From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id E9139B7043 for ; Thu, 24 Sep 2009 13:44:44 +1000 (EST) Subject: Re: [PATCH 00/10] Add support for GCC's __builtin_unreachable() and use it in BUG. From: Benjamin Herrenschmidt To: David Daney In-Reply-To: <4AA991C1.1050800@caviumnetworks.com> References: <4AA991C1.1050800@caviumnetworks.com> Content-Type: text/plain Date: Thu, 24 Sep 2009 13:37:13 +1000 Message-Id: <1253763433.7103.391.camel@pasglop> Mime-Version: 1.0 Cc: linux-mips@linux-mips.org, Heiko Carstens , linuxppc-dev@ozlabs.org, Paul Mackerras , "H. Peter Anvin" , linux-s390@vger.kernel.org, linux-am33-list@redhat.com, Helge Deller , x86@kernel.org, Ingo Molnar , Mike Frysinger , Ivan Kokshaysky , uclinux-dist-devel@blackfin.uclinux.org, Thomas Gleixner , Richard Henderson , Haavard Skinnemoen , linux-parisc@vger.kernel.org, ralf@linux-mips.org, Kyle McMartin , linux-alpha@vger.kernel.org, Martin Schwidefsky , linux390@de.ibm.com, Andrew Morton , Koichi Yasutake , Linus Torvalds List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2009-09-10 at 16:54 -0700, David Daney wrote: > Starting with version 4.5, GCC has a new built-in function called > __builtin_unreachable(). The function tells the compiler that control > flow will never reach that point. Currently we trick the compiler by > putting in for(;;); but this has the disadvantage that extra code is > emitted for an endless loop. For an i386 kernel using > __builtin_unreachable() results in an allyesconfig that is nearly 4000 > bytes smaller. For the powerpc part: Acked-by: Benjamin Herrenschmidt