From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id EE2813858D38; Tue, 6 Feb 2024 07:58:00 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org EE2813858D38 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1707206280; bh=F7zQv09NkAEuOROPpT/9aStTZ7TyJNQIULeAz5gk3B8=; h=From:To:Subject:Date:In-Reply-To:References:From; b=wUz+bi4UwCJyP99NAVySXi5EigNIMKpgj3b5nhlKbA/DbKjcWaDsjsgLaj7UAnnrR aEstm+kuIB88da69UrfE7zxmmuOs81SSRmilHUZHq/yFPoJp8wIdwSWZmYvW73HWIm FV4oItKMulHm0arEWe4Mkh5fh3E48bbo+XHKZ61o= From: "rguenth at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/113779] Very inefficient m68k code generated for simple copy loop Date: Tue, 06 Feb 2024 07:58:00 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: target X-Bugzilla-Version: 13.2.0 X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: normal X-Bugzilla-Who: rguenth 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: 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=3D113779 --- Comment #2 from Richard Biener --- I don't think IVOPTs would use postinc for the intermediate increments. It= 's constant propagation/forwarding that accumulates the increments to a consta= nt offset which removes dependences on the instructions and thus would allow t= he loads/stores to be executed in parallel (well, not that m68k uarchs likely = can do any of that ...). I wonder if the code we emit is measurably slower though? It's possibly a little bit larger due to the two IV increments.=