From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ben Hutchings <bhutchings@solarflare.com>
Subject: Re: [PATCH] net: remove tests on 64bit platforms
Date: Tue, 25 Jan 2011 14:28:49 +1000
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Cc: "David S. Miller" <davem@davemloft.net>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	"Pekka Savola (ipv6)" <pekkas@netcore.fi>,
	James Morris <jmorris@namei.org>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Patrick McHardy <kaber@trash.net>, netdev@vger.kernel.org
To: Changli Gao <xiaosuo@gmail.com>
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On Tue, 2011-01-25 at 12:21 +0800, Changli Gao wrote:
> On 64bit platforms, >31 bit shifting of a unsigned long variable is
> valid, so we can remove the related boundary tests, which may slow
> down the CPU if branch prediction fails.
[...]

It seems like it would be better to define generic shift functions that
correctly handle the case of a shift count >= word size.  There are many
places these would be useful.

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
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