From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 593493858D20; Wed, 1 Nov 2023 13:56:15 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 593493858D20 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1698846975; bh=hmgeKh5+805Vje1CzmaVldjljTezEq5vOaIqrOxmslk=; h=From:To:Subject:Date:In-Reply-To:References:From; b=rqNl4qmgelkedc3PgyaB5dIHED/KvE1urg6c6g1fU8hWXdw2e+Vgpw7rfZA3H2Kkf 7stavNFcZm1nuSyuCoE76aRnYZ9rM8ZK0jTWSkRs0m76bz+Kp06DjhzH9iZUfpX061 Nb4wDXnuERIe5rJbC6cOOBFdBjEq0SWdSgCokpuk= From: "law at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: =?UTF-8?B?W0J1ZyBydGwtb3B0aW1pemF0aW9uLzEwNDM4N10gYWFyY2g2NDog?= =?UTF-8?B?UmVkdW5kYW50IFNYVEggZm9yIOKAnGJhZyBvZiBiaXRz4oCdIG1vdmVz?= Date: Wed, 01 Nov 2023 13:56:14 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: rtl-optimization X-Bugzilla-Version: 12.0 X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: enhancement X-Bugzilla-Who: law 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: 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=3D104387 Jeffrey A. Law changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |law at gcc dot gnu.org --- Comment #5 from Jeffrey A. Law --- As noted in bz111384, this can be addressed via Joern's extension DCE pass = that we're beating on right now. Conceptually it tracks liveness of sub-word objects within a register and when it encounters an extension that sets bits that are never read, it eliminates the extension. Conceptually simple and w= e've confirmed it addresses the issue in 111384. I strongly suspect it would fix this one as well. It's still got bugs and isn't really for integration, but to date Joern's b= asic approach seems the most viable for eliminating unnecessary extensions.=