Add named links to dependent_code in Map objects in heap snapshot.

src/heap-snapshot-generator.cc

Index: src/heap-snapshot-generator.cc
diff --git a/src/heap-snapshot-generator.cc b/src/heap-snapshot-generator.cc
index 15e0a7ccef3bf2085e28c2c6bc691ed0b44ea69d..316b36a3ab613c511317234e237d629c98848639 100644
--- a/src/heap-snapshot-generator.cc
+++ b/src/heap-snapshot-generator.cc
@@ -892,7 +892,7 @@ class IndexedReferencesExtractor : public ObjectVisitor {
       : generator_(generator),
         parent_obj_(parent_obj),
         parent_(parent),
-        next_index_(1) {
+        next_index_(0) {
   }
   void VisitCodeEntry(Address entry_address) {
      Code* code = Code::cast(Code::GetObjectFromEntryAddress(entry_address));
@@ -1147,6 +1147,10 @@ void V8HeapExplorer::ExtractMapReferences(int entry, Map* map) {
   SetInternalReference(map, entry,
                        "constructor", map->constructor(),
                        Map::kConstructorOffset);
+  TagObject(map->dependent_code(), "(dependent code)");
+  SetInternalReference(map, entry,

[ulan, 2013/07/18 10:56:00]

Note that objects in dependent_code and transitions are weakly referenced.

[alph, 2013/07/18 14:17:37]

I'm curious where does this knowledge come from. AFAICT DependentCode object is
indistinguishable from regular FixedArray. So how does GC know that?

[ulan, 2013/07/18 15:01:46]

It is in StaticMarkingVisitor<StaticVisitor>::MarkMapContents() 

+                       "dependent_code", map->dependent_code(),
+                       Map::kDependentCodeOffset);
 }