From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-382719-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 23827 invoked by alias); 6 Feb 2012 21:37:11 -0000
Received: (qmail 23651 invoked by uid 22791); 6 Feb 2012 21:37:09 -0000
X-SWARE-Spam-Status: No, hits=-2.8 required=5.0	tests=ALL_TRUSTED,AWL,BAYES_00,TW_ZJ
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; Mon, 06 Feb 2012 21:36:57 +0000
From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/28685] Multiple comparisons are not simplified
Date: Mon, 06 Feb 2012 21:37:00 -0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: middle-end
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: enhancement
X-Bugzilla-Who: ubizjak at gmail dot com
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: ubizjak at gmail dot com
X-Bugzilla-Target-Milestone: 4.8.0
X-Bugzilla-Changed-Fields:
Message-ID: <bug-28685-4-CAMJ3BiWQt@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-28685-4@http.gcc.gnu.org/bugzilla/>
References: <bug-28685-4@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
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: 2012-02/txt/msg00653.txt.bz2

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28685

--- Comment #19 from Uros Bizjak <ubizjak at gmail dot com> 2012-02-06 21:36:01 UTC ---
(In reply to comment #4)
> Another similar, but yet different case:

Yet another similar test:

int test (int a, int b)
{
  int lt = a + b < 0;
  int eq = a + b == 0;
  if (lt)
    return 1;
  return eq;
}

combine pass creates:

            (set (reg:CCZ 17 flags)
                (compare:CCZ (plus:SI (reg/v:SI 63 [ a ])
                        (reg/v:SI 64 [ b ]))
                    (const_int 0 [0])))
            (set (reg:SI 60 [ D.1710 ])
                (plus:SI (reg/v:SI 63 [ a ])
                    (reg/v:SI 64 [ b ])))

we have a discrepancy here, since compare elimination pass expects RTX in the
form of:

 [(operate)
  (set-cc)]