[api] Move slow-path work behind fast path in InstantiateObject

src/api-natives.cc

 // Copyright 2015 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/api-natives.h"
 
 #include "src/api.h"
 #include "src/isolate-inl.h"
 #include "src/lookup.h"
 #include "src/messages.h"
@@ skipping 271 matching lines @@
       UnseededNumberDictionary::DeleteProperty(cache, entry);
   USE(result);
   DCHECK(result->IsTrue());
   auto new_cache = UnseededNumberDictionary::Shrink(cache, entry);
   isolate->native_context()->set_template_instantiations_cache(*new_cache);
 }
 
 MaybeHandle<JSObject> InstantiateObject(Isolate* isolate,
                                         Handle<ObjectTemplateInfo> info,
                                         bool is_hidden_prototype) {
-  // Enter a new scope.  Recursion could otherwise create a lot of handles.
-  HandleScope scope(isolate);
   // Fast path.
   Handle<JSObject> result;
-  auto constructor = handle(info->constructor(), isolate);
-  Handle<JSFunction> cons;
-  if (constructor->IsUndefined()) {
-    cons = isolate->object_function();
-  } else {
-    auto cons_templ = Handle<FunctionTemplateInfo>::cast(constructor);
-    ASSIGN_RETURN_ON_EXCEPTION(
-        isolate, cons, InstantiateFunction(isolate, cons_templ), JSFunction);
-  }
   auto serial_number = handle(Smi::cast(info->serial_number()), isolate);
   if (serial_number->value()) {
     // Probe cache.
     auto cache = isolate->template_instantiations_cache();
     int entry = cache->FindEntry(static_cast<uint32_t>(serial_number->value()));
     if (entry != UnseededNumberDictionary::kNotFound) {
       Object* boilerplate = cache->ValueAt(entry);
       result = handle(JSObject::cast(boilerplate), isolate);
       ASSIGN_RETURN_ON_EXCEPTION(
           isolate, result, JSObject::DeepCopyApiBoilerplate(result), JSObject);
-      return scope.CloseAndEscape(result);
+      return result;
     }
   }
+  // Enter a new scope.  Recursion could otherwise create a lot of handles.
+  HandleScope scope(isolate);
+  auto constructor = handle(info->constructor(), isolate);
+  Handle<JSFunction> cons;
+  if (constructor->IsUndefined()) {
+    cons = isolate->object_function();
+  } else {
+    auto cons_templ = Handle<FunctionTemplateInfo>::cast(constructor);
+    ASSIGN_RETURN_ON_EXCEPTION(
+        isolate, cons, InstantiateFunction(isolate, cons_templ), JSFunction);
+  }
   auto object = isolate->factory()->NewJSObject(cons);
   ASSIGN_RETURN_ON_EXCEPTION(
       isolate, result,
       ConfigureInstance(isolate, object, info, is_hidden_prototype),
       JSFunction);
   // TODO(dcarney): is this necessary?
   JSObject::MigrateSlowToFast(result, 0, "ApiNatives::InstantiateObject");
 
   if (serial_number->value()) {
     CacheTemplateInstantiation(isolate, serial_number, result);
@@ skipping 291 matching lines @@
     map->set_is_callable();
     map->set_is_constructor(true);
   }
 
   DCHECK(result->shared()->IsApiFunction());
   return result;
 }
 
 }  // namespace internal
 }  // namespace v8