Make choices of atomic implementation based on highest stability

include/atomic/nolock.h

@@ -25,17 +25,29 @@
 #  else
 #    define LOCK_prefix "lock"
 #  endif
-
-#  ifdef HAVE_GCC_ATOMIC_BUILTINS
-#    include "gcc_builtins.h"
-#  elif __GNUC__
-#    include "x86-gcc.h"
-#  elif defined(_MSC_VER)
+/*
+  We choose implementation as follows:
+  ------------------------------------
+  On Windows using Visual C++ the native implementation should be
+  preferrable. When using gcc we prefer the native x86 implementation,
+  we prefer the Solaris implementation before the gcc because of
+  stability preference, we choose gcc implementation if nothing else
+  works on gcc. If neither Visual C++ or gcc we still choose the
+  Solaris implementation on Solaris (mainly for SunStudio compiles.
+*/
+#  if defined(_MSV_VER)
 #    include "generic-msvc.h"
+#  elif __GNUC__
+#    if defined(__i386__) || defined(__x86_64__)
+#      include "x86-gcc.h"
+#    elif defined(HAVE_SOLARIS_ATOMIC)
+#      include "solaris.h"
+#    elif defined(HAVE_GCC_ATOMIC_BUILTINS)
+#      include "gcc_builtins.h"
+#    endif
+#  elif defined(HAVE_SOLARIS_ATOMIC)
+#    include "solaris.h"
 #  endif
-#elif defined(HAVE_SOLARIS_ATOMIC)
-#include "solaris.h"
-#endif
 
 #if defined(make_atomic_cas_body) || defined(MY_ATOMICS_MADE)
 /*