From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: David Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org,
Heiko Carstens <heiko.carstens@de.ibm.com>,
linuxppc-dev@ozlabs.org, Paul Mackerras <paulus@samba.org>,
"H. Peter Anvin" <hpa@zytor.com>,
linux-s390@vger.kernel.org, linux-am33-list@redhat.com,
Helge Deller <deller@gmx.de>,
x86@kernel.org, Ingo Molnar <mingo@redhat.com>,
Mike Frysinger <vapier@gentoo.org>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
uclinux-dist-devel@blackfin.uclinux.org,
Thomas Gleixner <tglx@linutronix.de>,
Richard Henderson <rth@twiddle.net>,
Haavard Skinnemoen <hskinnemoen@atmel.com>,
linux-parisc@vger.kernel.org, ralf@linux-mips.org,
Kyle McMartin <kyle@mcmartin.ca>,
linux-alpha@vger.kernel.org,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
linux390@de.ibm.com, Andrew Morton <akpm@linux-foundation.org>,
Koichi Yasutake <yasutake.koichi@jp.panasonic.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 00/10] Add support for GCC's __builtin_unreachable() and use it in BUG.
Date: Thu, 24 Sep 2009 13:37:13 +1000 [thread overview]
Message-ID: <1253763433.7103.391.camel@pasglop> (raw)
In-Reply-To: <4AA991C1.1050800@caviumnetworks.com>
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 <benh@kernel.crashing.org>
prev parent reply other threads:[~2009-09-24 3:44 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-10 23:54 [PATCH 00/10] Add support for GCC's __builtin_unreachable() and use it in BUG David Daney
2009-09-10 23:56 ` [PATCH 01/10] Add support for GCC-4.5's __builtin_unreachable() to compiler.h David Daney
2009-09-11 0:14 ` Richard Henderson
2009-09-11 14:32 ` Michael Buesch
2009-09-11 15:58 ` David Daney
2009-09-12 7:22 ` Geert Uytterhoeven
2009-09-14 15:40 ` David Daney
2009-09-10 23:56 ` [PATCH 07/10] powerpc: Convert BUG() to use unreachable() David Daney
2009-09-24 3:37 ` Benjamin Herrenschmidt [this message]
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