public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug inline-asm/63900] memory constrains needlessly doing memory clobber
Date: Sun, 16 Nov 2014 21:44:00 -0000	[thread overview]
Message-ID: <bug-63900-4-j2QZE3fHgX@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-63900-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63900

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Segher Boessenkool from comment #3)
> Reopened; this is a perfectly valid missed optimisation.
> 
> Nothing here does a "full memory clobber"; instead, CSE simply doesn't
> know how to handle a three-byte datum.

That is because it is BLKmode.  This is most likely going to be a won't fix
really because it is too hard to implement for small benefit.

Also in this case using memset would be better and optimize easier.


  parent reply	other threads:[~2014-11-16 21:44 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-16  2:13 [Bug inline-asm/63900] New: " gccbugzilla at limegreensocks dot com
2014-11-16  2:19 ` [Bug inline-asm/63900] " pinskia at gcc dot gnu.org
2014-11-16 10:55 ` aph at redhat dot com
2014-11-16 19:04 ` segher at gcc dot gnu.org
2014-11-16 21:44 ` pinskia at gcc dot gnu.org [this message]
2014-11-16 23:05 ` gccbugzilla at limegreensocks dot com
2015-01-08  1:39 ` hp at gcc dot gnu.org

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=bug-63900-4-j2QZE3fHgX@http.gcc.gnu.org/bugzilla/ \
    --to=gcc-bugzilla@gcc.gnu.org \
    --cc=gcc-bugs@gcc.gnu.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 read-only IMAP folder(s) and NNTP newsgroup(s).