From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-476975-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 26512 invoked by alias); 12 Feb 2015 09:00:15 -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 26426 invoked by uid 48); 12 Feb 2015 09:00:11 -0000
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/32667] block copy with exact overlap is expanded as memcpy
Date: Thu, 12 Feb 2015 09:00:00 -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: 4.2.0
X-Bugzilla-Keywords: wrong-code
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:
Message-ID: <bug-32667-4-ST4jlQZWg5@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-32667-4@http.gcc.gnu.org/bugzilla/>
References: <bug-32667-4@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: 2015-02/txt/msg01308.txt.bz2

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=32667

--- Comment #10 from Richard Biener <rguenth at gcc dot gnu.org> ---
One way to "fix" this is to emit the memcpy as

  if (p != q)
    memcpy (p, q, ...);

but of course that comes at a cost in code-size and runtime for no obvious good
reason (in practice).