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
Date: Sat, 9 Aug 2003 01:21:17 +0100 [thread overview]
Message-ID: <20030809002117.GB26375@mail.jlokier.co.uk> (raw)
In-Reply-To: <1060087479.796.50.camel@cube>
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
next prev parent reply other threads:[~2003-08-09 0:21 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-05 12:44 [PATCH] 2.4.22pre10: {,un}likely_p() macros for pointers Albert Cahalan
2003-08-09 0:21 ` Jamie Lokier [this message]
2003-08-09 8:13 ` Willy Tarreau
2003-08-09 8:51 ` David S. Miller
2003-08-09 9:36 ` Jamie Lokier
2003-08-09 10:10 ` Herbert Xu
2003-08-09 10:42 ` Alan Cox
2003-08-09 16:23 ` Jamie Lokier
2003-08-09 17:30 ` NULL. Again. (was Re: [PATCH] 2.4.22pre10: {,un}likely_p()) Chip Salzenberg
2003-08-09 17:43 ` Sean Neakums
2003-08-11 1:04 ` Jamie Lokier
2003-08-11 23:06 ` Timothy Miller
2003-08-09 19:44 ` Jamie Lokier
-- strict thread matches above, loose matches on Subject: below --
2003-08-10 4:03 [PATCH] 2.4.22pre10: {,un}likely_p() macros for pointers Albert Cahalan
2003-08-10 7:29 ` Willy Tarreau
2003-08-10 8:02 ` Willy Tarreau
2003-08-11 1:23 ` Chip Salzenberg
2003-08-11 2:09 ` Jamie Lokier
2003-08-11 2:39 ` Chip Salzenberg
2003-08-11 4:02 ` Albert Cahalan
2003-08-11 4:30 ` Jamie Lokier
2003-08-11 5:30 ` Willy Tarreau
2003-08-11 5:42 ` Jamie Lokier
2003-08-11 13:09 ` Albert Cahalan
2003-08-11 18:55 ` Andrew Morton
2003-08-11 23:13 ` Albert Cahalan
2003-08-13 19:42 ` Jamie Lokier
2003-08-11 4:55 ` Jamie Lokier
2003-08-11 5:26 ` Willy Tarreau
2003-08-11 5:38 ` Jamie Lokier
2003-08-04 17:06 Chip Salzenberg
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