cmake/modules/CheckAtomic.cmake

   1 # atomic builtins are required for threading support.
   2
   3 INCLUDE(CheckCXXSourceCompiles)
   4
   5 #ifdef _MSC_VER
   6 #include <windows.h>
   7 #endif
   8
   9 CHECK_CXX_SOURCE_COMPILES("
  10 int main() {
  11 #ifdef _MSC_VER
  12         volatile LONG val = 1;
  13         MemoryBarrier();
  14         InterlockedCompareExchange(&val, 0, 1);
  15         InterlockedIncrement(&val);
  16         InterlockedDecrement(&val);
  17 #else
  18         volatile unsigned long val = 1;
  19         __sync_synchronize();
  20         __sync_val_compare_and_swap(&val, 1, 0);
  21         __sync_add_and_fetch(&val, 1);
  22         __sync_sub_and_fetch(&val, 1);
  23 #endif
  24         return 0;
  25       }
  26 " LLVM_MULTITHREADED)
  27
  28 if( NOT LLVM_MULTITHREADED )
  29   message(STATUS "Warning: LLVM will be built thread-unsafe because atomic builtins are missing")
  30 endif()