From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751973Ab2BTRW3 (ORCPT ); Mon, 20 Feb 2012 12:22:29 -0500 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:43967 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751730Ab2BTRW2 (ORCPT ); Mon, 20 Feb 2012 12:22:28 -0500 Date: Mon, 20 Feb 2012 17:21:58 +0000 From: Russell King - ARM Linux To: Rabin Vincent Cc: linux-arm-kernel@lists.infradead.org, Jason Baron , linux-kernel@vger.kernel.org Subject: Re: [PATCHv2 5/6] jump label: detect %c support for ARM Message-ID: <20120220172158.GI26840@n2100.arm.linux.org.uk> References: <1327757725-10114-1-git-send-email-rabin@rab.in> <1327757725-10114-6-git-send-email-rabin@rab.in> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1327757725-10114-6-git-send-email-rabin@rab.in> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jan 28, 2012 at 07:05:24PM +0530, Rabin Vincent wrote: > Some versions of ARM GCC which do support asm goto, have problems > handling the the %c specifier. Since we need the %c to support jump > labels on ARM, detect that too in the asm goto detection script to avoid > build errors with these versions. I'm not sure how this detects properly working %c support. %c support has been rather flakey on ARM for some time, I'm not sure which version of gcc was fixed for it. > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48637 > > Cc: Jason Baron > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Rabin Vincent > --- > scripts/gcc-goto.sh | 18 +++++++++++++++++- > 1 files changed, 17 insertions(+), 1 deletions(-) > > diff --git a/scripts/gcc-goto.sh b/scripts/gcc-goto.sh > index 98cffcb..9b744de 100644 > --- a/scripts/gcc-goto.sh > +++ b/scripts/gcc-goto.sh > @@ -2,4 +2,20 @@ > # Test for gcc 'asm goto' support > # Copyright (C) 2010, Jason Baron > > -echo "int main(void) { entry: asm goto (\"\"::::entry); return 0; }" | $@ -x c - -c -o /dev/null >/dev/null 2>&1 && echo "y" > +cat << "END" | $@ -x c - -c -o /dev/null >/dev/null 2>&1 && echo "y" > +int main(void) > +{ > +#ifdef __arm__ > + /* > + * Not related to asm goto, but used by jump label > + * and broken on some ARM GCC versions (see GCC Bug 48637). > + */ > + static struct { int dummy; int state; } tp; > + asm ("@ %c0" :: "i" (&tp.state)); While this detects the presence of the ICE, previous compilers included the '#' before the constant, which leads to problems. I think a better check would be: asm(".long %c0" :: "i" (&tp.state)); to make sure that it spits out something purely numeric, rather than something prefixed with a '#'.