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