[promises] Move PromiseHasUserDefinedRejectHandler to c++

BUG=v8:5343

Review-Url: https://codereview.chromium.org/2604483002
Cr-Commit-Position: refs/heads/master@{#41947}

src/contexts.h

@@ -105,8 +105,6 @@ enum ContextLookupFlags {
   V(PROMISE_CATCH_INDEX, JSFunction, promise_catch)                           \
   V(PROMISE_CREATE_INDEX, JSFunction, promise_create)                         \
   V(PROMISE_FUNCTION_INDEX, JSFunction, promise_function)                     \
-  V(PROMISE_HAS_USER_DEFINED_REJECT_HANDLER_INDEX, JSFunction,                \
-    promise_has_user_defined_reject_handler)                                  \
   V(PROMISE_DEBUG_GET_INFO_INDEX, JSFunction, promise_debug_get_info)         \
   V(PROMISE_REJECT_INDEX, JSFunction, promise_reject)                         \
   V(PROMISE_INTERNAL_REJECT_INDEX, JSFunction, promise_internal_reject)       \

src/heap-symbols.h

@@ -218,7 +218,6 @@
   V(promise_debug_marker_symbol)       \
   V(promise_forwarding_handler_symbol) \
   V(promise_handled_by_symbol)         \
-  V(promise_handled_hint_symbol)       \
   V(sealed_symbol)                     \
   V(stack_trace_symbol)                \
   V(strict_function_transition_symbol) \

src/isolate.cc

@@ -1808,23 +1808,91 @@ void Isolate::PopPromise() {
   global_handles()->Destroy(global_promise.location());
 }
 
-bool Isolate::PromiseHasUserDefinedRejectHandler(Handle<Object> promise) {
-  Handle<JSFunction> fun = promise_has_user_defined_reject_handler();
-  Handle<Object> has_reject_handler;
-  // If we are, e.g., overflowing the stack, don't try to call out to JS
-  if (!AllowJavascriptExecution::IsAllowed(this)) return false;
-  // Call the registered function to check for a handler
-  if (Execution::TryCall(this, fun, promise, 0, NULL)
-          .ToHandle(&has_reject_handler)) {
-    return has_reject_handler->IsTrue(this);
+namespace {
+bool InternalPromiseHasUserDefinedRejectHandler(Isolate* isolate,
+                                                Handle<JSPromise> promise);
+
+bool PromiseHandlerCheck(Isolate* isolate, Handle<JSReceiver> handler,
+                         Handle<JSObject> deferred) {
+  // Recurse to the forwarding Promise, if any. This may be due to
+  //  - await reaction forwarding to the throwaway Promise, which has
+  //    a dependency edge to the outer Promise.
+  //  - PromiseIdResolveHandler forwarding to the output of .then
+  //  - Promise.all/Promise.race forwarding to a throwaway Promise, which
+  //    has a dependency edge to the generated outer Promise.
+  Handle<Symbol> key = isolate->factory()->promise_forwarding_handler_symbol();
+  Handle<Object> forwarding_handler = JSReceiver::GetDataProperty(handler, key);
+  if (forwarding_handler->IsUndefined(isolate)) {
+    return true;
   }
-  // If an exception is thrown in the course of execution of this built-in
-  // function, it indicates either a bug, or a synthetic uncatchable
-  // exception in the shutdown path. In either case, it's OK to predict either
-  // way in DevTools.
+
+  // TODO(gsathya): Remove this once we get rid of deferred objects.
+  Handle<String> promise_str = isolate->factory()->promise_string();
+  Handle<Object> deferred_promise_obj =
+      JSObject::GetDataProperty(deferred, promise_str);
+  if (!deferred_promise_obj->IsJSPromise()) {
+    return true;
+  }
+
+  return InternalPromiseHasUserDefinedRejectHandler(
+      isolate, Handle<JSPromise>::cast(deferred_promise_obj));
+
+  // Otherwise, this is a real reject handler for the Promise
+  return true;
+}
+
+bool InternalPromiseHasUserDefinedRejectHandler(Isolate* isolate,
+                                                Handle<JSPromise> promise) {
+  // If this promise was marked as being handled by a catch block
+  // in an async function, then it has a user-defined reject handler.
+  if (promise->handled_hint()) return true;
+
+  // If this Promise is subsumed by another Promise (a Promise resolved
+  // with another Promise, or an intermediate, hidden, throwaway Promise
+  // within async/await), then recurse on the outer Promise.
+  // In this case, the dependency is one possible way that the Promise
+  // could be resolved, so it does not subsume the other following cases.
+  Handle<Symbol> key = isolate->factory()->promise_handled_by_symbol();
+  Handle<Object> outer_promise_obj = JSObject::GetDataProperty(promise, key);
+  if (outer_promise_obj->IsJSPromise() &&
+      InternalPromiseHasUserDefinedRejectHandler(
+          isolate, Handle<JSPromise>::cast(outer_promise_obj))) {
+    return true;
+  }
+
+  Handle<Object> queue(promise->reject_reactions(), isolate);
+  Handle<Object> deferred(promise->deferred(), isolate);
+
+  if (queue->IsUndefined(isolate)) {
+    return false;
+  }
+
+  if (queue->IsCallable()) {
+    return PromiseHandlerCheck(isolate, Handle<JSReceiver>::cast(queue),
+                               Handle<JSObject>::cast(deferred));
+  }
+
+  Handle<FixedArray> queue_arr = Handle<FixedArray>::cast(queue);
+  Handle<FixedArray> deferred_arr = Handle<FixedArray>::cast(deferred);
+  for (int i = 0; i < deferred_arr->length(); i++) {
+    Handle<JSReceiver> queue_item(JSReceiver::cast(queue_arr->get(i)));
+    Handle<JSObject> deferred_item(JSObject::cast(deferred_arr->get(i)));
+    if (PromiseHandlerCheck(isolate, queue_item, deferred_item)) {
+      return true;
+    }
+  }
+
   return false;
 }
 
+}  // namespace
+
+bool Isolate::PromiseHasUserDefinedRejectHandler(Handle<Object> promise) {
+  if (!promise->IsJSPromise()) return false;
+  return InternalPromiseHasUserDefinedRejectHandler(
+      this, Handle<JSPromise>::cast(promise));
+}
+
 Handle<Object> Isolate::GetPromiseOnStackOnThrow() {
   Handle<Object> undefined = factory()->undefined_value();
   ThreadLocalTop* tltop = thread_local_top();
@@ -1842,7 +1910,7 @@ Handle<Object> Isolate::GetPromiseOnStackOnThrow() {
         continue;
       case HandlerTable::CAUGHT:
       case HandlerTable::DESUGARING:
-        if (retval->IsJSObject()) {
+        if (retval->IsJSPromise()) {
           // Caught the result of an inner async/await invocation.
           // Mark the inner promise as caught in the "synchronous case" so
           // that Debug::OnException will see. In the synchronous case,
@@ -1850,10 +1918,7 @@ Handle<Object> Isolate::GetPromiseOnStackOnThrow() {
           // await, the function which has this exception event has not yet
           // returned, so the generated Promise has not yet been marked
           // by AsyncFunctionAwaitCaught with promiseHandledHintSymbol.
-          Handle<Symbol> key = factory()->promise_handled_hint_symbol();
-          JSObject::SetProperty(Handle<JSObject>::cast(retval), key,
-                                factory()->true_value(), STRICT)
-              .Assert();
+          Handle<JSPromise>::cast(retval)->set_handled_hint(true);
         }
         return retval;
       case HandlerTable::PROMISE:

src/js/async-await.js

@@ -32,8 +32,6 @@ var promiseHandledBySymbol =
     utils.ImportNow("promise_handled_by_symbol");
 var promiseForwardingHandlerSymbol =
     utils.ImportNow("promise_forwarding_handler_symbol");
-var promiseHandledHintSymbol =
-    utils.ImportNow("promise_handled_hint_symbol");
 
 // -------------------------------------------------------------------
 
@@ -114,7 +112,7 @@ function AsyncFunctionAwaitUncaught(generator, awaited, outerPromise) {
 // prediction indicates that there is a locally surrounding catch block
 function AsyncFunctionAwaitCaught(generator, awaited, outerPromise) {
   if (DEBUG_IS_ACTIVE && %is_promise(awaited)) {
-    SET_PRIVATE(awaited, promiseHandledHintSymbol, true);
+    %PromiseMarkHandledHint(awaited);
   }
   AsyncFunctionAwait(generator, awaited, outerPromise);
 }

src/js/promise.js

@@ -18,8 +18,6 @@ var promiseHandledBySymbol =
     utils.ImportNow("promise_handled_by_symbol");
 var promiseForwardingHandlerSymbol =
     utils.ImportNow("promise_forwarding_handler_symbol");
-var promiseHandledHintSymbol =
-    utils.ImportNow("promise_handled_hint_symbol");
 var ObjectHasOwnProperty; // Used by HAS_PRIVATE.
 var GlobalPromise = global.Promise;
 
@@ -263,68 +261,6 @@ function PromiseRace(iterable) {
   return deferred.promise;
 }
 
-
-// Utility for debugger
-
-function PromiseHasUserDefinedRejectHandlerCheck(handler, deferred) {
-  // Recurse to the forwarding Promise, if any. This may be due to
-  //  - await reaction forwarding to the throwaway Promise, which has
-  //    a dependency edge to the outer Promise.
-  //  - PromiseIdResolveHandler forwarding to the output of .then
-  //  - Promise.all/Promise.race forwarding to a throwaway Promise, which
-  //    has a dependency edge to the generated outer Promise.
-  if (GET_PRIVATE(handler, promiseForwardingHandlerSymbol)) {
-    return PromiseHasUserDefinedRejectHandlerRecursive(deferred.promise);
-  }
-
-  // Otherwise, this is a real reject handler for the Promise
-  return true;
-}
-
-function PromiseHasUserDefinedRejectHandlerRecursive(promise) {
-  // If this promise was marked as being handled by a catch block
-  // in an async function, then it has a user-defined reject handler.
-  if (GET_PRIVATE(promise, promiseHandledHintSymbol)) return true;
-
-  // If this Promise is subsumed by another Promise (a Promise resolved
-  // with another Promise, or an intermediate, hidden, throwaway Promise
-  // within async/await), then recurse on the outer Promise.
-  // In this case, the dependency is one possible way that the Promise
-  // could be resolved, so it does not subsume the other following cases.
-  var outerPromise = GET_PRIVATE(promise, promiseHandledBySymbol);
-  if (outerPromise &&
-      PromiseHasUserDefinedRejectHandlerRecursive(outerPromise)) {
-    return true;
-  }
-
-  if (!%is_promise(promise)) return false;
-
-  var queue = %PromiseRejectReactions(promise);
-  var deferred = %PromiseDeferred(promise);
-
-  if (IS_UNDEFINED(queue)) return false;
-
-  if (!IS_ARRAY(queue)) {
-    return PromiseHasUserDefinedRejectHandlerCheck(queue, deferred);
-  }
-
-  for (var i = 0; i < queue.length; i++) {
-    if (PromiseHasUserDefinedRejectHandlerCheck(queue[i], deferred[i])) {
-      return true;
-    }
-  }
-  return false;
-}
-
-// Return whether the promise will be handled by a user-defined reject
-// handler somewhere down the promise chain. For this, we do a depth-first
-// search for a reject handler that's not the default PromiseIdRejectHandler.
-// This function also traverses dependencies of one Promise on another,
-// set up through async/await and Promises resolved with Promises.
-function PromiseHasUserDefinedRejectHandler() {
-  return PromiseHasUserDefinedRejectHandlerRecursive(this);
-};
-
 function MarkPromiseAsHandled(promise) {
   %PromiseMarkAsHandled(promise);
 }
@@ -341,7 +277,6 @@ utils.InstallFunctions(GlobalPromise, DONT_ENUM, [
 
 %InstallToContext([
   "promise_create", PromiseCreate,
-  "promise_has_user_defined_reject_handler", PromiseHasUserDefinedRejectHandler,
   "promise_reject", DoRejectPromise,
   // TODO(gsathya): Remove this once we update the promise builtin.
   "promise_internal_reject", RejectPromise,

src/objects-inl.h

@@ -7096,6 +7096,7 @@ ACCESSORS(JSPromise, fulfill_reactions, Object, kFulfillReactionsOffset)
 ACCESSORS(JSPromise, reject_reactions, Object, kRejectReactionsOffset)
 SMI_ACCESSORS(JSPromise, flags, kFlagsOffset)
 BOOL_ACCESSORS(JSPromise, flags, has_handler, kHasHandlerBit)
+BOOL_ACCESSORS(JSPromise, flags, handled_hint, kHandledHintBit)
 
 ACCESSORS(JSRegExp, data, Object, kDataOffset)
 ACCESSORS(JSRegExp, flags, Object, kFlagsOffset)

src/objects.h

@@ -8655,6 +8655,10 @@ class JSPromise : public JSObject {
   // [has_handler]: Whether this promise has a reject handler or not.
   DECL_BOOLEAN_ACCESSORS(has_handler)
 
+  // [handled_hint]: Whether this promise will be handled by a catch
+  // block in an async function.
+  DECL_BOOLEAN_ACCESSORS(handled_hint)
+
   static const char* Status(int status);
 
   DECLARE_CAST(JSPromise)
@@ -8675,6 +8679,7 @@ class JSPromise : public JSObject {
 
   // Flags layout.
   static const int kHasHandlerBit = 0;
+  static const int kHandledHintBit = 1;
 };
 
 // Regular expressions

src/runtime/runtime-promise.cc

@@ -279,7 +279,7 @@ RUNTIME_FUNCTION(Runtime_PromiseRejectReactions) {
 }
 
 RUNTIME_FUNCTION(Runtime_PromiseMarkAsHandled) {
-  HandleScope scope(isolate);
+  SealHandleScope shs(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSPromise, promise, 0);
 
@@ -287,6 +287,15 @@ RUNTIME_FUNCTION(Runtime_PromiseMarkAsHandled) {
   return isolate->heap()->undefined_value();
 }
 
+RUNTIME_FUNCTION(Runtime_PromiseMarkHandledHint) {
+  SealHandleScope shs(isolate);
+  DCHECK(args.length() == 1);
+  CONVERT_ARG_HANDLE_CHECKED(JSPromise, promise, 0);
+
+  promise->set_handled_hint(true);
+  return isolate->heap()->undefined_value();
+}
+
 RUNTIME_FUNCTION(Runtime_PromiseHookInit) {
   HandleScope scope(isolate);
   DCHECK_EQ(2, args.length());

src/runtime/runtime.h

@@ -313,6 +313,7 @@ namespace internal {
   F(PromiseHookBefore, 1, 1)                        \
   F(PromiseHookAfter, 1, 1)                         \
   F(PromiseMarkAsHandled, 1, 1)                     \
+  F(PromiseMarkHandledHint, 1, 1)                   \
   F(PromiseRejectEventFromStack, 2, 1)              \
   F(PromiseRejectReactions, 1, 1)                   \
   F(PromiseRevokeReject, 1, 1)                      \