[runtime] More LookupIterator / Transition related performance tweaks

src/lookup.cc

 // Copyright 2014 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/lookup.h"
 
 #include "src/bootstrapper.h"
 #include "src/deoptimizer.h"
 #include "src/elements.h"
 #include "src/field-type.h"
@@ skipping 163 matching lines @@
       holder_map_ = handle(holder->map(), isolate_);
     }
 
     // Copy the backing store if it is copy-on-write.
     if (IsFastSmiOrObjectElementsKind(to)) {
       JSObject::EnsureWritableFastElements(holder);
     }
 
     if (kind == to) return;
 
+  } else if (holder_map_->is_dictionary_map()) {
+    return;
   } else {
-    if (holder_map_->is_dictionary_map()) return;
     holder_map_ =
         Map::PrepareForDataProperty(holder_map_, descriptor_number(), value);
 
     if (holder->map() == *holder_map_) {
       // Update the property details if the representation was None.
       if (representation().IsNone()) {
         property_details_ = holder_map_->instance_descriptors()->GetDetails(
             descriptor_number());
       }
       return;
@@ skipping 44 matching lines @@
     Handle<JSObject> receiver, Handle<Object> value,
     PropertyAttributes attributes, Object::StoreFromKeyed store_mode) {
   DCHECK(receiver.is_identical_to(GetStoreTarget()));
   if (state_ == TRANSITION) return;
   DCHECK(state_ != LookupIterator::ACCESSOR ||
          (GetAccessors()->IsAccessorInfo() &&
           AccessorInfo::cast(*GetAccessors())->is_special_data_property()));
   DCHECK_NE(INTEGER_INDEXED_EXOTIC, state_);
   DCHECK(state_ == NOT_FOUND || !HolderIsReceiverOrHiddenPrototype());
 
-  auto transition = Map::TransitionToDataProperty(
-      handle(receiver->map(), isolate_), name_, value, attributes, store_mode);
+  Handle<Map> map(receiver->map(), isolate_);
+
+  // Dictionary maps can always have additional data properties.
+  if (map->is_dictionary_map()) {
+    state_ = TRANSITION;
+    if (map->IsJSGlobalObjectMap()) {
+      // Install a property cell.
+      InternalizeName();
+      auto cell = JSGlobalObject::EnsurePropertyCell(
+          Handle<JSGlobalObject>::cast(receiver), name());
+      DCHECK(cell->value()->IsTheHole());
+      transition_ = cell;
+    } else {
+      transition_ = map;
+    }
+    return;
+  }
+
+  Handle<Map> transition =
+      Map::TransitionToDataProperty(map, name_, value, attributes, store_mode);
   state_ = TRANSITION;
   transition_ = transition;
 
-  if (receiver->IsJSGlobalObject()) {
-    // Install a property cell.
-    InternalizeName();
-    auto cell = JSGlobalObject::EnsurePropertyCell(
-        Handle<JSGlobalObject>::cast(receiver), name());
-    DCHECK(cell->value()->IsTheHole());
-    transition_ = cell;
-  } else if (!transition->is_dictionary_map()) {
+  if (!transition->is_dictionary_map()) {
     property_details_ = transition->GetLastDescriptorDetails();
     has_property_ = true;
   }
 }
 
 void LookupIterator::ApplyTransitionToDataProperty(Handle<JSObject> receiver) {
   DCHECK_EQ(TRANSITION, state_);
 
   DCHECK(receiver.is_identical_to(GetStoreTarget()));
 
@@ skipping 415 matching lines @@
     // Fall through.
     default:
       return NOT_FOUND;
   }
   UNREACHABLE();
   return state_;
 }
 
 }  // namespace internal
 }  // namespace v8