Fix for HeapSnapshotAddressReuse test case.

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 6cbdcd67077b2a22001199e3552712304cc4d61c..58d396b0107f4e8ebc0ca7aa78aa1ec299fb9450 100644
--- a/src/heap-snapshot-generator.cc
+++ b/src/heap-snapshot-generator.cc
@@ -404,21 +404,32 @@ void HeapObjectsMap::MoveObject(Address from, Address to) {
   ASSERT(from != NULL);
   if (from == to) return;
   void* from_value = entries_map_.Remove(from, AddressHash(from));
-  if (from_value == NULL) return;
-  int from_entry_info_index =
-      static_cast<int>(reinterpret_cast<intptr_t>(from_value));
-  entries_.at(from_entry_info_index).addr = to;
-  HashMap::Entry* to_entry = entries_map_.Lookup(to, AddressHash(to), true);
-  if (to_entry->value != NULL) {
-    int to_entry_info_index =
+  if (from_value == NULL) {
+    // We don't know the object that may occupy the place of a known object.

[yurys, 2013/02/21 15:26:43]

I'd rephrase like this:

"It may occur that some untracked object moves to an address X and there is a
tracked object at that address. In this case we should remove the entry as we
know that the object has died."

+    // In that case we need to remove the entry for this died known object.

[yurys, 2013/02/21 15:26:43]

died -> dead

+    void* to_value = entries_map_.Remove(to, AddressHash(to));
+    if (to_value != NULL) {
+      int to_entry_info_index =
+        static_cast<int>(reinterpret_cast<intptr_t>(to_value));
+      entries_.at(to_entry_info_index).addr = NULL;
+    }
+  } else {
+    HashMap::Entry* to_entry = entries_map_.Lookup(to, AddressHash(to), true);
+    if (to_entry->value != NULL) {
+      // We found the entry with to address for an old object.

[yurys, 2013/02/21 15:26:43]

the entry -> existing entry

+      // Without this operation we will have two EntryInfo's with the same
+      // value in addr field. It is bad because later at RemoveDeadEntries
+      // one of this entry will be removed with the corresponding entries_map_
+      // entry.
+      int to_entry_info_index =
         static_cast<int>(reinterpret_cast<intptr_t>(to_entry->value));
-    // Without this operation we will have two EntryInfo's with the same
-    // value in addr field. It is bad because later at RemoveDeadEntries
-    // one of this entry will be removed with the corresponding entries_map_
-    // entry.
-    entries_.at(to_entry_info_index).addr = NULL;
+      entries_.at(to_entry_info_index).addr = NULL;
+      int from_entry_info_index =
+        static_cast<int>(reinterpret_cast<intptr_t>(from_value));
+      entries_.at(from_entry_info_index).addr = to;
+      to_entry->value = reinterpret_cast<void*>(from_entry_info_index);

[yurys, 2013/02/21 15:26:43]

to_entry->value = from_value; ?

+    }
   }
-  to_entry->value = reinterpret_cast<void*>(from_entry_info_index);
 }