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Subject: Re: [PATCH] 2.4.22pre10: {,un}likely_p() macros for pointers
From: Albert Cahalan <albert@users.sf.net>
To: Jamie Lokier <jamie@shareable.org>
Cc: Andrew Morton <akpm@digeo.com>, akpm@osdl.org,
       Willy Tarreau <willy@w.ods.org>, Chip Salzenberg <chip@pobox.com>,
       Albert Cahalan <albert@users.sourceforge.net>,
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On Mon, 2003-08-11 at 01:42, Jamie Lokier wrote:
> Willy Tarreau wrote:
> > So in any case, the !!(x) construct should be valid.
> 
> Yes, either of these is fine for pointers and integers alike:
> 
> 	#define likely(x)	__builtin_expect ((x) != 0, 1)
> 	#define unlikely(x)	__builtin_expect ((x) != 0, 0)
> 
> 	#define likely(x)	__builtin_expect (!!(x), 1)
> 	#define unlikely(x)	__builtin_expect (!!(x), 0)

Choosing the more familiar idiom for booleanizing a value, here we go:

diff -Naurd old/include/linux/compiler.h new/include/linux/compiler.h
--- old/include/linux/compiler.h	2003-08-11 09:02:18.000000000 -0400
+++ new/include/linux/compiler.h	2003-08-11 09:04:58.000000000 -0400
@@ -24,8 +24,8 @@
 #define __builtin_expect(x, expected_value) (x)
 #endif
 
-#define likely(x)	__builtin_expect((x),1)
-#define unlikely(x)	__builtin_expect((x),0)
+#define likely(x)	__builtin_expect(!!(x),1)
+#define unlikely(x)	__builtin_expect(!!(x),0)
 
 /*
  * Allow us to mark functions as 'deprecated' and have gcc emit a nice