From: Peter Maydell <peter.mayd...@linaro.org>
clang defines __ATOMIC_SEQ_CST but its implementation of the
__atomic_exchange() builtin differs from that of gcc. Move the
__clang__ branch of the ifdef ladder to the top and fix its
implementation (there is no such builtin as __sync_exchange),
so we can compile with clang again.
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
include/qemu/atomic.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h
index 0aa8913..492bce1 100644
--- a/include/qemu/atomic.h
+++ b/include/qemu/atomic.h
@@ -168,14 +168,14 @@
#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))
--
1.8.3.1
