From: Jeff Law <law@redhat.com>
To: Vladimir Makarov <vmakarov@redhat.com>
Cc: Ian Bolton <bolton@IceraSemi.com>, gcc@gcc.gnu.org
Subject: Re: Understanding IRA
Date: Fri, 16 Oct 2009 16:19:00 -0000 [thread overview]
Message-ID: <4AD89516.2070501@redhat.com> (raw)
In-Reply-To: <4AD888ED.1020102@redhat.com>
On 10/16/09 08:53, Vladimir Makarov wrote:
>
> The biggest problem of GCC RA is still reload pass. It frequently
> changes decisions of IRA not in a good way.
Agreed. Not only may reload make a bad choice, it's horribly
unpredictable. Trivial changes often lead to drastically different
reloading decisions which in turn drastically change the final output.
One of my favorites right now is the round-robin selection of spill
registers to encourage reload inheritance. While I certainly understand
the reasoning behind the code, it's amazingly frustrating to watch
reload choose the worst possible spill register simply because of the
round-robin selection.
I've got a little hack in the reload-v2 branch which queries IRA to
mitigate this problem, but it's merely a short-term hack until I can
make reload inheritance go away.
jeff
next prev parent reply other threads:[~2009-10-16 15:45 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-16 14:22 Ian Bolton
2009-10-16 15:23 ` Vladimir Makarov
2009-10-16 16:19 ` Jeff Law [this message]
2009-10-19 19:21 ` Ian Bolton
2009-10-19 21:09 ` Vladimir Makarov
2009-10-23 7:33 ` Jeff Law
2009-11-04 17:52 ` Ian Bolton
2009-11-04 19:49 ` Jeff Law
2009-10-16 15:45 ` Vladimir Makarov
2009-11-03 16:29 ` Ian Bolton
2009-11-03 23:02 ` Jeff Law
2009-11-04 17:13 ` Vladimir Makarov
2009-11-05 0:23 ` Jeff Law
2009-11-05 17:36 Ian Bolton
2009-11-05 18:05 ` Ian Bolton
2009-11-06 12:53 ` Dave Hudson
2009-11-09 14:13 ` Ian Bolton
2009-11-10 12:19 ` Dave Hudson
2009-11-10 17:21 ` Jeff Law
2009-11-10 17:38 ` Ian Bolton
2009-11-11 15:19 ` Ian Bolton
2009-11-11 16:12 ` Jeff Law
2009-11-11 17:04 ` Vladimir Makarov
2009-11-11 18:36 ` Ian Bolton
2009-11-11 20:09 ` Ian Bolton
2009-11-16 17:35 ` Ian Bolton
[not found] ` <4B01BB87.6020902@redhat.com>
2009-11-19 15:41 ` Ian Bolton
[not found] ` <4B1451C7.2010207@redhat.com>
2009-12-02 20:29 ` Ian Bolton
2009-12-03 19:16 ` Jeff Law
2009-12-07 13:30 ` Ian Bolton
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=4AD89516.2070501@redhat.com \
--to=law@redhat.com \
--cc=bolton@IceraSemi.com \
--cc=gcc@gcc.gnu.org \
--cc=vmakarov@redhat.com \
/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).