lkml.org 
[lkml]   [2001]   [Sep]   [27]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: Linux 2.4.10-pre11 -- __builtin_expect
FromAndreas Schwab <>
Date27 Sep 2001 18:28:08 +0200
James Antill <james@and.org> writes:

|> Andreas Schwab <schwab@suse.de> writes:
|> 
|> > James Antill <james@and.org> writes:
|> > 
|> > |>  unlikely() also needs to be...
|> > |> 
|> > |> #define unlikely(x)  __builtin_expect(!(x), 1) 
|> > |> 
|> > |> ...or...
|> > |> 
|> > |> #define unlikely(x)  __builtin_expect(!!(x), 0) 
|> > 
|> > This is not needed, since only 0 is the likely value and !! does not
|> > change that.
|> 
|>  Yes it is, given the code...
|> 
|> struct blah *ptr = NULL;
|> 
|> if (unlikely(ptr))
|> 
|> ...you'll get a warning from gcc because you are implicitly converting
|> from a pointer to a long.

You're right, seems like __builtin_expect is really only defined for pure
boolean values.

Andreas.

-- 
Andreas Schwab                                  "And now for something
Andreas.Schwab@suse.de				completely different."
SuSE Labs, SuSE GmbH, Schanzäckerstr. 10, D-90443 Nürnberg
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:03    [from the cache]
©2003-2008