From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id E76B13858D33; Tue, 6 Feb 2024 08:16:57 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E76B13858D33 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1707207417; bh=nKQzmwBjaDlDrGTBhKnrnQxnT39cBKSRMKANx1Oxl6k=; h=From:To:Subject:Date:In-Reply-To:References:From; b=qIiG9WvoHzTXJldIUj5ajSmENrt/Z/4ewXu6BNl/c7KpBOpknlCLFRr614pYkQi5O ClPgBgJyFn2TH4gTq5UyrzDADgjeaTrbUESMw5H238g58HGCC6MxhZjYrEZ0YQTBtv ts/hl6uOxUK96wklJnnht31kXjto2s9CQVnpxNog= From: "miro.kropacek at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/113779] Very inefficient m68k code generated for simple copy loop Date: Tue, 06 Feb 2024 08:16:56 +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: miro.kropacek at gmail dot com 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 #3 from Miro Kropacek --- > I wonder if the code we emit is measurably slower though? It's possibly a little bit larger due to the two IV increments. It's definitely slower as both offsets next to the An registers generate a separate instruction word. So instead of 2-byte instruction "move.l (a0)+,(a1)+" we have a 6-byte instruction "move.l off(a0),off(a1)" and that hurts a lot even on the 68060, not to mention the poor 68000.=