From: Jeff King <peff@peff.net>
To: Rasmus Villemoes <rv@rasmusvillemoes.dk>
Cc: git@vger.kernel.org, "Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>
Subject: Re: [PATCH 3/4] shallow.c: bit manipulation tweaks
Date: Sat, 3 Dec 2016 00:21:04 -0500 [thread overview]
Message-ID: <20161203052104.jbxhzpweupiaz7wi@sigill.intra.peff.net> (raw)
In-Reply-To: <1480710664-26290-3-git-send-email-rv@rasmusvillemoes.dk>
On Fri, Dec 02, 2016 at 09:31:03PM +0100, Rasmus Villemoes wrote:
> First of all, 1 << 31 is technically undefined behaviour, so let's just
> use an unsigned literal.
It took me a second to realize that you weren't talking about the
unsigned parameter here. You mean using "1U". It might be worth saying:
...use an unsigned literal, "1U".
to make it more obvious.
> If i is 'signed int' and gcc doesn't know that i is positive, gcc
> generates code to compute the C99-mandated values of "i / 32" and "i %
> 32", which is a lot more complicated than simple a simple shifts/mask.
Right, that makes sense (though it is a separate issue).
-Peff
next prev parent reply other threads:[~2016-12-03 5:21 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-02 20:31 [PATCH 1/4] shallow.c: make paint_alloc slightly more robust Rasmus Villemoes
2016-12-02 20:31 ` [PATCH 2/4] shallow.c: avoid theoretical pointer wrap-around Rasmus Villemoes
2016-12-03 5:17 ` Jeff King
2016-12-02 20:31 ` [PATCH 3/4] shallow.c: bit manipulation tweaks Rasmus Villemoes
2016-12-03 5:21 ` Jeff King [this message]
2016-12-02 20:31 ` [PATCH 4/4] shallow.c: remove useless test Rasmus Villemoes
2016-12-03 5:24 ` Jeff King
2016-12-05 12:00 ` Duy Nguyen
2016-12-03 5:14 ` [PATCH 1/4] shallow.c: make paint_alloc slightly more robust Jeff King
2016-12-05 10:02 ` Duy Nguyen
2016-12-06 12:53 ` [PATCH v2 0/6] shallow.c improvements Nguyễn Thái Ngọc Duy
2016-12-06 12:53 ` [PATCH v2 1/6] shallow.c: rename fields in paint_info to better express their purposes Nguyễn Thái Ngọc Duy
2016-12-06 12:53 ` [PATCH v2 2/6] shallow.c: stop abusing COMMIT_SLAB_SIZE for paint_info's memory pools Nguyễn Thái Ngọc Duy
2016-12-06 12:53 ` [PATCH v2 3/6] shallow.c: make paint_alloc slightly more robust Nguyễn Thái Ngọc Duy
2016-12-06 12:53 ` [PATCH v2 4/6] shallow.c: avoid theoretical pointer wrap-around Nguyễn Thái Ngọc Duy
2016-12-06 12:53 ` [PATCH v2 5/6] shallow.c: bit manipulation tweaks Nguyễn Thái Ngọc Duy
2016-12-06 12:53 ` [PATCH v2 6/6] shallow.c: remove useless code Nguyễn Thái Ngọc Duy
2016-12-06 13:42 ` [PATCH v2 0/6] shallow.c improvements Jeff King
2016-12-06 13:47 ` Duy Nguyen
2016-12-07 23:42 ` Junio C Hamano
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
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20161203052104.jbxhzpweupiaz7wi@sigill.intra.peff.net \
--to=peff@peff.net \
--cc=git@vger.kernel.org \
--cc=pclouds@gmail.com \
--cc=rv@rasmusvillemoes.dk \
/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.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).