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Diffstat (limited to 'lib/stdalign.in.h')
| -rw-r--r-- | lib/stdalign.in.h | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/lib/stdalign.in.h b/lib/stdalign.in.h new file mode 100644 index 0000000..3b117df --- /dev/null +++ b/lib/stdalign.in.h @@ -0,0 +1,127 @@ +/* A substitute for ISO C11 <stdalign.h>. + + Copyright 2011-2022 Free Software Foundation, Inc. + + This file is free software: you can redistribute it and/or modify + it under the terms of the GNU Lesser General Public License as + published by the Free Software Foundation; either version 2.1 of the + License, or (at your option) any later version. + + This file is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. */ + +/* Written by Paul Eggert and Bruno Haible. */ + +#ifndef _GL_STDALIGN_H +#define _GL_STDALIGN_H + +/* ISO C11 <stdalign.h> for platforms that lack it. + + 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. + + Include <stddef.h> for offsetof. */ +#include <stddef.h> + +/* 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 +# define _Alignof(type) alignof (type) +# else + template <class __t> struct __alignof_helper { char __a; __t __b; }; +# define _Alignof(type) offsetof (__alignof_helper<type>, __b) +# endif +# else +# define _Alignof(type) offsetof (struct { char __a; type __b; }, __b) +# endif +#endif +#if ! (defined __cplusplus && 201103 <= __cplusplus) +# 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; }; + + 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)). + + */ + +#if !defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 +# if defined __cplusplus && 201103 <= __cplusplus +# 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 __STDC_VERSION__ && 201112 <= __STDC_VERSION__)) +# define alignas _Alignas +#endif +#if defined alignas || (defined __cplusplus && 201103 <= __cplusplus) +# define __alignas_is_defined 1 +#endif + +#endif /* _GL_STDALIGN_H */ |