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Diffstat (limited to 'include/ruby/internal/assume.h')
-rw-r--r-- | include/ruby/internal/assume.h | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/include/ruby/internal/assume.h b/include/ruby/internal/assume.h new file mode 100644 index 0000000000..fa4a89514a --- /dev/null +++ b/include/ruby/internal/assume.h @@ -0,0 +1,90 @@ +#ifndef RBIMPL_ASSUME_H /*-*-C++-*-vi:se ft=cpp:*/ +#define RBIMPL_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 #RBIMPL_ASSUME / #RBIMPL_UNREACHABLE. + * + * These macros must be defined at once because: + * + * - #RBIMPL_ASSUME could fallback to #RBIMPL_UNREACHABLE. + * - #RBIMPL_UNREACHABLE could fallback to #RBIMPL_ASSUME. + */ +#include "ruby/impl/config.h" +#include "ruby/impl/cast.h" +#include "ruby/impl/compiler_since.h" +#include "ruby/impl/has/builtin.h" +#include "ruby/impl/warning_push.h" + +/** @cond INTERNAL_MACRO */ +#if RBIMPL_COMPILER_SINCE(MSVC, 13, 10, 0) +# define RBIMPL_HAVE___ASSUME + +#elif RBIMPL_COMPILER_SINCE(Intel, 13, 0, 0) +# define RBIMPL_HAVE___ASSUME +#endif +/** @endcond */ + +/** Wraps (or simulates) `__builtin_unreachable`. */ +#if RBIMPL_HAS_BUILTIN(__builtin_unreachable) +# define RBIMPL_UNREACHABLE_RETURN(_) __builtin_unreachable() + +#elif defined(RBIMPL_HAVE___ASSUME) +# define RBIMPL_UNREACHABLE_RETURN(_) return (__assume(0), (_)) + +#else +# define RBIMPL_UNREACHABLE_RETURN(_) return (_) +#endif + +/** Wraps (or simulates) `__builtin_unreachable`. */ +#if RBIMPL_HAS_BUILTIN(__builtin_unreachable) +# define RBIMPL_UNREACHABLE __builtin_unreachable + +#elif defined(RBIMPL_HAVE___ASSUME) +# define RBIMPL_UNREACHABLE() __assume(0) +#endif + +/** Wraps (or simulates) `__assume`. */ +#if RBIMPL_COMPILER_SINCE(Intel, 13, 0, 0) +# /* icc warnings are false positives. Ignore them. */ +# /* "warning #2261: __assume expression with side effects discarded" */ +# define RBIMPL_ASSUME(expr) \ + RBIMPL_WARNING_PUSH() \ + RBIMPL_WARNING_IGNORED(2261) \ + __assume(expr) \ + RBIMPL_WARNING_POP() + +#elif defined(RBIMPL_HAVE___ASSUME) +# define RBIMPL_ASSUME __assume + +#elif RBIMPL_HAS_BUILTIN(__builtin_assume) +# define RBIMPL_ASSUME __builtin_assume + +#elif ! defined(RBIMPL_UNREACHABLE) +# define RBIMPL_ASSUME(_) RBIMPL_CAST((void)(_)) + +#else +# define RBIMPL_ASSUME(_) \ + (RB_LIKELY(!!(_)) ? RBIMPL_CAST((void)0) : RBIMPL_UNREACHABLE()) +#endif + +#if ! defined(RBIMPL_UNREACHABLE) +# define RBIMPL_UNREACHABLE() RBIMPL_ASSUME(0) +#endif + +#endif /* RBIMPL_ASSUME_H */ |