From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-335046-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 10598 invoked by alias); 28 Oct 2010 19:01:42 -0000
Received: (qmail 10587 invoked by uid 22791); 28 Oct 2010 19:01:41 -0000
X-SWARE-Spam-Status: No, hits=-2.3 required=5.0	tests=ALL_TRUSTED,AWL,BAYES_00,MISSING_MID,TW_DX
X-Spam-Check-By: sourceware.org
Received: from localhost (HELO gcc.gnu.org) (127.0.0.1)    by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 28 Oct 2010 19:01:38 +0000
From: "davidxl at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/46200] [4.6 Regression] optimization regression in simple pointer loop
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: davidxl at gcc dot gnu.org
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 4.6.0
X-Bugzilla-Changed-Fields: Status CC
In-Reply-To: <bug-46200-4@http.gcc.gnu.org/bugzilla/>
References: <bug-46200-4@http.gcc.gnu.org/bugzilla/>
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
Content-Type: text/plain; charset="UTF-8"
MIME-Version: 1.0
Date: Thu, 28 Oct 2010 19:01:00 -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
X-SW-Source: 2010-10/txt/msg02435.txt.bz2
Message-ID: <20101028190100.cB0dVYX6JLLSvTAbnRCsG589CgpIwsMszZMC_3aIviE@z>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46200

davidxl <davidxl at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |davidxl at gcc dot gnu.org

--- Comment #5 from davidxl <davidxl at gcc dot gnu.org> 2010-10-28 19:01:16 UTC ---
Confirmed.

The problem seems to be in the cost computation for loop exit tests -- the cost
associated with iv update seem to be double counted (already considered as iv
cost, but included again in testing cost). If this is the root cause, it is
there since day-1, but exposed by the ivopt enhancement patch.

David