From: rubini-list@gnudd.com (Alessandro Rubini)
To: linux-arm-kernel@lists.infradead.org
Subject: some quesion about assembly when calling fork
Date: Wed, 16 Sep 2009 16:38:10 +0200 [thread overview]
Message-ID: <20090916143810.GA24967@mail.gnudd.com> (raw)
In-Reply-To: <3a665c760909160723g75823427t46639d1ae737e483@mail.gmail.com>
> if ((pid = fork()) < 0) {
> 84b4: ebffffb5 bl 8390 <.text-0x48>
> 84b8: e1a03000 mov r3, r0
> 84bc: e50b3010 str r3, [fp, #-16] xx1
> 84c0: e51b3010 ldr r3, [fp, #-16] xx2
> 84c4: e3530000 cmp r3, #0 ; 0x0
You are not optimizing. So the compiler follows the statements
literally: first it stores the result of fork in pid. Then loads pid to
compare with zero.
If you optimize, I'm sure it won't even copy r0 to r3 before comparing.
/alessandro
prev parent reply other threads:[~2009-09-16 14:38 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-16 14:23 some quesion about assembly when calling fork loody
2009-09-16 14:30 ` Ben Dooks
2009-09-16 14:38 ` Alessandro Rubini [this message]
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=20090916143810.GA24967@mail.gnudd.com \
--to=rubini-list@gnudd.com \
--cc=linux-arm-kernel@lists.infradead.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.