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-rw-r--r--gnulib-m4/stdalign.m4190
1 files changed, 131 insertions, 59 deletions
diff --git a/gnulib-m4/stdalign.m4 b/gnulib-m4/stdalign.m4
index 324e91da..e3c1e609 100644
--- a/gnulib-m4/stdalign.m4
+++ b/gnulib-m4/stdalign.m4
@@ -1,20 +1,22 @@
# Check for alignas and alignof that conform to C23.
-dnl Copyright 2011-2022 Free Software Foundation, Inc.
+dnl Copyright 2011-2024 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
+dnl Written by Paul Eggert and Bruno Haible.
+
# Prepare for substituting <stdalign.h> if it is not supported.
-AC_DEFUN([gl_STDALIGN_H],
+AC_DEFUN([gl_ALIGNASOF],
[
AC_CACHE_CHECK([for alignas and alignof],
[gl_cv_header_working_stdalign_h],
- [gl_save_CFLAGS=$CFLAGS
+ [gl_saved_CFLAGS=$CFLAGS
for gl_working in "yes, keywords" "yes, <stdalign.h> macros"; do
AS_CASE([$gl_working],
- [*stdalign.h*], [CFLAGS="$gl_save_CFLAGS -DINCLUDE_STDALIGN_H"])
+ [*stdalign.h*], [CFLAGS="$gl_saved_CFLAGS -DINCLUDE_STDALIGN_H"])
AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM(
[[#include <stdint.h>
@@ -54,81 +56,151 @@ AC_DEFUN([gl_STDALIGN_H],
[gl_cv_header_working_stdalign_h=$gl_working],
[gl_cv_header_working_stdalign_h=no])
- CFLAGS=$gl_save_CFLAGS
+ CFLAGS=$gl_saved_CFLAGS
test "$gl_cv_header_working_stdalign_h" != no && break
done])
- GL_GENERATE_STDALIGN_H=false
AS_CASE([$gl_cv_header_working_stdalign_h],
- [no],
- [GL_GENERATE_STDALIGN_H=true],
[yes*keyword*],
[AC_DEFINE([HAVE_C_ALIGNASOF], [1],
[Define to 1 if the alignas and alignof keywords work.])])
- AC_CHECK_HEADERS_ONCE([stdalign.h])
-
dnl The "zz" puts this toward config.h's end, to avoid potential
dnl collisions with other definitions.
AH_VERBATIM([zzalignas],
-[#if !defined HAVE_C_ALIGNASOF && __cplusplus < 201103 && !defined alignof
-# if HAVE_STDALIGN_H
+[#if !defined HAVE_C_ALIGNASOF \
+ && !(defined __cplusplus && 201103 <= __cplusplus) \
+ && !defined alignof
+# if defined HAVE_STDALIGN_H
# include <stdalign.h>
-# else
- /* Substitute. Keep consistent with gnulib/lib/stdalign.in.h. */
-# ifndef _GL_STDALIGN_H
-# define _GL_STDALIGN_H
-# undef _Alignas
-# undef _Alignof
-# 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)
+# endif
+
+/* ISO C23 alignas and alignof for platforms that lack it.
+
+ References:
+ ISO C23 (latest free draft
+ <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n3047.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. */
+
+/* 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))
+# undef/**/_Alignof
+# ifdef __cplusplus
+# if (201103 <= __cplusplus || defined _MSC_VER)
+# define _Alignof(type) alignof (type)
+# else
+ template <class __t> struct __alignof_helper { char __a; __t __b; };
+# if (defined __GNUC__ && 4 <= __GNUC__) || defined __clang__
+# define _Alignof(type) __builtin_offsetof (__alignof_helper<type>, __b)
# 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
+# define _GL_STDALIGN_NEEDS_STDDEF 1
+# endif
+# else
+# if (defined __GNUC__ && 4 <= __GNUC__) || defined __clang__
+# define _Alignof(type) __builtin_offsetof (struct { char __a; type __b; }, __b)
# else
# define _Alignof(type) offsetof (struct { char __a; type __b; }, __b)
# define _GL_STDALIGN_NEEDS_STDDEF 1
# endif
# endif
-# if ! (defined __cplusplus && (201103 <= __cplusplus || defined _MSC_VER))
-# define alignof _Alignof
-# endif
-# define __alignof_is_defined 1
-# 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 __cplusplus && (201103 <= __cplusplus || defined _MSC_VER)))
-# define __alignas_is_defined 1
-# endif
-# if _GL_STDALIGN_NEEDS_STDDEF
-# include <stddef.h>
-# endif
-# endif /* _GL_STDALIGN_H */
+# endif
+# if ! (defined __cplusplus && (201103 <= __cplusplus || defined _MSC_VER))
+# undef/**/alignof
+# define alignof _Alignof
+# endif
+
+/* 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 C23 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 || 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 HAVE_STDALIGN_H
+# if ((defined _Alignas \
+ && !(defined __cplusplus \
+ && (201103 <= __cplusplus || defined _MSC_VER))) \
+ || (defined __STDC_VERSION__ && 201112 <= __STDC_VERSION__))
+# define alignas _Alignas
+# endif
+# endif
+
+# if defined _GL_STDALIGN_NEEDS_STDDEF
+# include <stddef.h>
# endif
#endif])
])
+
+AC_DEFUN([gl_STDALIGN_H],
+[
+ AC_REQUIRE([gl_ALIGNASOF])
+ if test "$gl_cv_header_working_stdalign_h" = no; then
+ GL_GENERATE_STDALIGN_H=true
+ else
+ GL_GENERATE_STDALIGN_H=false
+ fi
+
+ gl_CHECK_NEXT_HEADERS([stdalign.h])
+ if test $ac_cv_header_stdalign_h = yes; then
+ HAVE_STDALIGN_H=1
+ else
+ HAVE_STDALIGN_H=0
+ fi
+ AC_SUBST([HAVE_STDALIGN_H])
+])