Distinguish weak references in heap snapshots, group GC roots.

src/heap.cc

 // Copyright 2011 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 5045 matching lines @@
 
 
 void Heap::IterateRoots(ObjectVisitor* v, VisitMode mode) {
   IterateStrongRoots(v, mode);
   IterateWeakRoots(v, mode);
 }
 
 
 void Heap::IterateWeakRoots(ObjectVisitor* v, VisitMode mode) {
   v->VisitPointer(reinterpret_cast<Object**>(&roots_[kSymbolTableRootIndex]));
-  v->Synchronize("symbol_table");
+  v->Synchronize(VisitorSynchronization::kSymbolTable);
   if (mode != VISIT_ALL_IN_SCAVENGE &&
       mode != VISIT_ALL_IN_SWEEP_NEWSPACE) {
     // Scavenge collections have special processing for this.
     external_string_table_.Iterate(v);
   }
-  v->Synchronize("external_string_table");
+  v->Synchronize(VisitorSynchronization::kExternalStringsTable);
 }
 
 
 void Heap::IterateStrongRoots(ObjectVisitor* v, VisitMode mode) {
   v->VisitPointers(&roots_[0], &roots_[kStrongRootListLength]);
-  v->Synchronize("strong_root_list");
+  v->Synchronize(VisitorSynchronization::kStrongRootList);
 
   v->VisitPointer(BitCast<Object**>(&hidden_symbol_));
-  v->Synchronize("symbol");
+  v->Synchronize(VisitorSynchronization::kSymbol);
 
   isolate_->bootstrapper()->Iterate(v);
-  v->Synchronize("bootstrapper");
+  v->Synchronize(VisitorSynchronization::kBootstrapper);
   isolate_->Iterate(v);
-  v->Synchronize("top");
+  v->Synchronize(VisitorSynchronization::kTop);
   Relocatable::Iterate(v);
-  v->Synchronize("relocatable");
+  v->Synchronize(VisitorSynchronization::kRelocatable);
 
 #ifdef ENABLE_DEBUGGER_SUPPORT
   isolate_->debug()->Iterate(v);
   if (isolate_->deoptimizer_data() != NULL) {
     isolate_->deoptimizer_data()->Iterate(v);
   }
 #endif
-  v->Synchronize("debug");
+  v->Synchronize(VisitorSynchronization::kDebug);
   isolate_->compilation_cache()->Iterate(v);
-  v->Synchronize("compilationcache");
+  v->Synchronize(VisitorSynchronization::kCompilationCache);
 
   // Iterate over local handles in handle scopes.
   isolate_->handle_scope_implementer()->Iterate(v);
-  v->Synchronize("handlescope");
+  v->Synchronize(VisitorSynchronization::kHandleScope);
 
   // Iterate over the builtin code objects and code stubs in the
   // heap. Note that it is not necessary to iterate over code objects
   // on scavenge collections.
   if (mode != VISIT_ALL_IN_SCAVENGE) {
     isolate_->builtins()->IterateBuiltins(v);
   }
-  v->Synchronize("builtins");
+  v->Synchronize(VisitorSynchronization::kBuiltins);
 
   // Iterate over global handles.
   switch (mode) {
     case VISIT_ONLY_STRONG:
       isolate_->global_handles()->IterateStrongRoots(v);
       break;
     case VISIT_ALL_IN_SCAVENGE:
       isolate_->global_handles()->IterateNewSpaceStrongAndDependentRoots(v);
       break;
     case VISIT_ALL_IN_SWEEP_NEWSPACE:
     case VISIT_ALL:
       isolate_->global_handles()->IterateAllRoots(v);
       break;
   }
-  v->Synchronize("globalhandles");
+  v->Synchronize(VisitorSynchronization::kGlobalHandles);
 
   // Iterate over pointers being held by inactive threads.
   isolate_->thread_manager()->Iterate(v);
-  v->Synchronize("threadmanager");
+  v->Synchronize(VisitorSynchronization::kThreadManager);
 
   // Iterate over the pointers the Serialization/Deserialization code is
   // holding.
   // During garbage collection this keeps the partial snapshot cache alive.
   // During deserialization of the startup snapshot this creates the partial
   // snapshot cache and deserializes the objects it refers to.  During
   // serialization this does nothing, since the partial snapshot cache is
   // empty.  However the next thing we do is create the partial snapshot,
   // filling up the partial snapshot cache with objects it needs as we go.
   SerializerDeserializer::Iterate(v);
@@ skipping 1343 matching lines @@
   isolate_->heap()->store_buffer()->Compact();
   isolate_->heap()->store_buffer()->Filter(MemoryChunk::ABOUT_TO_BE_FREED);
   for (chunk = chunks_queued_for_free_; chunk != NULL; chunk = next) {
     next = chunk->next_chunk();
     isolate_->memory_allocator()->Free(chunk);
   }
   chunks_queued_for_free_ = NULL;
 }
 
 } }  // namespace v8::internal