Implement identity hashes for proxies.

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index f0c37f2b9ecf2aa10c18d74d1bc972d428f5f433..bcb2168408b79065e19ef3a8a8fec7d447540c51 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -3290,6 +3290,7 @@ MaybeObject* Heap::AllocateJSProxy(Object* handler, Object* prototype) {
   if (!maybe_result->To<JSProxy>(&result)) return maybe_result;
   result->InitializeBody(map->instance_size(), Smi::FromInt(0));
   result->set_handler(handler);
+  result->set_hash(undefined_value());
   return result;
 }
 
@@ -3313,6 +3314,7 @@ MaybeObject* Heap::AllocateJSFunctionProxy(Object* handler,
   if (!maybe_result->To<JSFunctionProxy>(&result)) return maybe_result;
   result->InitializeBody(map->instance_size(), Smi::FromInt(0));
   result->set_handler(handler);
+  result->set_hash(undefined_value());
   result->set_call_trap(call_trap);
   result->set_construct_trap(construct_trap);
   return result;
@@ -3463,6 +3465,9 @@ MaybeObject* Heap::ReinitializeJSReceiver(
     JSReceiver* object, InstanceType type, int size) {
   ASSERT(type >= FIRST_JS_RECEIVER_TYPE);
 
+  // Save identity hash.
+  MaybeObject* maybe_hash = object->GetIdentityHash(JSReceiver::OMIT_CREATION);
+
   // Allocate fresh map.
   // TODO(rossberg): Once we optimize proxies, cache these maps.
   Map* map;
@@ -3511,6 +3516,18 @@ MaybeObject* Heap::ReinitializeJSReceiver(
         object->address() + map->instance_size(), size_difference);
   }
 
+  // Inherit identity, if it was present.
+  Object* hash;
+  if (maybe_hash->To<Object>(&hash) && hash->IsSmi()) {
+    JSObject* jsobj = JSObject::cast(object);
+    JSObject* hidden_props;
+    MaybeObject* maybe = jsobj->GetHiddenProperties(JSObject::ALLOW_CREATION);

[Michael Starzinger, 2011/09/09 09:40:00]

Can we move that into a separate method JSObject::SetIdentityHash() to keep the
identity hashing code together?

[rossberg, 2011/09/12 10:50:08]

Done.

+    if (!maybe->To<JSObject>(&hidden_props)) return maybe;
+    maybe = hidden_props->SetLocalPropertyIgnoreAttributes(
+        identity_hash_symbol(), hash, NONE);
+    if (maybe->IsFailure()) return maybe;
+  }
+
   return object;
 }