[heap] Two minor fixes in EstimatedSize

src/context-measure.cc

 // Copyright 2015 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/context-measure.h"
 
 #include "src/base/logging.h"
 #include "src/contexts.h"
 #include "src/objects-inl.h"
 
 namespace v8 {
 namespace internal {
 
 ContextMeasure::ContextMeasure(Context* context)
     : context_(context),
       root_index_map_(context->GetIsolate()),
       recursion_depth_(0),
       count_(0),
       size_(0) {
   DCHECK(context_->IsNativeContext());
   Object* next_link = context_->next_context_link();
+  context_->set(Context::NEXT_CONTEXT_LINK,
+                context->GetIsolate()->heap()->undefined_value());
   MeasureObject(context_);
   MeasureDeferredObjects();
   context_->set(Context::NEXT_CONTEXT_LINK, next_link);
 }
 
 
 bool ContextMeasure::IsShared(HeapObject* object) {
   if (object->IsScript()) return true;
   if (object->IsSharedFunctionInfo()) return true;
   if (object->IsScopeInfo()) return true;
   if (object->IsCode() && !Code::cast(object)->is_optimized_code()) return true;
   if (object->IsAccessorInfo()) return true;
   if (object->IsWeakCell()) return true;
+  if (object->IsMap()) return true;

[Yang, 2017/03/28 12:11:36]

This is not the right thing to do. Most maps actually belong to a context. Maybe
you can use the logic also used in JSReceiver::GetCreationContext?

[Dan Ehrenberg, 2017/03/28 16:51:06]

Sorry for my confusion; of course they do. The new logic uses GetCreationContext
and only charges objects to the ContextMeasure if they were created in the same
context.

   return false;
 }
 
 
 void ContextMeasure::MeasureObject(HeapObject* object) {
   if (reference_map_.Lookup(object).is_valid()) return;
   if (root_index_map_.Lookup(object) != RootIndexMap::kInvalidRootIndex) return;
   if (IsShared(object)) return;
   reference_map_.Add(object, SerializerReference::DummyReference());
   recursion_depth_++;
@@ skipping 24 matching lines @@
 
 
 void ContextMeasure::VisitPointers(Object** start, Object** end) {
   for (Object** current = start; current < end; current++) {
     if ((*current)->IsSmi()) continue;
     MeasureObject(HeapObject::cast(*current));
   }
 }
 }  // namespace internal
 }  // namespace v8