Map::ReconfigureProperty() should mark map as unstable when there is an element kind transition som…

src/objects.cc

 // Copyright 2013 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 <iomanip>
 #include <sstream>
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
@@ skipping 1388 matching lines @@
   }
   if (IsJSObject()) {
     HeapStringAllocator allocator;
     StringStream accumulator(&allocator);
     JSObject::cast(this)->JSObjectShortPrint(&accumulator);
     os << accumulator.ToCString().get();
     return;
   }
   switch (map()->instance_type()) {
     case MAP_TYPE:
-      os << "<Map(elements=" << Map::cast(this)->elements_kind() << ")>";
+      os << "<Map(" << ElementsKindToString(Map::cast(this)->elements_kind())
+         << ")>";
       break;
     case FIXED_ARRAY_TYPE:
       os << "<FixedArray[" << FixedArray::cast(this)->length() << "]>";
       break;
     case FIXED_DOUBLE_ARRAY_TYPE:
       os << "<FixedDoubleArray[" << FixedDoubleArray::cast(this)->length()
          << "]>";
       break;
     case BYTE_ARRAY_TYPE:
       os << "<ByteArray[" << ByteArray::cast(this)->length() << "]>";
@@ skipping 1531 matching lines @@
     split_attributes = new_attributes;
   } else {
     PropertyDetails split_prop_details = old_descriptors->GetDetails(split_nof);
     split_kind = split_prop_details.kind();
     split_attributes = split_prop_details.attributes();
   }
   bool transition_target_deprecated = split_map->DeprecateTarget(
       split_kind, old_descriptors->GetKey(split_nof), split_attributes,
       *new_descriptors, *new_layout_descriptor);
 
+  if (from_kind != to_kind) {
+    // There was an elements kind change in the middle of transition tree and
+    // we reconstructed the tree so that all elements kind transitions are
+    // done at the beginning, therefore the |old_map| is no longer stable.
+    old_map->NotifyLeafMapLayoutChange();
+  }
+
   // If |transition_target_deprecated| is true then the transition array
   // already contains entry for given descriptor. This means that the transition
   // could be inserted regardless of whether transitions array is full or not.
   if (!transition_target_deprecated &&
       !TransitionArray::CanHaveMoreTransitions(split_map)) {
     return CopyGeneralizeAllRepresentations(old_map, modify_index, store_mode,
                                             new_kind, new_attributes,
                                             "GenAll_CantHaveMoreTransitions");
   }
 
@@ skipping 14267 matching lines @@
 void PropertyCell::SetValueWithInvalidation(Handle<PropertyCell> cell,
                                             Handle<Object> new_value) {
   if (cell->value() != *new_value) {
     cell->set_value(*new_value);
     Isolate* isolate = cell->GetIsolate();
     cell->dependent_code()->DeoptimizeDependentCodeGroup(
         isolate, DependentCode::kPropertyCellChangedGroup);
   }
 }
 } }  // namespace v8::internal