From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4032 invoked by alias); 16 Dec 2014 14:17:02 -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 3963 invoked by uid 48); 16 Dec 2014 14:16:58 -0000 From: "mpolacek at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/63568] Missed optimization (a & ~mask) | (b & mask) = a ^ ((a ^ b) & mask) Date: Tue, 16 Dec 2014 14:17:00 -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: 5.0 X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: normal X-Bugzilla-Who: mpolacek at gcc dot gnu.org X-Bugzilla-Status: ASSIGNED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: mpolacek at gcc dot gnu.org X-Bugzilla-Target-Milestone: 5.0 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: 2014-12/txt/msg01883.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63568 --- Comment #5 from Marek Polacek --- True. E.g. on my x86_64 i7 Nehalem I see (using ./cc1 -quiet -O2 qq.c -mbmi) andn %edi, %edx, %edi andl %edx, %esi movl %edi, %eax orl %esi, %eax ret for return (a & ~m) | (b & m); and xorl %edi, %esi movl %edi, %eax andl %esi, %edx xorl %edx, %eax ret for return a ^ ((a ^ b) & m);