libplatform-254.40.4.tar.gz

[apple/libplatform.git] / src / os / atomic.c

diff --git a/src/os/atomic.c b/src/os/atomic.c
index 778611af7de2413c03f305dd64a462b1b7bdb24b..a64f7cad7e82957dd8b85d45bb44ece31d066e1c 100644 (file)
--- a/src/os/atomic.c
+++ b/src/os/atomic.c
@@ -22,7 +22,7 @@
 #include "resolver.h"
 #include "libkern/OSAtomic.h"
 
-#if TARGET_OS_IPHONE && !TARGET_OS_SIMULATOR
+#if defined(__arm__) || defined(__arm64__)
 
 OS_ATOMIC_EXPORT
 int32_t OSAtomicAdd32(int32_t v, volatile int32_t *p);
@@ -389,43 +389,63 @@ typedef struct {
        long gencount;
 } _OSQueueHead;
 
-
-void
-OSAtomicEnqueue(OSQueueHead *list, void *new, size_t offset)
+OS_ALWAYS_INLINE
+static inline void
+_OSAtomicEnqueue_llsc(OSQueueHead *list, void *new, size_t offset)
 {
        void * volatile *headptr = &(((_OSQueueHead*)list)->item);
        void * volatile *nextptr = (void*)((char*)new + offset);
-       void *head, *next;
+       void *head, *tmp, *next;
 
        head = os_atomic_load(headptr, relaxed);
        next = new;
        do {
-               *nextptr = head;
-       } while (!os_atomic_cmpxchgvw(headptr, head, next, &head, release));
+               *nextptr = tmp = head;
+               head = os_atomic_load_exclusive(headptr, relaxed);
+       } while (tmp != head || !os_atomic_store_exclusive(headptr, next, release));
 }
 
-void*
-OSAtomicDequeue(OSQueueHead *list, size_t offset)
+OS_ALWAYS_INLINE
+static inline void *
+_OSAtomicDequeue_llsc(OSQueueHead *list, size_t offset)
 {
        void * volatile *headptr = &(((_OSQueueHead*)list)->item);
        void * volatile *nextptr;
        void *head, *next;
 
-       os_atomic_rmw_loop(headptr, head, next, acquire, {
-               if (!head) os_atomic_rmw_loop_give_up(break);
+       do {
+               head = os_atomic_load_exclusive(headptr, acquire);
+               if (!head) {
+                       os_atomic_clear_exclusive();
+                       break;
+               }
                nextptr = (void*)((char*)head + offset);
                next = *nextptr;
-       });
+       } while (unlikely(!os_atomic_store_exclusive(headptr, next, relaxed)));
+
        return head;
 }
 
 
+void
+OSAtomicEnqueue(OSQueueHead *list, void *new, size_t offset)
+{
+       return _OSAtomicEnqueue_llsc(list, new, offset);
+}
+
+void*
+OSAtomicDequeue(OSQueueHead *list, size_t offset)
+{
+       return _OSAtomicDequeue_llsc(list, offset);
+}
+
+
 void
 OSMemoryBarrier(void)
 {
        os_atomic_thread_fence(seq_cst);
 }
 
-#endif // TARGET_OS_IPHONE && !TARGET_OS_SIMULATOR
+#endif // defined(__arm__) || defined(__arm64__)
 
 struct _os_empty_files_are_not_c_files;