From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 3538 invoked by alias); 20 Nov 2012 07:56:55 -0000 Received: (qmail 1684 invoked by uid 48); 20 Nov 2012 07:56:32 -0000 From: "jakub at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/55393] gcc/g++ multiplies two unsigned integers using the IMULQ instruction Date: Tue, 20 Nov 2012 07:56:00 -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-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: jakub at gcc dot gnu.org X-Bugzilla-Status: RESOLVED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Changed-Fields: Status Resolution Message-ID: In-Reply-To: References: X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 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 X-SW-Source: 2012-11/txt/msg01883.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55393 Jakub Jelinek changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Resolution| |INVALID --- Comment #3 from Jakub Jelinek 2012-11-20 07:56:32 UTC --- long long never stopped being 128-bit on x86_64 and other 64-bit architectures GCC supports, it simply always used to be 64-bit. If you want 128-bit type, there is unsigned __int128 supported in newer versions of GCC, so you can do something like: if (((unsigned __int128) num * mult) >> 64) std::cout << "overflow" << std::endl;