From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753121Ab0GJJHZ (ORCPT ); Sat, 10 Jul 2010 05:07:25 -0400 Received: from relay2-v.mail.gandi.net ([217.70.178.76]:36978 "EHLO mrelay2-v.mgt.gandi.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752059Ab0GJJHX (ORCPT ); Sat, 10 Jul 2010 05:07:23 -0400 X-Originating-IP: 217.70.178.37 X-Originating-IP: 74.107.143.84 Date: Sat, 10 Jul 2010 02:07:06 -0700 From: Josh Triplett To: Jiri Slaby Cc: christ.li@gmail.com, jirislaby@gmail.com, Larry Finger , linux-kernel@vger.kernel.org, linux-sparse@vger.kernel.org Subject: Re: [PATCH 2/2] parser: define __builtin_unreachable Message-ID: <20100710090705.GA14881@feather> References: <1278751162-10053-2-git-send-email-jslaby@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1278751162-10053-2-git-send-email-jslaby@suse.cz> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jul 10, 2010 at 10:39:22AM +0200, Jiri Slaby wrote: > Gcc 4.5 defines > extern void __builtin_unreachable(void); > so, add it also to sparse. > > Signed-off-by: Jiri Slaby > --- > lib.c | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/lib.c b/lib.c > index a218bfc..ae6a20c 100644 > --- a/lib.c > +++ b/lib.c > @@ -740,6 +740,7 @@ void declare_builtin_functions(void) > add_pre_buffer ("extern char * __builtin___strncpy_chk(char *, const char *, __SIZE_TYPE__, __SIZE_TYPE__);\n"); > add_pre_buffer ("extern int __builtin___vsprintf_chk(char *, int, __SIZE_TYPE__, const char *, __builtin_va_list);\n"); > add_pre_buffer ("extern int __builtin___vsnprintf_chk(char *, __SIZE_TYPE__, int, __SIZE_TYPE__, const char *, __builtin_va_list ap);\n"); > + add_pre_buffer ("extern void __builtin_unreachable(void);\n"); __builtin_unreachable has special semantics beyond just a function. This definition will suffice to allow compilation, but __builtin_unreachable should have the same effect in sparse that it does in GCC: mark the point (and the remainder of the basic block) as unreachable. Something like the mechanism used for handling noreturn would work here as well; declaring the function to have attribute noreturn would probably have almost the right semantics. - Josh Triplett