From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 112237 invoked by alias); 17 Dec 2018 15:55:07 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 112216 invoked by uid 89); 17 Dec 2018 15:55:06 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-1.2 required=5.0 tests=BAYES_00,KAM_MANYTO,KAM_NUMSUBJECT,RCVD_IN_DNSWL_NONE autolearn=no version=3.3.2 spammy=H*Ad:D*eu, accident, PR77904, pr77904 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; Mon, 17 Dec 2018 15:55:05 +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 wBHFsTuM030106; Mon, 17 Dec 2018 09:54:30 -0600 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id wBHFsQbF030098; Mon, 17 Dec 2018 09:54:26 -0600 Date: Mon, 17 Dec 2018 15:55:00 -0000 From: Segher Boessenkool To: Dimitar Dimitrov , Bernd Edlinger , Christophe Lyon , Thomas Preudhomme , "gcc-patches@gcc.gnu.org" , richard.sandiford@arm.com Subject: Re: [PATCH] [RFC] PR target/52813 and target/11807 Message-ID: <20181217155425.GW3803@gate.crashing.org> References: <85840089.MtehzfUrTt@tpdeb> <87woo84boh.fsf@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87woo84boh.fsf@arm.com> User-Agent: Mutt/1.4.2.3i X-IsSubscribed: yes X-SW-Source: 2018-12/txt/msg01230.txt.bz2 On Mon, Dec 17, 2018 at 11:47:42AM +0000, Richard Sandiford wrote: > Dimitar Dimitrov writes: > > On Sun, Dec 16 2018 at 14:36:26 EET Bernd Edlinger wrote: > >> Hi, > >> > >> if I understood that right, then clobbering sp is and has always been > >> ignored. > > PR77904 was about the clobber not being ignored, so the behaviour > hasn't been consistent. > > I'm also not sure it was always ignored in recent sources. The clobber > does get added to the associated rtl insn, and it'd be surprising if > that never had an effect. Yes, you will usually get a frame pointer. My point was that the epilogue will restore your stack pointer both with and without the asm clobber. > I don't think there's a good reason to treat this differently from the > preexisting PIC register error. If the argument for making it a warning > rather than an error is that the asm might happen to work by accident, > then the same is true for the PIC register. Yes. As well as quite a few more registers, many of those specific to the target. And there are many more things you can do terribly wrong in inline assembler, of course, most of which we can never detect. Segher