[field type tracking] Use breadth first traversal instead of recursion when updating field types.

... to avoid potential stack overflow when updating happens near the stack limit.

BUG=chromium:599440
LOG=Y

Review URL: https://codereview.chromium.org/1884653002

Cr-Commit-Position: refs/heads/master@{#35436}

src/objects.cc

@@ -3281,25 +3281,40 @@ void Map::UpdateFieldType(int descriptor, Handle<Name> name,
                           Representation new_representation,
                           Handle<Object> new_wrapped_type) {
   DCHECK(new_wrapped_type->IsSmi() || new_wrapped_type->IsWeakCell());
+  // We store raw pointers in the queue, so no allocations are allowed.
   DisallowHeapAllocation no_allocation;
   PropertyDetails details = instance_descriptors()->GetDetails(descriptor);
   if (details.type() != DATA) return;
-  Object* transitions = raw_transitions();
+
+  Zone zone(GetIsolate()->allocator());
+  ZoneQueue<Map*> backlog(&zone);
+  backlog.push(this);
+
+  while (!backlog.empty()) {
+    Map* current = backlog.front();
+    backlog.pop();
+
+    Object* transitions = current->raw_transitions();
     int num_transitions = TransitionArray::NumberOfTransitions(transitions);
     for (int i = 0; i < num_transitions; ++i) {
       Map* target = TransitionArray::GetTarget(transitions, i);
-    target->UpdateFieldType(descriptor, name, new_representation,
-                            new_wrapped_type);
+      backlog.push(target);
     }
+    DescriptorArray* descriptors = current->instance_descriptors();
+    PropertyDetails details = descriptors->GetDetails(descriptor);
+
     // It is allowed to change representation here only from None to something.
     DCHECK(details.representation().Equals(new_representation) ||
            details.representation().IsNone());
 
     // Skip if already updated the shared descriptor.
-  if (instance_descriptors()->GetValue(descriptor) == *new_wrapped_type) return;
-  DataDescriptor d(name, instance_descriptors()->GetFieldIndex(descriptor),
-                   new_wrapped_type, details.attributes(), new_representation);
-  instance_descriptors()->Replace(descriptor, &d);
+    if (descriptors->GetValue(descriptor) != *new_wrapped_type) {
+      DataDescriptor d(name, descriptors->GetFieldIndex(descriptor),
+                       new_wrapped_type, details.attributes(),
+                       new_representation);
+      descriptors->Replace(descriptor, &d);
+    }
+  }
 }
 
 bool FieldTypeIsCleared(Representation rep, FieldType* type) {