#endif
#ifndef atomic_xchg
-#ifdef __ATOMIC_SEQ_CST
+#if defined(__clang__)
+#define atomic_xchg(ptr, i) __sync_swap(ptr, i)
+#elif defined(__ATOMIC_SEQ_CST)
#define atomic_xchg(ptr, i) ({ \
typeof(*ptr) _new = (i), _old; \
__atomic_exchange(ptr, &_new, &_old, __ATOMIC_SEQ_CST); \
_old; \
})
-#elif defined __clang__
-#define atomic_xchg(ptr, i) __sync_exchange(ptr, i)
#else
/* __sync_lock_test_and_set() is documented to be an acquire barrier only. */
#define atomic_xchg(ptr, i) (smp_mb(), __sync_lock_test_and_set(ptr, i))