From: Zack Weinberg <zack@codesourcery.com>
To: Brad Lucier <lucier@math.purdue.edu>
Cc: gcc@gcc.gnu.org, Jan Hubicka <jh@suse.cz>
Subject: Re: Some statement counts for gcc
Date: Mon, 26 Aug 2002 00:17:00 -0000 [thread overview]
Message-ID: <20020826071657.GD28065@codesourcery.com> (raw)
In-Reply-To: <200208252304.g7PN4Bc18560@banach.math.purdue.edu>
On Sun, Aug 25, 2002 at 06:04:11PM -0500, Brad Lucier wrote:
> branch prediction : 165.11 (33%) usr 0.07 ( 1%) sys 165.50 (33%) wall
...
> A surprising (to me) number of lines in real.c are executed; I might look
> there to see what's going on.
The branch predictor uses emulated floating point numbers internally.
Jan Hubicka has explained why this is currently necessary -- can't
find the message at the moment though. However, real.c is indeed
quite slow; I suspect that accounts entirely for the amount of time
spent in this patch
If I remember correctly this code has a very complicated flow graph,
and branch prediction may not help much; perhaps the right thing is
to detect code like this and disable that optimization.
zw
next prev parent reply other threads:[~2002-08-26 0:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-08-25 16:04 Brad Lucier
2002-08-26 0:17 ` Zack Weinberg [this message]
2002-08-26 6:18 ` Brad Lucier
2002-08-29 16:54 ` Zack Weinberg
2002-08-30 3:54 ` Jan Hubicka
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=20020826071657.GD28065@codesourcery.com \
--to=zack@codesourcery.com \
--cc=gcc@gcc.gnu.org \
--cc=jh@suse.cz \
--cc=lucier@math.purdue.edu \
/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 read-only IMAP folder(s) and NNTP newsgroup(s).