From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 128479 invoked by alias); 17 Dec 2018 12:54:06 -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 127804 invoked by uid 89); 17 Dec 2018 12:54:06 -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,SPF_PASS autolearn=no version=3.3.2 spammy=H*Ad:D*eu, accident, pr77904, PR77904 X-HELO: mail-vs1-f65.google.com Received: from mail-vs1-f65.google.com (HELO mail-vs1-f65.google.com) (209.85.217.65) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 17 Dec 2018 12:54:04 +0000 Received: by mail-vs1-f65.google.com with SMTP id x1so7582983vsc.10 for ; Mon, 17 Dec 2018 04:54:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=CPIP2dEV32ZHvM51T5hWzROfKZVE3n8l7Vs7IdcTQjk=; b=RRnUFXDaAAOHRE7VhxC1xTXx9kxoVA9j67MR5fbIwdPFsAReAFlt/Gu9YlgCqS8eKo Myusp84D8KPeX9+bIxmdukUmOj6NQbuPnR6ma7BMf4fZOtB9zOAbYIvWmW+4qOAYS33o Y6scgAyAlSkjls801klJEhpayajZkBbMdcQbY= MIME-Version: 1.0 References: <85840089.MtehzfUrTt@tpdeb> <87woo84boh.fsf@arm.com> In-Reply-To: <87woo84boh.fsf@arm.com> From: Christophe Lyon Date: Mon, 17 Dec 2018 12:54:00 -0000 Message-ID: Subject: Re: [PATCH] [RFC] PR target/52813 and target/11807 To: Dimitar Dimitrov , Bernd Edlinger , Segher Boessenkool , Christophe Lyon , Thomas Preudhomme , "gcc-patches@gcc.gnu.org" , Richard Sandiford Content-Type: text/plain; charset="UTF-8" X-IsSubscribed: yes X-SW-Source: 2018-12/txt/msg01207.txt.bz2 On Mon, 17 Dec 2018 at 12:47, 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. > > >> 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. > If we leave the error, maybe a more explanatory message would be helpful? (along the lines of what I posted earlier in this thread, which may be too verbose) Christophe > Thanks, > Richard