From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 21709 invoked by alias); 6 Jun 2014 10:40:34 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 21641 invoked by uid 48); 6 Jun 2014 10:40:31 -0000 From: "terra at gnome dot org" To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/56888] memcpy implementation optimized as a call to memcpy Date: Fri, 06 Jun 2014 10:40:00 -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: 4.8.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: terra at gnome dot 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: cc Message-ID: In-Reply-To: References: 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: 2014-06/txt/msg00463.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56888 M Welinder changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |terra at gnome dot org --- Comment #31 from M Welinder --- Extra complication: the C library's memcpy may change errno to any non-zero value if it so desires. (C99 section 7.5 #5.) That means that raw calls to memcpy (and friends) cannot be generated anywhere where the compiler is unable to prove that the value of errno isn't used. Extra code to store and restore errno must be emitted otherwise.