From: "Radim Krčmář" <rkrcmar@redhat.com>
To: Dongsheng Song <dongsheng.song@gmail.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PULL 3/7] qxl: refactor rounding up to a nearest power of 2
Date: Thu, 5 Mar 2015 16:35:36 +0100 [thread overview]
Message-ID: <20150305153535.GB3361@potion.redhat.com> (raw)
In-Reply-To: <CAE8XmWqz8rkNqNaSWWsVdifT9-hot=Qdv_qZhN_DewqVaQEG1Q@mail.gmail.com>
2015-03-05 12:57+0800, Dongsheng Song:
> On Wed, Mar 4, 2015 at 10:30 PM, Gerd Hoffmann <kraxel@redhat.com> wrote:
> > +/* round up to the nearest power of 2 (0 if overflow) */
> > +uint64_t pow2ceil(uint64_t value)
> > +{
> > + uint8_t nlz = clz64(value);
> > +
> > + if (is_power_of_2(value)) {
> > + return value;
> > + }
>
> please call clz64 after is_power_of_2.
All callers under clz64() are inline, so the optimizer can see that
there are no side effects and move the code if it would be faster;
I thought that separating it would only make the code uglier, because
QEMU doesn't allow lazy declarations ...
Markus had another design issue with this patch, so I'll send a v2 after
reaching the conclusion there.
Thanks.
next prev parent reply other threads:[~2015-03-05 15:35 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-04 14:30 [Qemu-devel] [PULL 0/7] spice patch queue Gerd Hoffmann
2015-03-04 14:30 ` [Qemu-devel] [PULL 1/7] qxl: document minimal video memory for new modes Gerd Hoffmann
2015-03-04 14:30 ` [Qemu-devel] [PULL 2/7] spice: fix invalid memory access to vga.vram Gerd Hoffmann
2015-03-04 14:30 ` [Qemu-devel] [PULL 3/7] qxl: refactor rounding up to a nearest power of 2 Gerd Hoffmann
2015-03-05 4:57 ` Dongsheng Song
2015-03-05 15:35 ` Radim Krčmář [this message]
2015-03-05 9:52 ` Markus Armbruster
2015-03-05 10:11 ` Gerd Hoffmann
2015-03-05 15:12 ` Radim Krčmář
2015-03-04 14:30 ` [Qemu-devel] [PULL 4/7] vga: refactor vram_size clamping and rounding Gerd Hoffmann
2015-03-04 14:30 ` [Qemu-devel] [PULL 5/7] qxl: drop update_displaychangelistener call for secondary qxl devices Gerd Hoffmann
2015-03-04 14:30 ` [Qemu-devel] [PULL 6/7] hmp: info spice: Show string channel name Gerd Hoffmann
2015-03-04 14:30 ` [Qemu-devel] [PULL 7/7] hmp: info spice: take out webdav Gerd Hoffmann
2015-03-08 12:27 ` [Qemu-devel] [PULL 0/7] spice patch queue Peter Maydell
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=20150305153535.GB3361@potion.redhat.com \
--to=rkrcmar@redhat.com \
--cc=dongsheng.song@gmail.com \
--cc=kraxel@redhat.com \
--cc=qemu-devel@nongnu.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;
as well as URLs for NNTP newsgroup(s).