Add WeakCell support to heap profiler.

src/profiler/heap-snapshot-generator.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/profiler/heap-snapshot-generator.h"
 
 #include "src/code-stubs.h"
 #include "src/conversions.h"
 #include "src/debug/debug.h"
 #include "src/objects-body-descriptors.h"
@@ skipping 1029 matching lines @@
   } else if (obj->IsAccessorInfo()) {
     ExtractAccessorInfoReferences(entry, AccessorInfo::cast(obj));
   } else if (obj->IsAccessorPair()) {
     ExtractAccessorPairReferences(entry, AccessorPair::cast(obj));
   } else if (obj->IsCode()) {
     ExtractCodeReferences(entry, Code::cast(obj));
   } else if (obj->IsBox()) {
     ExtractBoxReferences(entry, Box::cast(obj));
   } else if (obj->IsCell()) {
     ExtractCellReferences(entry, Cell::cast(obj));
+  } else if (obj->IsWeakCell()) {
+    ExtractWeakCellReferences(entry, WeakCell::cast(obj));
   } else if (obj->IsPropertyCell()) {
     ExtractPropertyCellReferences(entry, PropertyCell::cast(obj));
   } else if (obj->IsAllocationSite()) {
     ExtractAllocationSiteReferences(entry, AllocationSite::cast(obj));
   }
   return true;
 }
 
 
 bool V8HeapExplorer::ExtractReferencesPass2(int entry, HeapObject* obj) {
@@ skipping 408 matching lines @@
   SetInternalReference(code, entry,
                        "gc_metadata", code->gc_metadata(),
                        Code::kGCMetadataOffset);
   if (code->kind() == Code::OPTIMIZED_FUNCTION) {
     SetWeakReference(code, entry,
                      "next_code_link", code->next_code_link(),
                      Code::kNextCodeLinkOffset);
   }
 }
 
-
 void V8HeapExplorer::ExtractBoxReferences(int entry, Box* box) {
   SetInternalReference(box, entry, "value", box->value(), Box::kValueOffset);
 }
 
-
 void V8HeapExplorer::ExtractCellReferences(int entry, Cell* cell) {
   SetInternalReference(cell, entry, "value", cell->value(), Cell::kValueOffset);
 }
 
+void V8HeapExplorer::ExtractWeakCellReferences(int entry, WeakCell* weak_cell) {
+  SetWeakReference(weak_cell, entry, "value", weak_cell->value(),
+                   WeakCell::kValueOffset);
+  TagObject(weak_cell->next(), "(weak cell)");
+  SetWeakReference(weak_cell, entry, "next", weak_cell->next(),

[ulan, 2016/08/02 12:32:17]

This is a non-essential reference. Might make sense to ignore it to speed up
snapshot generation.

[alph, 2016/08/02 13:00:11]

Done.

+                   WeakCell::kNextOffset);
+}
 
 void V8HeapExplorer::ExtractPropertyCellReferences(int entry,
                                                    PropertyCell* cell) {
   SetInternalReference(cell, entry, "value", cell->value(),
                        PropertyCell::kValueOffset);
   MarkAsWeakContainer(cell->dependent_code());
   SetInternalReference(cell, entry, "dependent_code", cell->dependent_code(),
                        PropertyCell::kDependentCodeOffset);
 }
 
@@ skipping 1623 matching lines @@
   for (int i = 1; i < sorted_strings.length(); ++i) {
     writer_->AddCharacter(',');
     SerializeString(sorted_strings[i]);
     if (writer_->aborted()) return;
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8