AllocationSite objects weakly linked for traversal

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index 945d002b908e23b4a33d756f29e93051f32084ec..2cec68b097573eab83f941c03940b01647f2e3e9 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -275,6 +275,24 @@ void LCallConstantFunction::PrintDataTo(StringStream* stream) {
 }
 
 
+ExternalReference LLinkObjectInList::GetReference(Isolate* isolate) {
+  switch (hydrogen()->known_list()) {
+    case HLinkObjectInList::ALLOCATION_SITE_LIST:
+      return ExternalReference::allocation_sites_list_address(isolate);
+  }
+
+  UNREACHABLE();
+  // Return a dummy value
+  return ExternalReference::isolate_address(isolate);
+}
+
+
+void LLinkObjectInList::PrintDataTo(StringStream* stream) {
+  object()->PrintTo(stream);
+  stream->Add(" offset %d", hydrogen()->store_field().offset());
+}
+
+
 void LLoadContextSlot::PrintDataTo(StringStream* stream) {
   context()->PrintTo(stream);
   stream->Add("[%d]", slot_index());
@@ -2028,6 +2046,13 @@ LInstruction* LChunkBuilder::DoStoreGlobalGeneric(HStoreGlobalGeneric* instr) {
 }
 
 
+LInstruction* LChunkBuilder::DoLinkObjectInList(HLinkObjectInList* instr) {
+  LOperand* object = UseRegister(instr->value());
+  LLinkObjectInList* result = new(zone()) LLinkObjectInList(object);
+  return result;
+}
+
+
 LInstruction* LChunkBuilder::DoLoadContextSlot(HLoadContextSlot* instr) {
   LOperand* context = UseRegisterAtStart(instr->value());
   LInstruction* result =