Remove CanRetainOtherContext since embedded objects are now weak.

src/type-info.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/v8.h"
 
 #include "src/ast.h"
 #include "src/code-stubs.h"
 #include "src/compiler.h"
 #include "src/ic/ic.h"
@@ skipping 34 matching lines @@
       return Handle<Object>(value, isolate());
     }
   }
   return Handle<Object>::cast(isolate()->factory()->undefined_value());
 }
 
 
 Handle<Object> TypeFeedbackOracle::GetInfo(FeedbackVectorSlot slot) {
   DCHECK(slot.ToInt() >= 0 && slot.ToInt() < feedback_vector_->length());
   Object* obj = feedback_vector_->Get(slot);
-  if (!obj->IsJSFunction() ||
-      !CanRetainOtherContext(JSFunction::cast(obj), *native_context_)) {
-    DCHECK(!obj->IsMap());
-    return Handle<Object>(obj, isolate());
-  }
-  return Handle<Object>::cast(isolate()->factory()->undefined_value());
+  return Handle<Object>(obj, isolate());
 }
 
 
 Handle<Object> TypeFeedbackOracle::GetInfo(FeedbackVectorICSlot slot) {
   DCHECK(slot.ToInt() >= 0 && slot.ToInt() < feedback_vector_->length());
   Handle<Object> undefined =
       Handle<Object>::cast(isolate()->factory()->undefined_value());
   Object* obj = feedback_vector_->Get(slot);
 
   // Vector-based ICs do not embed direct pointers to maps, functions.
   // Instead a WeakCell is always used.
   if (obj->IsWeakCell()) {
     WeakCell* cell = WeakCell::cast(obj);
     if (cell->cleared()) return undefined;
     obj = cell->value();
   }
 
-  if ((obj->IsJSFunction() &&
-       !CanRetainOtherContext(JSFunction::cast(obj), *native_context_)) ||
-      obj->IsAllocationSite() || obj->IsSymbol()) {
+  if (obj->IsJSFunction() || obj->IsAllocationSite() || obj->IsSymbol()) {
     return Handle<Object>(obj, isolate());
   }
 
   return undefined;
 }
 
 
 bool TypeFeedbackOracle::LoadIsUninitialized(TypeFeedbackId id) {
   Handle<Object> maybe_code = GetInfo(id);
   if (maybe_code->IsCode()) {
@@ skipping 150 matching lines @@
   Handle<Object> info = GetInfo(id);
   if (!info->IsCode()) {
     // For some comparisons we don't have ICs, e.g. LiteralCompareTypeof.
     *left_type = *right_type = *combined_type = Type::None(zone());
     return;
   }
   Handle<Code> code = Handle<Code>::cast(info);
 
   Handle<Map> map;
   Map* raw_map = code->FindFirstMap();
-  if (raw_map != NULL) {
-    if (Map::TryUpdate(handle(raw_map)).ToHandle(&map) &&
-        CanRetainOtherContext(*map, *native_context_)) {
-      map = Handle<Map>::null();
-    }
-  }
+  if (raw_map != NULL) Map::TryUpdate(handle(raw_map)).ToHandle(&map);
 
   if (code->is_compare_ic_stub()) {
     CompareICStub stub(code->stub_key(), isolate());
     *left_type = CompareICState::StateToType(zone(), stub.left());
     *right_type = CompareICState::StateToType(zone(), stub.right());
     *combined_type = CompareICState::StateToType(zone(), stub.state(), map);
   } else if (code->is_compare_nil_ic_stub()) {
     CompareNilICStub stub(isolate(), code->extra_ic_state());
     *combined_type = stub.GetType(zone(), map);
     *left_type = *right_type = stub.GetInputType(zone(), map);
@@ skipping 145 matching lines @@
       obj->ic_state() == MEGAMORPHIC) {
     types->Reserve(4, zone());
     isolate()->stub_cache()->CollectMatchingMaps(
         types, name, flags, native_context_, zone());
   } else {
     CollectReceiverTypes<T>(obj, types);
   }
 }
 
 
-// Check if a map originates from a given native context. We use this
-// information to filter out maps from different context to avoid
-// retaining objects from different tabs in Chrome via optimized code.
-bool TypeFeedbackOracle::CanRetainOtherContext(Map* map,
-                                               Context* native_context) {
-  Object* constructor = NULL;
-  while (!map->prototype()->IsNull()) {
-    constructor = map->GetConstructor();
-    if (!constructor->IsNull()) {
-      // If the constructor is not null or a JSFunction, we have to
-      // conservatively assume that it may retain a native context.
-      if (!constructor->IsJSFunction()) return true;
-      // Check if the constructor directly references a foreign context.
-      if (CanRetainOtherContext(JSFunction::cast(constructor),
-                                native_context)) {
-        return true;
-      }
-    }
-    map = HeapObject::cast(map->prototype())->map();
-  }
-  constructor = map->GetConstructor();
-  if (constructor->IsNull()) return false;
-  // If the constructor is not null or a JSFunction, we have to conservatively
-  // assume that it may retain a native context.
-  if (!constructor->IsJSFunction()) return true;
-  JSFunction* function = JSFunction::cast(constructor);
-  return CanRetainOtherContext(function, native_context);
-}
-
-
-bool TypeFeedbackOracle::CanRetainOtherContext(JSFunction* function,
-                                               Context* native_context) {
-  return function->context()->global_object() != native_context->global_object()
-      && function->context()->global_object() != native_context->builtins();
-}
-
-
 void TypeFeedbackOracle::CollectReceiverTypes(TypeFeedbackId ast_id,
                                               SmallMapList* types) {
   Handle<Object> object = GetInfo(ast_id);
   if (!object->IsCode()) return;
   Handle<Code> code = Handle<Code>::cast(object);
   CollectReceiverTypes<Code>(*code, types);
 }
 
 
 template <class T>
 void TypeFeedbackOracle::CollectReceiverTypes(T* obj, SmallMapList* types) {
   MapHandleList maps;
   if (obj->ic_state() == MONOMORPHIC) {
     Map* map = obj->FindFirstMap();
     if (map != NULL) maps.Add(handle(map));
   } else if (obj->ic_state() == POLYMORPHIC) {
     obj->FindAllMaps(&maps);
   } else {
     return;
   }
   types->Reserve(maps.length(), zone());
   for (int i = 0; i < maps.length(); i++) {
     Handle<Map> map(maps.at(i));

[Erik Corry, 2015/03/26 11:20:57]

Perhaps you don't need this variable if it's only used one place.

-    if (!CanRetainOtherContext(*map, *native_context_)) {
-      types->AddMapIfMissing(map, zone());
+    if (IsRelevantFeedback(*map, *native_context_)) {
+      types->AddMapIfMissing(maps.at(i), zone());
     }
   }
 }
 
 
 byte TypeFeedbackOracle::ToBooleanTypes(TypeFeedbackId id) {
   Handle<Object> object = GetInfo(id);
   return object->IsCode() ? Handle<Code>::cast(object)->to_boolean_state() : 0;
 }
 
@@ skipping 75 matching lines @@
          UnseededNumberDictionary::kNotFound);
   // Dictionary has been allocated with sufficient size for all elements.
   DisallowHeapAllocation no_need_to_resize_dictionary;
   HandleScope scope(isolate());
   USE(UnseededNumberDictionary::AtNumberPut(
       dictionary_, IdToKey(ast_id), handle(target, isolate())));
 }
 
 
 } }  // namespace v8::internal