[ic] Don't use slow stub handler for fresh transitioning stores.

Given that we got a store transition handler for free (because it's just
a transition map) there's no need to wait for a second "use" of that
transition in order to install a normal store transition handler.

Bug: v8:5988
Change-Id: Iecdcfdd096a8efffdd0662f1b1d604943e57d85a
Reviewed-on: https://chromium-review.googlesource.com/997553Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52442}

src/ic/ic.cc

@@ -1300,8 +1300,8 @@ bool StoreIC::LookupForWrite(LookupIterator* it, Handle<Object> value,
           if (it->HolderIsReceiverOrHiddenPrototype()) return false;
 
           if (it->ExtendingNonExtensible(receiver)) return false;
-          created_new_transition_ = it->PrepareTransitionToDataProperty(
-              receiver, value, NONE, store_mode);
+          it->PrepareTransitionToDataProperty(receiver, value, NONE,
+                                              store_mode);
           return it->IsCacheableTransition();
         }
       }
@@ -1310,8 +1310,7 @@ bool StoreIC::LookupForWrite(LookupIterator* it, Handle<Object> value,
 
   receiver = it->GetStoreTarget<JSObject>();
   if (it->ExtendingNonExtensible(receiver)) return false;
-  created_new_transition_ =
-      it->PrepareTransitionToDataProperty(receiver, value, NONE, store_mode);
+  it->PrepareTransitionToDataProperty(receiver, value, NONE, store_mode);
   return it->IsCacheableTransition();
 }
 
@@ -1435,13 +1434,6 @@ void StoreIC::UpdateCaches(LookupIterator* lookup, Handle<Object> value,
         return;
       }
     }
-    if (created_new_transition_) {
-      // The first time a transition is performed, there's a good chance that
-      // it won't be taken again, so don't bother creating a handler.
-      set_slow_stub_reason("new transition");
-      TraceIC("StoreIC", lookup->name());
-      return;
-    }
     handler = ComputeHandler(lookup);
   } else {
     set_slow_stub_reason("LookupForWrite said 'false'");

src/ic/ic.h

@@ -329,8 +329,6 @@ class StoreIC : public IC {
   Handle<Object> ComputeHandler(LookupIterator* lookup);
 
   friend class IC;
-
-  bool created_new_transition_ = false;
 };
 
 class StoreGlobalIC : public StoreIC {

src/lookup.cc

@@ -495,14 +495,12 @@ void LookupIterator::ReconfigureDataProperty(Handle<Object> value,
 
 // Can only be called when the receiver is a JSObject. JSProxy has to be handled
 // via a trap. Adding properties to primitive values is not observable.
-// Returns true if a new transition has been created, or false if an existing
-// transition was followed.
-bool LookupIterator::PrepareTransitionToDataProperty(
+void LookupIterator::PrepareTransitionToDataProperty(
     Handle<JSReceiver> receiver, Handle<Object> value,
     PropertyAttributes attributes, Object::StoreFromKeyed store_mode) {
   DCHECK_IMPLIES(receiver->IsJSProxy(), name()->IsPrivate());
   DCHECK(receiver.is_identical_to(GetStoreTarget<JSReceiver>()));
-  if (state_ == TRANSITION) return false;
+  if (state_ == TRANSITION) return;
 
   if (!IsElement() && name()->IsPrivate()) {
     attributes = static_cast<PropertyAttributes>(attributes | DONT_ENUM);
@@ -548,13 +546,11 @@ bool LookupIterator::PrepareTransitionToDataProperty(
           PropertyDetails(kData, attributes, PropertyCellType::kNoCell);
       transition_ = map;
     }
-    return false;
+    return;
   }
 
-  bool created_new_map;
   Handle<Map> transition = Map::TransitionToDataProperty(
-      map, name_, value, attributes, kDefaultFieldConstness, store_mode,
-      &created_new_map);
+      map, name_, value, attributes, kDefaultFieldConstness, store_mode);
   state_ = TRANSITION;
   transition_ = transition;
 
@@ -566,7 +562,6 @@ bool LookupIterator::PrepareTransitionToDataProperty(
     property_details_ = transition->GetLastDescriptorDetails();
     has_property_ = true;
   }
-  return created_new_map;
 }
 
 void LookupIterator::ApplyTransitionToDataProperty(

src/lookup.h

@@ -216,7 +216,7 @@ class V8_EXPORT_PRIVATE LookupIterator final BASE_EMBEDDED {
            (IsElement() || !name_->IsPrivate());
   }
   void PrepareForDataProperty(Handle<Object> value);
-  bool PrepareTransitionToDataProperty(Handle<JSReceiver> receiver,
+  void PrepareTransitionToDataProperty(Handle<JSReceiver> receiver,
                                        Handle<Object> value,
                                        PropertyAttributes attributes,
                                        Object::StoreFromKeyed store_mode);

src/objects.cc

@@ -9744,8 +9744,7 @@ Handle<Map> Map::TransitionToDataProperty(Handle<Map> map, Handle<Name> name,
                                           Handle<Object> value,
                                           PropertyAttributes attributes,
                                           PropertyConstness constness,
-                                          StoreFromKeyed store_mode,
-                                          bool* created_new_map) {
+                                          StoreFromKeyed store_mode) {
   RuntimeCallTimerScope stats_scope(
       *map, map->is_prototype_map()
                 ? RuntimeCallCounterId::kPrototypeMap_TransitionToDataProperty
@@ -9760,7 +9759,6 @@ Handle<Map> Map::TransitionToDataProperty(Handle<Map> map, Handle<Name> name,
   Map* maybe_transition =
       TransitionsAccessor(map).SearchTransition(*name, kData, attributes);
   if (maybe_transition != nullptr) {
-    *created_new_map = false;
     Handle<Map> transition(maybe_transition);
     int descriptor = transition->LastAdded();
 
@@ -9771,7 +9769,6 @@ Handle<Map> Map::TransitionToDataProperty(Handle<Map> map, Handle<Name> name,
     return UpdateDescriptorForValue(transition, descriptor, constness, value);
   }
 
-  *created_new_map = true;
   TransitionFlag flag = INSERT_TRANSITION;
   MaybeHandle<Map> maybe_map;
   if (!FLAG_track_constant_fields && value->IsJSFunction()) {

src/objects/map.h

@@ -681,10 +681,12 @@ class Map : public HeapObject {
   // transitions to avoid an explosion in the number of maps for objects used as
   // dictionaries.
   inline bool TooManyFastProperties(StoreFromKeyed store_mode) const;
-  static Handle<Map> TransitionToDataProperty(
-      Handle<Map> map, Handle<Name> name, Handle<Object> value,
-      PropertyAttributes attributes, PropertyConstness constness,
-      StoreFromKeyed store_mode, bool* created_new_map);
+  static Handle<Map> TransitionToDataProperty(Handle<Map> map,
+                                              Handle<Name> name,
+                                              Handle<Object> value,
+                                              PropertyAttributes attributes,
+                                              PropertyConstness constness,
+                                              StoreFromKeyed store_mode);
   static Handle<Map> TransitionToAccessorProperty(
       Isolate* isolate, Handle<Map> map, Handle<Name> name, int descriptor,
       Handle<Object> getter, Handle<Object> setter,

test/cctest/test-field-type-tracking.cc

@@ -368,10 +368,9 @@ class Expectations {
                  heap_type);
 
     Handle<String> name = MakeName("prop", property_index);
-    bool created_new_map;
     return Map::TransitionToDataProperty(
         map, name, value, attributes, constness,
-        Object::CERTAINLY_NOT_STORE_FROM_KEYED, &created_new_map);
+        Object::CERTAINLY_NOT_STORE_FROM_KEYED);
   }
 
   Handle<Map> TransitionToDataConstant(Handle<Map> map,
@@ -382,10 +381,9 @@ class Expectations {
     SetDataConstant(property_index, attributes, value);
 
     Handle<String> name = MakeName("prop", property_index);
-    bool created_new_map;
-    return Map::TransitionToDataProperty(map, name, value, attributes, kConst,
-                                         Object::CERTAINLY_NOT_STORE_FROM_KEYED,
-                                         &created_new_map);
+    return Map::TransitionToDataProperty(
+        map, name, value, attributes, kConst,
+        Object::CERTAINLY_NOT_STORE_FROM_KEYED);
   }
 
   Handle<Map> FollowDataTransition(Handle<Map> map,