public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
From: "rguenth at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/42108] [4.4/4.5 Regression] Vectorizer cannot deal with PAREN_EXPR gracefully, 50% performance regression
Date: Thu, 19 Nov 2009 16:50:00 -0000	[thread overview]
Message-ID: <20091119164952.27758.qmail@sourceware.org> (raw)
In-Reply-To: <bug-42108-9410@http.gcc.gnu.org/bugzilla/>



------- Comment #2 from rguenth at gcc dot gnu dot org  2009-11-19 16:49 -------
-ftree-vectorizer-verbose=2 tells you:

eval.f90:35: note: not vectorized: relevant stmt not supported: D.1684_73 =
((D.1683_72));

eval.f90:32: note: not vectorized: relevant stmt not supported: D.1684_58 =
((D.1683_57));

PAREN_EXPRs are new in 4.4 and I believe they cannot be turned off
right now.

The loops are

  do i=1,nnd
    x(i) = 1.d0 + (1.d0*i)/nnd
  end do
  do i=1,n
    foo4(i) = 1.d0 + (1.d0*i)/n
  end do

where the vectorizer doesn't know how to ensure evaluation order is
preserved when trying to vectorize (1.d0*i)/n.  Writing them as
1.d0*i/n vectorizes the function.

Still the performance is lower by a factor of two compared to 4.3
(even with -ffast-math).

Probably the bug should be split.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |irar at il dot ibm dot com,
                   |                            |rguenth at gcc dot gnu dot
                   |                            |org
           Severity|normal                      |enhancement
             Status|UNCONFIRMED                 |NEW
          Component|fortran                     |tree-optimization
     Ever Confirmed|0                           |1
           Keywords|                            |missed-optimization
   Last reconfirmed|0000-00-00 00:00:00         |2009-11-19 16:49:51
               date|                            |
            Summary|Performance drop from 4.3 to|[4.4/4.5 Regression]
                   |4.4/4.5                     |Vectorizer cannot deal with
                   |                            |PAREN_EXPR gracefully, 50%
                   |                            |performance regression
   Target Milestone|---                         |4.4.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42108


  parent reply	other threads:[~2009-11-19 16:50 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-11-19 16:01 [Bug fortran/42108] New: Performance drop from 4.3 to 4.4/4.5 sfilippone at uniroma2 dot it
2009-11-19 16:01 ` [Bug fortran/42108] " sfilippone at uniroma2 dot it
2009-11-19 16:50 ` rguenth at gcc dot gnu dot org [this message]
2009-11-19 17:17 ` [Bug tree-optimization/42108] [4.4/4.5 Regression] Vectorizer cannot deal with PAREN_EXPR gracefully, 50% performance regression sfilippone at uniroma2 dot it
2009-11-19 17:30 ` rguenther at suse dot de
2009-11-19 19:42 ` sfilippone at uniroma2 dot it
2009-11-19 19:53 ` toon at moene dot org
2009-11-19 22:33 ` anlauf at gmx dot de
2009-11-20  8:32 ` sfilippone at uniroma2 dot it
2009-11-20 13:45 ` dominiq at lps dot ens dot fr
2009-11-20 14:04 ` sfilippone at uniroma2 dot it
2009-11-20 14:12 ` sfilippone at uniroma2 dot it
2009-11-20 14:14 ` rguenth at gcc dot gnu dot org
2009-11-20 19:45 ` toon at moene dot org
2009-11-20 23:48 ` rguenth at gcc dot gnu dot org
2009-11-21 12:11 ` toon at moene dot org
2009-11-21 12:19 ` rguenther at suse dot de
2009-11-21 13:58 ` rguenth at gcc dot gnu dot org
2009-11-23  9:02 ` irar at il dot ibm dot com
2009-11-27 11:23 ` rguenth at gcc dot gnu dot org
2009-11-30  8:53 ` irar at il dot ibm dot com
2009-11-30  8:54 ` irar at il dot ibm dot com
2009-11-30 10:13 ` rguenther at suse dot de
2009-11-30 12:21 ` irar at il dot ibm dot com
2009-12-04 14:25 ` [Bug tree-optimization/42108] [4.4/4.5 Regression] " dominiq at lps dot ens dot fr
2009-12-13 23:48 ` matz at gcc dot gnu dot org
2009-12-14  4:55 ` matz at gcc dot gnu dot org
2009-12-14  5:26 ` matz at gcc dot gnu dot org
2009-12-14 10:51 ` dominiq at lps dot ens dot fr
2009-12-14 11:21 ` dominiq at lps dot ens dot fr
2009-12-14 11:23 ` rguenth at gcc dot gnu dot org
2009-12-14 11:50 ` rguenth at gcc dot gnu dot org
2009-12-14 12:27 ` rguenther at suse dot de
2009-12-14 12:30 ` rguenth at gcc dot gnu dot org
2009-12-14 12:58 ` rguenth at gcc dot gnu dot org
2009-12-14 16:58 ` matz at gcc dot gnu dot org
2009-12-15  7:10 ` tkoenig at gcc dot gnu dot org
2009-12-15 11:08 ` rguenth at gcc dot gnu dot org
2009-12-18 15:43 ` rguenth at gcc dot gnu dot org
2009-12-18 21:04 ` dominiq at lps dot ens dot fr
2009-12-18 21:40 ` matz at gcc dot gnu dot org
2009-12-18 23:44 ` rguenth at gcc dot gnu dot org
2009-12-19 11:25 ` rguenth at gcc dot gnu dot org
2009-12-19 19:29 ` rguenth at gcc dot gnu dot org
2009-12-19 19:41 ` rguenth at gcc dot gnu dot org
2009-12-19 21:10 ` rguenth at gcc dot gnu dot org
2010-01-21 13:15 ` jakub at gcc dot gnu dot org
2010-04-05 12:53 ` steven at gcc dot gnu dot org
2010-04-05 12:54 ` rguenther at suse dot de
2010-04-05 12:57 ` rguenther at suse dot de
2010-04-05 13:02 ` steven at gcc dot gnu dot org
2010-04-05 14:23 ` rguenth at gcc dot gnu dot org
2010-04-30  8:55 ` [Bug tree-optimization/42108] [4.4/4.5/4.6 " jakub at gcc dot gnu dot 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=20091119164952.27758.qmail@sourceware.org \
    --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).