linux-kernel - Re: [PATCH 2/7] PowerPC: add unlikely() to BUG

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Date:	Fri, 28 Jan 2011 11:14:16 +0100
From:	Andreas Schwab <schwab@...hat.com>
To:	"David Laight" <David.Laight@...LAB.COM>
Cc:	"David Daney" <ddaney@...iumnetworks.com>,
	"Coly Li" <bosong.ly@...bao.com>,
	Wang Cong <xiyou.wangcong@...il.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	Yong Zhang <yong.zhang0@...il.com>
Subject: Re: [PATCH 2/7] PowerPC: add unlikely() to BUG_ON()

"David Laight" <David.Laight@...LAB.COM> writes:

> Also, as (I think) in some of the generated code quoted,
> use of __builtin_expect() with a boolean expression can
> force some versions of gcc to generate the integer
> value of the expression

That's more likely a side effect of the definition of likely/unlikely:
they expand to !!(x).

Andreas.

-- 
Andreas Schwab, schwab@...hat.com
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