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