linux-kernel - Re: [PATCH 2/2] kernel/{exit.c, signal.c, power/process.c}: replace !likely(x) by likely(!x)

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Message-ID: <47B7B081.8050306@zytor.com>
Date:	Sat, 16 Feb 2008 19:56:49 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Rene Herman <rene.herman@...access.nl>
CC:	Roel Kluin <12o3l@...cali.nl>, lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] kernel/{exit.c, signal.c, power/process.c}: replace
 !likely(x) by likely(!x)

Rene Herman wrote:
> On 16-02-08 20:01, H. Peter Anvin wrote:
>> Roel Kluin wrote:
>>> Not entirely sure who to send this to
>>> ---
>>> Replace !likely(x) by likely(!x)
>>
>> Whoa...
>>
>> Are you sure this is correct?
>>
>> !likely(x) is equivalent to unlikely(!x)
> 
> Not with respect to its value I believe? likely(x) == !!(x), and 
> unlikely(!x) == !!(!x) = !x, so conditions work out differently?

You missed one ! sign:

!likely(x) == !!!(x) == unlikely(!x) == !!(!(x))

	-hpa
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