AllocationSite objects weakly linked for traversal

src/objects.h

 // Copyright 2012 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 7457 matching lines @@
 enum AllocationSiteMode {
   DONT_TRACK_ALLOCATION_SITE,
   TRACK_ALLOCATION_SITE,
   LAST_ALLOCATION_SITE_MODE = TRACK_ALLOCATION_SITE
 };
 
 
 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());
   }
 
   ElementsKind GetElementsKind() {
     ASSERT(!IsLiteralSite());
     return static_cast<ElementsKind>(Smi::cast(transition_info())->value());
   }
 
   void SetElementsKind(ElementsKind kind) {
     set_transition_info(Smi::FromInt(static_cast<int>(kind)));
   }
 
   bool IsLiteralSite() {
     // If transition_info is a smi, then it represents an ElementsKind
     // for a constructed array. Otherwise, it must be a boilerplate
     // for an array literal
     return transition_info()->IsJSArray();
   }
 
   DECLARE_PRINTER(AllocationSite)
   DECLARE_VERIFIER(AllocationSite)
 
   static inline AllocationSite* cast(Object* obj);
   static inline AllocationSiteMode GetMode(
       ElementsKind boilerplate_elements_kind);
   static inline AllocationSiteMode GetMode(ElementsKind from, ElementsKind to);
 
+  // Dispatched behavior.
+  inline void AllocationSiteIterateBody(ObjectVisitor* v);
+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(AllocationSite);
 };
 
 
 class AllocationSiteInfo: public Struct {
  public:
   static const int kAllocationSiteOffset = HeapObject::kHeaderSize;
   static const int kSize = kAllocationSiteOffset + kPointerSize;
 
@@ skipping 2217 matching lines @@
 
   // Visits a code target in the instruction stream.
   virtual void VisitCodeTarget(RelocInfo* rinfo);
 
   // Visits a code entry in a JS function.
   virtual void VisitCodeEntry(Address entry_address);
 
   // 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) {}
 
   // Visits the resource of an ASCII or two-byte string.
   virtual void VisitExternalAsciiString(
       v8::String::ExternalAsciiStringResource** resource) {}
   virtual void VisitExternalTwoByteString(
       v8::String::ExternalStringResource** resource) {}
 
   // Visits a debug call target in the instruction stream.
@@ skipping 61 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_