AllocationSite objects weakly linked for traversal

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 2cc232c50a75147c2c82bf17619c48ebd8562073..63966fc55b4f375ecd28d11cfefc691f62929196 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -7475,10 +7475,17 @@ enum AllocationSiteMode {
 class AllocationSite: public Struct {
  public:
   static const int kTransitionInfoOffset = HeapObject::kHeaderSize;
-  static const int kSize = kTransitionInfoOffset + kPointerSize;
+  static const int kWeakNextOffset = kTransitionInfoOffset + kPointerSize;
+  static const int kSize = kWeakNextOffset + kPointerSize;

[Michael Starzinger, 2013/07/16 18:14:46]

nit: The offset and size calculation should go to the bottom after the
dispatched behavior.

[mvstanton, 2013/07/16 19:34:57]

Hmm. I actually moved these constants to the top of the file per request by
Hannes to make this new class finally conform to the coding guide of putting
constants at the top. But it makes sense that file-wise convention trumps that.
Done.

+
   static const uint32_t kMaximumArrayBytesToPretransition = 8 * 1024;
 
+  typedef FixedBodyDescriptor<HeapObject::kHeaderSize,
+                              kTransitionInfoOffset + kPointerSize,
+                              kSize> BodyDescriptor;
+
   DECL_ACCESSORS(transition_info, Object)
+  DECL_ACCESSORS(weak_next, Object)
 
   void Initialize() {
     SetElementsKind(GetInitialFastElementsKind());
@@ -7508,6 +7515,9 @@ class AllocationSite: public Struct {
       ElementsKind boilerplate_elements_kind);
   static inline AllocationSiteMode GetMode(ElementsKind from, ElementsKind to);
 
+  // Dispatched behavior.
+  inline void AllocationSiteIterateBody(ObjectVisitor* v);
+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(AllocationSite);
 };
@@ -9745,6 +9755,10 @@ class ObjectVisitor BASE_EMBEDDED {
   // Visits a global property cell reference in the instruction stream.
   virtual void VisitCell(RelocInfo* rinfo);
 
+  virtual void VisitAllocationSite(HeapObject* site) {
+    AllocationSite::BodyDescriptor::IterateBody(site, this);
+  }
+
   // Visits a runtime entry in the instruction stream.
   virtual void VisitRuntimeEntry(RelocInfo* rinfo) {}