The Elements pointer in a JSObject can have a filler map instead of a

src/objects-debug.cc

 // 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 317 matching lines @@
         if (r.IsDouble()) ASSERT(value->IsHeapNumber());
         if (value->IsUninitialized()) continue;
         if (r.IsSmi()) ASSERT(value->IsSmi());
         if (r.IsHeapObject()) ASSERT(value->IsHeapObject());
       }
     }
   }
 
   // If a GC was caused while constructing this object, the elements
   // pointer may point to a one pointer filler map.
-  if ((FLAG_use_gvn && FLAG_use_allocation_folding) ||
-      (reinterpret_cast<Map*>(elements()) !=
-      GetHeap()->one_pointer_filler_map())) {
+  if (ElementsAreSafeToExamine()) {
     CHECK_EQ((map()->has_fast_smi_or_object_elements() ||
               (elements() == GetHeap()->empty_fixed_array())),
              (elements()->map() == GetHeap()->fixed_array_map() ||
               elements()->map() == GetHeap()->fixed_cow_array_map()));
     CHECK(map()->has_fast_object_elements() == HasFastObjectElements());
   }
 }
 
 
 void Map::MapVerify() {
@@ skipping 340 matching lines @@
     }
   }
 }
 
 
 void JSArray::JSArrayVerify() {
   JSObjectVerify();
   CHECK(length()->IsNumber() || length()->IsUndefined());
   // If a GC was caused while constructing this array, the elements
   // pointer may point to a one pointer filler map.
-  if ((FLAG_use_gvn && FLAG_use_allocation_folding) ||
-      (reinterpret_cast<Map*>(elements()) !=
-      GetHeap()->one_pointer_filler_map())) {
+  if (ElementsAreSafeToExamine()) {
     CHECK(elements()->IsUndefined() ||
           elements()->IsFixedArray() ||
           elements()->IsFixedDoubleArray());
   }
 }
 
 
 void JSSet::JSSetVerify() {
   CHECK(IsJSSet());
   JSObjectVerify();
@@ skipping 422 matching lines @@
          number_of_fast_used_elements_, number_of_fast_unused_elements_);
 
   PrintF("    - slow elements (#%d): %d (used) %d (unused)\n",
          number_of_objects_ - number_of_objects_with_fast_elements_,
          number_of_slow_used_elements_, number_of_slow_unused_elements_);
 
   PrintF("\n");
 }
 
 
+bool JSObject::ElementsAreSafeToExamine() {
+  return (FLAG_use_gvn && FLAG_use_allocation_folding) ||
+      reinterpret_cast<Map*>(elements()) !=
+      GetHeap()->one_pointer_filler_map();
+}
+
+
 bool DescriptorArray::IsSortedNoDuplicates(int valid_entries) {
   if (valid_entries == -1) valid_entries = number_of_descriptors();
   Name* current_key = NULL;
   uint32_t current = 0;
   for (int i = 0; i < number_of_descriptors(); i++) {
     Name* key = GetSortedKey(i);
     if (key == current_key) {
       PrintDescriptors();
       return false;
     }
@@ skipping 40 matching lines @@
   for (int i = 0; i < number_of_transitions(); ++i) {
     if (!CheckOneBackPointer(current_map, GetTarget(i))) return false;
   }
   return true;
 }
 
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal