From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 6E5823858404; Tue, 10 Jan 2023 19:28:08 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6E5823858404 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1673378888; bh=HDSNcRcUC4+1wEf+ByEww3TpdYylsbVA2osWeR/EEuA=; h=From:To:Subject:Date:In-Reply-To:References:From; b=JQLsJ8bqW8inGvna7KuI4AECggaM2RDsCIAQHqP54tVz9eZiEtyeMmC9S/eteNA0t 2rwy7Q02Nr6e/pZvYLHDNX8fRNdoZxYWpFm73MdELLHenDKX8jYpa+Xvqr695sG+e9 0rIcOBUNlO6Tku70khZb0c0ufPJI9N2MMyo+7Fy0= From: "amacleod at redhat dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/108360] [13 Regression] Dead Code Elimination Regression at -Os since r13-2048-g418b71c0d535bf Date: Tue, 10 Jan 2023 19:28:08 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: tree-optimization X-Bugzilla-Version: 13.0 X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: normal X-Bugzilla-Who: amacleod at redhat dot com 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: 13.0 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=3D108360 --- Comment #6 from Andrew Macleod --- and VRP1 turned that=20 if (_21 < 0) into=20 if (_21 =3D=3D -1) So yes, that was a correct transformation in FRE3, but the side effect is we lose the ability to look back and determine better ranges for _6 and h_23 a= s _6 is no longer part of the branch=