AllocationSite objects weakly linked for traversal

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 27c517aa1a5be38b03e3ec186532dea8da7aeebb..3f1b10478dedcae0249e0e1fd7828a7b9ebeeb3e 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -131,6 +131,7 @@ class LChunkBuilder;
   V(IsSmiAndBranch)                            \
   V(IsUndetectableAndBranch)                   \
   V(LeaveInlined)                              \
+  V(LinkObjectInList)                          \
   V(LoadContextSlot)                           \
   V(LoadExternalArrayPointer)                  \
   V(LoadFunctionPrototype)                     \
@@ -5326,6 +5327,10 @@ class HObjectAccess {
     return HObjectAccess(kInobject, AllocationSite::kTransitionInfoOffset);
   }
 
+  static HObjectAccess ForAllocationSiteWeakNext() {
+    return HObjectAccess(kInobject, AllocationSite::kWeakNextOffset);
+  }
+
   static HObjectAccess ForFixedArrayLength() {
     return HObjectAccess(kArrayLengths, FixedArray::kLengthOffset);
   }
@@ -5416,6 +5421,38 @@ class HObjectAccess {
 };
 
 
+class HLinkObjectInList: public HUnaryOperation {
+ public:
+  // There needs to be a mapping from every KnownList to an external reference
+  enum KnownList {
+    ALLOCATION_SITE_LIST
+  };
+
+  HLinkObjectInList(HValue* object, HObjectAccess store_field,
+                    KnownList known_list)
+      : HUnaryOperation(object),
+      store_field_(store_field),
+      known_list_(known_list) {
+    set_representation(Representation::Tagged());
+  }
+
+  HObjectAccess store_field() const { return store_field_; }
+  KnownList known_list() const { return known_list_; }
+
+  virtual Representation RequiredInputRepresentation(int index) {
+    return Representation::Tagged();
+  }
+
+  virtual void PrintDataTo(StringStream* stream);
+
+  DECLARE_CONCRETE_INSTRUCTION(LinkObjectInList)
+
+ private:
+  HObjectAccess store_field_;
+  KnownList known_list_;
+};
+
+
 class HLoadNamedField: public HTemplateInstruction<2> {
  public:
   HLoadNamedField(HValue* object,