From: David Daney <ddaney@caviumnetworks.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ARM: Convert BUG() to use unreachable()
Date: Thu, 10 Dec 2009 09:55:51 -0800 [thread overview]
Message-ID: <4B213627.5000007@caviumnetworks.com> (raw)
In-Reply-To: <20091210175007.GC13210@n2100.arm.linux.org.uk>
Russell King - ARM Linux wrote:
> On Tue, Dec 08, 2009 at 10:55:38AM +0100, Uwe Kleine-König wrote:
>> Use the new unreachable() macro instead of for(;;);
>
> Have you investigated what effect this has on generated code?
Yes.
Pre GCC-4.5 the generated code should be identical as 'unreachable()'
just expands to 'for(;;);' in this case.
Post GCC-4.5 the generated code should be smaller.
I have not tested on ARM, but on x86_64, i686, and mips64 this is the
case. The code size reduction is due to not emitting an endless loop
after the asm() that never returns.
David Daney
next prev parent reply other threads:[~2009-12-10 17:57 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-08 9:55 [PATCH] ARM: Convert BUG() to use unreachable() Uwe Kleine-König
2009-12-08 17:07 ` David Daney
2009-12-10 17:50 ` Russell King - ARM Linux
2009-12-10 17:55 ` David Daney [this message]
2009-12-16 13:58 ` Uwe Kleine-König
2009-12-17 15:01 ` Jamie Lokier
2009-12-17 17:09 ` David Daney
2009-12-17 17:17 ` Richard Guenther
2009-12-17 18:17 ` Russell King - ARM Linux
2009-12-17 18:35 ` Joe Buck
2009-12-17 19:06 ` Russell King - ARM Linux
2009-12-17 19:14 ` Joe Buck
2009-12-17 19:33 ` David Daney
2009-12-17 19:33 ` Russell King - ARM Linux
2009-12-17 19:38 ` Jamie Lokier
2009-12-17 19:48 ` Russell King - ARM Linux
2009-12-17 19:58 ` Russell King - ARM Linux
2009-12-17 19:04 ` Jamie Lokier
2009-12-21 19:30 ` Richard Henderson
2009-12-21 20:10 ` Russell King - ARM Linux
2009-12-22 14:09 ` Dave Korn
2009-12-22 14:12 ` Russell King - ARM Linux
2009-12-22 14:49 ` Dave Korn
2009-12-22 11:33 ` Paolo Bonzini
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