[promises] Use TF_BUILTIN

src/builtins/builtins-promise.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/builtins/builtins-utils.h"
 #include "src/builtins/builtins.h"
 #include "src/code-factory.h"
 #include "src/code-stub-assembler.h"
 #include "src/promise-utils.h"
 
 namespace v8 {
 namespace internal {
 
-// ES#sec-promise-reject-functions
-// Promise Reject Functions
-BUILTIN(PromiseRejectClosure) {
-  HandleScope scope(isolate);
+typedef compiler::Node Node;
+typedef CodeStubAssembler::ParameterMode ParameterMode;
+typedef compiler::CodeAssemblerState CodeAssemblerState;
 
-  Handle<Context> context(isolate->context(), isolate);
+class PromiseBuiltinsAssembler : public CodeStubAssembler {
+ public:
+  explicit PromiseBuiltinsAssembler(CodeAssemblerState* state)
+      : CodeStubAssembler(state) {}
 
-  if (PromiseUtils::HasAlreadyVisited(context)) {
-    return isolate->heap()->undefined_value();
+ protected:
+  Node* ThrowIfNotJSReceiver(Node* context, Node* value,
+                             MessageTemplate::Template msg_template);
+
+  Node* SpeciesConstructor(Node* context, Node* object,
+                           Node* default_constructor);
+
+  Node* PromiseHasHandler(Node* promise);
+
+  void PromiseSetHasHandler(Node* promise);
+
+  void AppendPromiseCallback(int offset, compiler::Node* promise,
+                             compiler::Node* value);
+
+  Node* InternalPerformPromiseThen(Node* context, Node* promise,
+                                   Node* on_resolve, Node* on_reject,
+                                   Node* deferred);
+
+  void InternalResolvePromise(Node* context, Node* promise, Node* result,
+                              Label* out);
+
+  void BranchIfFastPath(Node* context, Node* promise, Label* if_isunmodified,
+                        Label* if_ismodified);
+};
+
+Node* PromiseBuiltinsAssembler::ThrowIfNotJSReceiver(
+    Node* context, Node* value, MessageTemplate::Template msg_template) {
+  Label out(this), throw_exception(this, Label::kDeferred);
+  Variable var_value_map(this, MachineRepresentation::kTagged);
+
+  GotoIf(TaggedIsSmi(value), &throw_exception);
+
+  // Load the instance type of the {value}.
+  var_value_map.Bind(LoadMap(value));
+  Node* const value_instance_type = LoadMapInstanceType(var_value_map.value());
+
+  Branch(IsJSReceiverInstanceType(value_instance_type), &out, &throw_exception);
+
+  // The {value} is not a compatible receiver for this method.
+  Bind(&throw_exception);
+  {
+    Node* const message_id = SmiConstant(msg_template);
+    CallRuntime(Runtime::kThrowTypeError, context, message_id);
+    var_value_map.Bind(UndefinedConstant());
+    Goto(&out);  // Never reached.
   }
 
-  PromiseUtils::SetAlreadyVisited(context);
-  Handle<Object> value = args.atOrUndefined(isolate, 1);
-  Handle<JSObject> promise = handle(PromiseUtils::GetPromise(context), isolate);
-  Handle<Object> debug_event =
-      handle(PromiseUtils::GetDebugEvent(context), isolate);
-  MaybeHandle<Object> maybe_result;
-  Handle<Object> argv[] = {promise, value, debug_event};
-  RETURN_FAILURE_ON_EXCEPTION(
-      isolate, Execution::Call(isolate, isolate->promise_internal_reject(),
-                               isolate->factory()->undefined_value(),
-                               arraysize(argv), argv));
-  return isolate->heap()->undefined_value();
-}
-
-// ES#sec-createresolvingfunctions
-// CreateResolvingFunctions ( promise )
-BUILTIN(CreateResolvingFunctions) {
-  HandleScope scope(isolate);
-  DCHECK_EQ(3, args.length());
-
-  Handle<JSObject> promise = args.at<JSObject>(1);
-  Handle<Object> debug_event = args.at(2);
-  Handle<JSFunction> resolve, reject;
-
-  PromiseUtils::CreateResolvingFunctions(isolate, promise, debug_event,
-                                         &resolve, &reject);
-
-  Handle<FixedArray> result = isolate->factory()->NewFixedArray(2);
-  result->set(0, *resolve);
-  result->set(1, *reject);
-
-  return *isolate->factory()->NewJSArrayWithElements(result, FAST_ELEMENTS, 2,
-                                                     NOT_TENURED);
-}
-
-void Builtins::Generate_PromiseConstructor(
-    compiler::CodeAssemblerState* state) {
-  CodeStubAssembler a(state);
-  typedef CodeStubAssembler::Variable Variable;
-  typedef CodeStubAssembler::Label Label;
-  typedef compiler::Node Node;
-
-  Node* const executor = a.Parameter(1);
-  Node* const new_target = a.Parameter(2);
-  Node* const context = a.Parameter(4);
-  Isolate* isolate = a.isolate();
-
-  Label if_targetisundefined(&a, Label::kDeferred);
-
-  a.GotoIf(a.IsUndefined(new_target), &if_targetisundefined);
-
-  Label if_notcallable(&a, Label::kDeferred);
-
-  a.GotoIf(a.TaggedIsSmi(executor), &if_notcallable);
-
-  Node* const executor_map = a.LoadMap(executor);
-  a.GotoUnless(a.IsCallableMap(executor_map), &if_notcallable);
-
-  Node* const native_context = a.LoadNativeContext(context);
-  Node* const promise_fun =
-      a.LoadContextElement(native_context, Context::PROMISE_FUNCTION_INDEX);
-  Node* const is_debug_active = a.IsDebugActive();
-  Label if_targetisnotmodified(&a), if_targetismodified(&a, Label::kDeferred),
-      run_executor(&a), debug_push(&a, Label::kDeferred), init(&a);
-
-  a.Branch(a.WordEqual(promise_fun, new_target), &if_targetisnotmodified,
-           &if_targetismodified);
-
-  Variable var_result(&a, MachineRepresentation::kTagged),
-      var_reject_call(&a, MachineRepresentation::kTagged),
-      var_reason(&a, MachineRepresentation::kTagged);
-
-  a.Bind(&if_targetisnotmodified);
-  {
-    Node* const instance = a.AllocateJSPromise(context);
-    var_result.Bind(instance);
-    a.Goto(&init);
-  }
-
-  a.Bind(&if_targetismodified);
-  {
-    Callable fast_new_object_stub = CodeFactory::FastNewObject(isolate);
-    Node* const instance =
-        a.CallStub(fast_new_object_stub, context, promise_fun, new_target);
-
-    var_result.Bind(instance);
-    a.Goto(&init);
-  }
-
-  a.Bind(&init);
-  {
-    a.PromiseInit(var_result.value());
-    a.Branch(is_debug_active, &debug_push, &run_executor);
-  }
-
-  a.Bind(&debug_push);
-  {
-    a.CallRuntime(Runtime::kDebugPushPromise, context, var_result.value());
-    a.Goto(&run_executor);
-  }
-
-  a.Bind(&run_executor);
-  {
-    Label out(&a), if_rejectpromise(&a), debug_pop(&a, Label::kDeferred);
-
-    // TODO(gsathya): Move this to TF.
-    Node* const resolving_functions = a.CallRuntime(
-        Runtime::kCreateResolvingFunctions, context, var_result.value());
-    Node* const resolve =
-        a.LoadFixedArrayElement(resolving_functions, a.IntPtrConstant(0));
-    Node* const reject =
-        a.LoadFixedArrayElement(resolving_functions, a.IntPtrConstant(1));
-    Callable call_callable = CodeFactory::Call(isolate);
-
-    Node* const maybe_exception =
-        a.CallJS(call_callable, context, executor, a.UndefinedConstant(),
-                 resolve, reject);
-
-    a.GotoIfException(maybe_exception, &if_rejectpromise, &var_reason);
-    a.Branch(is_debug_active, &debug_pop, &out);
-
-    a.Bind(&if_rejectpromise);
-    {
-      Callable call_callable = CodeFactory::Call(isolate);
-      a.CallJS(call_callable, context, reject, a.UndefinedConstant(),
-               var_reason.value());
-      a.Branch(is_debug_active, &debug_pop, &out);
-    }
-
-    a.Bind(&debug_pop);
-    {
-      a.CallRuntime(Runtime::kDebugPopPromise, context);
-      a.Goto(&out);
-    }
-    a.Bind(&out);
-    a.Return(var_result.value());
-  }
-
-  // 1. If NewTarget is undefined, throw a TypeError exception.
-  a.Bind(&if_targetisundefined);
-  {
-    Node* const message_id = a.SmiConstant(MessageTemplate::kNotAPromise);
-    a.CallRuntime(Runtime::kThrowTypeError, context, message_id, new_target);
-    a.Return(a.UndefinedConstant());  // Never reached.
-  }
-
-  // 2. If IsCallable(executor) is false, throw a TypeError exception.
-  a.Bind(&if_notcallable);
-  {
-    Node* const message_id =
-        a.SmiConstant(MessageTemplate::kResolverNotAFunction);
-    a.CallRuntime(Runtime::kThrowTypeError, context, message_id, executor);
-    a.Return(a.UndefinedConstant());  // Never reached.
-  }
-}
-
-void Builtins::Generate_PromiseInternalConstructor(
-    compiler::CodeAssemblerState* state) {
-  typedef compiler::Node Node;
-  CodeStubAssembler a(state);
-
-  Node* const context = a.Parameter(3);
-  Node* const instance = a.AllocateJSPromise(context);
-  a.PromiseInit(instance);
-  a.Return(instance);
-}
-
-void Builtins::Generate_PromiseCreateAndSet(
-    compiler::CodeAssemblerState* state) {
-  typedef compiler::Node Node;
-  CodeStubAssembler a(state);
-
-  Node* const status = a.Parameter(1);
-  Node* const result = a.Parameter(2);
-  Node* const context = a.Parameter(5);
-
-  Node* const instance = a.AllocateJSPromise(context);
-  a.PromiseSet(instance, status, result);
-  a.Return(instance);
-}
-
-namespace {
-
-compiler::Node* ThrowIfNotJSReceiver(CodeStubAssembler* a, Isolate* isolate,
-                                     compiler::Node* context,
-                                     compiler::Node* value,
-                                     MessageTemplate::Template msg_template) {
-  typedef compiler::Node Node;
-  typedef CodeStubAssembler::Label Label;
-  typedef CodeStubAssembler::Variable Variable;
-
-  Label out(a), throw_exception(a, Label::kDeferred);
-  Variable var_value_map(a, MachineRepresentation::kTagged);
-
-  a->GotoIf(a->TaggedIsSmi(value), &throw_exception);
-
-  // Load the instance type of the {value}.
-  var_value_map.Bind(a->LoadMap(value));
-  Node* const value_instance_type =
-      a->LoadMapInstanceType(var_value_map.value());
-
-  a->Branch(a->IsJSReceiverInstanceType(value_instance_type), &out,
-            &throw_exception);
-
-  // The {value} is not a compatible receiver for this method.
-  a->Bind(&throw_exception);
-  {
-    Node* const message_id = a->SmiConstant(msg_template);
-    a->CallRuntime(Runtime::kThrowTypeError, context, message_id);
-    var_value_map.Bind(a->UndefinedConstant());
-    a->Goto(&out);  // Never reached.
-  }
-
-  a->Bind(&out);
+  Bind(&out);
   return var_value_map.value();
 }
 
-}  // namespace
-
-void Builtins::Generate_IsPromise(compiler::CodeAssemblerState* state) {
-  CodeStubAssembler a(state);
-  typedef compiler::Node Node;
-  typedef CodeStubAssembler::Label Label;
-
-  Node* const maybe_promise = a.Parameter(1);
-  Label if_notpromise(&a, Label::kDeferred);
-
-  a.GotoIf(a.TaggedIsSmi(maybe_promise), &if_notpromise);
-
-  Node* const result = a.SelectBooleanConstant(
-      a.HasInstanceType(maybe_promise, JS_PROMISE_TYPE));
-  a.Return(result);
-
-  a.Bind(&if_notpromise);
-  a.Return(a.FalseConstant());
+Node* PromiseBuiltinsAssembler::PromiseHasHandler(Node* promise) {
+  Node* const flags = LoadObjectField(promise, JSPromise::kFlagsOffset);
+  return IsSetWord(SmiUntag(flags), 1 << JSPromise::kHasHandlerBit);
 }
 
-namespace {
-
-compiler::Node* PromiseHasHandler(CodeStubAssembler* a,
-                                  compiler::Node* promise) {
-  typedef compiler::Node Node;
-
-  Node* const flags = a->LoadObjectField(promise, JSPromise::kFlagsOffset);
-  return a->IsSetWord(a->SmiUntag(flags), 1 << JSPromise::kHasHandlerBit);
+void PromiseBuiltinsAssembler::PromiseSetHasHandler(Node* promise) {
+  Node* const flags =
+      SmiUntag(LoadObjectField(promise, JSPromise::kFlagsOffset));
+  Node* const new_flags =
+      WordOr(flags, IntPtrConstant(1 << JSPromise::kHasHandlerBit));
+  StoreObjectField(promise, JSPromise::kFlagsOffset, SmiTag(new_flags));
 }
 
-void PromiseSetHasHandler(CodeStubAssembler* a, compiler::Node* promise) {
-  typedef compiler::Node Node;
-
-  Node* const flags =
-      a->SmiUntag(a->LoadObjectField(promise, JSPromise::kFlagsOffset));
-  Node* const new_flags =
-      a->WordOr(flags, a->IntPtrConstant(1 << JSPromise::kHasHandlerBit));
-  a->StoreObjectField(promise, JSPromise::kFlagsOffset, a->SmiTag(new_flags));
-}
-
-compiler::Node* SpeciesConstructor(CodeStubAssembler* a, Isolate* isolate,
-                                   compiler::Node* context,
-                                   compiler::Node* object,
-                                   compiler::Node* default_constructor) {
-  typedef compiler::Node Node;
-  typedef CodeStubAssembler::Label Label;
-  typedef CodeStubAssembler::Variable Variable;
-
-  Variable var_result(a, MachineRepresentation::kTagged);
+Node* PromiseBuiltinsAssembler::SpeciesConstructor(Node* context, Node* object,
+                                                   Node* default_constructor) {
+  Isolate* isolate = this->isolate();
+  Variable var_result(this, MachineRepresentation::kTagged);
   var_result.Bind(default_constructor);
 
   // 2. Let C be ? Get(O, "constructor").
   Node* const constructor_str =
-      a->HeapConstant(isolate->factory()->constructor_string());
-  Callable getproperty_callable = CodeFactory::GetProperty(a->isolate());
+      HeapConstant(isolate->factory()->constructor_string());
+  Callable getproperty_callable = CodeFactory::GetProperty(isolate);
   Node* const constructor =
-      a->CallStub(getproperty_callable, context, object, constructor_str);
+      CallStub(getproperty_callable, context, object, constructor_str);
 
   // 3. If C is undefined, return defaultConstructor.
-  Label out(a);
-  a->GotoIf(a->IsUndefined(constructor), &out);
+  Label out(this);
+  GotoIf(IsUndefined(constructor), &out);
 
   // 4. If Type(C) is not Object, throw a TypeError exception.
-  ThrowIfNotJSReceiver(a, a->isolate(), context, constructor,
+  ThrowIfNotJSReceiver(context, constructor,
                        MessageTemplate::kConstructorNotReceiver);
 
   // 5. Let S be ? Get(C, @@species).
   Node* const species_symbol =
-      a->HeapConstant(isolate->factory()->species_symbol());
+      HeapConstant(isolate->factory()->species_symbol());
   Node* const species =
-      a->CallStub(getproperty_callable, context, constructor, species_symbol);
+      CallStub(getproperty_callable, context, constructor, species_symbol);
 
   // 6. If S is either undefined or null, return defaultConstructor.
-  a->GotoIf(a->IsUndefined(species), &out);
-  a->GotoIf(a->WordEqual(species, a->NullConstant()), &out);
+  GotoIf(IsUndefined(species), &out);
+  GotoIf(WordEqual(species, NullConstant()), &out);
 
   // 7. If IsConstructor(S) is true, return S.
-  Label throw_error(a);
-  Node* species_bitfield = a->LoadMapBitField(a->LoadMap(species));
-  a->GotoUnless(
-      a->Word32Equal(a->Word32And(species_bitfield,
-                                  a->Int32Constant((1 << Map::kIsConstructor))),
-                     a->Int32Constant(1 << Map::kIsConstructor)),
-      &throw_error);
+  Label throw_error(this);
+  Node* species_bitfield = LoadMapBitField(LoadMap(species));
+  GotoUnless(Word32Equal(Word32And(species_bitfield,
+                                   Int32Constant((1 << Map::kIsConstructor))),
+                         Int32Constant(1 << Map::kIsConstructor)),
+             &throw_error);
   var_result.Bind(species);
-  a->Goto(&out);
+  Goto(&out);
 
   // 8. Throw a TypeError exception.
-  a->Bind(&throw_error);
+  Bind(&throw_error);
   {
     Node* const message_id =
-        a->SmiConstant(MessageTemplate::kSpeciesNotConstructor);
-    a->CallRuntime(Runtime::kThrowTypeError, context, message_id);
-    a->Goto(&out);
+        SmiConstant(MessageTemplate::kSpeciesNotConstructor);
+    CallRuntime(Runtime::kThrowTypeError, context, message_id);
+    Goto(&out);
   }
 
-  a->Bind(&out);
+  Bind(&out);
   return var_result.value();
 }
 
-void AppendPromiseCallback(CodeStubAssembler* a, int offset,
-                           compiler::Node* promise, compiler::Node* value) {
-  typedef compiler::Node Node;
+void PromiseBuiltinsAssembler::AppendPromiseCallback(int offset, Node* promise,
+                                                     Node* value) {
+  Node* elements = LoadObjectField(promise, offset);
+  Node* length = LoadFixedArrayBaseLength(elements);
+  CodeStubAssembler::ParameterMode mode = OptimalParameterMode();
+  length = TaggedToParameter(length, mode);
 
-  Node* elements = a->LoadObjectField(promise, offset);
-  Node* length = a->LoadFixedArrayBaseLength(elements);
-  CodeStubAssembler::ParameterMode mode = a->OptimalParameterMode();
-  length = a->TaggedToParameter(length, mode);
-
-  Node* delta = a->IntPtrOrSmiConstant(1, mode);
-  Node* new_capacity = a->IntPtrOrSmiAdd(length, delta, mode);
+  Node* delta = IntPtrOrSmiConstant(1, mode);
+  Node* new_capacity = IntPtrOrSmiAdd(length, delta, mode);
 
   const ElementsKind kind = FAST_ELEMENTS;
   const WriteBarrierMode barrier_mode = UPDATE_WRITE_BARRIER;
   const CodeStubAssembler::AllocationFlags flags =
       CodeStubAssembler::kAllowLargeObjectAllocation;
   int additional_offset = 0;
 
-  Node* new_elements = a->AllocateFixedArray(kind, new_capacity, mode, flags);
-
-  a->CopyFixedArrayElements(kind, elements, new_elements, length, barrier_mode,
-                            mode);
-  a->StoreFixedArrayElement(new_elements, length, value, barrier_mode,
-                            additional_offset, mode);
-
-  a->StoreObjectField(promise, offset, new_elements);
-}
-
-compiler::Node* InternalPerformPromiseThen(CodeStubAssembler* a,
-                                           compiler::Node* context,
-                                           compiler::Node* promise,
-                                           compiler::Node* on_resolve,
-                                           compiler::Node* on_reject,
-                                           compiler::Node* deferred) {
-  typedef CodeStubAssembler::Variable Variable;
-  typedef CodeStubAssembler::Label Label;
-  typedef compiler::Node Node;
-  Isolate* isolate = a->isolate();
-  Node* const native_context = a->LoadNativeContext(context);
-
-  Variable var_on_resolve(a, MachineRepresentation::kTagged),
-      var_on_reject(a, MachineRepresentation::kTagged);
+  Node* new_elements = AllocateFixedArray(kind, new_capacity, mode, flags);
+
+  CopyFixedArrayElements(kind, elements, new_elements, length, barrier_mode,
+                         mode);
+  StoreFixedArrayElement(new_elements, length, value, barrier_mode,
+                         additional_offset, mode);
+
+  StoreObjectField(promise, offset, new_elements);
+}
+
+Node* PromiseBuiltinsAssembler::InternalPerformPromiseThen(Node* context,
+                                                           Node* promise,
+                                                           Node* on_resolve,
+                                                           Node* on_reject,
+                                                           Node* deferred) {
+  Node* const native_context = LoadNativeContext(context);
+
+  Variable var_on_resolve(this, MachineRepresentation::kTagged),
+      var_on_reject(this, MachineRepresentation::kTagged);
 
   var_on_resolve.Bind(on_resolve);
   var_on_reject.Bind(on_reject);
 
-  Label out(a), if_onresolvenotcallable(a), onrejectcheck(a),
-      append_callbacks(a);
-  a->GotoIf(a->TaggedIsSmi(on_resolve), &if_onresolvenotcallable);
-
-  Node* const on_resolve_map = a->LoadMap(on_resolve);
-  a->Branch(a->IsCallableMap(on_resolve_map), &onrejectcheck,
-            &if_onresolvenotcallable);
-
-  a->Bind(&if_onresolvenotcallable);
-  {
-    var_on_resolve.Bind(a->LoadContextElement(
+  Label out(this), if_onresolvenotcallable(this), onrejectcheck(this),
+      append_callbacks(this);
+  GotoIf(TaggedIsSmi(on_resolve), &if_onresolvenotcallable);
+
+  Node* const on_resolve_map = LoadMap(on_resolve);
+  Branch(IsCallableMap(on_resolve_map), &onrejectcheck,
+         &if_onresolvenotcallable);
+
+  Bind(&if_onresolvenotcallable);
+  {
+    var_on_resolve.Bind(LoadContextElement(
         native_context, Context::PROMISE_ID_RESOLVE_HANDLER_INDEX));
-    a->Goto(&onrejectcheck);
-  }
-
-  a->Bind(&onrejectcheck);
-  {
-    Label if_onrejectnotcallable(a);
-    a->GotoIf(a->TaggedIsSmi(on_reject), &if_onrejectnotcallable);
-
-    Node* const on_reject_map = a->LoadMap(on_reject);
-    a->Branch(a->IsCallableMap(on_reject_map), &append_callbacks,
-              &if_onrejectnotcallable);
-
-    a->Bind(&if_onrejectnotcallable);
+    Goto(&onrejectcheck);
+  }
+
+  Bind(&onrejectcheck);
+  {
+    Label if_onrejectnotcallable(this);
+    GotoIf(TaggedIsSmi(on_reject), &if_onrejectnotcallable);
+
+    Node* const on_reject_map = LoadMap(on_reject);
+    Branch(IsCallableMap(on_reject_map), &append_callbacks,
+           &if_onrejectnotcallable);
+
+    Bind(&if_onrejectnotcallable);
     {
-      var_on_reject.Bind(a->LoadContextElement(
+      var_on_reject.Bind(LoadContextElement(
           native_context, Context::PROMISE_ID_REJECT_HANDLER_INDEX));
-      a->Goto(&append_callbacks);
+      Goto(&append_callbacks);
     }
   }
 
-  a->Bind(&append_callbacks);
-  {
-    Label fulfilled_check(a);
-    Node* const status = a->LoadObjectField(promise, JSPromise::kStatusOffset);
-    a->GotoUnless(a->SmiEqual(status, a->SmiConstant(kPromisePending)),
-                  &fulfilled_check);
+  Bind(&append_callbacks);
+  {
+    Label fulfilled_check(this);
+    Node* const status = LoadObjectField(promise, JSPromise::kStatusOffset);
+    GotoUnless(SmiEqual(status, SmiConstant(kPromisePending)),
+               &fulfilled_check);
 
     Node* const existing_deferred =
-        a->LoadObjectField(promise, JSPromise::kDeferredOffset);
-
-    Label if_noexistingcallbacks(a), if_existingcallbacks(a);
-    a->Branch(a->IsUndefined(existing_deferred), &if_noexistingcallbacks,
-              &if_existingcallbacks);
-
-    a->Bind(&if_noexistingcallbacks);
+        LoadObjectField(promise, JSPromise::kDeferredOffset);
+
+    Label if_noexistingcallbacks(this), if_existingcallbacks(this);
+    Branch(IsUndefined(existing_deferred), &if_noexistingcallbacks,
+           &if_existingcallbacks);
+
+    Bind(&if_noexistingcallbacks);
     {
       // Store callbacks directly in the slots.
-      a->StoreObjectField(promise, JSPromise::kDeferredOffset, deferred);
-      a->StoreObjectField(promise, JSPromise::kFulfillReactionsOffset,
-                          var_on_resolve.value());
-      a->StoreObjectField(promise, JSPromise::kRejectReactionsOffset,
-                          var_on_reject.value());
-      a->Goto(&out);
+      StoreObjectField(promise, JSPromise::kDeferredOffset, deferred);
+      StoreObjectField(promise, JSPromise::kFulfillReactionsOffset,
+                       var_on_resolve.value());
+      StoreObjectField(promise, JSPromise::kRejectReactionsOffset,
+                       var_on_reject.value());
+      Goto(&out);
     }
 
-    a->Bind(&if_existingcallbacks);
+    Bind(&if_existingcallbacks);
     {
-      Label if_singlecallback(a), if_multiplecallbacks(a);
-      a->BranchIfJSObject(existing_deferred, &if_singlecallback,
-                          &if_multiplecallbacks);
-
-      a->Bind(&if_singlecallback);
+      Label if_singlecallback(this), if_multiplecallbacks(this);
+      BranchIfJSObject(existing_deferred, &if_singlecallback,
+                       &if_multiplecallbacks);
+
+      Bind(&if_singlecallback);
       {
         // Create new FixedArrays to store callbacks, and migrate
         // existing callbacks.
         Node* const deferreds =
-            a->AllocateFixedArray(FAST_ELEMENTS, a->IntPtrConstant(2));
-        a->StoreFixedArrayElement(deferreds, 0, existing_deferred);
-        a->StoreFixedArrayElement(deferreds, 1, deferred);
+            AllocateFixedArray(FAST_ELEMENTS, IntPtrConstant(2));
+        StoreFixedArrayElement(deferreds, 0, existing_deferred);
+        StoreFixedArrayElement(deferreds, 1, deferred);
 
         Node* const fulfill_reactions =
-            a->AllocateFixedArray(FAST_ELEMENTS, a->IntPtrConstant(2));
-        a->StoreFixedArrayElement(
+            AllocateFixedArray(FAST_ELEMENTS, IntPtrConstant(2));
+        StoreFixedArrayElement(
             fulfill_reactions, 0,
-            a->LoadObjectField(promise, JSPromise::kFulfillReactionsOffset));
-        a->StoreFixedArrayElement(fulfill_reactions, 1, var_on_resolve.value());
+            LoadObjectField(promise, JSPromise::kFulfillReactionsOffset));
+        StoreFixedArrayElement(fulfill_reactions, 1, var_on_resolve.value());
 
         Node* const reject_reactions =
-            a->AllocateFixedArray(FAST_ELEMENTS, a->IntPtrConstant(2));
-        a->StoreFixedArrayElement(
+            AllocateFixedArray(FAST_ELEMENTS, IntPtrConstant(2));
+        StoreFixedArrayElement(
             reject_reactions, 0,
-            a->LoadObjectField(promise, JSPromise::kRejectReactionsOffset));
-        a->StoreFixedArrayElement(reject_reactions, 1, var_on_reject.value());
+            LoadObjectField(promise, JSPromise::kRejectReactionsOffset));
+        StoreFixedArrayElement(reject_reactions, 1, var_on_reject.value());
 
         // Store new FixedArrays in promise.
-        a->StoreObjectField(promise, JSPromise::kDeferredOffset, deferreds);
-        a->StoreObjectField(promise, JSPromise::kFulfillReactionsOffset,
-                            fulfill_reactions);
-        a->StoreObjectField(promise, JSPromise::kRejectReactionsOffset,
-                            reject_reactions);
-        a->Goto(&out);
+        StoreObjectField(promise, JSPromise::kDeferredOffset, deferreds);
+        StoreObjectField(promise, JSPromise::kFulfillReactionsOffset,
+                         fulfill_reactions);
+        StoreObjectField(promise, JSPromise::kRejectReactionsOffset,
+                         reject_reactions);
+        Goto(&out);
       }
 
-      a->Bind(&if_multiplecallbacks);
+      Bind(&if_multiplecallbacks);
       {
-        AppendPromiseCallback(a, JSPromise::kDeferredOffset, promise, deferred);
-        AppendPromiseCallback(a, JSPromise::kFulfillReactionsOffset, promise,
+        AppendPromiseCallback(JSPromise::kDeferredOffset, promise, deferred);
+        AppendPromiseCallback(JSPromise::kFulfillReactionsOffset, promise,
                               var_on_resolve.value());
-        AppendPromiseCallback(a, JSPromise::kRejectReactionsOffset, promise,
+        AppendPromiseCallback(JSPromise::kRejectReactionsOffset, promise,
                               var_on_reject.value());
-        a->Goto(&out);
+        Goto(&out);
       }
     }
 
-    a->Bind(&fulfilled_check);
+    Bind(&fulfilled_check);
     {
-      Label reject(a);
-      Node* const result =
-          a->LoadObjectField(promise, JSPromise::kResultOffset);
-      a->GotoUnless(a->WordEqual(status, a->SmiConstant(kPromiseFulfilled)),
-                    &reject);
+      Label reject(this);
+      Node* const result = LoadObjectField(promise, JSPromise::kResultOffset);
+      GotoUnless(WordEqual(status, SmiConstant(kPromiseFulfilled)), &reject);
 
       // TODO(gsathya): Move this to TF.
-      a->CallRuntime(Runtime::kEnqueuePromiseReactionJob, context, promise,
-                     result, var_on_resolve.value(), deferred,
-                     a->SmiConstant(kPromiseFulfilled));
-      a->Goto(&out);
-
-      a->Bind(&reject);
+      CallRuntime(Runtime::kEnqueuePromiseReactionJob, context, promise, result,
+                  var_on_resolve.value(), deferred,
+                  SmiConstant(kPromiseFulfilled));
+      Goto(&out);
+
+      Bind(&reject);
       {
-        Node* const has_handler = PromiseHasHandler(a, promise);
-        Label enqueue(a);
+        Node* const has_handler = PromiseHasHandler(promise);
+        Label enqueue(this);
 
         // TODO(gsathya): Fold these runtime calls and move to TF.
-        a->GotoIf(has_handler, &enqueue);
-        a->CallRuntime(Runtime::kPromiseRevokeReject, context, promise);
-        a->Goto(&enqueue);
-
-        a->Bind(&enqueue);
+        GotoIf(has_handler, &enqueue);
+        CallRuntime(Runtime::kPromiseRevokeReject, context, promise);
+        Goto(&enqueue);
+
+        Bind(&enqueue);
         {
-          a->CallRuntime(Runtime::kEnqueuePromiseReactionJob, context, promise,
-                         result, var_on_reject.value(), deferred,
-                         a->SmiConstant(kPromiseRejected));
-
-          a->Goto(&out);
+          CallRuntime(Runtime::kEnqueuePromiseReactionJob, context, promise,
+                      result, var_on_reject.value(), deferred,
+                      SmiConstant(kPromiseRejected));
+
+          Goto(&out);
         }
       }
     }
   }
 
-  a->Bind(&out);
-  PromiseSetHasHandler(a, promise);
+  Bind(&out);
+  PromiseSetHasHandler(promise);
 
   // TODO(gsathya): This call will be removed once we don't have to
   // deal with deferred objects.
+  Isolate* isolate = this->isolate();
   Callable getproperty_callable = CodeFactory::GetProperty(isolate);
   Node* const key =
-      a->HeapConstant(isolate->factory()->NewStringFromAsciiChecked("promise"));
-  Node* const result =
-      a->CallStub(getproperty_callable, context, deferred, key);
+      HeapConstant(isolate->factory()->NewStringFromAsciiChecked("promise"));
+  Node* const result = CallStub(getproperty_callable, context, deferred, key);
 
   return result;
 }
 
-}  // namespace
-
-void Builtins::Generate_PerformPromiseThen(
-    compiler::CodeAssemblerState* state) {
-  CodeStubAssembler a(state);
-  typedef compiler::Node Node;
-
-  Node* const promise = a.Parameter(1);
-  Node* const on_resolve = a.Parameter(2);
-  Node* const on_reject = a.Parameter(3);
-  Node* const deferred = a.Parameter(4);
-  Node* const context = a.Parameter(7);
-
-  Node* const result = InternalPerformPromiseThen(
-      &a, context, promise, on_resolve, on_reject, deferred);
-
-  // TODO(gsathya): This is unused, but value is returned according to spec.
-  a.Return(result);
-}
-
-void Builtins::Generate_PromiseThen(compiler::CodeAssemblerState* state) {
-  CodeStubAssembler a(state);
-  typedef compiler::Node Node;
-  typedef CodeStubAssembler::Label Label;
-  typedef CodeStubAssembler::Variable Variable;
-
-  // 1. Let promise be the this value.
-  Node* const promise = a.Parameter(0);
-  Node* const on_resolve = a.Parameter(1);
-  Node* const on_reject = a.Parameter(2);
-  Node* const context = a.Parameter(5);
-  Isolate* isolate = a.isolate();
-
-  // 2. If IsPromise(promise) is false, throw a TypeError exception.
-  a.ThrowIfNotInstanceType(context, promise, JS_PROMISE_TYPE,
-                           "Promise.prototype.then");
-
-  Node* const native_context = a.LoadNativeContext(context);
-  Node* const promise_fun =
-      a.LoadContextElement(native_context, Context::PROMISE_FUNCTION_INDEX);
-
-  // 3. Let C be ? SpeciesConstructor(promise, %Promise%).
-  Node* constructor =
-      SpeciesConstructor(&a, isolate, context, promise, promise_fun);
-
-  // 4. Let resultCapability be ? NewPromiseCapability(C).
-  Callable call_callable = CodeFactory::Call(isolate);
-  Label fast_promise_capability(&a), promise_capability(&a),
-      perform_promise_then(&a);
-  Variable var_deferred(&a, MachineRepresentation::kTagged);
-
-  a.Branch(a.WordEqual(promise_fun, constructor), &fast_promise_capability,
-           &promise_capability);
-
-  // TODO(gsathya): Remove deferred object and move
-  // NewPromiseCapbability functions to TF.
-  a.Bind(&fast_promise_capability);
-  {
-    // TODO(gsathya): Move this to TF.
-    Node* const promise_internal_capability = a.LoadContextElement(
-        native_context, Context::INTERNAL_PROMISE_CAPABILITY_INDEX);
-    Node* const capability =
-        a.CallJS(call_callable, context, promise_internal_capability,
-                 a.UndefinedConstant());
-    var_deferred.Bind(capability);
-    a.Goto(&perform_promise_then);
-  }
-
-  a.Bind(&promise_capability);
-  {
-    // TODO(gsathya): Move this to TF.
-    Node* const new_promise_capability = a.LoadContextElement(
-        native_context, Context::NEW_PROMISE_CAPABILITY_INDEX);
-    Node* const capability =
-        a.CallJS(call_callable, context, new_promise_capability,
-                 a.UndefinedConstant(), constructor);
-    var_deferred.Bind(capability);
-    a.Goto(&perform_promise_then);
-  }
-
-  // 5. Return PerformPromiseThen(promise, onFulfilled, onRejected,
-  //    resultCapability).
-  a.Bind(&perform_promise_then);
-  Node* const result = InternalPerformPromiseThen(
-      &a, context, promise, on_resolve, on_reject, var_deferred.value());
-  a.Return(result);
-}
-
-namespace {
-
 // Promise fast path implementations rely on unmodified JSPromise instances.
 // We use a fairly coarse granularity for this and simply check whether both
 // the promise itself is unmodified (i.e. its map has not changed) and its
 // prototype is unmodified.
 // TODO(gsathya): Refactor this out to prevent code dupe with builtins-regexp
-void BranchIfFastPath(CodeStubAssembler* a, compiler::Node* context,
-                      compiler::Node* promise,
-                      CodeStubAssembler::Label* if_isunmodified,
-                      CodeStubAssembler::Label* if_ismodified) {
-  typedef compiler::Node Node;
-
+void PromiseBuiltinsAssembler::BranchIfFastPath(Node* context, Node* promise,
+                                                Label* if_isunmodified,
+                                                Label* if_ismodified) {
   // TODO(gsathya): Assert if promise is receiver
-  Node* const map = a->LoadMap(promise);
-  Node* const native_context = a->LoadNativeContext(context);
+  Node* const map = LoadMap(promise);
+  Node* const native_context = LoadNativeContext(context);
   Node* const promise_fun =
-      a->LoadContextElement(native_context, Context::PROMISE_FUNCTION_INDEX);
+      LoadContextElement(native_context, Context::PROMISE_FUNCTION_INDEX);
   Node* const initial_map =
-      a->LoadObjectField(promise_fun, JSFunction::kPrototypeOrInitialMapOffset);
-  Node* const has_initialmap = a->WordEqual(map, initial_map);
-
-  a->GotoUnless(has_initialmap, if_ismodified);
-
-  Node* const initial_proto_initial_map = a->LoadContextElement(
-      native_context, Context::PROMISE_PROTOTYPE_MAP_INDEX);
-  Node* const proto_map = a->LoadMap(a->LoadMapPrototype(map));
+      LoadObjectField(promise_fun, JSFunction::kPrototypeOrInitialMapOffset);
+  Node* const has_initialmap = WordEqual(map, initial_map);
+
+  GotoUnless(has_initialmap, if_ismodified);
+
+  Node* const initial_proto_initial_map =
+      LoadContextElement(native_context, Context::PROMISE_PROTOTYPE_MAP_INDEX);
+  Node* const proto_map = LoadMap(LoadMapPrototype(map));
   Node* const proto_has_initialmap =
-      a->WordEqual(proto_map, initial_proto_initial_map);
-
-  a->Branch(proto_has_initialmap, if_isunmodified, if_ismodified);
-}
-
-void InternalResolvePromise(CodeStubAssembler* a, compiler::Node* context,
-                            compiler::Node* promise, compiler::Node* result,
-                            CodeStubAssembler::Label* out) {
-  typedef CodeStubAssembler::Variable Variable;
-  typedef CodeStubAssembler::Label Label;
-  typedef compiler::Node Node;
-
-  Isolate* isolate = a->isolate();
-
-  Variable var_reason(a, MachineRepresentation::kTagged),
-      var_then(a, MachineRepresentation::kTagged);
-
-  Label do_enqueue(a), fulfill(a), if_cycle(a, Label::kDeferred),
-      if_rejectpromise(a, Label::kDeferred);
+      WordEqual(proto_map, initial_proto_initial_map);
+
+  Branch(proto_has_initialmap, if_isunmodified, if_ismodified);
+}
+
+void PromiseBuiltinsAssembler::InternalResolvePromise(Node* context,
+                                                      Node* promise,
+                                                      Node* result,
+                                                      Label* out) {
+  Isolate* isolate = this->isolate();
+
+  Variable var_reason(this, MachineRepresentation::kTagged),
+      var_then(this, MachineRepresentation::kTagged);
+
+  Label do_enqueue(this), fulfill(this), if_cycle(this, Label::kDeferred),
+      if_rejectpromise(this, Label::kDeferred);
 
   // 6. If SameValue(resolution, promise) is true, then
-  a->GotoIf(a->SameValue(promise, result, context), &if_cycle);
+  GotoIf(SameValue(promise, result, context), &if_cycle);
 
   // 7. If Type(resolution) is not Object, then
-  a->GotoIf(a->TaggedIsSmi(result), &fulfill);
-  a->GotoUnless(a->IsJSReceiver(result), &fulfill);
-
-  Label if_nativepromise(a), if_notnativepromise(a, Label::kDeferred);
-  BranchIfFastPath(a, context, result, &if_nativepromise, &if_notnativepromise);
+  GotoIf(TaggedIsSmi(result), &fulfill);
+  GotoUnless(IsJSReceiver(result), &fulfill);
+
+  Label if_nativepromise(this), if_notnativepromise(this, Label::kDeferred);
+  BranchIfFastPath(context, result, &if_nativepromise, &if_notnativepromise);
 
   // Resolution is a native promise and if it's already resolved or
   // rejected, shortcircuit the resolution procedure by directly
   // reusing the value from the promise.
-  a->Bind(&if_nativepromise);
+  Bind(&if_nativepromise);
   {
     Node* const thenable_status =
-        a->LoadObjectField(result, JSPromise::kStatusOffset);
+        LoadObjectField(result, JSPromise::kStatusOffset);
     Node* const thenable_value =
-        a->LoadObjectField(result, JSPromise::kResultOffset);
-
-    Label if_isnotpending(a);
-    a->GotoUnless(a->SmiEqual(a->SmiConstant(kPromisePending), thenable_status),
-                  &if_isnotpending);
+        LoadObjectField(result, JSPromise::kResultOffset);
+
+    Label if_isnotpending(this);
+    GotoUnless(SmiEqual(SmiConstant(kPromisePending), thenable_status),
+               &if_isnotpending);
 
     // TODO(gsathya): Use a marker here instead of the actual then
     // callback, and check for the marker in PromiseResolveThenableJob
     // and perform PromiseThen.
-    Node* const native_context = a->LoadNativeContext(context);
+    Node* const native_context = LoadNativeContext(context);
     Node* const then =
-        a->LoadContextElement(native_context, Context::PROMISE_THEN_INDEX);
+        LoadContextElement(native_context, Context::PROMISE_THEN_INDEX);
     var_then.Bind(then);
-    a->Goto(&do_enqueue);
-
-    a->Bind(&if_isnotpending);
+    Goto(&do_enqueue);
+
+    Bind(&if_isnotpending);
     {
-      Label if_fulfilled(a), if_rejected(a);
-      a->Branch(a->SmiEqual(a->SmiConstant(kPromiseFulfilled), thenable_status),
-                &if_fulfilled, &if_rejected);
-
-      a->Bind(&if_fulfilled);
+      Label if_fulfilled(this), if_rejected(this);
+      Branch(SmiEqual(SmiConstant(kPromiseFulfilled), thenable_status),
+             &if_fulfilled, &if_rejected);
+
+      Bind(&if_fulfilled);
       {
-        a->CallRuntime(Runtime::kPromiseFulfill, context, promise,
-                       a->SmiConstant(kPromiseFulfilled), thenable_value);
-        PromiseSetHasHandler(a, promise);
-        a->Goto(out);
+        CallRuntime(Runtime::kPromiseFulfill, context, promise,
+                    SmiConstant(kPromiseFulfilled), thenable_value);
+        PromiseSetHasHandler(promise);
+        Goto(out);
       }
 
-      a->Bind(&if_rejected);
+      Bind(&if_rejected);
       {
-        Label reject(a);
-        Node* const has_handler = PromiseHasHandler(a, result);
+        Label reject(this);
+        Node* const has_handler = PromiseHasHandler(result);
 
         // Promise has already been rejected, but had no handler.
         // Revoke previously triggered reject event.
-        a->GotoIf(has_handler, &reject);
-        a->CallRuntime(Runtime::kPromiseRevokeReject, context, result);
-        a->Goto(&reject);
-
-        a->Bind(&reject);
+        GotoIf(has_handler, &reject);
+        CallRuntime(Runtime::kPromiseRevokeReject, context, result);
+        Goto(&reject);
+
+        Bind(&reject);
         // Don't cause a debug event as this case is forwarding a rejection
-        a->CallRuntime(Runtime::kPromiseReject, context, promise,
-                       thenable_value, a->FalseConstant());
-        PromiseSetHasHandler(a, result);
-        a->Goto(out);
+        CallRuntime(Runtime::kPromiseReject, context, promise, thenable_value,
+                    FalseConstant());
+        PromiseSetHasHandler(result);
+        Goto(out);
       }
     }
   }
 
-  a->Bind(&if_notnativepromise);
+  Bind(&if_notnativepromise);
   {
     // 8. Let then be Get(resolution, "then").
-    Node* const then_str = a->HeapConstant(isolate->factory()->then_string());
-    Callable getproperty_callable = CodeFactory::GetProperty(a->isolate());
+    Node* const then_str = HeapConstant(isolate->factory()->then_string());
+    Callable getproperty_callable = CodeFactory::GetProperty(isolate);
     Node* const then =
-        a->CallStub(getproperty_callable, context, result, then_str);
+        CallStub(getproperty_callable, context, result, then_str);
 
     // 9. If then is an abrupt completion, then
-    a->GotoIfException(then, &if_rejectpromise, &var_reason);
+    GotoIfException(then, &if_rejectpromise, &var_reason);
 
     // 11. If IsCallable(thenAction) is false, then
-    a->GotoIf(a->TaggedIsSmi(then), &fulfill);
-    Node* const then_map = a->LoadMap(then);
-    a->GotoUnless(a->IsCallableMap(then_map), &fulfill);
+    GotoIf(TaggedIsSmi(then), &fulfill);
+    Node* const then_map = LoadMap(then);
+    GotoUnless(IsCallableMap(then_map), &fulfill);
     var_then.Bind(then);
-    a->Goto(&do_enqueue);
-  }
-
-  a->Bind(&do_enqueue);
-  {
-    Label enqueue(a);
-    a->GotoUnless(a->IsDebugActive(), &enqueue);
-    a->GotoIf(a->TaggedIsSmi(result), &enqueue);
-    a->GotoUnless(a->HasInstanceType(result, JS_PROMISE_TYPE), &enqueue);
+    Goto(&do_enqueue);
+  }
+
+  Bind(&do_enqueue);
+  {
+    Label enqueue(this);
+    GotoUnless(IsDebugActive(), &enqueue);
+    GotoIf(TaggedIsSmi(result), &enqueue);
+    GotoUnless(HasInstanceType(result, JS_PROMISE_TYPE), &enqueue);
     // Mark the dependency of the new promise on the resolution
     Node* const key =
-        a->HeapConstant(isolate->factory()->promise_handled_by_symbol());
-    a->CallRuntime(Runtime::kSetProperty, context, result, key, promise,
-                   a->SmiConstant(STRICT));
-    a->Goto(&enqueue);
+        HeapConstant(isolate->factory()->promise_handled_by_symbol());
+    CallRuntime(Runtime::kSetProperty, context, result, key, promise,
+                SmiConstant(STRICT));
+    Goto(&enqueue);
 
     // 12. Perform EnqueueJob("PromiseJobs",
     // PromiseResolveThenableJob, « promise, resolution, thenAction
     // »).
-    a->Bind(&enqueue);
-    a->CallRuntime(Runtime::kEnqueuePromiseResolveThenableJob, context, promise,
-                   result, var_then.value());
-    a->Goto(out);
-  }
+    Bind(&enqueue);
+    CallRuntime(Runtime::kEnqueuePromiseResolveThenableJob, context, promise,
+                result, var_then.value());
+    Goto(out);
+  }
+
   // 7.b Return FulfillPromise(promise, resolution).
-  a->Bind(&fulfill);
-  {
-    a->CallRuntime(Runtime::kPromiseFulfill, context, promise,
-                   a->SmiConstant(kPromiseFulfilled), result);
-    a->Goto(out);
-  }
-
-  a->Bind(&if_cycle);
+  Bind(&fulfill);
+  {
+    CallRuntime(Runtime::kPromiseFulfill, context, promise,
+                SmiConstant(kPromiseFulfilled), result);
+    Goto(out);
+  }
+
+  Bind(&if_cycle);
   {
     // 6.a Let selfResolutionError be a newly created TypeError object.
-    Node* const message_id = a->SmiConstant(MessageTemplate::kPromiseCyclic);
+    Node* const message_id = SmiConstant(MessageTemplate::kPromiseCyclic);
     Node* const error =
-        a->CallRuntime(Runtime::kNewTypeError, context, message_id, result);
+        CallRuntime(Runtime::kNewTypeError, context, message_id, result);
     var_reason.Bind(error);
 
     // 6.b Return RejectPromise(promise, selfResolutionError).
-    a->Goto(&if_rejectpromise);
+    Goto(&if_rejectpromise);
   }
 
   // 9.a Return RejectPromise(promise, then.[[Value]]).
-  a->Bind(&if_rejectpromise);
-  {
-    a->CallRuntime(Runtime::kPromiseReject, context, promise,
-                   var_reason.value(), a->TrueConstant());
-    a->Goto(out);
-  }
-}
-
-}  // namespace
+  Bind(&if_rejectpromise);
+  {
+    CallRuntime(Runtime::kPromiseReject, context, promise, var_reason.value(),
+                TrueConstant());
+    Goto(out);
+  }
+}
+
+// ES#sec-promise-reject-functions
+// Promise Reject Functions
+BUILTIN(PromiseRejectClosure) {
+  HandleScope scope(isolate);
+
+  Handle<Context> context(isolate->context(), isolate);
+
+  if (PromiseUtils::HasAlreadyVisited(context)) {
+    return isolate->heap()->undefined_value();
+  }
+
+  PromiseUtils::SetAlreadyVisited(context);
+  Handle<Object> value = args.atOrUndefined(isolate, 1);
+  Handle<JSObject> promise = handle(PromiseUtils::GetPromise(context), isolate);
+  Handle<Object> debug_event =
+      handle(PromiseUtils::GetDebugEvent(context), isolate);
+  MaybeHandle<Object> maybe_result;
+  Handle<Object> argv[] = {promise, value, debug_event};
+  RETURN_FAILURE_ON_EXCEPTION(
+      isolate, Execution::Call(isolate, isolate->promise_internal_reject(),
+                               isolate->factory()->undefined_value(),
+                               arraysize(argv), argv));
+  return isolate->heap()->undefined_value();
+}
+
+// ES#sec-createresolvingfunctions
+// CreateResolvingFunctions ( promise )
+BUILTIN(CreateResolvingFunctions) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(3, args.length());
+
+  Handle<JSObject> promise = args.at<JSObject>(1);
+  Handle<Object> debug_event = args.at<Object>(2);
+  Handle<JSFunction> resolve, reject;
+
+  PromiseUtils::CreateResolvingFunctions(isolate, promise, debug_event,
+                                         &resolve, &reject);
+
+  Handle<FixedArray> result = isolate->factory()->NewFixedArray(2);
+  result->set(0, *resolve);
+  result->set(1, *reject);
+
+  return *isolate->factory()->NewJSArrayWithElements(result, FAST_ELEMENTS, 2,
+                                                     NOT_TENURED);
+}
+
+TF_BUILTIN(PromiseConstructor, PromiseBuiltinsAssembler) {
+  Node* const executor = Parameter(1);
+  Node* const new_target = Parameter(2);
+  Node* const context = Parameter(4);
+  Isolate* isolate = this->isolate();
+
+  Label if_targetisundefined(this, Label::kDeferred);
+
+  GotoIf(IsUndefined(new_target), &if_targetisundefined);
+
+  Label if_notcallable(this, Label::kDeferred);
+
+  GotoIf(TaggedIsSmi(executor), &if_notcallable);
+
+  Node* const executor_map = LoadMap(executor);
+  GotoUnless(IsCallableMap(executor_map), &if_notcallable);
+
+  Node* const native_context = LoadNativeContext(context);
+  Node* const promise_fun =
+      LoadContextElement(native_context, Context::PROMISE_FUNCTION_INDEX);
+  Node* const is_debug_active = IsDebugActive();
+  Label if_targetisnotmodified(this),
+      if_targetismodified(this, Label::kDeferred), run_executor(this),
+      debug_push(this, Label::kDeferred), init(this);
+
+  Branch(WordEqual(promise_fun, new_target), &if_targetisnotmodified,
+         &if_targetismodified);
+
+  Variable var_result(this, MachineRepresentation::kTagged),
+      var_reject_call(this, MachineRepresentation::kTagged),
+      var_reason(this, MachineRepresentation::kTagged);
+
+  Bind(&if_targetisnotmodified);
+  {
+    Node* const instance = AllocateJSPromise(context);
+    var_result.Bind(instance);
+    Goto(&init);
+  }
+
+  Bind(&if_targetismodified);
+  {
+    Callable fast_new_object_stub = CodeFactory::FastNewObject(isolate);
+    Node* const instance =
+        CallStub(fast_new_object_stub, context, promise_fun, new_target);
+
+    var_result.Bind(instance);
+    Goto(&init);
+  }
+
+  Bind(&init);
+  {
+    PromiseInit(var_result.value());
+    Branch(is_debug_active, &debug_push, &run_executor);
+  }
+
+  Bind(&debug_push);
+  {
+    CallRuntime(Runtime::kDebugPushPromise, context, var_result.value());
+    Goto(&run_executor);
+  }
+
+  Bind(&run_executor);
+  {
+    Label out(this), if_rejectpromise(this), debug_pop(this, Label::kDeferred);
+
+    // TODO(gsathya): Move this to TF.
+    Node* const resolving_functions = CallRuntime(
+        Runtime::kCreateResolvingFunctions, context, var_result.value());
+    Node* const resolve =
+        LoadFixedArrayElement(resolving_functions, IntPtrConstant(0));
+    Node* const reject =
+        LoadFixedArrayElement(resolving_functions, IntPtrConstant(1));
+    Callable call_callable = CodeFactory::Call(isolate);
+
+    Node* const maybe_exception = CallJS(call_callable, context, executor,
+                                         UndefinedConstant(), resolve, reject);
+
+    GotoIfException(maybe_exception, &if_rejectpromise, &var_reason);
+    Branch(is_debug_active, &debug_pop, &out);
+
+    Bind(&if_rejectpromise);
+    {
+      Callable call_callable = CodeFactory::Call(isolate);
+      CallJS(call_callable, context, reject, UndefinedConstant(),
+             var_reason.value());
+      Branch(is_debug_active, &debug_pop, &out);
+    }
+
+    Bind(&debug_pop);
+    {
+      CallRuntime(Runtime::kDebugPopPromise, context);
+      Goto(&out);
+    }
+    Bind(&out);
+    Return(var_result.value());
+  }
+
+  // 1. If NewTarget is undefined, throw a TypeError exception.
+  Bind(&if_targetisundefined);
+  {
+    Node* const message_id = SmiConstant(MessageTemplate::kNotAPromise);
+    CallRuntime(Runtime::kThrowTypeError, context, message_id, new_target);
+    Return(UndefinedConstant());  // Never reached.
+  }
+
+  // 2. If IsCallable(executor) is false, throw a TypeError exception.
+  Bind(&if_notcallable);
+  {
+    Node* const message_id =
+        SmiConstant(MessageTemplate::kResolverNotAFunction);
+    CallRuntime(Runtime::kThrowTypeError, context, message_id, executor);
+    Return(UndefinedConstant());  // Never reached.
+  }
+}
+
+TF_BUILTIN(PromiseInternalConstructor, PromiseBuiltinsAssembler) {
+  Node* const context = Parameter(3);
+  Node* const instance = AllocateJSPromise(context);
+  PromiseInit(instance);
+  Return(instance);
+}
+
+TF_BUILTIN(PromiseCreateAndSet, PromiseBuiltinsAssembler) {
+  Node* const status = Parameter(1);
+  Node* const result = Parameter(2);
+  Node* const context = Parameter(5);
+
+  Node* const instance = AllocateJSPromise(context);
+  PromiseSet(instance, status, result);
+  Return(instance);
+}
+
+TF_BUILTIN(IsPromise, PromiseBuiltinsAssembler) {
+  Node* const maybe_promise = Parameter(1);
+  Label if_notpromise(this, Label::kDeferred);
+
+  GotoIf(TaggedIsSmi(maybe_promise), &if_notpromise);
+
+  Node* const result =
+      SelectBooleanConstant(HasInstanceType(maybe_promise, JS_PROMISE_TYPE));
+  Return(result);
+
+  Bind(&if_notpromise);
+  Return(FalseConstant());
+}
+
+TF_BUILTIN(PerformPromiseThen, PromiseBuiltinsAssembler) {
+  Node* const promise = Parameter(1);
+  Node* const on_resolve = Parameter(2);
+  Node* const on_reject = Parameter(3);
+  Node* const deferred = Parameter(4);
+  Node* const context = Parameter(7);
+
+  Node* const result = InternalPerformPromiseThen(context, promise, on_resolve,
+                                                  on_reject, deferred);
+
+  // TODO(gsathya): This is unused, but value is returned according to spec.
+  Return(result);
+}
+
+TF_BUILTIN(PromiseThen, PromiseBuiltinsAssembler) {
+  // 1. Let promise be the this value.
+  Node* const promise = Parameter(0);
+  Node* const on_resolve = Parameter(1);
+  Node* const on_reject = Parameter(2);
+  Node* const context = Parameter(5);
+  Isolate* isolate = this->isolate();
+
+  // 2. If IsPromise(promise) is false, throw a TypeError exception.
+  ThrowIfNotInstanceType(context, promise, JS_PROMISE_TYPE,
+                         "Promise.prototype.then");
+
+  Node* const native_context = LoadNativeContext(context);
+  Node* const promise_fun =
+      LoadContextElement(native_context, Context::PROMISE_FUNCTION_INDEX);
+
+  // 3. Let C be ? SpeciesConstructor(promise, %Promise%).
+  Node* constructor = SpeciesConstructor(context, promise, promise_fun);
+
+  // 4. Let resultCapability be ? NewPromiseCapability(C).
+  Callable call_callable = CodeFactory::Call(isolate);
+  Label fast_promise_capability(this), promise_capability(this),
+      perform_promise_then(this);
+  Variable var_deferred(this, MachineRepresentation::kTagged);
+
+  Branch(WordEqual(promise_fun, constructor), &fast_promise_capability,
+         &promise_capability);
+
+  // TODO(gsathya): Remove deferred object and move
+  // NewPromiseCapabability functions to TF.
+  Bind(&fast_promise_capability);
+  {
+    // TODO(gsathya): Move this to TF.
+    Node* const promise_internal_capability = LoadContextElement(
+        native_context, Context::INTERNAL_PROMISE_CAPABILITY_INDEX);
+    Node* const capability =
+        CallJS(call_callable, context, promise_internal_capability,
+               UndefinedConstant());
+    var_deferred.Bind(capability);
+    Goto(&perform_promise_then);
+  }
+
+  Bind(&promise_capability);
+  {
+    // TODO(gsathya): Move this to TF.
+    Node* const new_promise_capability = LoadContextElement(
+        native_context, Context::NEW_PROMISE_CAPABILITY_INDEX);
+    Node* const capability =
+        CallJS(call_callable, context, new_promise_capability,
+               UndefinedConstant(), constructor);
+    var_deferred.Bind(capability);
+    Goto(&perform_promise_then);
+  }
+
+  // 5. Return PerformPromiseThen(promise, onFulfilled, onRejected,
+  //    resultCapability).
+  Bind(&perform_promise_then);
+  Node* const result = InternalPerformPromiseThen(
+      context, promise, on_resolve, on_reject, var_deferred.value());
+  Return(result);
+}
 
 // ES#sec-promise-resolve-functions
 // Promise Resolve Functions
-void Builtins::Generate_PromiseResolveClosure(
-    compiler::CodeAssemblerState* state) {
-  CodeStubAssembler a(state);
-  typedef compiler::Node Node;
-  typedef CodeStubAssembler::Label Label;
-
-  Node* const value = a.Parameter(1);
-  Node* const context = a.Parameter(4);
-
-  Label out(&a);
+TF_BUILTIN(PromiseResolveClosure, PromiseBuiltinsAssembler) {
+  Node* const value = Parameter(1);
+  Node* const context = Parameter(4);
+
+  Label out(this);
 
   // 3. Let alreadyResolved be F.[[AlreadyResolved]].
   Node* const has_already_visited_slot =
-      a.IntPtrConstant(PromiseUtils::kAlreadyVisitedSlot);
+      IntPtrConstant(PromiseUtils::kAlreadyVisitedSlot);
 
   Node* const has_already_visited =
-      a.LoadFixedArrayElement(context, has_already_visited_slot);
+      LoadFixedArrayElement(context, has_already_visited_slot);
 
   // 4. If alreadyResolved.[[Value]] is true, return undefined.
-  a.GotoIf(a.SmiEqual(has_already_visited, a.SmiConstant(1)), &out);
+  GotoIf(SmiEqual(has_already_visited, SmiConstant(1)), &out);
 
   // 5.Set alreadyResolved.[[Value]] to true.
-  a.StoreFixedArrayElement(context, has_already_visited_slot, a.SmiConstant(1));
+  StoreFixedArrayElement(context, has_already_visited_slot, SmiConstant(1));
 
   // 2. Let promise be F.[[Promise]].
-  Node* const promise = a.LoadFixedArrayElement(
-      context, a.IntPtrConstant(PromiseUtils::kPromiseSlot));
-
-  InternalResolvePromise(&a, context, promise, value, &out);
-
-  a.Bind(&out);
-  a.Return(a.UndefinedConstant());
-}
-
-void Builtins::Generate_ResolvePromise(compiler::CodeAssemblerState* state) {
-  CodeStubAssembler a(state);
-  typedef compiler::Node Node;
-  typedef CodeStubAssembler::Label Label;
-
-  Node* const promise = a.Parameter(1);
-  Node* const result = a.Parameter(2);
-  Node* const context = a.Parameter(5);
-
-  Label out(&a);
-  InternalResolvePromise(&a, context, promise, result, &out);
-
-  a.Bind(&out);
-  a.Return(a.UndefinedConstant());
-}
-
-void Builtins::Generate_PromiseHandleReject(
-    compiler::CodeAssemblerState* state) {
-  CodeStubAssembler a(state);
-  typedef compiler::Node Node;
-  typedef CodeStubAssembler::Label Label;
-  typedef CodeStubAssembler::Variable Variable;
+  Node* const promise = LoadFixedArrayElement(
+      context, IntPtrConstant(PromiseUtils::kPromiseSlot));
+
+  InternalResolvePromise(context, promise, value, &out);
+
+  Bind(&out);
+  Return(UndefinedConstant());
+}
+
+TF_BUILTIN(ResolvePromise, PromiseBuiltinsAssembler) {
+  Node* const promise = Parameter(1);
+  Node* const result = Parameter(2);
+  Node* const context = Parameter(5);
+
+  Label out(this);
+  InternalResolvePromise(context, promise, result, &out);
+
+  Bind(&out);
+  Return(UndefinedConstant());
+}
+
+TF_BUILTIN(PromiseHandleReject, PromiseBuiltinsAssembler) {
   typedef PromiseHandleRejectDescriptor Descriptor;
 
-  Node* const promise = a.Parameter(Descriptor::kPromise);
-  Node* const on_reject = a.Parameter(Descriptor::kOnReject);
-  Node* const exception = a.Parameter(Descriptor::kException);
-  Node* const context = a.Parameter(Descriptor::kContext);
-  Isolate* isolate = a.isolate();
-
-  Callable call_callable = CodeFactory::Call(isolate);
-  Variable var_unused(&a, MachineRepresentation::kTagged);
-
-  Label if_internalhandler(&a), if_customhandler(&a, Label::kDeferred);
-  a.Branch(a.IsUndefined(on_reject), &if_internalhandler, &if_customhandler);
-
-  a.Bind(&if_internalhandler);
-  {
-    a.CallRuntime(Runtime::kPromiseReject, context, promise, exception,
-                  a.FalseConstant());
-    a.Return(a.UndefinedConstant());
-  }
-
-  a.Bind(&if_customhandler);
-  {
-    a.CallJS(call_callable, context, on_reject, a.UndefinedConstant(),
-             exception);
-    a.Return(a.UndefinedConstant());
-  }
-}
-
-void Builtins::Generate_PromiseHandle(compiler::CodeAssemblerState* state) {
-  CodeStubAssembler a(state);
-  typedef compiler::Node Node;
-  typedef CodeStubAssembler::Label Label;
-  typedef CodeStubAssembler::Variable Variable;
-
-  Node* const value = a.Parameter(2);
-  Node* const handler = a.Parameter(3);
-  Node* const deferred = a.Parameter(4);
-  Node* const context = a.Parameter(7);
-  Isolate* isolate = a.isolate();
+  Node* const promise = Parameter(Descriptor::kPromise);
+  Node* const on_reject = Parameter(Descriptor::kOnReject);
+  Node* const exception = Parameter(Descriptor::kException);
+  Node* const context = Parameter(Descriptor::kContext);
+
+  Callable call_callable = CodeFactory::Call(isolate());
+  Variable var_unused(this, MachineRepresentation::kTagged);
+
+  Label if_internalhandler(this), if_customhandler(this, Label::kDeferred);
+  Branch(IsUndefined(on_reject), &if_internalhandler, &if_customhandler);
+
+  Bind(&if_internalhandler);
+  {
+    CallRuntime(Runtime::kPromiseReject, context, promise, exception,
+                FalseConstant());
+    Return(UndefinedConstant());
+  }
+
+  Bind(&if_customhandler);
+  {
+    CallJS(call_callable, context, on_reject, UndefinedConstant(), exception);
+    Return(UndefinedConstant());
+  }
+}
+
+TF_BUILTIN(PromiseHandle, PromiseBuiltinsAssembler) {
+  Node* const value = Parameter(2);
+  Node* const handler = Parameter(3);
+  Node* const deferred = Parameter(4);
+  Node* const context = Parameter(7);
+  Isolate* isolate = this->isolate();
 
   // Get promise from deferred
   // TODO(gsathya): Remove this lookup by getting rid of the deferred object.
   Callable getproperty_callable = CodeFactory::GetProperty(isolate);
-  Node* const key = a.HeapConstant(isolate->factory()->promise_string());
+  Node* const key = HeapConstant(isolate->factory()->promise_string());
   Node* const deferred_promise =
-      a.CallStub(getproperty_callable, context, deferred, key);
-
-  Variable var_reason(&a, MachineRepresentation::kTagged);
-
-  Node* const is_debug_active = a.IsDebugActive();
-  Label run_handler(&a), if_rejectpromise(&a), debug_push(&a, Label::kDeferred),
-      debug_pop(&a, Label::kDeferred);
-  a.Branch(is_debug_active, &debug_push, &run_handler);
-
-  a.Bind(&debug_push);
-  {
-    a.CallRuntime(Runtime::kDebugPushPromise, context, deferred_promise);
-    a.Goto(&run_handler);
-  }
-
-  a.Bind(&run_handler);
+      CallStub(getproperty_callable, context, deferred, key);
+
+  Variable var_reason(this, MachineRepresentation::kTagged);
+
+  Node* const is_debug_active = IsDebugActive();
+  Label run_handler(this), if_rejectpromise(this),
+      debug_push(this, Label::kDeferred), debug_pop(this, Label::kDeferred);
+  Branch(is_debug_active, &debug_push, &run_handler);
+
+  Bind(&debug_push);
+  {
+    CallRuntime(Runtime::kDebugPushPromise, context, deferred_promise);
+    Goto(&run_handler);
+  }
+
+  Bind(&run_handler);
   {
     Callable call_callable = CodeFactory::Call(isolate);
 
     Node* const result =
-        a.CallJS(call_callable, context, handler, a.UndefinedConstant(), value);
-
-    a.GotoIfException(result, &if_rejectpromise, &var_reason);
+        CallJS(call_callable, context, handler, UndefinedConstant(), value);
+
+    GotoIfException(result, &if_rejectpromise, &var_reason);
 
     // TODO(gsathya): Remove this lookup by getting rid of the deferred object.
-    Node* const key = a.HeapConstant(isolate->factory()->resolve_string());
+    Node* const key = HeapConstant(isolate->factory()->resolve_string());
     Node* const on_resolve =
-        a.CallStub(getproperty_callable, context, deferred, key);
-
-    Label if_internalhandler(&a), if_customhandler(&a, Label::kDeferred);
-    a.Branch(a.IsUndefined(on_resolve), &if_internalhandler, &if_customhandler);
-
-    a.Bind(&if_internalhandler);
-    InternalResolvePromise(&a, context, deferred_promise, result, &debug_pop);
-
-    a.Bind(&if_customhandler);
+        CallStub(getproperty_callable, context, deferred, key);
+
+    Label if_internalhandler(this), if_customhandler(this, Label::kDeferred);
+    Branch(IsUndefined(on_resolve), &if_internalhandler, &if_customhandler);
+
+    Bind(&if_internalhandler);
+    InternalResolvePromise(context, deferred_promise, result, &debug_pop);
+
+    Bind(&if_customhandler);
     {
-      Node* const maybe_exception = a.CallJS(call_callable, context, on_resolve,
-                                             a.UndefinedConstant(), result);
-      a.GotoIfException(maybe_exception, &if_rejectpromise, &var_reason);
-      a.Goto(&debug_pop);
+      Node* const maybe_exception = CallJS(call_callable, context, on_resolve,
+                                           UndefinedConstant(), result);
+      GotoIfException(maybe_exception, &if_rejectpromise, &var_reason);
+      Goto(&debug_pop);
     }
   }
 
-  a.Bind(&if_rejectpromise);
+  Bind(&if_rejectpromise);
   {
     // TODO(gsathya): Remove this lookup by getting rid of the deferred object.
-    Node* const key = a.HeapConstant(isolate->factory()->reject_string());
+    Node* const key = HeapConstant(isolate->factory()->reject_string());
     Node* const on_reject =
-        a.CallStub(getproperty_callable, context, deferred, key);
+        CallStub(getproperty_callable, context, deferred, key);
 
     Callable promise_handle_reject = CodeFactory::PromiseHandleReject(isolate);
-    a.CallStub(promise_handle_reject, context, deferred_promise, on_reject,
-               var_reason.value());
-    a.Goto(&debug_pop);
-  }
-
-  a.Bind(&debug_pop);
-  {
-    Label out(&a);
-
-    a.GotoUnless(is_debug_active, &out);
-    a.CallRuntime(Runtime::kDebugPopPromise, context);
-    a.Goto(&out);
-
-    a.Bind(&out);
-    a.Return(a.UndefinedConstant());
-  }
-}
-
+    CallStub(promise_handle_reject, context, deferred_promise, on_reject,
+             var_reason.value());
+    Goto(&debug_pop);
+  }
+
+  Bind(&debug_pop);
+  {
+    Label out(this);
+
+    GotoUnless(is_debug_active, &out);
+    CallRuntime(Runtime::kDebugPopPromise, context);
+    Goto(&out);
+
+    Bind(&out);
+    Return(UndefinedConstant());
+  }
+}
+
 }  // namespace internal
 }  // namespace v8