From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 1714 invoked by alias); 8 Aug 2019 19:19:28 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 1703 invoked by uid 89); 8 Aug 2019 19:19:28 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-2.2 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 spammy=H*i:sk:2EEBCFA, H*f:sk:2EEBCFA, degradation, H*Ad:U*john X-HELO: gate.crashing.org Received: from gate.crashing.org (HELO gate.crashing.org) (63.228.1.57) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 08 Aug 2019 19:19:26 +0000 Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id x78JJF8w019810; Thu, 8 Aug 2019 14:19:15 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id x78JJEVw019809; Thu, 8 Aug 2019 14:19:14 -0500 Date: Thu, 08 Aug 2019 19:19:00 -0000 From: Segher Boessenkool To: Paul Koning Cc: Vladimir Makarov , John Darrington , gcc@gcc.gnu.org Subject: Re: Indirect memory addresses vs. lra Message-ID: <20190808191914.GK31406@gate.crashing.org> References: <20190804191822.x4hwnfcyplnto3xc@jocasta.intra> <2B3A4EAB-D69E-4714-8FC4-C25E36B07BFF@comcast.net> <20190808172102.GH31406@gate.crashing.org> <2EEBCFAE-FF25-4664-AA5F-B3299CEA3CB1@comcast.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2EEBCFAE-FF25-4664-AA5F-B3299CEA3CB1@comcast.net> User-Agent: Mutt/1.4.2.3i X-IsSubscribed: yes X-SW-Source: 2019-08/txt/msg00057.txt.bz2 On Thu, Aug 08, 2019 at 01:30:41PM -0400, Paul Koning wrote: > > > > On Aug 8, 2019, at 1:21 PM, Segher Boessenkool wrote: > > > > On Thu, Aug 08, 2019 at 12:43:52PM -0400, Paul Koning wrote: > >>> On Aug 8, 2019, at 12:25 PM, Vladimir Makarov wrote: > >>> The old reload (reload[1].c) supports such addressing. As modern mainstream architectures have no this kind of addressing, it was not implemented in LRA. > >> > >> Is LRA only intended for "modern mainstream architectures"? > > > > I sure hope not! But it has only been *used* and *tested* much on such, > > so far. > > That's not entirely accurate. At the prodding of people pushing for > the removal of CC0 and reload, I've added LRA support to pdp11 in the > V9 cycle. I said "much" :-) Pretty much all design input so far has been from "modern mainstream architectures", as far as I can make out. Now one of those has the most "interesting" (for RA) features that many less mainstream archs have (a not-so-very-flat register file), so it should still work pretty well hopefully. > And it works pretty well, in the sense of passing the > compile tests. But I haven't yet examined the code quality vs. the > old one in any detail. That would be quite interesting to see, also for the other ports that still need conversion: how much (if any) degradation should you expect from a straight-up conversion of a port to LRA, without any retuning? Segher