From: Matt Mackall <mpm@selenic.com>
To: Chuck Ebbert <76306.1226@compuserve.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] only use 48-bit lba when necessary
Date: Thu, 17 Apr 2003 23:18:20 -0500 [thread overview]
Message-ID: <20030418041820.GB6645@waste.org> (raw)
In-Reply-To: <200304172137_MC3-1-34EB-2D39@compuserve.com>
On Thu, Apr 17, 2003 at 09:34:37PM -0400, Chuck Ebbert wrote:
> Matt Mackall wrote:
>
>
> >FYI, GCC as of 3.2.3 doesn't yet reduce the if(...) form to branchless
> >code but the & and && versions come out the same with -O2.
>
> The operands of & can be evaluated in any order, while && requires
> left-to-right and does not evaluate the right operand if the left one
> is false. Only the simplest cases could possibly generate the same
> code.
Actually, any where the arguments to && are already boolean (pretty
common) and have no side effects (pretty common) will be equivalent
and could very well result in the same code. Only the simplest cases
are interesting anyway, otherwise the branchless & obfuscation is a
loss due to extra evaluation.
--
Matt Mackall : http://www.selenic.com : of or relating to the moon
next prev parent reply other threads:[~2003-04-18 4:07 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-04-18 1:34 Chuck Ebbert
2003-04-18 4:18 ` Matt Mackall [this message]
2003-04-18 14:34 ` Timothy Miller
-- strict thread matches above, loose matches on Subject: below --
2003-04-18 9:50 Chuck Ebbert
2003-04-18 3:32 linux-kernel
2003-04-04 17:02 Chuck Ebbert
2003-04-17 14:20 ` Matt Mackall
2003-04-17 15:24 ` Timothy Miller
2003-04-17 16:05 ` Matt Mackall
2003-04-17 18:49 ` Timothy Miller
2003-04-04 12:29 Jens Axboe
2003-04-04 13:19 ` Juan Quintela
2003-04-04 13:22 ` Jens Axboe
2003-04-04 15:48 ` Juan Quintela
2003-04-04 15:54 ` Jens Axboe
2003-04-04 17:06 ` John Bradford
2003-04-04 14:40 ` Andries Brouwer
2003-04-04 15:13 ` Jens Axboe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20030418041820.GB6645@waste.org \
--to=mpm@selenic.com \
--cc=76306.1226@compuserve.com \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®