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Date: Sat, 9 Aug 2003 01:21:17 +0100
From: Jamie Lokier <jamie@shareable.org>
To: Albert Cahalan <albert@users.sourceforge.net>
Cc: linux-kernel mailing list <linux-kernel@vger.kernel.org>, chip@pobox.com
Subject: Re: [PATCH] 2.4.22pre10: {,un}likely_p() macros for pointers
Message-ID: <20030809002117.GB26375@mail.jlokier.co.uk>
References: <1060087479.796.50.camel@cube>
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Albert Cahalan wrote:
> // tell gcc what to expect:   if(unlikely(err)) die(err);
> #define likely(x)       __builtin_expect(!!(x),1)
> #define unlikely(x)     __builtin_expect(!!(x),0)
> #define expected(x,y)   __builtin_expect((x),(y))

You may want to check that GCC generates the same code as for

	#define likely(x)	__builtin_expect((x),1)
	#define unlikely(x)	__builtin_expect((x),0)

I tried this once, and I don't recall the precise result but I do
recall it generating different code (i.e. not optimal for one of the
definitions).

-- Jamie