OpenSceneGraph/CMakeModules/CheckAtomicOps.cmake

# Check for availability of atomic operations 
# This module defines
# OPENTHREADS_HAVE_ATOMIC_OPS

OPTION(OPENTHREADS_ATOMIC_USE_MUTEX "Set to ON to force OpenThreads to use a mutex for Atmoic." OFF)

IF (OPENTHREADS_ATOMIC_USE_MUTEX)

    SET(_OPENTHREADS_ATOMIC_USE_GCC_BUILTINS 0)
    SET(_OPENTHREADS_ATOMIC_USE_MIPOSPRO_BUILTINS 0)
    SET(_OPENTHREADS_ATOMIC_USE_SUN 0)
    SET(_OPENTHREADS_ATOMIC_USE_WIN32_INTERLOCKED 0)
    SET(_OPENTHREADS_ATOMIC_USE_BSD_ATOMIC 0)

    SET(_OPENTHREADS_ATOMIC_USE_MUTEX 1)

ELSE()

    INCLUDE(CheckCXXSourceRuns)

    # Do step by step checking,
    CHECK_CXX_SOURCE_RUNS("
    #include <cstdlib>

    int main()
    {
       unsigned value = 0;
       void* ptr = &value;
       __sync_add_and_fetch(&value, 1);
       __sync_synchronize();
       __sync_sub_and_fetch(&value, 1);
       if (!__sync_bool_compare_and_swap(&value, 0, 1))
          return EXIT_FAILURE;

       if (!__sync_bool_compare_and_swap(&ptr, ptr, ptr))
          return EXIT_FAILURE;

       return EXIT_SUCCESS;
    }
    " _OPENTHREADS_ATOMIC_USE_GCC_BUILTINS)

    CHECK_CXX_SOURCE_RUNS("
    #include <stdlib.h>

    int main(int, const char**)
    {
       unsigned value = 0;
       void* ptr = &value;
       __add_and_fetch(&value, 1);
       __synchronize(value);
       __sub_and_fetch(&value, 1);
       if (!__compare_and_swap(&value, 0, 1))
          return EXIT_FAILURE;

       if (!__compare_and_swap((unsigned long*)&ptr, (unsigned long)ptr, (unsigned long)ptr))
          return EXIT_FAILURE;

       return EXIT_SUCCESS;
    }
    " _OPENTHREADS_ATOMIC_USE_MIPOSPRO_BUILTINS)

    CHECK_CXX_SOURCE_RUNS("
    #include <atomic.h>
    #include <cstdlib>

    int main(int, const char**)
    {
       uint_t value = 0;
       void* ptr = &value;
       atomic_inc_uint_nv(&value);
       membar_consumer();
       atomic_dec_uint_nv(&value);
       if (0 != atomic_cas_uint(&value, 0, 1))
          return EXIT_FAILURE;

       if (ptr != atomic_cas_ptr(&ptr, ptr, ptr))
          return EXIT_FAILURE;

       return EXIT_SUCCESS;
    }
    " _OPENTHREADS_ATOMIC_USE_SUN)

    CHECK_CXX_SOURCE_RUNS("
    #include <windows.h>
    #include <intrin.h>
    #include <cstdlib>

    #pragma intrinsic(_InterlockedAnd)
    #pragma intrinsic(_InterlockedOr)
    #pragma intrinsic(_InterlockedXor)

    int main(int, const char**)
    {
       volatile long value = 0;
       long data = 0;
       long* volatile ptr = &data;

       InterlockedIncrement(&value);
       MemoryBarrier();
       InterlockedDecrement(&value);

       if (0 != InterlockedCompareExchange(&value, 1, 0))
          return EXIT_FAILURE;

       if (ptr != InterlockedCompareExchangePointer((PVOID volatile*)&ptr, (PVOID)ptr, (PVOID)ptr))
          return EXIT_FAILURE;

       return EXIT_SUCCESS;
    }
    " _OPENTHREADS_ATOMIC_USE_WIN32_INTERLOCKED)

    CHECK_CXX_SOURCE_RUNS("
    #include <libkern/OSAtomic.h>

    int main()
    {
      volatile int32_t value = 0;
      long data = 0;
      long * volatile ptr = &data;

      OSAtomicIncrement32(&value);
      OSMemoryBarrier();
      OSAtomicDecrement32(&value);
      OSAtomicCompareAndSwapInt(value, 1, &value);
      OSAtomicCompareAndSwapPtr(ptr, ptr, (void * volatile *)&ptr);
    }
    " _OPENTHREADS_ATOMIC_USE_BSD_ATOMIC)

    IF(NOT _OPENTHREADS_ATOMIC_USE_GCC_BUILTINS AND
       NOT _OPENTHREADS_ATOMIC_USE_MIPOSPRO_BUILTINS AND
       NOT _OPENTHREADS_ATOMIC_USE_SUN AND
       NOT _OPENTHREADS_ATOMIC_USE_WIN32_INTERLOCKED AND
       NOT _OPENTHREADS_ATOMIC_USE_BSD_ATOMIC)
               SET(_OPENTHREADS_ATOMIC_USE_MUTEX 1)
    ENDIF()

ENDIF()