[promises] Refactor CreatePromise

src/code-stub-assembler.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/code-stub-assembler.h"
 #include "src/code-factory.h"
 #include "src/frames-inl.h"
 #include "src/frames.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 8227 matching lines @@
 }
 
 Node* CodeStubAssembler::IsPromiseHookEnabled() {
   Node* const is_promisehook_enabled =
       Load(MachineType::Uint8(),
            ExternalConstant(
                ExternalReference::is_promisehook_enabled_address(isolate())));
   return WordNotEqual(is_promisehook_enabled, Int32Constant(0));
 }
 
+Node* CodeStubAssembler::AllocateJSPromise(Node* context) {
+  Node* const native_context = LoadNativeContext(context);
+  Node* const promise_fun =
+      LoadContextElement(native_context, Context::PROMISE_FUNCTION_INDEX);
+  Node* const initial_map =
+      LoadObjectField(promise_fun, JSFunction::kPrototypeOrInitialMapOffset);
+  Node* const instance = AllocateJSObjectFromMap(initial_map);
+
+  return instance;
+}
+
+void CodeStubAssembler::PromiseInit(Node* promise) {
+  StoreObjectField(promise, JSPromise::kStatusOffset,
+                   SmiConstant(kPromisePending));
+  StoreObjectField(promise, JSPromise::kFlagsOffset, SmiConstant(0));
+}
+
+void CodeStubAssembler::PromiseSet(Node* promise, Node* status, Node* result) {
+  CSA_ASSERT(this, TaggedIsSmi(status));
+  StoreObjectField(promise, JSPromise::kStatusOffset, status);
+  StoreObjectField(promise, JSPromise::kResultOffset, result);
+  StoreObjectField(promise, JSPromise::kFlagsOffset, SmiConstant(0));
+}
+
 }  // namespace internal
 }  // namespace v8