3 # Define HAVE_C___ATOMIC if __atomic works.
4 AN_IDENTIFIER([__atomic], [AC_C___ATOMIC])
5 AC_DEFUN([AC_C___ATOMIC],
6 [AC_CACHE_CHECK([for __atomic], ac_cv_c___atomic,
10 main (int argc, char **argv)
12 volatile unsigned long ul1 = 1, ul2 = 0, ul3 = 2;
13 __atomic_compare_exchange(&ul1, &ul2, &ul3, 1, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
14 __atomic_fetch_add(&ul1, 1, __ATOMIC_SEQ_CST);
15 __atomic_fetch_sub(&ul3, 1, __ATOMIC_SEQ_CST);
16 volatile unsigned long long ull1 = 1, ull2 = 0, ull3 = 2;
17 __atomic_compare_exchange(&ull1, &ull2, &ull3, 1, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
18 __atomic_fetch_add(&ull1, 1, __ATOMIC_SEQ_CST);
19 __atomic_fetch_sub(&ull3, 1, __ATOMIC_SEQ_CST);
23 [ac_cv_c___atomic=yes],
24 [ac_cv_c___atomic=no])])
25 if test $ac_cv_c___atomic = yes; then
26 AC_DEFINE([HAVE_C___ATOMIC], 1,
27 [Define to 1 if __atomic operations work.])