[TSan][Linux] Fix libdispatch interception macros compilation errors

[yln]

Summary

Most libdispatch functions come in two variants: callbacks can be
specified via blocks or function pointers. Some of our interceptors for
the block variant actually forward to the function variant. However, on
Linux, DECLARE_REAL(name) has to appear before REAL(name).

This patch reorders _f variant interceptors before _b variants
where possible and forward declares the _f variant in the remaining
cases (cyclic dependency between _f and _b interceptors).

Also rename macro to DISPATCH_INTERCEPT_ASYNC_F for better consistency.

compiler-rt/trunk/lib/tsan/rtl/tsan_libdispatch.cc

 }
 
 static void invoke_and_release_block(void *param) {
   dispatch_block_t block = (dispatch_block_t)param;
   block();
   Block_release(block);
 }
 
-#define DISPATCH_INTERCEPT_B(name, barrier)                                  \
+#define DISPATCH_INTERCEPT_ASYNC_B(name, barrier)                            \
   TSAN_INTERCEPTOR(void, name, dispatch_queue_t q, dispatch_block_t block) { \
     SCOPED_TSAN_INTERCEPTOR(name, q, block);                                 \
     SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();                           \
     dispatch_block_t heap_block = Block_copy(block);                         \
     SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();                             \
     block_context_t *new_context =                                           \
         AllocContext(thr, pc, q, heap_block, &invoke_and_release_block);     \
     new_context->is_barrier_block = barrier;                                 \
block_context_t new_context = {                                          \
         q, block, &invoke_block, false, true, barrier, 0};                   \
     Release(thr, pc, (uptr)&new_context);                                    \
     SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();                           \
     REAL(name##_f)(q, &new_context, dispatch_callback_wrap);                 \
     SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();                             \
     Acquire(thr, pc, (uptr)&new_context);                                    \
   }
 
-#define DISPATCH_INTERCEPT_F(name, barrier)                       \
+#define DISPATCH_INTERCEPT_ASYNC_F(name, barrier)                 \
   TSAN_INTERCEPTOR(void, name, dispatch_queue_t q, void *context, \
                    dispatch_function_t work) {                    \
     SCOPED_TSAN_INTERCEPTOR(name, q, context, work);              \
     block_context_t *new_context =                                \
         AllocContext(thr, pc, q, context, work);                  \
     new_context->is_barrier_block = barrier;                      \
     Release(thr, pc, (uptr)new_context);                          \
     SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();                \
block_context_t new_context = {                                           \
         q, context, work, false, true, barrier, 0};                           \
     Release(thr, pc, (uptr)&new_context);                                     \
     SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();                            \
     REAL(name)(q, &new_context, dispatch_callback_wrap);                      \
     SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();                              \
     Acquire(thr, pc, (uptr)&new_context);                                     \
   }
 
+#define DISPATCH_INTERCEPT(name, barrier)             \
+  DISPATCH_INTERCEPT_ASYNC_F(name##_async_f, barrier) \
+  DISPATCH_INTERCEPT_ASYNC_B(name##_async, barrier)   \
+  DISPATCH_INTERCEPT_SYNC_F(name##_sync_f, barrier)   \
+  DISPATCH_INTERCEPT_SYNC_B(name##_sync, barrier)
+
 // We wrap dispatch_async, dispatch_sync and friends where we allocate a new
 // context, which is used to synchronize (we release the context before
 // submitting, and the callback acquires it before executing the original
 // callback).
-DISPATCH_INTERCEPT_B(dispatch_async, false)
-DISPATCH_INTERCEPT_B(dispatch_barrier_async, true)
-DISPATCH_INTERCEPT_F(dispatch_async_f, false)
-DISPATCH_INTERCEPT_F(dispatch_barrier_async_f, true)
-DISPATCH_INTERCEPT_SYNC_B(dispatch_sync, false)
-DISPATCH_INTERCEPT_SYNC_B(dispatch_barrier_sync, true)
-DISPATCH_INTERCEPT_SYNC_F(dispatch_sync_f, false)
-DISPATCH_INTERCEPT_SYNC_F(dispatch_barrier_sync_f, true)
+DISPATCH_INTERCEPT(dispatch, false)
+DISPATCH_INTERCEPT(dispatch_barrier, true)
+
+DECLARE_REAL(void, dispatch_after_f, dispatch_time_t when,
+             dispatch_queue_t queue, void *context, dispatch_function_t work)
 
 TSAN_INTERCEPTOR(void, dispatch_after, dispatch_time_t when,
                  dispatch_queue_t queue, dispatch_block_t block) {
   SCOPED_TSAN_INTERCEPTOR(dispatch_after, when, queue, block);
   SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();
   dispatch_block_t heap_block = Block_copy(block);
   SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();
   block_context_t *new_context =
TSAN_INTERCEPTOR(void, dispatch_group_async_f, dispatch_group_t group,
   dispatch_group_enter(group);
   WRAP(dispatch_async)(queue, ^(void) {
     work(context);
     WRAP(dispatch_group_leave)(group);
     dispatch_release(group);
   });
 }
 
+DECLARE_REAL(void, dispatch_group_notify_f, dispatch_group_t group,
+             dispatch_queue_t q, void *context, dispatch_function_t work)
+
 TSAN_INTERCEPTOR(void, dispatch_group_notify, dispatch_group_t group,
                  dispatch_queue_t q, dispatch_block_t block) {
   SCOPED_TSAN_INTERCEPTOR(dispatch_group_notify, group, q, block);
 
   // To make sure the group is still available in the callback (otherwise
   // it can be already destroyed).  Will be released in the callback.
   dispatch_retain(group);