Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753241AbbGARi4 (ORCPT ); Wed, 1 Jul 2015 13:38:56 -0400 Received: from mail-la0-f48.google.com ([209.85.215.48]:36860 "EHLO mail-la0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750963AbbGARit (ORCPT ); Wed, 1 Jul 2015 13:38:49 -0400 MIME-Version: 1.0 In-Reply-To: <559424D4.6010908@redhat.com> References: <20150630213736.GQ10247@tucnak.redhat.com> <559405E5.7000405@redhat.com> <20150701153133.GY10247@tucnak.redhat.com> <559424D4.6010908@redhat.com> From: Andy Lutomirski Date: Wed, 1 Jul 2015 10:38:26 -0700 Message-ID: Subject: Re: gcc feature request / RFC: extra clobbered regs To: Vladimir Makarov Cc: Jakub Jelinek , Andy Lutomirski , gcc@gcc.gnu.org, "linux-kernel@vger.kernel.org" , Linus Torvalds , "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 927 Lines: 20 On Wed, Jul 1, 2015 at 10:35 AM, Vladimir Makarov wrote: > Actually it raise a question for me. If we describe that a function > clobbers more than calling convention and then use it as a value (assigning > a variable or passing as an argument) and loosing a track of it and than > call it. How can RA know what the call clobbers actually. So for the > function with the attributes we should prohibit use it as a value or make > the attributes as a part of the function type, or at least say it is unsafe. I think it should be part of the type. This shouldn't compile: void func(void) __attribute__((used_reg("r12"))); void (*x)(void); x = func; --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/