git.m6w6.name Git - m6w6/libmemcached/blob - CMake/CheckAtomics.cmake

   1 # sets HAVE_ATOMICS, checks for :
   2 # - C++11 std::atomic:  HAVE_CXX_STDATOMIC
   3 # - C11 stdatomic:      HAVE_C_STDATOMIC
   4 # - builtin __atomic:   HAVE_BUILTIN_ATOMIC
   5 # - builtin __sync:     HAVE_BUILTIN_SYNC
   6 # - atomic_add_nv:      HAVE_ATOMIC_ADD_NV
   7
   8 configure_define(HAVE_ATOMICS)
   9
  10 check_cxx_source("
  11         #include <atomic>
  12         int main() {
  13             std::atomic<int> i(0);
  14             return atomic_load(&i);
  15         }"
  16         HAVE_CXX_STDATOMIC)
  17
  18 check_c_source("
  19         #include <stdatomic.h>
  20         int main() {
  21             atomic_int i;
  22             atomic_init(&i, 0);
  23             return atomic_load(&i);
  24         }"
  25         HAVE_C_STDATOMIC)
  26
  27
  28 configure_define(HAVE_BUILTIN_ATOMIC)
  29 configure_define_literal(BUILTIN_ATOMIC_PREFIX)
  30 foreach(BUILTIN_ATOMIC_PREFIX IN ITEMS __c11 _ "")
  31     check_c_source("
  32             int main() {
  33                 long l = -1;
  34                 return ${BUILTIN_ATOMIC_PREFIX}_atomic_add_fetch(&l,1,__ATOMIC_RELAXED);
  35             }"
  36             HAVE_BUILTIN_ATOMIC${BUILTIN_ATOMIC_PREFIX})
  37     if (HAVE_BUILTIN_ATOMIC${BUILTIN_ATOMIC_PREFIX})
  38         set(HAVE_BUILTIN_ATOMIC 1)
  39         break()
  40     endif()
  41 endforeach()
  42
  43 check_c_source("
  44         int main() {
  45             long l = -1;
  46             return __sync_add_and_fetch(&l,1);
  47         }"
  48         HAVE_BUILTIN_SYNC)
  49
  50 check_c_source("
  51         #include <atomic.h>
  52         int main() {
  53             volatile uint_t i = 0;
  54             return atomic_add_int_nv(&i, 1) == 1 ? 0 : -1;
  55         }"
  56         HAVE_ATOMIC_ADD_NV)
  57
  58
  59 if (        (HAVE_CXX_STDATOMIC)
  60         OR  (HAVE_C_STDATOMIC)
  61         OR  (HAVE_BUILTIN_ATOMIC)
  62         OR  (HAVE_BUILTIN_SYNC)
  63         OR  (HAVE_ATOMIC_ADD_NV))
  64     set(HAVE_ATOMICS 1 CACHE INTERNAL "HAVE_ATOMICS")
  65 endif()