From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 1256 invoked by alias); 16 Feb 2015 09:05:36 -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 1214 invoked by uid 48); 16 Feb 2015 09:05:31 -0000 From: "terry.guo at arm dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/65067] regression on accessing volatile bit field Date: Mon, 16 Feb 2015 09:05:00 -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: 5.0 X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: major X-Bugzilla-Who: terry.guo at arm dot com 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: 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: 2015-02/txt/msg01698.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65067 --- Comment #2 from Terry Guo --- (In reply to Richard Biener from comment #1) > This looks more like a failure to use bfi rather than shifts and bit > operations. If the above IF clause returns false, which means we don't need to consider strict bit field, the gcc will try to check whether we can use BFI instruction. Is it a good idea to do same check and attempt when IF clause returns True?