[Bug c++/64383] missed warning for unused variable.

["manu at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64383

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |diagnostic
                 CC|                            |manu at gcc dot gnu.org

--- Comment #1 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
A minimized testcase would be helpful. Using delta would probably remove
already a lot: https://gcc.gnu.org/wiki/A_guide_to_testcase_reduction
>From gcc-bugs-return-471668-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Tue Dec 23 20:55:35 2014
Return-Path: <gcc-bugs-return-471668-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Delivered-To: listarch-gcc-bugs@gcc.gnu.org
Received: (qmail 15693 invoked by alias); 23 Dec 2014 20:55:34 -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
Delivered-To: mailing list gcc-bugs@gcc.gnu.org
Received: (qmail 15669 invoked by uid 48); 23 Dec 2014 20:55:31 -0000
From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/64396] Missed optimization in post-loop register handling
Date: Tue, 23 Dec 2014 20:55:00 -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-Version: 4.9.0
X-Bugzilla-Keywords:
X-Bugzilla-Severity: minor
X-Bugzilla-Who: pinskia at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
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:
Message-ID: <bug-64396-4-8TRno2tHgb@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-64396-4@http.gcc.gnu.org/bugzilla/>
References: <bug-64396-4@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: 2014-12/txt/msg02675.txt.bz2
Content-length: 374

https://gcc.gnu.org/bugzilla/show_bug.cgi?idd396

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The reason is GCC tries to be smart of calculating s4 outside of the loop
because the iv that might be selected is not related at all to s4.  That is it
might do:
int limit = es4-s4;
int i = 0;

  for(i=0;i<limit;i++) {
    add_carry32(sum, *s4[i]);
  }