[ic] Support data handlers that represent transitioning stores.

src/ic/ic.cc

 // Copyright 2012 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/ic/ic.h"
 
 #include <iostream>
 
 #include "src/accessors.h"
 #include "src/api-arguments-inl.h"
@@ skipping 834 matching lines @@
     TRACE_HANDLER_STATS(isolate(), LoadIC_LoadFieldDH);
     return LoadHandler::LoadField(isolate(), index);
   }
   TRACE_HANDLER_STATS(isolate(), LoadIC_LoadFieldStub);
   LoadFieldStub stub(isolate(), index);
   return stub.GetCode();
 }
 
 namespace {
 
-template <bool fill_array>
+template <bool fill_array = true>
 int InitPrototypeChecks(Isolate* isolate, Handle<Map> receiver_map,
                         Handle<JSObject> holder, Handle<FixedArray> array,
-                        Handle<Name> name) {
+                        Handle<Name> name, int first_index) {
   DCHECK(holder.is_null() || holder->HasFastProperties());
 
   // The following kinds of receiver maps require custom handler compilation.
   if (receiver_map->IsJSGlobalObjectMap()) {
     return -1;
   }
   // We don't encode the requirement to check access rights because we already
   // passed the access check for current native context and the access
   // can't be revoked.
 
   HandleScope scope(isolate);
   int checks_count = 0;
 
   // Create/count entries for each global or dictionary prototype appeared in
   // the prototype chain contains from receiver till holder.
   for (PrototypeIterator iter(receiver_map); !iter.IsAtEnd(); iter.Advance()) {
     Handle<JSObject> current = PrototypeIterator::GetCurrent<JSObject>(iter);
     if (holder.is_identical_to(current)) break;
     Handle<Map> current_map(current->map(), isolate);
 
     if (current_map->IsJSGlobalObjectMap()) {
       if (fill_array) {
         Handle<JSGlobalObject> global = Handle<JSGlobalObject>::cast(current);
         Handle<PropertyCell> cell = JSGlobalObject::EnsureEmptyPropertyCell(
             global, name, PropertyCellType::kInvalidated);
         DCHECK(cell->value()->IsTheHole(isolate));
         Handle<WeakCell> weak_cell = isolate->factory()->NewWeakCell(cell);
-        array->set(LoadHandler::kFirstPrototypeIndex + checks_count,
-                   *weak_cell);
+        array->set(first_index + checks_count, *weak_cell);
       }
       checks_count++;
 
     } else if (current_map->is_dictionary_map()) {
       DCHECK(!current_map->IsJSGlobalProxyMap());  // Proxy maps are fast.
       if (fill_array) {
         DCHECK_EQ(NameDictionary::kNotFound,
                   current->property_dictionary()->FindEntry(name));
         Handle<WeakCell> weak_cell =
             Map::GetOrCreatePrototypeWeakCell(current, isolate);
-        array->set(LoadHandler::kFirstPrototypeIndex + checks_count,
-                   *weak_cell);
+        array->set(first_index + checks_count, *weak_cell);
       }
       checks_count++;
     }
   }
   return checks_count;
 }
 
+// Returns 0 if the validity cell check is enough to ensure that the
+// prototype chain from |receiver_map| till |holder| did not change.
+// If the |holder| is an empty handle then the full prototype chain is
+// checked.
+// Returns -1 if the handler has to be compiled or the number of prototype
+// checks otherwise.
+int GetPrototypeCheckCount(Isolate* isolate, Handle<Map> receiver_map,
+                           Handle<JSObject> holder) {
+  return InitPrototypeChecks<false>(isolate, receiver_map, holder,
+                                    Handle<FixedArray>(), Handle<Name>(), 0);
+}
+
 }  // namespace
 
-int LoadIC::GetPrototypeCheckCount(Handle<Map> receiver_map,
-                                   Handle<JSObject> holder) {
-  return InitPrototypeChecks<false>(isolate(), receiver_map, holder,
-                                    Handle<FixedArray>(), Handle<Name>());
-}
-
 Handle<Object> LoadIC::LoadFromPrototype(Handle<Map> receiver_map,
                                          Handle<JSObject> holder,
                                          Handle<Name> name,
                                          Handle<Object> smi_handler) {
-  int checks_count = GetPrototypeCheckCount(receiver_map, holder);
+  int checks_count = GetPrototypeCheckCount(isolate(), receiver_map, holder);
   DCHECK_LE(0, checks_count);
 
   if (receiver_map->IsJSGlobalObjectMap()) {
     UNREACHABLE();
   } else if (receiver_map->is_dictionary_map()) {
     smi_handler =
         LoadHandler::EnableNegativeLookupOnReceiver(isolate(), smi_handler);
   }
 
   Handle<Cell> validity_cell =
       Map::GetOrCreatePrototypeChainValidityCell(receiver_map, isolate());
   DCHECK(!validity_cell.is_null());
 
   Handle<WeakCell> holder_cell =
       Map::GetOrCreatePrototypeWeakCell(holder, isolate());
 
   if (checks_count == 0) {
     return isolate()->factory()->NewTuple3(holder_cell, smi_handler,
                                            validity_cell);
   }
   Handle<FixedArray> handler_array(isolate()->factory()->NewFixedArray(
       LoadHandler::kFirstPrototypeIndex + checks_count, TENURED));
   handler_array->set(LoadHandler::kSmiHandlerIndex, *smi_handler);
   handler_array->set(LoadHandler::kValidityCellIndex, *validity_cell);
   handler_array->set(LoadHandler::kHolderCellIndex, *holder_cell);
-  InitPrototypeChecks<true>(isolate(), receiver_map, holder, handler_array,
-                            name);
+  InitPrototypeChecks(isolate(), receiver_map, holder, handler_array, name,
+                      LoadHandler::kFirstPrototypeIndex);
   return handler_array;
 }
 
 Handle<Object> LoadIC::LoadNonExistent(Handle<Map> receiver_map,
                                        Handle<Name> name) {
   Handle<JSObject> holder;  // null handle
-  int checks_count = GetPrototypeCheckCount(receiver_map, holder);
+  int checks_count = GetPrototypeCheckCount(isolate(), receiver_map, holder);
   DCHECK_LE(0, checks_count);
   DCHECK(!receiver_map->IsJSGlobalObjectMap());
 
   Handle<Object> smi_handler = LoadHandler::LoadNonExistent(
       isolate(), receiver_map->is_dictionary_map());
 
   Handle<Object> validity_cell =
       Map::GetOrCreatePrototypeChainValidityCell(receiver_map, isolate());
   if (validity_cell.is_null()) {
     // This must be a case when receiver's prototype is null.
     DCHECK_EQ(*isolate()->factory()->null_value(),
               receiver_map->GetPrototypeChainRootMap(isolate())->prototype());
     DCHECK_EQ(0, checks_count);
     validity_cell = handle(Smi::FromInt(0), isolate());
   }
 
   Factory* factory = isolate()->factory();
   if (checks_count == 0) {
     return factory->NewTuple3(factory->null_value(), smi_handler,
                               validity_cell);
   }
   Handle<FixedArray> handler_array(factory->NewFixedArray(
       LoadHandler::kFirstPrototypeIndex + checks_count, TENURED));
   handler_array->set(LoadHandler::kSmiHandlerIndex, *smi_handler);
   handler_array->set(LoadHandler::kValidityCellIndex, *validity_cell);
   handler_array->set(LoadHandler::kHolderCellIndex, *factory->null_value());
-  InitPrototypeChecks<true>(isolate(), receiver_map, holder, handler_array,
-                            name);
+  InitPrototypeChecks(isolate(), receiver_map, holder, handler_array, name,
+                      LoadHandler::kFirstPrototypeIndex);
   return handler_array;
 }
 
 bool IsCompatibleReceiver(LookupIterator* lookup, Handle<Map> receiver_map) {
   DCHECK(lookup->state() == LookupIterator::ACCESSOR);
   Isolate* isolate = lookup->isolate();
   Handle<Object> accessors = lookup->GetAccessors();
   if (accessors->IsAccessorInfo()) {
     Handle<AccessorInfo> info = Handle<AccessorInfo>::cast(accessors);
     if (info->getter() != NULL &&
@@ skipping 820 matching lines @@
   if (!use_ic) {
     TRACE_GENERIC_IC(isolate(), "StoreIC", "LookupForWrite said 'false'");
   }
   Handle<Object> handler = use_ic ? ComputeHandler(lookup, value)
                                   : Handle<Object>::cast(slow_stub());
 
   PatchCache(lookup->name(), handler);
   TRACE_IC("StoreIC", lookup->name());
 }
 
+Handle<Object> StoreIC::StoreTransition(Handle<Map> receiver_map,
+                                        Handle<JSObject> holder,
+                                        Handle<Map> transition,
+                                        Handle<Name> name) {
+  int descriptor = transition->LastAdded();
+  Handle<DescriptorArray> descriptors(transition->instance_descriptors());
+  PropertyDetails details = descriptors->GetDetails(descriptor);
+  Representation representation = details.representation();
+  DCHECK(!representation.IsNone());
+
+  // Stub is never generated for objects that require access checks.

[Jakob Kummerow, 2016/11/10 14:13:07]

No stubs are generated at all ;-) Suggestion:
"Declarative handlers don't support access checks."

[Igor Sheludko, 2016/11/10 15:31:55]

Done.

+  DCHECK(!transition->is_access_check_needed());
+
+  Handle<Object> smi_handler;
+  if (details.type() == DATA_CONSTANT) {
+    smi_handler = StoreHandler::TransitionToConstant(isolate(), descriptor);
+
+  } else {
+    DCHECK_EQ(DATA, details.type());
+    bool extend_storage =
+        Map::cast(transition->GetBackPointer())->unused_property_fields() == 0;
+
+    FieldIndex index = FieldIndex::ForDescriptor(*transition, descriptor);
+    smi_handler = StoreHandler::TransitionToField(
+        isolate(), descriptor, index, representation, extend_storage);
+  }
+
+  int checks_count = GetPrototypeCheckCount(isolate(), receiver_map, holder);
+  DCHECK_LE(0, checks_count);
+  DCHECK(!receiver_map->IsJSGlobalObjectMap());
+
+  // Stub is never generated for objects that require access checks.

[Jakob Kummerow, 2016/11/10 14:13:07]

You've already checked this above.

[Igor Sheludko, 2016/11/10 15:31:55]

Done.

+  DCHECK(!transition->is_access_check_needed());
+
+  Handle<Object> validity_cell =
+      Map::GetOrCreatePrototypeChainValidityCell(receiver_map, isolate());
+  if (validity_cell.is_null()) {
+    // This must be a case when receiver's prototype is null.
+    DCHECK_EQ(*isolate()->factory()->null_value(),
+              receiver_map->GetPrototypeChainRootMap(isolate())->prototype());
+    DCHECK_EQ(0, checks_count);
+    validity_cell = handle(Smi::FromInt(0), isolate());
+  }
+
+  Handle<WeakCell> transition_cell = Map::WeakCellForMap(transition);
+
+  Factory* factory = isolate()->factory();
+  if (checks_count == 0) {
+    return factory->NewTuple3(transition_cell, smi_handler, validity_cell);
+  }
+  Handle<FixedArray> handler_array(factory->NewFixedArray(
+      LoadHandler::kFirstPrototypeIndex + checks_count, TENURED));

[Jakob Kummerow, 2016/11/10 14:13:07]

s/LoadHandler/StoreHandler/ here and in the next three lines

[Igor Sheludko, 2016/11/10 15:31:55]

Done.

+  handler_array->set(LoadHandler::kSmiHandlerIndex, *smi_handler);
+  handler_array->set(LoadHandler::kValidityCellIndex, *validity_cell);
+  handler_array->set(LoadHandler::kHolderCellIndex, *transition_cell);

[Jakob Kummerow, 2016/11/10 14:13:07]

s/kHolderCellIndex/kTransitionCellIndex/

[Igor Sheludko, 2016/11/10 15:31:55]

Done.

+  InitPrototypeChecks(isolate(), receiver_map, holder, handler_array, name,
+                      StoreHandler::kFirstPrototypeIndex);
+  return handler_array;
+}
 
 static Handle<Code> PropertyCellStoreHandler(
     Isolate* isolate, Handle<JSObject> receiver, Handle<JSGlobalObject> holder,
     Handle<Name> name, Handle<PropertyCell> cell, PropertyCellType type) {
   auto constant_type = Nothing<PropertyCellConstantType>();
   if (type == PropertyCellType::kConstantType) {
     constant_type = Just(cell->GetConstantType());
   }
   StoreGlobalStub stub(isolate, type, constant_type,
                        receiver->IsJSGlobalProxy());
@@ skipping 16 matching lines @@
       auto store_target = lookup->GetStoreTarget();
       if (store_target->IsJSGlobalObject()) {
         break;  // Custom-compiled handler.
       }
       // Currently not handled by CompileStoreTransition.
       if (!holder->HasFastProperties()) {
         TRACE_GENERIC_IC(isolate(), "StoreIC", "transition from slow");
         TRACE_HANDLER_STATS(isolate(), StoreIC_SlowStub);
         return slow_stub();
       }
-
       DCHECK(lookup->IsCacheableTransition());
+      if (FLAG_tf_store_ic_stub) {
+        Handle<Map> transition = lookup->transition_map();
+        TRACE_HANDLER_STATS(isolate(), StoreIC_StoreTransitionDH);
+        return StoreTransition(receiver_map(), holder, transition,
+                               lookup->name());
+      }
       break;  // Custom-compiled handler.
     }
 
     case LookupIterator::INTERCEPTOR: {
       DCHECK(!holder->GetNamedInterceptor()->setter()->IsUndefined(isolate()));
       TRACE_HANDLER_STATS(isolate(), StoreIC_StoreInterceptorStub);
       StoreInterceptorStub stub(isolate());
       return stub.GetCode();
     }
 
@@ skipping 119 matching lines @@
       if (store_target->IsJSGlobalObject()) {
         TRACE_HANDLER_STATS(isolate(), StoreIC_StoreGlobalTransition);
         Handle<PropertyCell> cell = lookup->transition_cell();
         cell->set_value(*value);
         Handle<Code> code = PropertyCellStoreHandler(
             isolate(), store_target, Handle<JSGlobalObject>::cast(store_target),
             lookup->name(), cell, PropertyCellType::kConstant);
         cell->set_value(isolate()->heap()->the_hole_value());
         return code;
       }
+      DCHECK(!FLAG_tf_store_ic_stub);
       Handle<Map> transition = lookup->transition_map();
       // Currently not handled by CompileStoreTransition.
       DCHECK(holder->HasFastProperties());
 
       DCHECK(lookup->IsCacheableTransition());
       TRACE_HANDLER_STATS(isolate(), StoreIC_StoreTransition);
       NamedStoreHandlerCompiler compiler(isolate(), receiver_map(), holder);
       return compiler.CompileStoreTransition(transition, lookup->name());
     }
 
@@ skipping 1136 matching lines @@
     DCHECK_EQ(LookupIterator::INTERCEPTOR, it.state());
     it.Next();
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, result,
                                        Object::GetProperty(&it));
   }
 
   return *result;
 }
 }  // namespace internal
 }  // namespace v8