From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 45744 invoked by alias); 17 Dec 2018 11:47:48 -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 45733 invoked by uid 89); 17 Dec 2018 11:47:47 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-1.4 required=5.0 tests=BAYES_00,KAM_NUMSUBJECT,SPF_PASS autolearn=no version=3.3.2 spammy=accident, PR77904, preexisting, pr77904 X-HELO: foss.arm.com Received: from usa-sjc-mx-foss1.foss.arm.com (HELO foss.arm.com) (217.140.101.70) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 17 Dec 2018 11:47:46 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0A777EBD; Mon, 17 Dec 2018 03:47:45 -0800 (PST) Received: from localhost (unknown [10.32.99.101]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C33883F6A8; Mon, 17 Dec 2018 03:47:43 -0800 (PST) From: Richard Sandiford To: Dimitar Dimitrov Mail-Followup-To: Dimitar Dimitrov ,Bernd Edlinger , Segher Boessenkool , Christophe Lyon , Thomas Preudhomme , "gcc-patches\@gcc.gnu.org" , richard.sandiford@arm.com Cc: Bernd Edlinger , Segher Boessenkool , Christophe Lyon , Thomas Preudhomme , "gcc-patches\@gcc.gnu.org" Subject: Re: [PATCH] [RFC] PR target/52813 and target/11807 References: <85840089.MtehzfUrTt@tpdeb> Date: Mon, 17 Dec 2018 11:47:00 -0000 In-Reply-To: <85840089.MtehzfUrTt@tpdeb> (Dimitar Dimitrov's message of "Sun, 16 Dec 2018 18:13:57 +0200") Message-ID: <87woo84boh.fsf@arm.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-SW-Source: 2018-12/txt/msg01202.txt.bz2 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. >> If that is right, then I would much prefer a warning, that says exactly >> that, because that would also help to understand why removing that clobber >> statement is safe even for old gcc versions. If the asm does leave sp with a different value, then it's never been safe, regardless of the gcc version. That's why an error seems more appropriate. > Thank you. Looks like general consensus is to have a warning. See attached > patch that switches the error to a warning. 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. Thanks, Richard