* UNLIKELY
@ 2012-01-09 13:38 Dmitry Nadezhin
2012-01-23 18:48 ` UNLIKELY Anthony Green
0 siblings, 1 reply; 2+ messages in thread
From: Dmitry Nadezhin @ 2012-01-09 13:38 UTC (permalink / raw)
To: libffi-discuss
The ffi_common.h contains definitions:
#define LIKELY(x) __builtin_expect((x),1)
#define UNLIKELY(x) __builtin_expect((x),1)
I guess that the definition of UNLIKELY should be:
#define UNLIKELY(x) __builtin_expect((x),0)
Also some libraries prefer to define LIKELY like this:
#define _X_LIKELY(x) __builtin_expect(!!(x), 1)
#define __GMP_LIKELY(cond) __builtin_expect ((cond) != 0, 1)
but I'm not sure if it changes the generated code on any platform.
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: UNLIKELY
2012-01-09 13:38 UNLIKELY Dmitry Nadezhin
@ 2012-01-23 18:48 ` Anthony Green
0 siblings, 0 replies; 2+ messages in thread
From: Anthony Green @ 2012-01-23 18:48 UTC (permalink / raw)
To: Dmitry Nadezhin; +Cc: libffi-discuss
On Mon, Jan 9, 2012 at 8:38 AM, Dmitry Nadezhin
<dmitry.nadezhin@gmail.com> wrote:
> The ffi_common.h contains definitions:
>
> #define LIKELY(x) __builtin_expect((x),1)
> #define UNLIKELY(x) __builtin_expect((x),1)
>
> I guess that the definition of UNLIKELY should be:
>
> #define UNLIKELY(x) __builtin_expect((x),0)
Oops! Nice catch.
Thanks,
Anthony Green
>
> Also some libraries prefer to define LIKELY like this:
> #define _X_LIKELY(x) __builtin_expect(!!(x), 1)
> #define __GMP_LIKELY(cond) __builtin_expect ((cond) != 0, 1)
> but I'm not sure if it changes the generated code on any platform.
^ permalink raw reply [flat|nested] 2+ messages in thread
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