cmake/modules/CheckAtomic.cmake

   1 # atomic builtins are required for threading support.
   2
   3 INCLUDE(CheckCXXSourceCompiles)
   4
   5 CHECK_CXX_SOURCE_COMPILES("
   6 int main() {
   7         volatile unsigned long val = 1;
   8         __sync_synchronize();
   9         __sync_val_compare_and_swap(&val, 1, 0);
  10         __sync_add_and_fetch(&val, 1);
  11         __sync_sub_and_fetch(&val, 1);
  12         return 0;
  13       }
  14 " LLVM_MULTITHREADED)
  15
  16 if( NOT LLVM_MULTITHREADED )
  17   message(STATUS "Warning: LLVM will be built thread-unsafe because atomic builtins are missing")
  18 endif()