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Diffstat (limited to 'include/ruby/internal/stdalign.h')
| -rw-r--r-- | include/ruby/internal/stdalign.h | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/include/ruby/internal/stdalign.h b/include/ruby/internal/stdalign.h new file mode 100644 index 0000000000..a3dcfb90ef --- /dev/null +++ b/include/ruby/internal/stdalign.h @@ -0,0 +1,124 @@ +#ifndef RBIMPL_STDALIGN_H /*-*-C++-*-vi:se ft=cpp:*/ +#define RBIMPL_STDALIGN_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_ALIGNAS / #RBIMPL_ALIGNOF + */ +#include "ruby/impl/config.h" + +#ifdef HAVE_STDALIGN_H +# include <stdalign.h> +#endif + +#include "ruby/impl/compiler_is.h" +#include "ruby/impl/compiler_since.h" +#include "ruby/impl/has/feature.h" +#include "ruby/impl/has/extension.h" +#include "ruby/impl/has/attribute.h" +#include "ruby/impl/has/declspec_attribute.h" + +/** + * Wraps (or simulates) `alignas`. This is C++11's `alignas` and is _different_ + * from C11 `_Alignas`. For instance, + * + * ```CXX + * typedef struct alignas(128) foo { int foo } foo; + * ``` + * + * is a valid C++ while + * + * ```C + * typedef struct _Alignas(128) foo { int foo } foo; + * ``` + * + * is an invalid C because: + * + * - You cannot `struct _Alignas`. + * - A `typedef` cannot have alignments. + */ +#if defined(__cplusplus) && RBIMPL_HAS_FEATURE(cxx_alignas) +# define RBIMPL_ALIGNAS alignas + +#elif defined(__cplusplus) && (__cplusplus >= 201103L) +# define RBIMPL_ALIGNAS alignas + +#elif defined(__INTEL_CXX11_MODE__) +# define RBIMPL_ALIGNAS alignas + +#elif defined(__GXX_EXPERIMENTAL_CXX0X__) +# define RBIMPL_ALIGNAS alignas + +#elif RBIMPL_HAS_DECLSPEC_ATTRIBUTE(align) +# define RBIMPL_ALIGNAS(_) __declspec(align(_)) + +#elif RBIMPL_HAS_ATTRIBUTE(aliged) +# define RBIMPL_ALIGNAS(_) __attribute__((__aligned__(_))) + +#else +# define RBIMPL_ALIGNAS(_) /* void */ +#endif + +/** + * Wraps (or simulates) `alignof`. Unlike #RBIMPL_ALIGNAS, we can safely say + * both C/C++ definitions are effective. + */ +#if defined(__cplusplus) && RBIMPL_HAS_EXTENSION(cxx_alignof) +# define RBIMPL_ALIGNOF __extension__ alignof + +#elif defined(__cplusplus) && (__cplusplus >= 201103L) +# define RBIMPL_ALIGNOF alignof + +#elif defined(__INTEL_CXX11_MODE__) +# define RBIMPL_ALIGNOF alignof + +#elif defined(__GXX_EXPERIMENTAL_CXX0X__) +# define RBIMPL_ALIGNOF alignof + +#elif defined(__STDC_VERSION__) && RBIMPL_HAS_EXTENSION(c_alignof) +# define RBIMPL_ALIGNOF __extension__ _Alignof + +#elif defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L) +# define RBIMPL_ALIGNOF _Alignof + +#elif RBIMPL_COMPILER_IS(MSVC) +# define RBIMPL_ALIGNOF __alignof + +#elif defined(__GNUC__) +# /* At least GCC 2.95 had this. */ +# define RBIMPL_ALIGNOF __extension__ __alignof__ + +#elif defined(__alignof_is_defined) || defined(__DOXYGEN__) +# /* OK, we can safely take <stdalign.h> definition. */ +# define RBIMPL_ALIGNOF alignof + +#elif RBIMPL_COMPILER_SINCE(SunPro, 5, 9, 0) +# /* According to their manual, Sun Studio 12 introduced __alignof__ for both +# * C/C++. */ +# define RBIMPL_ALIGNOF __alignof__ + +#elif 0 +# /* THIS IS NG, you cannot define a new type inside of offsetof. */ +# /* see: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm */ +# define RBIMPL_ALIGNOF(T) offsetof(struct { char _; T t; }, t) + +#else +# error :FIXME: add your compiler here to obtain an alignment. +#endif + +#endif /* RBIMPL_STDALIGN_H */ |