[promises] Move promise constructor to TFS

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/promise-utils.h"
 
 namespace v8 {
 namespace internal {
 
 // ES#sec-promise-resolve-functions
 // Promise Resolve Functions
 BUILTIN(PromiseResolveClosure) {
   HandleScope scope(isolate);
 
@@ skipping 55 matching lines @@
                                          &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.WordEqual(new_target, a.UndefinedConstant()),
+           &if_targetisundefined);
+
+  Label if_notcallable(&a, Label::kDeferred),
+      if_rejectpromise(&a, Label::kDeferred);

[jgruber, 2016/11/22 08:55:55]

if_rejectpromise could be moved into the run_executor branch.

[gsathya, 2016/11/23 14:31:18]

Done.

+
+  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);
+
+  Label if_targetisnotmodified(&a), if_targetismodified(&a, Label::kDeferred),
+      run_executor(&a), out(&a), debug_push(&a, Label::kDeferred),
+      debug_pop(&a, Label::kDeferred);
+  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 initial_map = a.LoadObjectField(
+        promise_fun, JSFunction::kPrototypeOrInitialMapOffset);
+
+    Node* const instance = a.AllocateJSObjectFromMap(initial_map);
+    var_result.Bind(instance);
+    a.Branch(a.IsDebugActive(), &debug_push, &run_executor);
+  }
+
+  a.Bind(&if_targetismodified);
+  {
+    Node* const instance =
+        a.CallRuntime(Runtime::kNewObject, context, promise_fun, new_target);

[jgruber, 2016/11/22 08:55:55]

Just curious, why is it not possible to call a.AllocateJSObjectFromMap in this
case?

[gsathya, 2016/11/23 14:31:18]

The subclass setup seemed more involved and I wasn't sure if it was worth it? I
guess we don't have to worry about Proxy subclassing though. 
https://cs.chromium.org/chromium/src/v8/src/objects.cc?sq=package:chromium&rc...

I could call FastNewObjectStub though. Changed.

+
+    var_result.Bind(instance);
+    a.Branch(a.IsDebugActive(), &debug_push, &run_executor);
+  }
+
+  a.Bind(&debug_push);
+  {
+    a.CallRuntime(Runtime::kDebugPushPromise, context, var_result.value());
+    a.Goto(&run_executor);
+  }
+
+  a.Bind(&run_executor);
+  {
+    Node* const key =
+        a.HeapConstant(a.isolate()->factory()->promise_state_symbol());
+    Node* const value = a.SmiConstant(Smi::FromInt(kPromisePending));
+    Node* const language_mode = a.SmiConstant(Smi::FromInt(STRICT));
+    a.CallRuntime(Runtime::kSetProperty, context, var_result.value(), key,
+                  value, language_mode);
+    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));
+    var_reject_call.Bind(reject);

[jgruber, 2016/11/22 08:55:55]

Seems like you can just use the Node* reject variable instead of var_reject if
you move if_rejectpromise into the run_executor block. You could also move the
definition of if_rejectpromise and possibly debug_pop in here.

[gsathya, 2016/11/23 14:31:18]

Done.

+    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(a.IsDebugActive(), &debug_pop, &out);
+  }
+
+  a.Bind(&if_rejectpromise);
+  {
+    Callable call_callable = CodeFactory::Call(isolate);
+    a.CallJS(call_callable, context, var_reject_call.value(),
+             a.UndefinedConstant(), var_reason.value());
+    a.Branch(a.IsDebugActive(), &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(Smi::FromInt(MessageTemplate::kNotAPromise));

[jgruber, 2016/11/22 08:55:55]

Here and elsewhere: since recently you can just call a.SmiConstant([int])
instead of a.SmiConstant(Smi::FromInt([int])).

[gsathya, 2016/11/23 14:31:18]

Done.

+    a.CallRuntime(Runtime::kThrowTypeError, context, message_id, new_target);
+    // a.ToString(a, new_target));

[jgruber, 2016/11/22 08:55:55]

Please remove comment.

[gsathya, 2016/11/23 14:31:18]

Done.

+    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(Smi::FromInt(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 native_context = a.LoadNativeContext(context);
+  Node* const promise_fun =
+      a.LoadContextElement(native_context, Context::PROMISE_FUNCTION_INDEX);
+  Node* const initial_map =
+      a.LoadObjectField(promise_fun, JSFunction::kPrototypeOrInitialMapOffset);
+  Node* const instance = a.AllocateJSObjectFromMap(initial_map);
+  a.Return(instance);
+}
+
+// TODO(gsathya): Refactor promise.js::IsPromise to use this.
+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_ispromise(&a), if_isnotpromise(&a, Label::kDeferred);
+  a.GotoIf(a.TaggedIsSmi(maybe_promise), &if_isnotpromise);
+
+  Node* const maybe_promise_type =
+      a.LoadMapInstanceType(a.LoadMap(maybe_promise));
+
+  a.Branch(a.Word32Equal(maybe_promise_type, a.Int32Constant(JS_PROMISE_TYPE)),
+           &if_ispromise, &if_isnotpromise);
+
+  a.Bind(&if_ispromise);
+  a.Return(a.BooleanConstant(true));
+
+  a.Bind(&if_isnotpromise);
+  a.Return(a.BooleanConstant(false));
+}
+
 }  // namespace internal
 }  // namespace v8