diff options
Diffstat (limited to 'lib/stdalign.in.h')
| -rw-r--r-- | lib/stdalign.in.h | 120 |
1 files changed, 18 insertions, 102 deletions
diff --git a/lib/stdalign.in.h b/lib/stdalign.in.h index 0a58e3208a5..ff9e5ec6d67 100644 --- a/lib/stdalign.in.h +++ b/lib/stdalign.in.h @@ -17,117 +17,33 @@ /* Written by Paul Eggert and Bruno Haible. */ -#ifndef _GL_STDALIGN_H -#define _GL_STDALIGN_H +/* Define two obsolescent C11 macros, assuming alignas and alignof are + either keywords or alignasof-defined macros. */ -/* ISO C11 <stdalign.h> for platforms that lack it. +#ifndef _@GUARD_PREFIX@_STDALIGN_H - References: - ISO C11 (latest free draft - <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf>) - sections 6.5.3.4, 6.7.5, 7.15. - C++11 (latest free draft - <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf>) - section 18.10. */ - -/* alignof (TYPE), also known as _Alignof (TYPE), yields the alignment - requirement of a structure member (i.e., slot or field) that is of - type TYPE, as an integer constant expression. - - This differs from GCC's and clang's __alignof__ operator, which can - yield a better-performing alignment for an object of that type. For - example, on x86 with GCC and on Linux/x86 with clang, - __alignof__ (double) and __alignof__ (long long) are 8, whereas - alignof (double) and alignof (long long) are 4 unless the option - '-malign-double' is used. - - The result cannot be used as a value for an 'enum' constant, if you - want to be portable to HP-UX 10.20 cc and AIX 3.2.5 xlc. */ - -/* FreeBSD 9.1 <sys/cdefs.h>, included by <stddef.h> and lots of other - standard headers, defines conflicting implementations of _Alignas - and _Alignof that are no better than ours; override them. */ -#undef _Alignas -#undef _Alignof - -/* GCC releases before GCC 4.9 had a bug in _Alignof. See GCC bug 52023 - <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023>. - clang versions < 8.0.0 have the same bug. */ -#if (!defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 \ - || (defined __GNUC__ && __GNUC__ < 4 + (__GNUC_MINOR__ < 9) \ - && !defined __clang__) \ - || (defined __clang__ && __clang_major__ < 8)) -# ifdef __cplusplus -# if (201103 <= __cplusplus || defined _MSC_VER) -# define _Alignof(type) alignof (type) -# else - template <class __t> struct __alignof_helper { char __a; __t __b; }; -# define _Alignof(type) offsetof (__alignof_helper<type>, __b) -# define _GL_STDALIGN_NEEDS_STDDEF 1 -# endif -# else -# define _Alignof(type) offsetof (struct { char __a; type __b; }, __b) -# define _GL_STDALIGN_NEEDS_STDDEF 1 -# endif +#if __GNUC__ >= 3 +@PRAGMA_SYSTEM_HEADER@ #endif -#if ! (defined __cplusplus && (201103 <= __cplusplus || defined _MSC_VER)) -# define alignof _Alignof -#endif -#define __alignof_is_defined 1 - -/* alignas (A), also known as _Alignas (A), aligns a variable or type - to the alignment A, where A is an integer constant expression. For - example: - - int alignas (8) foo; - struct s { int a; int alignas (8) bar; }; +@PRAGMA_COLUMNS@ - aligns the address of FOO and the offset of BAR to be multiples of 8. - - A should be a power of two that is at least the type's alignment - and at most the implementation's alignment limit. This limit is - 2**28 on typical GNUish hosts, and 2**13 on MSVC. To be portable - to MSVC through at least version 10.0, A should be an integer - constant, as MSVC does not support expressions such as 1 << 3. - To be portable to Sun C 5.11, do not align auto variables to - anything stricter than their default alignment. - - The following C11 requirements are not supported here: - - - If A is zero, alignas has no effect. - - alignas can be used multiple times; the strictest one wins. - - alignas (TYPE) is equivalent to alignas (alignof (TYPE)). +/* We need to include the system's <stdalign.h> when it exists, because it might + define 'alignof' as a macro when it's not a keyword or compiler built-in. */ +#if @HAVE_STDALIGN_H@ +/* The include_next requires a split double-inclusion guard. */ +# @INCLUDE_NEXT@ @NEXT_STDALIGN_H@ +#endif - */ +#ifndef _@GUARD_PREFIX@_STDALIGN_H +#define _@GUARD_PREFIX@_STDALIGN_H -#if !defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 -# if defined __cplusplus && (201103 <= __cplusplus || defined _MSC_VER) -# define _Alignas(a) alignas (a) -# elif (!defined __attribute__ \ - && ((defined __APPLE__ && defined __MACH__ \ - ? 4 < __GNUC__ + (1 <= __GNUC_MINOR__) \ - : __GNUC__ && !defined __ibmxl__) \ - || (4 <= __clang_major__) \ - || (__ia64 && (61200 <= __HP_cc || 61200 <= __HP_aCC)) \ - || __ICC || 0x590 <= __SUNPRO_C || 0x0600 <= __xlC__)) -# define _Alignas(a) __attribute__ ((__aligned__ (a))) -# elif 1300 <= _MSC_VER -# define _Alignas(a) __declspec (align (a)) -# endif -#endif -#if ((defined _Alignas \ - && !(defined __cplusplus && (201103 <= __cplusplus || defined _MSC_VER))) \ - || (defined __STDC_VERSION__ && 201112 <= __STDC_VERSION__)) -# define alignas _Alignas -#endif #if (defined alignas \ + || (defined __STDC_VERSION__ && 202311 <= __STDC_VERSION__) \ || (defined __cplusplus && (201103 <= __cplusplus || defined _MSC_VER))) # define __alignas_is_defined 1 #endif -/* Include <stddef.h> if needed for offsetof. */ -#if _GL_STDALIGN_NEEDS_STDDEF -# include <stddef.h> -#endif +#define __alignof_is_defined 1 -#endif /* _GL_STDALIGN_H */ +#endif /* _@GUARD_PREFIX@_STDALIGN_H */ +#endif /* _@GUARD_PREFIX@_STDALIGN_H */ |