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ruby32
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include
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ruby
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backward
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Filename :
assume.h
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#ifndef RUBY_BACKWARD2_ASSUME_H /*-*-C++-*-vi:se ft=cpp:*/ #define RUBY_BACKWARD2_ASSUME_H /** * @file * @author Ruby developers <ruby-core@ruby-lang.org> * @copyright This file is a part of the programming language Ruby. * Permission is hereby granted, to either redistribute and/or * modify this file, provided that the conditions mentioned in the * file COPYING are met. Consult the file for details. * @warning Symbols prefixed with either `RBIMPL` or `rbimpl` are * implementation details. Don't take them as canon. They could * rapidly appear then vanish. The name (path) of this header file * is also an implementation detail. Do not expect it to persist * at the place it is now. Developers are free to move it anywhere * anytime at will. * @note To ruby-core: remember that this header can be possibly * 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. * @brief Defines #ASSUME / #RB_LIKELY / #UNREACHABLE */ #include "ruby/internal/config.h" #include "ruby/internal/assume.h" #include "ruby/internal/has/builtin.h" #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)) /** * 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) #endif #endif /* RUBY_BACKWARD2_ASSUME_H */