Verify the symbol table contents before and after all...

src/mark-compact.cc

 // Copyright 2006-2008 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 78 matching lines @@
   Finish();
 
   // Save the count of marked objects remaining after the collection and
   // null out the GC tracer.
   previous_marked_count_ = tracer_->marked_count();
   ASSERT(previous_marked_count_ == 0);
   tracer_ = NULL;
 }
 
 
-#ifdef DEBUG
-// Helper class for verifying the symbol table.
-class SymbolTableVerifier : public ObjectVisitor {
- public:
-  SymbolTableVerifier() { }
-  void VisitPointers(Object** start, Object** end) {
-    // Visit all HeapObject pointers in [start, end).
-    for (Object** p = start; p < end; p++) {
-      if ((*p)->IsHeapObject()) {
-        // Check that the symbol is actually a symbol.
-        ASSERT((*p)->IsNull() || (*p)->IsUndefined() || (*p)->IsSymbol());
-      }
-    }
-  }
-};
-#endif  // DEBUG
-
-
 void MarkCompactCollector::Prepare(GCTracer* tracer) {
   // Rather than passing the tracer around we stash it in a static member
   // variable.
   tracer_ = tracer;
 
   static const int kFragmentationLimit = 50;  // Percent.
 #ifdef DEBUG
   ASSERT(state_ == IDLE);
   state_ = PREPARE_GC;
 #endif
@@ skipping 32 matching lines @@
     Page::set_rset_state(Page::NOT_IN_USE);
   }
 #endif
 
   PagedSpaces spaces;
   while (PagedSpace* space = spaces.next()) {
     space->PrepareForMarkCompact(compacting_collection_);
   }
 
 #ifdef DEBUG
-  SymbolTable* symbol_table = SymbolTable::cast(Heap::symbol_table());
-  SymbolTableVerifier v;
-  symbol_table->IterateElements(&v);
-
   live_bytes_ = 0;
   live_young_objects_ = 0;
   live_old_pointer_objects_ = 0;
   live_old_data_objects_ = 0;
   live_code_objects_ = 0;
   live_map_objects_ = 0;
   live_lo_objects_ = 0;
 #endif
 }
 
 
 void MarkCompactCollector::Finish() {
 #ifdef DEBUG
-  SymbolTable* symbol_table = SymbolTable::cast(Heap::symbol_table());
-  SymbolTableVerifier v;
-  symbol_table->IterateElements(&v);
-
   ASSERT(state_ == SWEEP_SPACES || state_ == REBUILD_RSETS);
   state_ = IDLE;
 #endif
   // The stub cache is not traversed during GC; clear the cache to
   // force lazy re-initialization of it. This must be done after the
   // GC, because it relies on the new address of certain old space
   // objects (empty string, illegal builtin).
   StubCache::Clear();
 }
 
@@ skipping 39 matching lines @@
   //
   // The check performed is:
   //   object->IsConsString() && !object->IsSymbol() &&
   //   (ConsString::cast(object)->second() == Heap::empty_string())
   // except the maps for the object and its possible substrings might be
   // marked.
   HeapObject* object = HeapObject::cast(*p);
   MapWord map_word = object->map_word();
   map_word.ClearMark();
   InstanceType type = map_word.ToMap()->instance_type();
-  if (type >= FIRST_NONSTRING_TYPE || (type & kIsSymbolMask) != 0) {
-    return object;
-  }
-
-  StringRepresentationTag rep =
-      static_cast<StringRepresentationTag>(type & kStringRepresentationMask);
-  if (rep != kConsStringTag) return object;
+  if ((type & kShortcutTypeMask) != kShortcutTypeTag) return object;
 
   Object* second = reinterpret_cast<ConsString*>(object)->unchecked_second();
   if (reinterpret_cast<String*>(second) != Heap::empty_string()) return object;
 
   // Since we don't have the object's start, it is impossible to update the
   // remembered set.  Therefore, we only replace the string with its left
   // substring when the remembered set does not change.
   Object* first = reinterpret_cast<ConsString*>(object)->unchecked_first();
   if (!Heap::InNewSpace(object) && Heap::InNewSpace(first)) return object;
 
@@ skipping 1518 matching lines @@
 
 void MarkCompactCollector::RebuildRSets() {
 #ifdef DEBUG
   ASSERT(state_ == RELOCATE_OBJECTS);
   state_ = REBUILD_RSETS;
 #endif
   Heap::RebuildRSets();
 }
 
 } }  // namespace v8::internal