Cleanup atomic ops on OS X
diff --git a/src/hb-atomic-private.hh b/src/hb-atomic-private.hh
index ba52773..458c984 100644
--- a/src/hb-atomic-private.hh
+++ b/src/hb-atomic-private.hh
@@ -55,10 +55,9 @@
#include <libkern/OSAtomic.h>
typedef int32_t hb_atomic_int_t;
-#define hb_atomic_int_add(AI, V) (OSAtomicAdd32Barrier((V), &(AI)), (AI) - (V))
-#define hb_atomic_int_set(AI, V) \
- do {} while (!OSAtomicCompareAndSwap32 (hb_atomic_int_get (AI), (V), (&(AI))))
-#define hb_atomic_int_get(AI) OSAtomicAdd32Barrier(0, &(AI))
+#define hb_atomic_int_add(AI, V) (OSAtomicAdd32Barrier ((V), &(AI)) - (V))
+#define hb_atomic_int_set(AI, V) ((AI) = (V), OSMemoryBarrier ())
+#define hb_atomic_int_get(AI) (OSMemoryBarrier (), (AI))
#elif !defined(HB_NO_MT) && defined(HAVE_GLIB)
