 8:50 ` Juanma Barranquero
2010-07-02 9:31 ` Jan Djärv
2010-07-02 9:37 ` Juanma Barranquero
2010-07-02 13:09 ` Jan Djärv
2010-07-02 14:19 ` Juanma Barranquero
2010-07-02 15:55 ` Jan Djärv
2010-07-02 17:31 ` Juanma Barranquero
2010-07-02 20:41 ` Eli Zaretskii
2010-07-02 20:57 ` Andreas Schwab
2010-07-03 7:07 ` Eli Zaretskii
2010-07-02 18:26 ` Dan Nicolaescu
2010-07-02 10:58 ` Eli Zaretskii
2010-07-02 18:28 ` Dan Nicolaescu
2010-07-03 0:58 ` Dan Nicolaescu
[not found] ` <yxq7hlblldz.fsf@fencepost.gnu.org>
2010-07-04 15:35 ` Juanma Barranquero
2010-07-04 15:55 ` Dan Nicolaescu
2010-07-04 16:26 ` Juanma Barranquero
2010-07-04 16:42 ` Dan Nicolaescu
2010-07-04 20:42 ` Juanma Barranquero
2010-07-04 20:20 ` Chong Yidong
2010-07-04 16:46 ` Dan Nicolaescu
2010-07-04 19:12 ` Dan Nicolaescu
2010-07-04 19:16 ` Dan Nicolaescu
2010-07-04 23:58 ` Juanma Barranquero
2010-07-05 0:05 ` Juanma Barranquero
2010-07-05 0:28 ` Juanma Barranquero
2010-07-05 1:25 ` Juanma Barranquero
2010-07-05 4:57 ` Dan Nicolaescu
2010-07-05 17:19 ` Andreas Schwab
2010-07-04 21:24 ` Ken Raeburn
2010-07-05 0:29 ` Juanma Barranquero
2010-07-05 3:05 ` Eli Zaretskii
2010-07-05 3:38 ` Juanma Barranquero
2010-07-05 17:31 ` Eli Zaretskii
2010-07-05 18:59 ` Ken Raeburn
2010-07-05 23:48 ` Juanma Barranquero
2010-07-06 3:00 ` Eli Zaretskii
2010-07-06 3:23 ` Dan Nicolaescu
2010-07-09 22:19 ` Dan Nicolaescu
2010-07-10 8:45 ` David Kastrup
2010-07-10 23:51 ` Juanma Barranquero
2010-07-05 3:42 ` Ken Raeburn
2010-07-06 4:32 ` Stephen J. Turnbull [this message]
2010-07-06 6:37 ` Ken Raeburn
2010-07-06 7:50 ` Stephen J. Turnbull
2010-07-05 5:51 ` Dan Nicolaescu
2010-07-05 6:14 ` Ken Raeburn
2010-07-06 2:50 ` Dan Nicolaescu
2010-07-02 8:56 ` Andreas Schwab
2010-07-02 18:30 ` Dan Nicolaescu
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