From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 6DC92385700A; Sat, 5 Dec 2020 03:18:39 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6DC92385700A From: "pinskia at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/98151] integer output gives different results with -O2 and -O3 Date: Sat, 05 Dec 2020 03:18:39 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: c++ X-Bugzilla-Version: 10.2.1 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: pinskia at gcc dot gnu.org X-Bugzilla-Status: WAITING X-Bugzilla-Resolution: 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: cf_gcchost bug_status cf_reconfirmed_on everconfirmed Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: gcc-bugs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-bugs mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 05 Dec 2020 03:18:39 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D98151 Andrew Pinski changed: What |Removed |Added ---------------------------------------------------------------------------- Host|Linux | |5.8.15-301.fc33.x86_64 | Status|UNCONFIRMED |WAITING Last reconfirmed| |2020-12-05 Ever confirmed|0 |1 --- Comment #1 from Andrew Pinski --- I think you have an signed integer overflow happening. Take a look at: 10 * result + s[index++] - '0' To avoid the overflow, do instead: 10 * result + (s[index++] - '0')=