From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 21E5538582BB; Thu, 1 Feb 2024 10:02:00 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 21E5538582BB DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1706781720; bh=s7Ghwbq/MO26qv8az47nOwFvBu8mbiPGu9Tk+Ohngjg=; h=From:To:Subject:Date:In-Reply-To:References:From; b=LxjogIA6YB++XWTmOF2UpXF+Z6uTU1mvn3bgBfTvzziv2Kn9Rjz7um7fG8aDFRAFY Xcgl6v/KuWg6G78rQhMg65oR7b4t2l5CWskZUkp6KbpefsXaWGvEywaQriR83f3IOb nZB9Hx+eSCauBFb5igjJcOkFZWr7pODQPNSkLhEg= From: "xry111 at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug c/113702] -fsanitize=undefined missed a check under GCC 12.2.0 compared to 13.2.0 Date: Thu, 01 Feb 2024 10:01:59 +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: 12.2.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: xry111 at gcc dot gnu.org X-Bugzilla-Status: UNCONFIRMED 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: cc 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=3D113702 Xi Ruoyao changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |xry111 at gcc dot gnu.org --- Comment #2 from Xi Ruoyao --- With GCC 12 the expression is "optimized" early (already in original tree) into: g_A[0] =3D g_A[0] + (unsigned char) ((signed char) ((unsigned char) g_A[1] * (unsigned char) g_B) & (signed char) (g_A[1] & g_A[0]) | (signed char) g_A[= 0]) and the optimization is arguably wrong (or at lease undesired) with sanitiz= er.=