From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by sourceware.org (Postfix) with ESMTP id A02323948A81 for ; Mon, 30 Mar 2020 11:26:35 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org A02323948A81 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: sourceware.org; spf=fail smtp.mailfrom=segher@kernel.crashing.org Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 02UBQDSN004221; Mon, 30 Mar 2020 06:26:13 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 02UBQCgw004218; Mon, 30 Mar 2020 06:26:12 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Mon, 30 Mar 2020 06:26:12 -0500 From: Segher Boessenkool To: Peter Bergner via Gcc-patches , Peter Bergner , "ian@airs.com" , richard.sandiford@arm.com Subject: Re: [PATCH] lower-subreg: PR94123, SVN r273240, causes gcc.target/powerpc/pr87507.c to fail Message-ID: <20200330112612.GQ22482@gate.crashing.org> References: <20ee8944-f0bf-cec1-e3d1-5dd5e9c6a4ef@linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i X-Spam-Status: No, score=-47.1 required=5.0 tests=BAYES_00, JMQ_SPF_NEUTRAL, KAM_DMARC_STATUS, RCVD_IN_DNSWL_NONE, TXREP, T_SPF_HELO_PERMERROR, T_SPF_PERMERROR autolearn=no autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 30 Mar 2020 11:26:37 -0000 Hi! On Mon, Mar 30, 2020 at 09:50:05AM +0100, Richard Sandiford wrote: > Peter Bergner via Gcc-patches writes: > > - if (HARD_REGISTER_NUM_P (rd) || HARD_REGISTER_NUM_P (rs)) > > + if (HARD_REGISTER_NUM_P (rd)) > > return false; > > > > b = reg_copy_graph[rs]; > > I guess this would also work if we dropped the rd check instead. > So how about s/||/&&/ instead, to avoid the assymetry? > > I agree something like this is a better fix long-term, since we > shouldn't be relying on make_more_copies outside combine. Yes; on the other hand, most RTL passes should do something to not have hard registers forwarded into non-move instructions (where they can cause problems later). (make_more_copies itself is a technicality specific to how combine works, and we might be able to drop it in the future). > With this change, the only remaining function of -fsplit-wide-types-early > is to act as a double lock on one pass. IMO it'd make more sense to remove > that double lock and make -fsplit-wide-types-early and -fsplit-wide-types > act as independent options, a bit like -fschedule-insns{,2}. Sure, that would simplify things a bit (at least conceptually). With or without that change, the documentation could use some tweaking as well, after this patch. Segher