Added a DependentCode field to AllocationSite.

src/code-stubs-hydrogen.cc

Index: src/code-stubs-hydrogen.cc
diff --git a/src/code-stubs-hydrogen.cc b/src/code-stubs-hydrogen.cc
index 1a6ae007ba6278701313b8e68bc29e229d92dd12..3e00f15bc1a5553f2274445b43c83a4b224acc30 100644
--- a/src/code-stubs-hydrogen.cc
+++ b/src/code-stubs-hydrogen.cc
@@ -474,14 +474,27 @@ HValue* CodeStubGraphBuilder<CreateAllocationSiteStub>::BuildCodeStub() {
                         HObjectAccess::ForAllocationSiteTransitionInfo(),
                         initial_elements_kind);
 
+  // Store an empty fixed array for the code dependency.
+  HConstant* empty_fixed_array =
+    Add<HConstant>(isolate()->factory()->empty_fixed_array());
+  ASSERT(!isolate()->heap()->InNewSpace(
+      isolate()->heap()->empty_fixed_array()));

[Michael Starzinger, 2013/09/19 13:56:17]

nit: Let's drop this assert, see comment below.

[mvstanton, 2013/09/19 14:06:11]

Done.

+  HStoreNamedField* store = Add<HStoreNamedField>(
+      object,
+      HObjectAccess::ForAllocationSiteDependentCode(),
+      empty_fixed_array);
+  // SkipWriteBarrier because we just created this object, and because
+  // empty_fixed_array won't be in new space
+  store->SkipWriteBarrier();

[Michael Starzinger, 2013/09/19 13:56:17]

We should just add the empty fixed array to the list of immortal immovable
objects and not worry about WBs here. The graph builder should not need to think
about WBs.

[mvstanton, 2013/09/19 14:06:11]

Right on, done!

+
   // Link the object to the allocation site list
   HValue* site_list = Add<HConstant>(
       ExternalReference::allocation_sites_list_address(isolate()));
   HValue* site = Add<HLoadNamedField>(site_list,
                                       HObjectAccess::ForAllocationSiteList());
-  HStoreNamedField* store =
-      Add<HStoreNamedField>(object, HObjectAccess::ForAllocationSiteWeakNext(),
-                            site);
+  store = Add<HStoreNamedField>(object,
+                                HObjectAccess::ForAllocationSiteWeakNext(),
+                                site);
   store->SkipWriteBarrier();
   Add<HStoreNamedField>(site_list, HObjectAccess::ForAllocationSiteList(),
                         object);