Libsanitizer: merge from trunk with merge.sh.

2019-11-05  Martin Liska  <mliska@suse.cz>

	* all source files: Merge from upstream r375507.

From-SVN: r277834

1 files changed, 782 insertions, 0 deletions

diff --git a/libsanitizer/tsan/tsan_interceptors_libdispatch.cpp b/libsanitizer/tsan/tsan_interceptors_libdispatch.cpp
new file mode 100644
index 00000000000..5dacd3256ab
--- /dev/null
+++ b/libsanitizer/tsan/tsan_interceptors_libdispatch.cpp
@@ -0,0 +1,782 @@
+//===-- tsan_interceptors_libdispatch.cpp ---------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of ThreadSanitizer (TSan), a race detector.
+//
+// Support for intercepting libdispatch (GCD).
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_common/sanitizer_common.h"
+#include "interception/interception.h"
+#include "tsan_interceptors.h"
+#include "tsan_rtl.h"
+
+#include "BlocksRuntime/Block.h"
+#include "tsan_dispatch_defs.h"
+
+namespace __tsan {
+  typedef u16 uint16_t;
+
+typedef struct {
+  dispatch_queue_t queue;
+  void *orig_context;
+  dispatch_function_t orig_work;
+  bool free_context_in_callback;
+  bool submitted_synchronously;
+  bool is_barrier_block;
+  uptr non_queue_sync_object;
+} block_context_t;
+
+// The offsets of different fields of the dispatch_queue_t structure, exported
+// by libdispatch.dylib.
+extern "C" struct dispatch_queue_offsets_s {
+  const uint16_t dqo_version;
+  const uint16_t dqo_label;
+  const uint16_t dqo_label_size;
+  const uint16_t dqo_flags;
+  const uint16_t dqo_flags_size;
+  const uint16_t dqo_serialnum;
+  const uint16_t dqo_serialnum_size;
+  const uint16_t dqo_width;
+  const uint16_t dqo_width_size;
+  const uint16_t dqo_running;
+  const uint16_t dqo_running_size;
+  const uint16_t dqo_suspend_cnt;
+  const uint16_t dqo_suspend_cnt_size;
+  const uint16_t dqo_target_queue;
+  const uint16_t dqo_target_queue_size;
+  const uint16_t dqo_priority;
+  const uint16_t dqo_priority_size;
+} dispatch_queue_offsets;
+
+static bool IsQueueSerial(dispatch_queue_t q) {
+  CHECK_EQ(dispatch_queue_offsets.dqo_width_size, 2);
+  uptr width = *(uint16_t *)(((uptr)q) + dispatch_queue_offsets.dqo_width);
+  CHECK_NE(width, 0);
+  return width == 1;
+}
+
+static dispatch_queue_t GetTargetQueueFromQueue(dispatch_queue_t q) {
+  CHECK_EQ(dispatch_queue_offsets.dqo_target_queue_size, 8);
+  dispatch_queue_t tq = *(
+      dispatch_queue_t *)(((uptr)q) + dispatch_queue_offsets.dqo_target_queue);
+  return tq;
+}
+
+static dispatch_queue_t GetTargetQueueFromSource(dispatch_source_t source) {
+  dispatch_queue_t tq = GetTargetQueueFromQueue((dispatch_queue_t)source);
+  CHECK_NE(tq, 0);
+  return tq;
+}
+
+static block_context_t *AllocContext(ThreadState *thr, uptr pc,
+                                     dispatch_queue_t queue, void *orig_context,
+                                     dispatch_function_t orig_work) {
+  block_context_t *new_context =
+      (block_context_t *)user_alloc_internal(thr, pc, sizeof(block_context_t));
+  new_context->queue = queue;
+  new_context->orig_context = orig_context;
+  new_context->orig_work = orig_work;
+  new_context->free_context_in_callback = true;
+  new_context->submitted_synchronously = false;
+  new_context->is_barrier_block = false;
+  new_context->non_queue_sync_object = 0;
+  return new_context;
+}
+
+#define GET_QUEUE_SYNC_VARS(context, q)                                  \
+  bool is_queue_serial = q && IsQueueSerial(q);                          \
+  uptr sync_ptr = (uptr)q ?: context->non_queue_sync_object;             \
+  uptr serial_sync = (uptr)sync_ptr;                                     \
+  uptr concurrent_sync = sync_ptr ? ((uptr)sync_ptr) + sizeof(uptr) : 0; \
+  bool serial_task = context->is_barrier_block || is_queue_serial
+
+static void dispatch_sync_pre_execute(ThreadState *thr, uptr pc,
+                                      block_context_t *context) {
+  uptr submit_sync = (uptr)context;
+  Acquire(thr, pc, submit_sync);
+
+  dispatch_queue_t q = context->queue;
+  do {
+    GET_QUEUE_SYNC_VARS(context, q);
+    if (serial_sync) Acquire(thr, pc, serial_sync);
+    if (serial_task && concurrent_sync) Acquire(thr, pc, concurrent_sync);
+
+    if (q) q = GetTargetQueueFromQueue(q);
+  } while (q);
+}
+
+static void dispatch_sync_post_execute(ThreadState *thr, uptr pc,
+                                       block_context_t *context) {
+  uptr submit_sync = (uptr)context;
+  if (context->submitted_synchronously) Release(thr, pc, submit_sync);
+
+  dispatch_queue_t q = context->queue;
+  do {
+    GET_QUEUE_SYNC_VARS(context, q);
+    if (serial_task && serial_sync) Release(thr, pc, serial_sync);
+    if (!serial_task && concurrent_sync) Release(thr, pc, concurrent_sync);
+
+    if (q) q = GetTargetQueueFromQueue(q);
+  } while (q);
+}
+
+static void dispatch_callback_wrap(void *param) {
+  SCOPED_INTERCEPTOR_RAW(dispatch_callback_wrap);
+  block_context_t *context = (block_context_t *)param;
+
+  dispatch_sync_pre_execute(thr, pc, context);
+
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();
+  context->orig_work(context->orig_context);
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();
+
+  dispatch_sync_post_execute(thr, pc, context);
+
+  if (context->free_context_in_callback) user_free(thr, pc, context);
+}
+
+static void invoke_block(void *param) {
+  dispatch_block_t block = (dispatch_block_t)param;
+  block();
+}
+
+static void invoke_and_release_block(void *param) {
+  dispatch_block_t block = (dispatch_block_t)param;
+  block();
+  Block_release(block);
+}
+
+#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;                                 \
+    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();                             \
+  }
+
+#define DISPATCH_INTERCEPT_SYNC_B(name, barrier)                             \
+  TSAN_INTERCEPTOR(void, name, dispatch_queue_t q,                           \
+                   DISPATCH_NOESCAPE dispatch_block_t block) {               \
+    SCOPED_TSAN_INTERCEPTOR(name, q, block);                                 \
+    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_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();                \
+    REAL(name)(q, new_context, dispatch_callback_wrap);           \
+    SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();                  \
+  }
+
+#define DISPATCH_INTERCEPT_SYNC_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 = {                                           \
+        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(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 =
+      AllocContext(thr, pc, queue, heap_block, &invoke_and_release_block);
+  Release(thr, pc, (uptr)new_context);
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();
+  REAL(dispatch_after_f)(when, queue, new_context, dispatch_callback_wrap);
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();
+}
+
+TSAN_INTERCEPTOR(void, dispatch_after_f, dispatch_time_t when,
+                 dispatch_queue_t queue, void *context,
+                 dispatch_function_t work) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_after_f, when, queue, context, work);
+  WRAP(dispatch_after)(when, queue, ^(void) {
+    work(context);
+  });
+}
+
+// GCD's dispatch_once implementation has a fast path that contains a racy read
+// and it's inlined into user's code. Furthermore, this fast path doesn't
+// establish a proper happens-before relations between the initialization and
+// code following the call to dispatch_once. We could deal with this in
+// instrumented code, but there's not much we can do about it in system
+// libraries. Let's disable the fast path (by never storing the value ~0 to
+// predicate), so the interceptor is always called, and let's add proper release
+// and acquire semantics. Since TSan does not see its own atomic stores, the
+// race on predicate won't be reported - the only accesses to it that TSan sees
+// are the loads on the fast path. Loads don't race. Secondly, dispatch_once is
+// both a macro and a real function, we want to intercept the function, so we
+// need to undefine the macro.
+#undef dispatch_once
+TSAN_INTERCEPTOR(void, dispatch_once, dispatch_once_t *predicate,
+                 DISPATCH_NOESCAPE dispatch_block_t block) {
+  SCOPED_INTERCEPTOR_RAW(dispatch_once, predicate, block);
+  atomic_uint32_t *a = reinterpret_cast<atomic_uint32_t *>(predicate);
+  u32 v = atomic_load(a, memory_order_acquire);
+  if (v == 0 &&
+      atomic_compare_exchange_strong(a, &v, 1, memory_order_relaxed)) {
+    SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();
+    block();
+    SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();
+    Release(thr, pc, (uptr)a);
+    atomic_store(a, 2, memory_order_release);
+  } else {
+    while (v != 2) {
+      internal_sched_yield();
+      v = atomic_load(a, memory_order_acquire);
+    }
+    Acquire(thr, pc, (uptr)a);
+  }
+}
+
+#undef dispatch_once_f
+TSAN_INTERCEPTOR(void, dispatch_once_f, dispatch_once_t *predicate,
+                 void *context, dispatch_function_t function) {
+  SCOPED_INTERCEPTOR_RAW(dispatch_once_f, predicate, context, function);
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();
+  WRAP(dispatch_once)(predicate, ^(void) {
+    function(context);
+  });
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();
+}
+
+TSAN_INTERCEPTOR(long_t, dispatch_semaphore_signal,
+                 dispatch_semaphore_t dsema) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_semaphore_signal, dsema);
+  Release(thr, pc, (uptr)dsema);
+  return REAL(dispatch_semaphore_signal)(dsema);
+}
+
+TSAN_INTERCEPTOR(long_t, dispatch_semaphore_wait, dispatch_semaphore_t dsema,
+                 dispatch_time_t timeout) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_semaphore_wait, dsema, timeout);
+  long_t result = REAL(dispatch_semaphore_wait)(dsema, timeout);
+  if (result == 0) Acquire(thr, pc, (uptr)dsema);
+  return result;
+}
+
+TSAN_INTERCEPTOR(long_t, dispatch_group_wait, dispatch_group_t group,
+                 dispatch_time_t timeout) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_group_wait, group, timeout);
+  long_t result = REAL(dispatch_group_wait)(group, timeout);
+  if (result == 0) Acquire(thr, pc, (uptr)group);
+  return result;
+}
+
+// Used, but not intercepted.
+extern "C" void dispatch_group_enter(dispatch_group_t group);
+
+TSAN_INTERCEPTOR(void, dispatch_group_leave, dispatch_group_t group) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_group_leave, group);
+  // Acquired in the group notification callback in dispatch_group_notify[_f].
+  Release(thr, pc, (uptr)group);
+  REAL(dispatch_group_leave)(group);
+}
+
+TSAN_INTERCEPTOR(void, dispatch_group_async, dispatch_group_t group,
+                 dispatch_queue_t queue, dispatch_block_t block) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_group_async, group, queue, block);
+  dispatch_retain(group);
+  dispatch_group_enter(group);
+  __block dispatch_block_t block_copy = (dispatch_block_t)Block_copy(block);
+  WRAP(dispatch_async)(queue, ^(void) {
+    block_copy();
+    Block_release(block_copy);
+    WRAP(dispatch_group_leave)(group);
+    dispatch_release(group);
+  });
+}
+
+TSAN_INTERCEPTOR(void, dispatch_group_async_f, dispatch_group_t group,
+                 dispatch_queue_t queue, void *context,
+                 dispatch_function_t work) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_group_async_f, group, queue, context, work);
+  dispatch_retain(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);
+
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();
+  dispatch_block_t heap_block = Block_copy(^(void) {
+    {
+      SCOPED_INTERCEPTOR_RAW(dispatch_read_callback);
+      // Released when leaving the group (dispatch_group_leave).
+      Acquire(thr, pc, (uptr)group);
+    }
+    dispatch_release(group);
+    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 = true;
+  Release(thr, pc, (uptr)new_context);
+  REAL(dispatch_group_notify_f)(group, q, new_context, dispatch_callback_wrap);
+}
+
+TSAN_INTERCEPTOR(void, dispatch_group_notify_f, dispatch_group_t group,
+                 dispatch_queue_t q, void *context, dispatch_function_t work) {
+  WRAP(dispatch_group_notify)(group, q, ^(void) { work(context); });
+}
+
+TSAN_INTERCEPTOR(void, dispatch_source_set_event_handler,
+                 dispatch_source_t source, dispatch_block_t handler) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_source_set_event_handler, source, handler);
+  if (handler == nullptr)
+    return REAL(dispatch_source_set_event_handler)(source, nullptr);
+  dispatch_queue_t q = GetTargetQueueFromSource(source);
+  __block block_context_t new_context = {
+      q, handler, &invoke_block, false, false, false, 0 };
+  dispatch_block_t new_handler = Block_copy(^(void) {
+    new_context.orig_context = handler;  // To explicitly capture "handler".
+    dispatch_callback_wrap(&new_context);
+  });
+  uptr submit_sync = (uptr)&new_context;
+  Release(thr, pc, submit_sync);
+  REAL(dispatch_source_set_event_handler)(source, new_handler);
+  Block_release(new_handler);
+}
+
+TSAN_INTERCEPTOR(void, dispatch_source_set_event_handler_f,
+                 dispatch_source_t source, dispatch_function_t handler) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_source_set_event_handler_f, source, handler);
+  if (handler == nullptr)
+    return REAL(dispatch_source_set_event_handler)(source, nullptr);
+  dispatch_block_t block = ^(void) {
+    handler(dispatch_get_context(source));
+  };
+  WRAP(dispatch_source_set_event_handler)(source, block);
+}
+
+TSAN_INTERCEPTOR(void, dispatch_source_set_cancel_handler,
+                 dispatch_source_t source, dispatch_block_t handler) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_source_set_cancel_handler, source, handler);
+  if (handler == nullptr)
+    return REAL(dispatch_source_set_cancel_handler)(source, nullptr);
+  dispatch_queue_t q = GetTargetQueueFromSource(source);
+  __block block_context_t new_context = {
+      q, handler, &invoke_block, false, false, false, 0};
+  dispatch_block_t new_handler = Block_copy(^(void) {
+    new_context.orig_context = handler;  // To explicitly capture "handler".
+    dispatch_callback_wrap(&new_context);
+  });
+  uptr submit_sync = (uptr)&new_context;
+  Release(thr, pc, submit_sync);
+  REAL(dispatch_source_set_cancel_handler)(source, new_handler);
+  Block_release(new_handler);
+}
+
+TSAN_INTERCEPTOR(void, dispatch_source_set_cancel_handler_f,
+                 dispatch_source_t source, dispatch_function_t handler) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_source_set_cancel_handler_f, source,
+                          handler);
+  if (handler == nullptr)
+    return REAL(dispatch_source_set_cancel_handler)(source, nullptr);
+  dispatch_block_t block = ^(void) {
+    handler(dispatch_get_context(source));
+  };
+  WRAP(dispatch_source_set_cancel_handler)(source, block);
+}
+
+TSAN_INTERCEPTOR(void, dispatch_source_set_registration_handler,
+                 dispatch_source_t source, dispatch_block_t handler) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_source_set_registration_handler, source,
+                          handler);
+  if (handler == nullptr)
+    return REAL(dispatch_source_set_registration_handler)(source, nullptr);
+  dispatch_queue_t q = GetTargetQueueFromSource(source);
+  __block block_context_t new_context = {
+      q, handler, &invoke_block, false, false, false, 0};
+  dispatch_block_t new_handler = Block_copy(^(void) {
+    new_context.orig_context = handler;  // To explicitly capture "handler".
+    dispatch_callback_wrap(&new_context);
+  });
+  uptr submit_sync = (uptr)&new_context;
+  Release(thr, pc, submit_sync);
+  REAL(dispatch_source_set_registration_handler)(source, new_handler);
+  Block_release(new_handler);
+}
+
+TSAN_INTERCEPTOR(void, dispatch_source_set_registration_handler_f,
+                 dispatch_source_t source, dispatch_function_t handler) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_source_set_registration_handler_f, source,
+                          handler);
+  if (handler == nullptr)
+    return REAL(dispatch_source_set_registration_handler)(source, nullptr);
+  dispatch_block_t block = ^(void) {
+    handler(dispatch_get_context(source));
+  };
+  WRAP(dispatch_source_set_registration_handler)(source, block);
+}
+
+TSAN_INTERCEPTOR(void, dispatch_apply, size_t iterations,
+                 dispatch_queue_t queue,
+                 DISPATCH_NOESCAPE void (^block)(size_t)) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_apply, iterations, queue, block);
+
+  u8 sync1, sync2;
+  uptr parent_to_child_sync = (uptr)&sync1;
+  uptr child_to_parent_sync = (uptr)&sync2;
+
+  Release(thr, pc, parent_to_child_sync);
+  void (^new_block)(size_t) = ^(size_t iteration) {
+    SCOPED_INTERCEPTOR_RAW(dispatch_apply);
+    Acquire(thr, pc, parent_to_child_sync);
+    SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();
+    block(iteration);
+    SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();
+    Release(thr, pc, child_to_parent_sync);
+  };
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();
+  REAL(dispatch_apply)(iterations, queue, new_block);
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();
+  Acquire(thr, pc, child_to_parent_sync);
+}
+
+static void invoke_block_iteration(void *param, size_t iteration) {
+  auto block = (void (^)(size_t)) param;
+  block(iteration);
+}
+
+TSAN_INTERCEPTOR(void, dispatch_apply_f, size_t iterations,
+                 dispatch_queue_t queue, void *context,
+                 void (*work)(void *, size_t)) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_apply_f, iterations, queue, context, work);
+
+  // Unfortunately, we cannot delegate to dispatch_apply, since libdispatch
+  // implements dispatch_apply in terms of dispatch_apply_f.
+  u8 sync1, sync2;
+  uptr parent_to_child_sync = (uptr)&sync1;
+  uptr child_to_parent_sync = (uptr)&sync2;
+
+  Release(thr, pc, parent_to_child_sync);
+  void (^new_block)(size_t) = ^(size_t iteration) {
+    SCOPED_INTERCEPTOR_RAW(dispatch_apply_f);
+    Acquire(thr, pc, parent_to_child_sync);
+    SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();
+    work(context, iteration);
+    SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();
+    Release(thr, pc, child_to_parent_sync);
+  };
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();
+  REAL(dispatch_apply_f)(iterations, queue, new_block, invoke_block_iteration);
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();
+  Acquire(thr, pc, child_to_parent_sync);
+}
+
+DECLARE_REAL_AND_INTERCEPTOR(void, free, void *ptr)
+DECLARE_REAL_AND_INTERCEPTOR(int, munmap, void *addr, long_t sz)
+
+TSAN_INTERCEPTOR(dispatch_data_t, dispatch_data_create, const void *buffer,
+                 size_t size, dispatch_queue_t q, dispatch_block_t destructor) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_data_create, buffer, size, q, destructor);
+  if ((q == nullptr) || (destructor == DISPATCH_DATA_DESTRUCTOR_DEFAULT))
+    return REAL(dispatch_data_create)(buffer, size, q, destructor);
+
+  if (destructor == DISPATCH_DATA_DESTRUCTOR_FREE)
+    destructor = ^(void) { WRAP(free)((void *)(uintptr_t)buffer); };
+  else if (destructor == DISPATCH_DATA_DESTRUCTOR_MUNMAP)
+    destructor = ^(void) { WRAP(munmap)((void *)(uintptr_t)buffer, size); };
+
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_START();
+  dispatch_block_t heap_block = Block_copy(destructor);
+  SCOPED_TSAN_INTERCEPTOR_USER_CALLBACK_END();
+  block_context_t *new_context =
+      AllocContext(thr, pc, q, heap_block, &invoke_and_release_block);
+  uptr submit_sync = (uptr)new_context;
+  Release(thr, pc, submit_sync);
+  return REAL(dispatch_data_create)(buffer, size, q, ^(void) {
+    dispatch_callback_wrap(new_context);
+  });
+}
+
+typedef void (^fd_handler_t)(dispatch_data_t data, int error);
+typedef void (^cleanup_handler_t)(int error);
+
+TSAN_INTERCEPTOR(void, dispatch_read, dispatch_fd_t fd, size_t length,
+                 dispatch_queue_t q, fd_handler_t h) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_read, fd, length, q, h);
+  __block block_context_t new_context = {
+      q, nullptr, &invoke_block, false, false, false, 0};
+  fd_handler_t new_h = Block_copy(^(dispatch_data_t data, int error) {
+    new_context.orig_context = ^(void) {
+      h(data, error);
+    };
+    dispatch_callback_wrap(&new_context);
+  });
+  uptr submit_sync = (uptr)&new_context;
+  Release(thr, pc, submit_sync);
+  REAL(dispatch_read)(fd, length, q, new_h);
+  Block_release(new_h);
+}
+
+TSAN_INTERCEPTOR(void, dispatch_write, dispatch_fd_t fd, dispatch_data_t data,
+                 dispatch_queue_t q, fd_handler_t h) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_write, fd, data, q, h);
+  __block block_context_t new_context = {
+      q, nullptr, &invoke_block, false, false, false, 0};
+  fd_handler_t new_h = Block_copy(^(dispatch_data_t data, int error) {
+    new_context.orig_context = ^(void) {
+      h(data, error);
+    };
+    dispatch_callback_wrap(&new_context);
+  });
+  uptr submit_sync = (uptr)&new_context;
+  Release(thr, pc, submit_sync);
+  REAL(dispatch_write)(fd, data, q, new_h);
+  Block_release(new_h);
+}
+
+TSAN_INTERCEPTOR(void, dispatch_io_read, dispatch_io_t channel, off_t offset,
+                 size_t length, dispatch_queue_t q, dispatch_io_handler_t h) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_io_read, channel, offset, length, q, h);
+  __block block_context_t new_context = {
+      q, nullptr, &invoke_block, false, false, false, 0};
+  dispatch_io_handler_t new_h =
+      Block_copy(^(bool done, dispatch_data_t data, int error) {
+        new_context.orig_context = ^(void) {
+          h(done, data, error);
+        };
+        dispatch_callback_wrap(&new_context);
+      });
+  uptr submit_sync = (uptr)&new_context;
+  Release(thr, pc, submit_sync);
+  REAL(dispatch_io_read)(channel, offset, length, q, new_h);
+  Block_release(new_h);
+}
+
+TSAN_INTERCEPTOR(void, dispatch_io_write, dispatch_io_t channel, off_t offset,
+                 dispatch_data_t data, dispatch_queue_t q,
+                 dispatch_io_handler_t h) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_io_write, channel, offset, data, q, h);
+  __block block_context_t new_context = {
+      q, nullptr, &invoke_block, false, false, false, 0};
+  dispatch_io_handler_t new_h =
+      Block_copy(^(bool done, dispatch_data_t data, int error) {
+        new_context.orig_context = ^(void) {
+          h(done, data, error);
+        };
+        dispatch_callback_wrap(&new_context);
+      });
+  uptr submit_sync = (uptr)&new_context;
+  Release(thr, pc, submit_sync);
+  REAL(dispatch_io_write)(channel, offset, data, q, new_h);
+  Block_release(new_h);
+}
+
+TSAN_INTERCEPTOR(void, dispatch_io_barrier, dispatch_io_t channel,
+                 dispatch_block_t barrier) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_io_barrier, channel, barrier);
+  __block block_context_t new_context = {
+      nullptr, nullptr, &invoke_block, false, false, false, 0};
+  new_context.non_queue_sync_object = (uptr)channel;
+  new_context.is_barrier_block = true;
+  dispatch_block_t new_block = Block_copy(^(void) {
+    new_context.orig_context = ^(void) {
+      barrier();
+    };
+    dispatch_callback_wrap(&new_context);
+  });
+  uptr submit_sync = (uptr)&new_context;
+  Release(thr, pc, submit_sync);
+  REAL(dispatch_io_barrier)(channel, new_block);
+  Block_release(new_block);
+}
+
+TSAN_INTERCEPTOR(dispatch_io_t, dispatch_io_create, dispatch_io_type_t type,
+                 dispatch_fd_t fd, dispatch_queue_t q, cleanup_handler_t h) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_io_create, type, fd, q, h);
+  __block dispatch_io_t new_channel = nullptr;
+  __block block_context_t new_context = {
+      q, nullptr, &invoke_block, false, false, false, 0};
+  cleanup_handler_t new_h = Block_copy(^(int error) {
+    {
+      SCOPED_INTERCEPTOR_RAW(dispatch_io_create_callback);
+      Acquire(thr, pc, (uptr)new_channel);  // Release() in dispatch_io_close.
+    }
+    new_context.orig_context = ^(void) {
+      h(error);
+    };
+    dispatch_callback_wrap(&new_context);
+  });
+  uptr submit_sync = (uptr)&new_context;
+  Release(thr, pc, submit_sync);
+  new_channel = REAL(dispatch_io_create)(type, fd, q, new_h);
+  Block_release(new_h);
+  return new_channel;
+}
+
+TSAN_INTERCEPTOR(dispatch_io_t, dispatch_io_create_with_path,
+                 dispatch_io_type_t type, const char *path, int oflag,
+                 mode_t mode, dispatch_queue_t q, cleanup_handler_t h) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_io_create_with_path, type, path, oflag, mode,
+                          q, h);
+  __block dispatch_io_t new_channel = nullptr;
+  __block block_context_t new_context = {
+      q, nullptr, &invoke_block, false, false, false, 0};
+  cleanup_handler_t new_h = Block_copy(^(int error) {
+    {
+      SCOPED_INTERCEPTOR_RAW(dispatch_io_create_callback);
+      Acquire(thr, pc, (uptr)new_channel);  // Release() in dispatch_io_close.
+    }
+    new_context.orig_context = ^(void) {
+      h(error);
+    };
+    dispatch_callback_wrap(&new_context);
+  });
+  uptr submit_sync = (uptr)&new_context;
+  Release(thr, pc, submit_sync);
+  new_channel =
+      REAL(dispatch_io_create_with_path)(type, path, oflag, mode, q, new_h);
+  Block_release(new_h);
+  return new_channel;
+}
+
+TSAN_INTERCEPTOR(dispatch_io_t, dispatch_io_create_with_io,
+                 dispatch_io_type_t type, dispatch_io_t io, dispatch_queue_t q,
+                 cleanup_handler_t h) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_io_create_with_io, type, io, q, h);
+  __block dispatch_io_t new_channel = nullptr;
+  __block block_context_t new_context = {
+      q, nullptr, &invoke_block, false, false, false, 0};
+  cleanup_handler_t new_h = Block_copy(^(int error) {
+    {
+      SCOPED_INTERCEPTOR_RAW(dispatch_io_create_callback);
+      Acquire(thr, pc, (uptr)new_channel);  // Release() in dispatch_io_close.
+    }
+    new_context.orig_context = ^(void) {
+      h(error);
+    };
+    dispatch_callback_wrap(&new_context);
+  });
+  uptr submit_sync = (uptr)&new_context;
+  Release(thr, pc, submit_sync);
+  new_channel = REAL(dispatch_io_create_with_io)(type, io, q, new_h);
+  Block_release(new_h);
+  return new_channel;
+}
+
+TSAN_INTERCEPTOR(void, dispatch_io_close, dispatch_io_t channel,
+                 dispatch_io_close_flags_t flags) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_io_close, channel, flags);
+  Release(thr, pc, (uptr)channel);  // Acquire() in dispatch_io_create[_*].
+  return REAL(dispatch_io_close)(channel, flags);
+}
+
+// Resuming a suspended queue needs to synchronize with all subsequent
+// executions of blocks in that queue.
+TSAN_INTERCEPTOR(void, dispatch_resume, dispatch_object_t o) {
+  SCOPED_TSAN_INTERCEPTOR(dispatch_resume, o);
+  Release(thr, pc, (uptr)o);  // Synchronizes with the Acquire() on serial_sync
+                              // in dispatch_sync_pre_execute
+  return REAL(dispatch_resume)(o);
+}
+
+void InitializeLibdispatchInterceptors() {
+  INTERCEPT_FUNCTION(dispatch_async);
+  INTERCEPT_FUNCTION(dispatch_async_f);
+  INTERCEPT_FUNCTION(dispatch_sync);
+  INTERCEPT_FUNCTION(dispatch_sync_f);
+  INTERCEPT_FUNCTION(dispatch_barrier_async);
+  INTERCEPT_FUNCTION(dispatch_barrier_async_f);
+  INTERCEPT_FUNCTION(dispatch_barrier_sync);
+  INTERCEPT_FUNCTION(dispatch_barrier_sync_f);
+  INTERCEPT_FUNCTION(dispatch_after);
+  INTERCEPT_FUNCTION(dispatch_after_f);
+  INTERCEPT_FUNCTION(dispatch_once);
+  INTERCEPT_FUNCTION(dispatch_once_f);
+  INTERCEPT_FUNCTION(dispatch_semaphore_signal);
+  INTERCEPT_FUNCTION(dispatch_semaphore_wait);
+  INTERCEPT_FUNCTION(dispatch_group_wait);
+  INTERCEPT_FUNCTION(dispatch_group_leave);
+  INTERCEPT_FUNCTION(dispatch_group_async);
+  INTERCEPT_FUNCTION(dispatch_group_async_f);
+  INTERCEPT_FUNCTION(dispatch_group_notify);
+  INTERCEPT_FUNCTION(dispatch_group_notify_f);
+  INTERCEPT_FUNCTION(dispatch_source_set_event_handler);
+  INTERCEPT_FUNCTION(dispatch_source_set_event_handler_f);
+  INTERCEPT_FUNCTION(dispatch_source_set_cancel_handler);
+  INTERCEPT_FUNCTION(dispatch_source_set_cancel_handler_f);
+  INTERCEPT_FUNCTION(dispatch_source_set_registration_handler);
+  INTERCEPT_FUNCTION(dispatch_source_set_registration_handler_f);
+  INTERCEPT_FUNCTION(dispatch_apply);
+  INTERCEPT_FUNCTION(dispatch_apply_f);
+  INTERCEPT_FUNCTION(dispatch_data_create);
+  INTERCEPT_FUNCTION(dispatch_read);
+  INTERCEPT_FUNCTION(dispatch_write);
+  INTERCEPT_FUNCTION(dispatch_io_read);
+  INTERCEPT_FUNCTION(dispatch_io_write);
+  INTERCEPT_FUNCTION(dispatch_io_barrier);
+  INTERCEPT_FUNCTION(dispatch_io_create);
+  INTERCEPT_FUNCTION(dispatch_io_create_with_path);
+  INTERCEPT_FUNCTION(dispatch_io_create_with_io);
+  INTERCEPT_FUNCTION(dispatch_io_close);
+  INTERCEPT_FUNCTION(dispatch_resume);
+}
+
+}  // namespace __tsan