diff options
Diffstat (limited to 'include/ruby/backward/2/assume.h')
| -rw-r--r-- | include/ruby/backward/2/assume.h | 27 |
1 files changed, 20 insertions, 7 deletions
diff --git a/include/ruby/backward/2/assume.h b/include/ruby/backward/2/assume.h index 3fbb81439a..d148710127 100644 --- a/include/ruby/backward/2/assume.h +++ b/include/ruby/backward/2/assume.h @@ -17,24 +17,37 @@ * recursively included from extension libraries written in C++. * Do not expect for instance `__VA_ARGS__` is always available. * We assume C99 for ruby itself but we don't assume languages of - * extension libraries. They could be written in C++98. + * extension libraries. They could be written in C++98. * @brief Defines #ASSUME / #RB_LIKELY / #UNREACHABLE */ #include "ruby/internal/config.h" #include "ruby/internal/assume.h" #include "ruby/internal/has/builtin.h" -#undef ASSUME /* Kill config.h definition */ -#undef UNREACHABLE /* Kill config.h definition */ -#define ASSUME RBIMPL_ASSUME -#define UNREACHABLE RBIMPL_UNREACHABLE() -#define UNREACHABLE_RETURN RBIMPL_UNREACHABLE_RETURN +#define ASSUME RBIMPL_ASSUME /**< @old{RBIMPL_ASSUME} */ +#define UNREACHABLE RBIMPL_UNREACHABLE() /**< @old{RBIMPL_UNREACHABLE} */ +#define UNREACHABLE_RETURN RBIMPL_UNREACHABLE_RETURN /**< @old{RBIMPL_UNREACHABLE_RETURN} */ /* likely */ #if RBIMPL_HAS_BUILTIN(__builtin_expect) +/** + * Asserts that the given Boolean expression likely holds. + * + * @param x An expression that likely holds. + * + * @note Consider this macro carefully. It has been here since when CPUs were + * like babies, but contemporary processors are beasts. They are + * smarter than mare mortals like us today. Their branch predictions + * highly expectedly outperform your use of this macro. + */ # define RB_LIKELY(x) (__builtin_expect(!!(x), 1)) -# define RB_UNLIKELY(x) (__builtin_expect(!!(x), 0)) +/** + * Asserts that the given Boolean expression likely doesn't hold. + * + * @param x An expression that likely doesn't hold. + */ +# define RB_UNLIKELY(x) (__builtin_expect(!!(x), 0)) #else # define RB_LIKELY(x) (x) # define RB_UNLIKELY(x) (x) |