| # atomic builtins are required for threading support. | |
| INCLUDE(CheckCXXSourceCompiles) | |
| CHECK_CXX_SOURCE_COMPILES(" | |
| #ifdef _MSC_VER | |
| #include <windows.h> | |
| #endif | |
| int main() { | |
| #ifdef _MSC_VER | |
| volatile LONG val = 1; | |
| MemoryBarrier(); | |
| InterlockedCompareExchange(&val, 0, 1); | |
| InterlockedIncrement(&val); | |
| InterlockedDecrement(&val); | |
| #else | |
| volatile unsigned long val = 1; | |
| __sync_synchronize(); | |
| __sync_val_compare_and_swap(&val, 1, 0); | |
| __sync_add_and_fetch(&val, 1); | |
| __sync_sub_and_fetch(&val, 1); | |
| #endif | |
| return 0; | |
| } | |
| " LLVM_HAS_ATOMICS) | |
| if( NOT LLVM_HAS_ATOMICS ) | |
| message(STATUS "Warning: LLVM will be built thread-unsafe because atomic builtins are missing") | |
| endif() |