[cleanup] Remove dead TransitionAccessor::Encoding::kHandler + related code.

This is also pre-work for in-place weak refs.

BUG=v8:7308, v8:5988

Change-Id: Ie78b0c59695c1e6af9780fffb363c931e2ee34e2
Reviewed-on: https://chromium-review.googlesource.com/1013583
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52658}

src/ic/handler-configuration-inl.h

@@ -187,14 +187,6 @@ Handle<Smi> StoreHandler::StoreApiSetter(Isolate* isolate,
   return handle(Smi::FromInt(config), isolate);
 }
 
-// static
-WeakCell* StoreHandler::GetTransitionCell(Object* handler) {
-  DCHECK(handler->IsStoreHandler());
-  WeakCell* cell = WeakCell::cast(StoreHandler::cast(handler)->data1());
-  DCHECK(!cell->cleared());
-  return cell;
-}
-
 }  // namespace internal
 }  // namespace v8
 

src/ic/handler-configuration.cc

@@ -287,35 +287,5 @@ Handle<Object> StoreHandler::StoreProxy(Isolate* isolate,
                                holder_cell);
 }
 
-Object* StoreHandler::ValidHandlerOrNull(Object* raw_handler, Name* name,
-                                         Handle<Map>* out_transition) {
-  Smi* valid = Smi::FromInt(Map::kPrototypeChainValid);
-
-  DCHECK(raw_handler->IsStoreHandler());
-
-  // Check validity cell.
-  StoreHandler* handler = StoreHandler::cast(raw_handler);
-
-  Object* raw_validity_cell = handler->validity_cell();
-  // |raw_valitity_cell| can be Smi::kZero if no validity cell is required
-  // (which counts as valid).
-  if (raw_validity_cell->IsCell() &&
-      Cell::cast(raw_validity_cell)->value() != valid) {
-    return nullptr;
-  }
-  // We use this ValidHandlerOrNull() function only for transitioning store
-  // handlers which are not applicable to receivers that require access checks.
-  DCHECK(handler->smi_handler()->IsSmi());
-  DCHECK(
-      !DoAccessCheckOnReceiverBits::decode(Smi::ToInt(handler->smi_handler())));
-
-  // Check if the transition target is deprecated.
-  WeakCell* target_cell = GetTransitionCell(raw_handler);
-  Map* transition = Map::cast(target_cell->value());
-  if (transition->is_deprecated()) return nullptr;
-  *out_transition = handle(transition);
-  return raw_handler;
-}
-
 }  // namespace internal
 }  // namespace v8

src/ic/handler-configuration.h

@@ -243,10 +243,6 @@ class StoreHandler final : public DataHandler {
   // Make sure we don't overflow the smi.
   STATIC_ASSERT(FieldIndexBits::kNext <= kSmiValueSize);
 
-  static inline WeakCell* GetTransitionCell(Object* handler);
-  static Object* ValidHandlerOrNull(Object* handler, Name* name,
-                                    Handle<Map>* out_transition);
-
   // Creates a Smi-handler for storing a field to fast object.
   static inline Handle<Smi> StoreField(Isolate* isolate, int descriptor,
                                        FieldIndex field_index,

src/objects-printer.cc

@@ -2024,7 +2024,7 @@ void DescriptorArray::Print() {
 }
 // static
 void TransitionsAccessor::PrintOneTransition(std::ostream& os, Name* key,
-                                             Map* target, Object* raw_target) {
+                                             Map* target) {
   os << "\n     ";
 #ifdef OBJECT_PRINT
   key->NamePrint(os);
@@ -2054,9 +2054,6 @@ void TransitionsAccessor::PrintOneTransition(std::ostream& os, Name* key,
     os << ")";
   }
   os << " -> " << Brief(target);
-  if (!raw_target->IsMap() && !raw_target->IsWeakCell()) {
-    os << " (handler: " << Brief(raw_target) << ")";
-  }
 }
 
 void TransitionArray::Print() {
@@ -2071,32 +2068,25 @@ void TransitionArray::Print(std::ostream& os) {
   for (int i = 0; i < num_transitions; i++) {
     Name* key = GetKey(i);
     Map* target = GetTarget(i);
-    Object* raw_target = GetRawTarget(i);
-    TransitionsAccessor::PrintOneTransition(os, key, target, raw_target);
+    TransitionsAccessor::PrintOneTransition(os, key, target);
   }
   os << "\n" << std::flush;
 }
 
 void TransitionsAccessor::PrintTransitions(std::ostream& os) {  // NOLINT
-  Map* target;
   switch (encoding()) {
     case kPrototypeInfo:
     case kUninitialized:
       return;
-    case kWeakRef:
-      target = Map::cast(raw_transitions_->ToWeakHeapObject());
-      break;
-    case kHandler: {
-      WeakCell* cell = GetTargetCell();
-      DCHECK(!cell->cleared());
-      target = Map::cast(cell->value());
+    case kWeakRef: {
+      Map* target = Map::cast(raw_transitions_->ToWeakHeapObject());
+      Name* key = GetSimpleTransitionKey(target);
+      PrintOneTransition(os, key, target);
       break;
     }
     case kFullTransitionArray:
       return transitions()->Print(os);
   }
-  Name* key = GetSimpleTransitionKey(target);
-  PrintOneTransition(os, key, target, raw_transitions_->GetHeapObject());
 }
 
 void TransitionsAccessor::PrintTransitionTree() {

src/transitions-inl.h

@@ -15,15 +15,6 @@
 namespace v8 {
 namespace internal {
 
-WeakCell* TransitionsAccessor::GetTargetCell() {
-  DCHECK(!needs_reload_);
-  if (target_cell_ == nullptr) {
-    target_cell_ =
-        StoreHandler::GetTransitionCell(raw_transitions_->ToStrongHeapObject());
-  }
-  return target_cell_;
-}
-
 TransitionArray* TransitionsAccessor::transitions() {
   DCHECK_EQ(kFullTransitionArray, encoding());
   return TransitionArray::cast(raw_transitions_->ToStrongHeapObject());
@@ -66,25 +57,19 @@ Name* TransitionArray::GetKey(int transition_number) {
 }
 
 Name* TransitionsAccessor::GetKey(int transition_number) {
-  Map* map = nullptr;
   switch (encoding()) {
     case kPrototypeInfo:
     case kUninitialized:
       UNREACHABLE();
       return nullptr;
-    case kWeakRef:
-      map = Map::cast(raw_transitions_->ToWeakHeapObject());
-      break;
-    case kHandler: {
-      WeakCell* cell = GetTargetCell();
-      DCHECK(!cell->cleared());
-      map = Map::cast(cell->value());
-      break;
+    case kWeakRef: {
+      Map* map = Map::cast(raw_transitions_->ToWeakHeapObject());
+      return GetSimpleTransitionKey(map);
     }
     case kFullTransitionArray:
       return transitions()->GetKey(transition_number);
   }
-  return GetSimpleTransitionKey(map);
+  UNREACHABLE();
 }
 
 void TransitionArray::SetKey(int transition_number, Name* key) {
@@ -109,8 +94,7 @@ PropertyDetails TransitionsAccessor::GetTargetDetails(Name* name, Map* target) {
 
 // static
 Map* TransitionsAccessor::GetTargetFromRaw(Object* raw) {
-  if (raw->IsWeakCell()) return Map::cast(WeakCell::cast(raw)->value());
-  return Map::cast(StoreHandler::GetTransitionCell(raw)->value());
+  return Map::cast(WeakCell::cast(raw)->value());
 }
 
 Object* TransitionArray::GetRawTarget(int transition_number) {
@@ -131,11 +115,6 @@ Map* TransitionsAccessor::GetTarget(int transition_number) {
       return nullptr;
     case kWeakRef:
       return Map::cast(raw_transitions_->ToWeakHeapObject());
-    case kHandler: {
-      WeakCell* cell = GetTargetCell();
-      DCHECK(!cell->cleared());
-      return Map::cast(cell->value());
-    }
     case kFullTransitionArray:
       return transitions()->GetTarget(transition_number);
   }

src/transitions.cc

@@ -20,9 +20,7 @@ void TransitionsAccessor::Initialize() {
   } else if (raw_transitions_->IsWeakHeapObject()) {
     encoding_ = kWeakRef;
   } else if (raw_transitions_->ToStrongHeapObject(&heap_object)) {
-    if (heap_object->IsStoreHandler()) {
-      encoding_ = kHandler;
-    } else if (heap_object->IsTransitionArray()) {
+    if (heap_object->IsTransitionArray()) {
       encoding_ = kFullTransitionArray;
     } else {
       DCHECK(heap_object->IsPrototypeInfo());
@@ -31,7 +29,6 @@ void TransitionsAccessor::Initialize() {
   } else {
     UNREACHABLE();
   }
-  target_cell_ = nullptr;
 #if DEBUG
   needs_reload_ = false;
 #endif
@@ -41,8 +38,6 @@ Map* TransitionsAccessor::GetSimpleTransition() {
   switch (encoding()) {
     case kWeakRef:
       return Map::cast(raw_transitions_->ToWeakHeapObject());
-    case kHandler:
-      return Map::cast(GetTargetCell()->value());
     default:
       return nullptr;
   }
@@ -52,10 +47,6 @@ bool TransitionsAccessor::HasSimpleTransitionTo(Map* map) {
   switch (encoding()) {
     case kWeakRef:
       return raw_transitions_->ToWeakHeapObject() == map;
-    case kHandler:
-      return StoreHandler::GetTransitionCell(
-                 raw_transitions_->ToStrongHeapObject())
-                 ->value() == map;
     case kPrototypeInfo:
     case kUninitialized:
     case kFullTransitionArray:
@@ -108,9 +99,6 @@ void TransitionsAccessor::Insert(Handle<Name> name, Handle<Map> target,
       DCHECK_EQ(*map, simple_transition);
       if (encoding_ == kWeakRef) {
         result->Set(0, GetSimpleTransitionKey(simple_transition), *weak_cell);
-      } else if (encoding_ == kHandler) {
-        result->Set(0, GetSimpleTransitionKey(simple_transition),
-                    raw_transitions_->ToStrongHeapObject());
       } else {
         UNREACHABLE();
       }
@@ -224,19 +212,14 @@ void TransitionsAccessor::Insert(Handle<Name> name, Handle<Map> target,
 Map* TransitionsAccessor::SearchTransition(Name* name, PropertyKind kind,
                                            PropertyAttributes attributes) {
   DCHECK(name->IsUniqueName());
-  Map* map = nullptr;
   switch (encoding()) {
     case kPrototypeInfo:
     case kUninitialized:
       return nullptr;
-    case kWeakRef:
-      map = Map::cast(raw_transitions_->ToWeakHeapObject());
-      break;
-    case kHandler: {
-      WeakCell* cell = GetTargetCell();
-      DCHECK(!cell->cleared());
-      map = Map::cast(cell->value());
-      break;
+    case kWeakRef: {
+      Map* map = Map::cast(raw_transitions_->ToWeakHeapObject());
+      if (!IsMatchingMap(map, name, kind, attributes)) return nullptr;
+      return map;
     }
     case kFullTransitionArray: {
       int transition = transitions()->Search(kind, name, attributes);
@@ -244,8 +227,7 @@ Map* TransitionsAccessor::SearchTransition(Name* name, PropertyKind kind,
       return transitions()->GetTarget(transition);
     }
   }
-  if (!IsMatchingMap(map, name, kind, attributes)) return nullptr;
-  return map;
+  UNREACHABLE();
 }
 
 Map* TransitionsAccessor::SearchSpecial(Symbol* name) {
@@ -283,29 +265,23 @@ MaybeHandle<Map> TransitionsAccessor::FindTransitionToDataProperty(
 
 Handle<String> TransitionsAccessor::ExpectedTransitionKey() {
   DisallowHeapAllocation no_gc;
-  Map* target = nullptr;
   switch (encoding()) {
     case kPrototypeInfo:
     case kUninitialized:
     case kFullTransitionArray:
       return Handle<String>::null();
-    case kWeakRef:
-      target = Map::cast(raw_transitions_->ToWeakHeapObject());
-      break;
-    case kHandler: {
-      WeakCell* cell = GetTargetCell();
-      DCHECK(!cell->cleared());
-      target = Map::cast(cell->value());
-      break;
+    case kWeakRef: {
+      Map* target = Map::cast(raw_transitions_->ToWeakHeapObject());
+      PropertyDetails details = GetSimpleTargetDetails(target);
+      if (details.location() != kField) return Handle<String>::null();
+      DCHECK_EQ(kData, details.kind());
+      if (details.attributes() != NONE) return Handle<String>::null();
+      Name* name = GetSimpleTransitionKey(target);
+      if (!name->IsString()) return Handle<String>::null();
+      return handle(String::cast(name));
     }
   }
-  PropertyDetails details = GetSimpleTargetDetails(target);
-  if (details.location() != kField) return Handle<String>::null();
-  DCHECK_EQ(kData, details.kind());
-  if (details.attributes() != NONE) return Handle<String>::null();
-  Name* name = GetSimpleTransitionKey(target);
-  if (!name->IsString()) return Handle<String>::null();
-  return handle(String::cast(name));
+  UNREACHABLE();
 }
 
 Handle<Map> TransitionsAccessor::ExpectedTransitionTarget() {
@@ -452,7 +428,6 @@ int TransitionsAccessor::NumberOfTransitions() {
     case kUninitialized:
       return 0;
     case kWeakRef:
-    case kHandler:
       return 1;
     case kFullTransitionArray:
       return transitions()->number_of_transitions();
@@ -528,17 +503,16 @@ void TransitionsAccessor::EnsureHasFullTransitionArray() {
 
 void TransitionsAccessor::TraverseTransitionTreeInternal(
     TraverseCallback callback, void* data, DisallowHeapAllocation* no_gc) {
-  Map* simple_target = nullptr;
   switch (encoding()) {
     case kPrototypeInfo:
     case kUninitialized:
       break;
-    case kWeakRef:
-      simple_target = Map::cast(raw_transitions_->ToWeakHeapObject());
-      break;
-    case kHandler:
-      simple_target = Map::cast(GetTargetCell()->value());
+    case kWeakRef: {
+      Map* simple_target = Map::cast(raw_transitions_->ToWeakHeapObject());
+      TransitionsAccessor(simple_target, no_gc)
+          .TraverseTransitionTreeInternal(callback, data, no_gc);
       break;
+    }
     case kFullTransitionArray: {
       if (transitions()->HasPrototypeTransitions()) {
         FixedArray* proto_trans = transitions()->GetPrototypeTransitions();
@@ -558,10 +532,6 @@ void TransitionsAccessor::TraverseTransitionTreeInternal(
       break;
     }
   }
-  if (simple_target != nullptr) {
-    TransitionsAccessor(simple_target, no_gc)
-        .TraverseTransitionTreeInternal(callback, data, no_gc);
-  }
   callback(map_, data);
 }
 

src/transitions.h

@@ -106,8 +106,7 @@ class TransitionsAccessor {
 
 #if DEBUG || OBJECT_PRINT
   void PrintTransitions(std::ostream& os);
-  static void PrintOneTransition(std::ostream& os, Name* key, Map* target,
-                                 Object* raw_target);
+  static void PrintOneTransition(std::ostream& os, Name* key, Map* target);
   void PrintTransitionTree();
   void PrintTransitionTree(std::ostream& os, int level,
                            DisallowHeapAllocation* no_gc);
@@ -125,9 +124,6 @@ class TransitionsAccessor {
     kPrototypeInfo,
     kUninitialized,
     kWeakRef,
-    // TODO(ishell): drop support for kHandler encoding since we use maps
-    // as transition handlers.
-    kHandler,
     kFullTransitionArray,
   };
 
@@ -170,8 +166,6 @@ class TransitionsAccessor {
 
   void ReplaceTransitions(MaybeObject* new_transitions);
 
-  inline WeakCell* GetTargetCell();
-
   inline Map* GetTargetMapFromWeakRef();
 
   void EnsureHasFullTransitionArray();
@@ -187,7 +181,6 @@ class TransitionsAccessor {
   Map* map_;
   MaybeObject* raw_transitions_;
   Encoding encoding_;
-  WeakCell* target_cell_;
 #if DEBUG
   bool needs_reload_;
 #endif