From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 1E4A63858C29; Fri, 19 Jan 2024 07:14:05 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 1E4A63858C29 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1705648445; bh=pj6WHZO2ahdSjJwwM2tNY6M55fbUQvD7N3HoyqEh9Vo=; h=From:To:Subject:Date:In-Reply-To:References:From; b=BR9tkkuzk+/Tx7VkC6CtggZ6LjNJK/WuCcEFIwLW85muuQT/62J9avkIE8jz693kF 5Fr0h1BewfaHEdsnCXJv9ebxgQuabn7X9yGBDIqK/m9UCAyUCkzcXgut94STQpJeGH RkSKzNlkHc8OGDeDYL321H9QkEfkPuaddWelrF8s= From: "rguenth at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/113487] Missed optimization:simplify demanded bits on multi-use instructions like select Date: Fri, 19 Jan 2024 07:14:04 +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: 14.0 X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: enhancement X-Bugzilla-Who: rguenth 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: --- 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=3D113487 --- Comment #3 from Richard Biener --- Feels more like reassoc to me. You could also view it as "bit-DCE", eliding defs of dead bits. Which might make it suitable for backprop (currently doing sth similar for the sign "bit").=