1# =========================================================================== 2# https://www.gnu.org/software/autoconf-archive/ax_gcc_func_attribute.html 3# =========================================================================== 4# 5# SYNOPSIS 6# 7# AX_GCC_FUNC_ATTRIBUTE(ATTRIBUTE) 8# 9# DESCRIPTION 10# 11# This macro checks if the compiler supports one of GCC's function 12# attributes; many other compilers also provide function attributes with 13# the same syntax. Compiler warnings are used to detect supported 14# attributes as unsupported ones are ignored by default so quieting 15# warnings when using this macro will yield false positives. 16# 17# The ATTRIBUTE parameter holds the name of the attribute to be checked. 18# 19# If ATTRIBUTE is supported define HAVE_FUNC_ATTRIBUTE_<ATTRIBUTE>. 20# 21# The macro caches its result in the ax_cv_have_func_attribute_<attribute> 22# variable. 23# 24# The macro currently supports the following function attributes: 25# 26# alias 27# aligned 28# alloc_size 29# always_inline 30# artificial 31# cold 32# const 33# constructor 34# constructor_priority for constructor attribute with priority 35# deprecated 36# destructor 37# dllexport 38# dllimport 39# error 40# externally_visible 41# fallthrough 42# flatten 43# format 44# format_arg 45# gnu_inline 46# hot 47# ifunc 48# leaf 49# malloc 50# noclone 51# noinline 52# nonnull 53# noreturn 54# nothrow 55# optimize 56# pure 57# sentinel 58# sentinel_position 59# unused 60# used 61# visibility 62# warning 63# warn_unused_result 64# weak 65# weakref 66# 67# Unsupported function attributes will be tested with a prototype 68# returning an int and not accepting any arguments and the result of the 69# check might be wrong or meaningless so use with care. 70# 71# LICENSE 72# 73# Copyright (c) 2013 Gabriele Svelto <gabriele.svelto@gmail.com> 74# 75# Copying and distribution of this file, with or without modification, are 76# permitted in any medium without royalty provided the copyright notice 77# and this notice are preserved. This file is offered as-is, without any 78# warranty. 79 80#serial 9 81 82AC_DEFUN([AX_GCC_FUNC_ATTRIBUTE], [ 83 AS_VAR_PUSHDEF([ac_var], [ax_cv_have_func_attribute_$1]) 84 85 AC_CACHE_CHECK([for __attribute__(($1))], [ac_var], [ 86 AC_LINK_IFELSE([AC_LANG_PROGRAM([ 87 m4_case([$1], 88 [alias], [ 89 int foo( void ) { return 0; } 90 int bar( void ) __attribute__(($1("foo"))); 91 ], 92 [aligned], [ 93 int foo( void ) __attribute__(($1(32))); 94 ], 95 [alloc_size], [ 96 void *foo(int a) __attribute__(($1(1))); 97 ], 98 [always_inline], [ 99 inline __attribute__(($1)) int foo( void ) { return 0; } 100 ], 101 [artificial], [ 102 inline __attribute__(($1)) int foo( void ) { return 0; } 103 ], 104 [cold], [ 105 int foo( void ) __attribute__(($1)); 106 ], 107 [const], [ 108 int foo( void ) __attribute__(($1)); 109 ], 110 [constructor_priority], [ 111 int foo( void ) __attribute__((__constructor__(65535/2))); 112 ], 113 [constructor], [ 114 int foo( void ) __attribute__(($1)); 115 ], 116 [deprecated], [ 117 int foo( void ) __attribute__(($1(""))); 118 ], 119 [destructor], [ 120 int foo( void ) __attribute__(($1)); 121 ], 122 [dllexport], [ 123 __attribute__(($1)) int foo( void ) { return 0; } 124 ], 125 [dllimport], [ 126 int foo( void ) __attribute__(($1)); 127 ], 128 [error], [ 129 int foo( void ) __attribute__(($1(""))); 130 ], 131 [externally_visible], [ 132 int foo( void ) __attribute__(($1)); 133 ], 134 [fallthrough], [ 135 int foo( void ) {switch (0) { case 1: __attribute__(($1)); case 2: break ; }}; 136 ], 137 [flatten], [ 138 int foo( void ) __attribute__(($1)); 139 ], 140 [format], [ 141 int foo(const char *p, ...) __attribute__(($1(printf, 1, 2))); 142 ], 143 [format_arg], [ 144 char *foo(const char *p) __attribute__(($1(1))); 145 ], 146 [gnu_inline], [ 147 inline __attribute__(($1)) int foo( void ) { return 0; } 148 ], 149 [hot], [ 150 int foo( void ) __attribute__(($1)); 151 ], 152 [ifunc], [ 153 int my_foo( void ) { return 0; } 154 static int (*resolve_foo(void))(void) { return my_foo; } 155 int foo( void ) __attribute__(($1("resolve_foo"))); 156 ], 157 [leaf], [ 158 __attribute__(($1)) int foo( void ) { return 0; } 159 ], 160 [malloc], [ 161 void *foo( void ) __attribute__(($1)); 162 ], 163 [noclone], [ 164 int foo( void ) __attribute__(($1)); 165 ], 166 [noinline], [ 167 __attribute__(($1)) int foo( void ) { return 0; } 168 ], 169 [nonnull], [ 170 int foo(char *p) __attribute__(($1(1))); 171 ], 172 [noreturn], [ 173 void foo( void ) __attribute__(($1)); 174 ], 175 [nothrow], [ 176 int foo( void ) __attribute__(($1)); 177 ], 178 [optimize], [ 179 __attribute__(($1(3))) int foo( void ) { return 0; } 180 ], 181 [pure], [ 182 int foo( void ) __attribute__(($1)); 183 ], 184 [sentinel], [ 185 int foo(void *p, ...) __attribute__(($1)); 186 ], 187 [sentinel_position], [ 188 int foo(void *p, ...) __attribute__(($1(1))); 189 ], 190 [returns_nonnull], [ 191 void *foo( void ) __attribute__(($1)); 192 ], 193 [unused], [ 194 int foo( void ) __attribute__(($1)); 195 ], 196 [used], [ 197 int foo( void ) __attribute__(($1)); 198 ], 199 [visibility], [ 200 int foo_def( void ) __attribute__(($1("default"))); 201 int foo_hid( void ) __attribute__(($1("hidden"))); 202 int foo_int( void ) __attribute__(($1("internal"))); 203 int foo_pro( void ) __attribute__(($1("protected"))); 204 ], 205 [warning], [ 206 int foo( void ) __attribute__(($1(""))); 207 ], 208 [warn_unused_result], [ 209 int foo( void ) __attribute__(($1)); 210 ], 211 [weak], [ 212 int foo( void ) __attribute__(($1)); 213 ], 214 [weakref], [ 215 static int foo( void ) { return 0; } 216 static int bar( void ) __attribute__(($1("foo"))); 217 ], 218 [target], [ 219 static int bar( void ) __attribute__(($1("sse2"))); 220 ], 221 [ 222 m4_warn([syntax], [Unsupported attribute $1, the test may fail]) 223 int foo( void ) __attribute__(($1)); 224 ] 225 )], []) 226 ], 227 dnl GCC doesn't exit with an error if an unknown attribute is 228 dnl provided but only outputs a warning, so accept the attribute 229 dnl only if no warning were issued. 230 [AS_IF([test -s conftest.err], 231 [AS_VAR_SET([ac_var], [no])], 232 [AS_VAR_SET([ac_var], [yes])])], 233 [AS_VAR_SET([ac_var], [no])]) 234 ]) 235 236 AS_IF([test yes = AS_VAR_GET([ac_var])], 237 [AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_FUNC_ATTRIBUTE_$1), 1, 238 [Define to 1 if the system has the `$1' function attribute])], []) 239 240 AS_VAR_POPDEF([ac_var]) 241]) 242
