From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 7A283385841B; Mon, 12 Jun 2023 19:17:01 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 7A283385841B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1686597421; bh=xn4Kfu/Ocpr6M6BKxLuaG6sCVIaCSkYzFxaTHTxpyuY=; h=From:To:Subject:Date:In-Reply-To:References:From; b=fACug08fgtaZBZxgOi8KRnnofStCWfGEQDn4hvfGHljrBlpeaLyb0f3T7p+bL/G9g jNlMxGwnRTTP1B82rn4PLfvawQJ+tJ3M/eCLXkCjjCuZ3Q3sd6iFYNrqP9Dj/hFAXG e1S90DiY4ZBj4MjYpu4ENsYt5igVgPjMsHfOQjp8= From: "pinskia at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/110228] [14 Regression] llvm-16 miscompiled due to an maybe uninitialized and optimizations saying that the uninitialized has a nonzero bits of 1. Date: Mon, 12 Jun 2023 19:17:01 +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: 14.0 X-Bugzilla-Keywords: wrong-code X-Bugzilla-Severity: normal X-Bugzilla-Who: pinskia at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 14.0 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=3D110228 --- Comment #8 from Andrew Pinski --- So the `&` case with r14-1597-g64d90d06d2db43538c8a45 should be ok always I think as you are anding with a known non-uninitialized variable (that is al= ways 0 or 1) that will produce a value which is known to be 0 or 1. It is one th= at produces `|` that exposes the issue here. Even if gimple level says it is 0= /1, doing a `|` will produce an uninitialized value still and the upper bits are not defined and things go off in the weeds then.=