From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 3484 invoked by alias); 6 Feb 2014 10:22:20 -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 3193 invoked by uid 48); 6 Feb 2014 10:22:17 -0000 From: "rguenth at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/60086] suboptimal asm generated for a loop (store/load false aliasing) Date: Thu, 06 Feb 2014 10:22:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: rtl-optimization X-Bugzilla-Version: 4.7.3 X-Bugzilla-Keywords: 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: 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: 2014-02/txt/msg00556.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60086 --- Comment #4 from Richard Biener --- As of posix_memalign the issue is not so much that of alias analysis (we could handle it but we don't have a builtin right now) but that of alignment analysis which doesn't implement alignment tracking of pointers stored in memory. We could "lower" posix_memalign (&ptr, align, size); to posix_memalign (&ptr, align, size); ptr = __builtin_assume_algined (ptr, align); and hope for FRE to fix things up enough to make that useful. I have opened PR60092.