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80 lines
2.8 KiB
C
80 lines
2.8 KiB
C
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/** \noop-*-C++-*-vi:ft=cpp
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* @file
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* @author Ruby developers <ruby-core@ruby-lang.org>
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* @copyright This file is a part of the programming language Ruby.
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* Permission is hereby granted, to either redistribute and/or
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* modify this file, provided that the conditions mentioned in the
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* file COPYING are met. Consult the file for details.
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* @warning Symbols prefixed with either `RUBY3` or `ruby3` are
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* implementation details. Don't take them as canon. They could
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* rapidly appear then vanish. The name (path) of this header file
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* is also an implementation detail. Do not expect it to persist
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* at the place it is now. Developers are free to move it anywhere
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* anytime at will.
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* @note To ruby-core: remember that this header can be possibly
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* recursively included from extension libraries written in C++.
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* Do not expect for instance `__VA_ARGS__` is always available.
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* We assume C99 for ruby itself but we don't assume languages of
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* extension libraries. They could be written in C++98.
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* @brief Defines #RUBY3_ASSUME / #RUBY3_UNREACHABLE.
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*
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* These macros must be defined at once because:
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*
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* - #RUBY3_ASSUME could fallback to #RUBY3_UNREACHABLE.
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* - #RUBY3_UNREACHABLE could fallback to #RUBY3_ASSUME.
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*/
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#ifndef RUBY3_ASSUME_H
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#define RUBY3_ASSUME_H
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#include "ruby/3/config.h"
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#include "ruby/3/cast.h"
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#include "ruby/3/has/builtin.h"
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/** @cond INTERNAL_MACRO */
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#if RUBY3_COMPILER_SINCE(MSVC, 13, 10, 0)
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# define RUBY3_HAVE___ASSUME
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#elif RUBY3_COMPILER_SINCE(Intel, 13, 0, 0)
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# define RUBY3_HAVE___ASSUME
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#endif
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/** @endcond */
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/** Wraps (or simulates) `__builtin_unreachable`. */
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#if RUBY3_HAS_BUILTIN(__builtin_unreachable)
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# define RUBY3_UNREACHABLE_RETURN(_) __builtin_unreachable()
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#elif defined(RUBY3_HAVE___ASSUME)
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# define RUBY3_UNREACHABLE_RETURN(_) return (__assume(0), (_))
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#else
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# define RUBY3_UNREACHABLE_RETURN(_) return (_)
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#endif
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/** Wraps (or simulates) `__builtin_unreachable`. */
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#if RUBY3_HAS_BUILTIN(__builtin_unreachable)
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# define RUBY3_UNREACHABLE __builtin_unreachable
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#elif defined(RUBY3_HAVE___ASSUME)
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# define RUBY3_UNREACHABLE() __assume(0)
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#endif
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/** Wraps (or simulates) `__asume`. */
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#if defined(RUBY3_HAVE___ASSUME)
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# define RUBY3_ASSUME __assume
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#elif RUBY3_HAS_BUILTIN(__builtin_assume)
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# define RUBY3_ASSUME __builtin_assume
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#elif ! defined(RUBY3_UNREACHABLE)
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# define RUBY3_ASSUME(_) RUBY3_CAST((void)(_))
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#else
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# define RUBY3_ASSUME(_) \
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(RB_LIKELY(!!(_)) ? RUBY3_CAST((void)0) : RUBY3_UNREACHABLE())
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#endif
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#if ! defined(RUBY3_UNREACHABLE)
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# define RUBY3_UNREACHABLE() RUBY3_ASSUME(0)
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#endif
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#endif /* RUBY3_ASSUME_H */
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