Add zapping of Map contents in debug mode.

src/objects-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3333 matching lines @@
 
 void Map::init_instance_descriptors() {
   WRITE_FIELD(this, kInstanceDescriptorsOrBitField3Offset, Smi::FromInt(0));
 }
 
 
 void Map::clear_instance_descriptors() {
   Object* object = READ_FIELD(this,
                               kInstanceDescriptorsOrBitField3Offset);
   if (!object->IsSmi()) {
+#ifdef DEBUG
+    ZapInstanceDescriptors();
+#endif
     WRITE_FIELD(
         this,
         kInstanceDescriptorsOrBitField3Offset,
         Smi::FromInt(DescriptorArray::cast(object)->bit_field3_storage()));
   }
 }
 
 
 void Map::set_instance_descriptors(DescriptorArray* value,
                                    WriteBarrierMode mode) {
   Object* object = READ_FIELD(this,
                               kInstanceDescriptorsOrBitField3Offset);
   Heap* heap = GetHeap();
   if (value == heap->empty_descriptor_array()) {
     clear_instance_descriptors();
     return;
   } else {
     if (object->IsSmi()) {
       value->set_bit_field3_storage(Smi::cast(object)->value());
     } else {
       value->set_bit_field3_storage(
           DescriptorArray::cast(object)->bit_field3_storage());
     }
   }
   ASSERT(!is_shared());
+#ifdef DEBUG
+  if (value != instance_descriptors()) {
+    ZapInstanceDescriptors();
+  }
+#endif
   WRITE_FIELD(this, kInstanceDescriptorsOrBitField3Offset, value);
   CONDITIONAL_WRITE_BARRIER(
       heap, this, kInstanceDescriptorsOrBitField3Offset, value, mode);
 }
 
 
 int Map::bit_field3() {
   Object* object = READ_FIELD(this,
                               kInstanceDescriptorsOrBitField3Offset);
   if (object->IsSmi()) {
@@ skipping 52 matching lines @@
   } else {
     return GetHeap()->empty_fixed_array();
   }
 }
 
 
 void Map::set_prototype_transitions(FixedArray* value, WriteBarrierMode mode) {
   Heap* heap = GetHeap();
   ASSERT(value != heap->empty_fixed_array());
   value->set(kProtoTransitionBackPointerOffset, GetBackPointer());
+#ifdef DEBUG
+  if (value != prototype_transitions()) {
+    ZapPrototypeTransitions();
+  }
+#endif
   WRITE_FIELD(this, kPrototypeTransitionsOrBackPointerOffset, value);
   CONDITIONAL_WRITE_BARRIER(
       heap, this, kPrototypeTransitionsOrBackPointerOffset, value, mode);
 }
 
 
 void Map::init_prototype_transitions(Object* undefined) {
   ASSERT(undefined->IsUndefined());
   WRITE_FIELD(this, kPrototypeTransitionsOrBackPointerOffset, undefined);
 }
@@ skipping 1553 matching lines @@
 #undef WRITE_UINT32_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_