From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-424981-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 8111 invoked by alias); 24 Jun 2013 11:05:21 -0000
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
Received: (qmail 8062 invoked by uid 48); 24 Jun 2013 11:05:16 -0000
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug other/57668] Regression in vectorizing memcpy pattern.
Date: Mon, 24 Jun 2013 11:05:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: other
X-Bugzilla-Version: 4.9.0
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenth at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags:
X-Bugzilla-Changed-Fields: bug_status cf_reconfirmed_on cc everconfirmed
Message-ID: <bug-57668-4-5qEa9E4ulY@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-57668-4@http.gcc.gnu.org/bugzilla/>
References: <bug-57668-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-SW-Source: 2013-06/txt/msg01360.txt.bz2

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57668

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-06-24
                 CC|                            |hubicka at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.

memcpy_byte.c:2: note: Completely unroll loop 14 times

the new unrolling code unrolls the epilogue loop completely:

Estimating sizes for loop 3
 BB: 8, after_exit: 0
  size:   0 i.0_40 = (sizetype) i_38;
  size:   1 _41 = s_7(D) + i.0_40;
  size:   1 _42 = d_9(D) + i.0_40;
  size:   1 _43 = *_42;
  size:   1 *_41 = _43;
  size:   1 i_45 = i_38 + 1;
  size:   2 if (i_45 < _16)
   Exit condition will be eliminated in last copy.
 BB: 9, after_exit: 1
size: 7-0, last_iteration: 7-2
  Loop size: 7
  Estimated size after unrolling: 68

And loop distribution fails to detect the memcpy clone, too.