From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 405033858C50; Wed, 8 Feb 2023 16:47:51 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 405033858C50 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1675874871; bh=7KA0TNom/s3FIssb5FUuPhCQXl3w+mnvrh/YzNPFJJg=; h=From:To:Subject:Date:In-Reply-To:References:From; b=C1s7tJw7wkgM9gs/3biJ093zId7+G6re5LX3g/Tgg8cFHjEyHlWTqVWZEbyFYGflI 6RAbmca7iJhT9u8OEzfG7zMZkkoS+odL7y6W0e9lGHFEXoYu4XbPIOWWEOkd7Cm5A0 lIAkgZ398eun6KQST6uqrBVAmy7/6HcWh6JrfmPI= From: "pinskia at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug c/108720] INT_MIN * -1 is incorrect Date: Wed, 08 Feb 2023 16:47:51 +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: 11.3.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: pinskia at gcc dot gnu.org X-Bugzilla-Status: RESOLVED X-Bugzilla-Resolution: INVALID 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: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 List-Id: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108720 --- Comment #3 from Andrew Pinski --- int x =3D=20 # 6 "err_file.c" 3 4 (-0x7fffffff - 1) # 6 "err_file.c" ; int y =3D x * -1; x*-1 invokes undefined behavior because signed integer overflow is undefine= d. So anything can happen after undefined behavior including but not limited to inconsistent results. You can detect signed integer overflow at run time with -fsanitize=3Dundefi= ned.=