[FFmpeg-devel] [PATCH 1/3] avutil/attributes: add av_likely and av_unlikely

[Rostislav Pehlivanov]

On Thu, 24 Jan 2019 at 20:38, Marton Balint <cus at passwd.hu> wrote:

> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
>  doc/APIchanges         | 3 +++
>  libavutil/attributes.h | 8 ++++++++
>  libavutil/version.h    | 2 +-
>  3 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/doc/APIchanges b/doc/APIchanges
> index a39a3ff2ba..38b5b980a6 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -15,6 +15,9 @@ libavutil:     2017-10-21
>
>  API changes, most recent first:
>
> +2019-01-xx - xxxxxxxxxx - lavu 56.27.100 - attributes.h
> +  Add av_likely and av_unlikely
> +
>  2019-01-08 - xxxxxxxxxx - lavu 56.26.100 - frame.h
>    Add AV_FRAME_DATA_REGIONS_OF_INTEREST
>
> diff --git a/libavutil/attributes.h b/libavutil/attributes.h
> index ced108aa2c..60972e5109 100644
> --- a/libavutil/attributes.h
> +++ b/libavutil/attributes.h
> @@ -164,4 +164,12 @@
>  #    define av_noreturn
>  #endif
>
> +#if AV_GCC_VERSION_AT_LEAST(2,96) || defined(__clang__)
> +# define av_likely(x)      __builtin_expect(!!(x), 1)
> +# define av_unlikely(x)    __builtin_expect(!!(x), 0)
> +#else
> +# define av_likely(x)      (x)
> +# define av_unlikely(x)    (x)
> +#endif
> +
>  #endif /* AVUTIL_ATTRIBUTES_H */
> diff --git a/libavutil/version.h b/libavutil/version.h
> index 1fcdea95bf..12b4f9fc3a 100644
> --- a/libavutil/version.h
> +++ b/libavutil/version.h
> @@ -79,7 +79,7 @@
>   */
>
>  #define LIBAVUTIL_VERSION_MAJOR  56
> -#define LIBAVUTIL_VERSION_MINOR  26
> +#define LIBAVUTIL_VERSION_MINOR  27
>  #define LIBAVUTIL_VERSION_MICRO 100
>
>  #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
> --
> 2.16.4
>
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NAK, NAK, NAK.
I will NAK the hell out of any patch that does that. They're completely
unnecessary, they're commonly used by complete idiots who add them thinking
their code will go faster (and it might - only on their antiquated GCC
3.1), they're religiously used by the same people and won't back down on
using them and finally they're ugly when added to every single bloody
branch and the people who maintain such code will demand they be added to
every single bloody branch for no reason other that what I've just iterated
on.
The ONLY way I'll accept them is in platform-specific files, e.g.
libavcodec/ppc/*, and even then only on non-x86 arches (which need them for
having bad compilers with primitive processors having awful branch
prediction) and even then I'd never accept their inclusioin into
system-installed headers.