From Mathias Froehlich, OpenThreads::Atomic support

CMakeModules/CheckAtomicOps.cmake

@@ -0,0 +1,102 @@
+# Check for availability of atomic operations 
+# This module defines
+# OPENTHREADS_HAVE_ATOMIC_OPS
+
+INCLUDE(CheckCXXSourceRuns)
+
+# Do step by step checking, 
+CHECK_CXX_SOURCE_RUNS("
+#include <cstdlib>
+
+int main()
+{
+#ifdef __i386__
+   // Bad, gcc behaves dependent on the compilers -march=... flags.
+   // Since the osg::Referenced stuff is code distributed in headers, it is
+   // unclear if we will have this feature available at compile time of the
+   // headers. So just do not use this feature for 32 bit code.
+   // May be we can implement around that limitation at some time..
+   return EXIT_FAILURE;
+#else
+   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;
+#endif
+}
+" _OPENTHREADS_ATOMIC_USE_GCC_BUILTINS)
+
+CHECK_CXX_SOURCE_RUNS("
+#include <cstdlib>
+
+int main(int, const char**)
+{
+   unsigned value = 0;
+   void* ptr = &value;
+   __add_and_fetch(&value, 1);
+   __synchronize(value);
+   __sub_and_fetch(&value, 1);
+   if (!__sync_compare_and_swap(&value, 0, 1))
+      return EXIT_FAILURE;
+   
+   if (!__sync_compare_and_swap(&ptr, ptr, 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 <cstdlib>
+
+int main(int, const char**)
+{
+   __declspec(align(32)) volatile long value = 0;
+   __declspec(align(32)) volatile void* ptr = &value;
+
+   InterlockedIncrement(&value);
+   InterlockedDecrement(&value);
+
+   if (0 != InterlockedCompareExchange(&value, 1, 0))
+      return EXIT_FAILURE;
+
+   if (ptr != InterlockedCompareExchangePointer(&ptr, ptr, ptr))
+      return EXIT_FAILURE;
+
+   return EXIT_SUCCESS;
+}
+" _OPENTHREADS_ATOMIC_USE_WIN32_INTERLOCKED)
+
+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)
+  SET(_OPENTHREADS_ATOMIC_USE_MUTEX)
+ENDIF(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)