[turbofan] First part of brokerization/serialization for instanceof

- Move SerializePrototype out of DependOnStablePrototypes into
  ComputePropertyAccessInfo.
- Brokerize JSNativeContextSpecialization::InferHasInPrototypeChain.
- Brokerize JSNativeContextSpecialization::ReduceJSOrdinaryHasInstance
  (modulo the call to ReduceJSInstanceOf).
- Brokerize JSNativeContextSpecialization::ReduceJSHasInPrototypeChain.
- Serialize for JSCallReducer::ReduceObjectPrototypeIsPrototypeOf.
- Serialize for JSNativeContextSpecialization::ReduceJSInstanceOf. This
  is still incomplete.

Bug: v8:7790
Change-Id: Ic56eab5ddd8d725a13d2980e5b55db53ae82e822
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1709408
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62920}

src/compiler/access-info.cc

@@ -537,6 +537,7 @@ PropertyAccessInfo AccessInfoFactory::ComputePropertyAccessInfo(
     }
 
     // Walk up the prototype chain.
+    MapRef(broker(), map).SerializePrototype();
     if (!map->prototype().IsJSObject()) {
       // Perform the implicit ToObject for primitives here.
       // Implemented according to ES6 section 7.3.2 GetV (V, P).

src/compiler/compilation-dependencies.cc

@@ -550,13 +550,7 @@ namespace {
 // This function expects to never see a JSProxy.
 void DependOnStablePrototypeChain(CompilationDependencies* deps, MapRef map,
                                   base::Optional<JSObjectRef> last_prototype) {
-  // TODO(neis): Remove heap access (SerializePrototype call).
-  AllowCodeDependencyChange dependency_change_;
-  AllowHandleAllocation handle_allocation_;
-  AllowHandleDereference handle_dereference_;
-  AllowHeapAllocation heap_allocation_;
   while (true) {
-    map.SerializePrototype();
     HeapObjectRef proto = map.prototype();
     if (!proto.IsJSObject()) {
       CHECK_EQ(proto.map().oddball_type(), OddballType::kNull);

src/compiler/heap-refs.h

@@ -70,6 +70,8 @@ enum class OddballType : uint8_t {
   V(InternalizedString)            \
   V(String)                        \
   V(Symbol)                        \
+  /* Subtypes of JSReceiver */     \
+  V(JSObject)                      \
   /* Subtypes of HeapObject */     \
   V(AccessorInfo)                  \
   V(AllocationSite)                \
@@ -83,7 +85,7 @@ enum class OddballType : uint8_t {
   V(FixedArrayBase)                \
   V(FunctionTemplateInfo)          \
   V(HeapNumber)                    \
-  V(JSObject)                      \
+  V(JSReceiver)                    \
   V(Map)                           \
   V(MutableHeapNumber)             \
   V(Name)                          \
@@ -223,9 +225,15 @@ class PropertyCellRef : public HeapObjectRef {
   ObjectRef value() const;
 };
 
-class JSObjectRef : public HeapObjectRef {
+class JSReceiverRef : public HeapObjectRef {
  public:
   using HeapObjectRef::HeapObjectRef;
+  Handle<JSReceiver> object() const;
+};
+
+class JSObjectRef : public JSReceiverRef {
+ public:
+  using JSReceiverRef::JSReceiverRef;
   Handle<JSObject> object() const;
 
   uint64_t RawFastDoublePropertyAsBitsAt(FieldIndex index) const;
@@ -261,9 +269,10 @@ class JSBoundFunctionRef : public JSObjectRef {
   Handle<JSBoundFunction> object() const;
 
   void Serialize();
+  bool serialized() const;
 
   // The following are available only after calling Serialize().
-  ObjectRef bound_target_function() const;
+  JSReceiverRef bound_target_function() const;
   ObjectRef bound_this() const;
   FixedArrayRef bound_arguments() const;
 };

src/compiler/js-call-reducer.cc

@@ -847,6 +847,8 @@ Reduction JSCallReducer::ReduceObjectPrototypeHasOwnProperty(Node* node) {
 
 // ES #sec-object.prototype.isprototypeof
 Reduction JSCallReducer::ReduceObjectPrototypeIsPrototypeOf(Node* node) {
+  DisallowHeapAccessIf no_heap_access(FLAG_concurrent_inlining);
+
   DCHECK_EQ(IrOpcode::kJSCall, node->opcode());
   Node* receiver = NodeProperties::GetValueInput(node, 1);
   Node* value = node->op()->ValueInputCount() > 2

src/compiler/js-heap-broker.cc

@@ -256,7 +256,14 @@ class JSObjectField {
   uint64_t number_bits_ = 0;
 };
 
-class JSObjectData : public HeapObjectData {
+class JSReceiverData : public HeapObjectData {
+ public:
+  JSReceiverData(JSHeapBroker* broker, ObjectData** storage,
+                 Handle<JSReceiver> object)
+      : HeapObjectData(broker, storage, object) {}
+};
+
+class JSObjectData : public JSReceiverData {
  public:
   JSObjectData(JSHeapBroker* broker, ObjectData** storage,
                Handle<JSObject> object);
@@ -462,6 +469,7 @@ class JSBoundFunctionData : public JSObjectData {
                       Handle<JSBoundFunction> object);
 
   void Serialize(JSHeapBroker* broker);
+  bool serialized() const { return serialized_; }
 
   ObjectData* bound_target_function() const { return bound_target_function_; }
   ObjectData* bound_this() const { return bound_this_; }
@@ -1309,21 +1317,26 @@ void JSBoundFunctionData::Serialize(JSHeapBroker* broker) {
   Handle<JSBoundFunction> function = Handle<JSBoundFunction>::cast(object());
 
   DCHECK_NULL(bound_target_function_);
-  DCHECK_NULL(bound_this_);
-  DCHECK_NULL(bound_arguments_);
-
   bound_target_function_ =
       broker->GetOrCreateData(function->bound_target_function());
-  bound_this_ = broker->GetOrCreateData(function->bound_this());
+  if (bound_target_function_->IsJSBoundFunction()) {
+    bound_target_function_->AsJSBoundFunction()->Serialize(broker);
+  } else if (bound_target_function_->IsJSFunction()) {
+    bound_target_function_->AsJSFunction()->Serialize(broker);
+  }
+
+  DCHECK_NULL(bound_arguments_);
   bound_arguments_ =
       broker->GetOrCreateData(function->bound_arguments())->AsFixedArray();
-
   bound_arguments_->SerializeContents(broker);
+
+  DCHECK_NULL(bound_this_);
+  bound_this_ = broker->GetOrCreateData(function->bound_this());
 }
 
 JSObjectData::JSObjectData(JSHeapBroker* broker, ObjectData** storage,
                            Handle<JSObject> object)
-    : HeapObjectData(broker, storage, object),
+    : JSReceiverData(broker, storage, object),
       inobject_fields_(broker->zone()),
       own_constant_elements_(broker->zone()),
       own_properties_(broker->zone()) {}
@@ -2979,7 +2992,7 @@ BIMODAL_ACCESSOR(HeapObject, Map, map)
 
 BIMODAL_ACCESSOR(JSArray, Object, length)
 
-BIMODAL_ACCESSOR(JSBoundFunction, Object, bound_target_function)
+BIMODAL_ACCESSOR(JSBoundFunction, JSReceiver, bound_target_function)
 BIMODAL_ACCESSOR(JSBoundFunction, Object, bound_this)
 BIMODAL_ACCESSOR(JSBoundFunction, FixedArray, bound_arguments)
 
@@ -3792,6 +3805,11 @@ void JSBoundFunctionRef::Serialize() {
   data()->AsJSBoundFunction()->Serialize(broker());
 }
 
+bool JSBoundFunctionRef::serialized() const {
+  CHECK_NE(broker()->mode(), JSHeapBroker::kDisabled);
+  return data()->AsJSBoundFunction()->serialized();
+}
+
 void PropertyCellRef::Serialize() {
   if (broker()->mode() == JSHeapBroker::kDisabled) return;
   CHECK_EQ(broker()->mode(), JSHeapBroker::kSerializing);

src/compiler/js-native-context-specialization.cc

@@ -381,6 +381,10 @@ Reduction JSNativeContextSpecialization::ReduceJSGetSuperConstructor(
 }
 
 Reduction JSNativeContextSpecialization::ReduceJSInstanceOf(Node* node) {
+  // TODO(neis): Eliminate heap accesses.
+  AllowHandleDereference allow_handle_dereference;
+  AllowHandleAllocation allow_handle_allocation;
+
   DCHECK_EQ(IrOpcode::kJSInstanceOf, node->opcode());
   FeedbackParameter const& p = FeedbackParameterOf(node->op());
   Node* object = NodeProperties::GetValueInput(node, 0);
@@ -502,7 +506,7 @@ Reduction JSNativeContextSpecialization::ReduceJSInstanceOf(Node* node) {
 
 JSNativeContextSpecialization::InferHasInPrototypeChainResult
 JSNativeContextSpecialization::InferHasInPrototypeChain(
-    Node* receiver, Node* effect, Handle<HeapObject> prototype) {
+    Node* receiver, Node* effect, HeapObjectRef const& prototype) {
   ZoneHandleSet<Map> receiver_maps;
   NodeProperties::InferReceiverMapsResult result =
       NodeProperties::InferReceiverMapsUnsafe(broker(), receiver, effect,
@@ -515,28 +519,31 @@ JSNativeContextSpecialization::InferHasInPrototypeChain(
   bool all = true;
   bool none = true;
   for (size_t i = 0; i < receiver_maps.size(); ++i) {
-    Handle<Map> receiver_map = receiver_maps[i];
-    if (receiver_map->instance_type() <= LAST_SPECIAL_RECEIVER_TYPE) {
+    MapRef map(broker(), receiver_maps[i]);
+    while (true) {
+      if (IsSpecialReceiverInstanceType(map.instance_type())) {
         return kMayBeInPrototypeChain;
       }
       if (result == NodeProperties::kUnreliableReceiverMaps &&
-        !receiver_map->is_stable()) {
+          !map.is_stable()) {
         return kMayBeInPrototypeChain;
       }
-    for (PrototypeIterator it(isolate(), receiver_map);; it.Advance()) {
-      if (it.IsAtEnd()) {
+      if (!map.IsJSObjectMap()) {
         all = false;
         break;
       }
-      Handle<HeapObject> current =
-          PrototypeIterator::GetCurrent<HeapObject>(it);
-      if (current.is_identical_to(prototype)) {
+      if (FLAG_concurrent_inlining && !map.serialized_prototype()) {
+        TRACE_BROKER_MISSING(broker(), "prototype data for map " << map);
+        return kMayBeInPrototypeChain;
+      }
+      if (map.prototype().equals(prototype)) {
         none = false;
         break;
       }
-      if (!current->map().is_stable() ||
-          current->map().instance_type() <= LAST_SPECIAL_RECEIVER_TYPE) {
-        return kMayBeInPrototypeChain;
+      map = map.prototype().map();
+      if (map.oddball_type() == OddballType::kNull) {
+        all = false;
+        break;
       }
     }
   }
@@ -552,8 +559,8 @@ JSNativeContextSpecialization::InferHasInPrototypeChain(
       // might be a different object each time, so it's much simpler to include
       // {prototype}. That does, however, mean that we must check {prototype}'s
       // map stability.
-      if (!prototype->map().is_stable()) return kMayBeInPrototypeChain;
-      last_prototype.emplace(broker(), Handle<JSObject>::cast(prototype));
+      if (!prototype.map().is_stable()) return kMayBeInPrototypeChain;
+      last_prototype = prototype.AsJSObject();
     }
     WhereToStart start = result == NodeProperties::kUnreliableReceiverMaps
                              ? kStartAtReceiver
@@ -568,6 +575,8 @@ JSNativeContextSpecialization::InferHasInPrototypeChain(
 
 Reduction JSNativeContextSpecialization::ReduceJSHasInPrototypeChain(
     Node* node) {
+  DisallowHeapAccessIf no_heap_access(FLAG_concurrent_inlining);
+
   DCHECK_EQ(IrOpcode::kJSHasInPrototypeChain, node->opcode());
   Node* value = NodeProperties::GetValueInput(node, 0);
   Node* prototype = NodeProperties::GetValueInput(node, 1);
@@ -578,7 +587,7 @@ Reduction JSNativeContextSpecialization::ReduceJSHasInPrototypeChain(
   HeapObjectMatcher m(prototype);
   if (m.HasValue()) {
     InferHasInPrototypeChainResult result =
-        InferHasInPrototypeChain(value, effect, m.Value());
+        InferHasInPrototypeChain(value, effect, m.Ref(broker()));
     if (result != kMayBeInPrototypeChain) {
       Node* value = jsgraph()->BooleanConstant(result == kIsInPrototypeChain);
       ReplaceWithValue(node, value);
@@ -591,6 +600,8 @@ Reduction JSNativeContextSpecialization::ReduceJSHasInPrototypeChain(
 
 Reduction JSNativeContextSpecialization::ReduceJSOrdinaryHasInstance(
     Node* node) {
+  DisallowHeapAccessIf no_heap_access(FLAG_concurrent_inlining);
+
   DCHECK_EQ(IrOpcode::kJSOrdinaryHasInstance, node->opcode());
   Node* constructor = NodeProperties::GetValueInput(node, 0);
   Node* object = NodeProperties::GetValueInput(node, 1);
@@ -599,34 +610,41 @@ Reduction JSNativeContextSpecialization::ReduceJSOrdinaryHasInstance(
   HeapObjectMatcher m(constructor);
   if (!m.HasValue()) return NoChange();
 
-  // Check if the {constructor} is a JSBoundFunction.
-  if (m.Value()->IsJSBoundFunction()) {
-    // OrdinaryHasInstance on bound functions turns into a recursive
-    // invocation of the instanceof operator again.
-    // ES6 section 7.3.19 OrdinaryHasInstance (C, O) step 2.
-    Handle<JSBoundFunction> function = Handle<JSBoundFunction>::cast(m.Value());
-    Handle<JSReceiver> bound_target_function(function->bound_target_function(),
-                                             isolate());
+  if (m.Ref(broker()).IsJSBoundFunction()) {
+    // OrdinaryHasInstance on bound functions turns into a recursive invocation
+    // of the instanceof operator again.
+    JSBoundFunctionRef function = m.Ref(broker()).AsJSBoundFunction();
+    if (FLAG_concurrent_inlining && !function.serialized()) {
+      TRACE_BROKER_MISSING(broker(), "data for function " << function);
+      return NoChange();
+    }
+
+    JSReceiverRef bound_target_function = function.bound_target_function();
+
     NodeProperties::ReplaceValueInput(node, object, 0);
     NodeProperties::ReplaceValueInput(
-        node, jsgraph()->HeapConstant(bound_target_function), 1);
+        node, jsgraph()->Constant(bound_target_function), 1);
     NodeProperties::ChangeOp(node, javascript()->InstanceOf(VectorSlotPair()));
     Reduction const reduction = ReduceJSInstanceOf(node);
     return reduction.Changed() ? reduction : Changed(node);
   }
 
+  if (m.Ref(broker()).IsJSFunction()) {
     // Optimize if we currently know the "prototype" property.
-  if (m.Value()->IsJSFunction()) {
+
     JSFunctionRef function = m.Ref(broker()).AsJSFunction();
-    // TODO(neis): This is a temporary hack needed because the copy reducer
-    // runs only after this pass.
-    function.Serialize();
+    if (FLAG_concurrent_inlining && !function.serialized()) {
+      TRACE_BROKER_MISSING(broker(), "data for function " << function);
+      return NoChange();
+    }
+
     // TODO(neis): Remove the has_prototype_slot condition once the broker is
     // always enabled.
     if (!function.map().has_prototype_slot() || !function.has_prototype() ||
         function.PrototypeRequiresRuntimeLookup()) {
       return NoChange();
     }
+
     ObjectRef prototype = dependencies()->DependOnPrototypeProperty(function);
     Node* prototype_constant = jsgraph()->Constant(prototype);
 

src/compiler/js-native-context-specialization.h

@@ -234,7 +234,7 @@ class V8_EXPORT_PRIVATE JSNativeContextSpecialization final
     kMayBeInPrototypeChain
   };
   InferHasInPrototypeChainResult InferHasInPrototypeChain(
-      Node* receiver, Node* effect, Handle<HeapObject> prototype);
+      Node* receiver, Node* effect, HeapObjectRef const& prototype);
 
   Graph* graph() const;
   JSGraph* jsgraph() const { return jsgraph_; }

src/compiler/serializer-for-background-compilation.cc

@@ -92,7 +92,6 @@ namespace compiler {
   V(TestEqualStrict)              \
   V(TestGreaterThan)              \
   V(TestGreaterThanOrEqual)       \
-  V(TestInstanceOf)               \
   V(TestLessThan)                 \
   V(TestLessThanOrEqual)          \
   V(TestNull)                     \
@@ -208,6 +207,7 @@ namespace compiler {
   V(SwitchOnGeneratorState)           \
   V(SwitchOnSmiNoFeedback)            \
   V(TestIn)                           \
+  V(TestInstanceOf)                   \
   CLEAR_ACCUMULATOR_LIST(V)           \
   CLEAR_ENVIRONMENT_LIST(V)           \
   CONDITIONAL_JUMPS_LIST(V)           \
@@ -374,6 +374,7 @@ class SerializerForBackgroundCompilation {
                                   FeedbackSlot slot, AccessMode mode);
   void ProcessMapHintsForPromises(Hints const& receiver_hints);
   void ProcessHintsForPromiseResolve(Hints const& resolution_hints);
+  void ProcessHintsForObjectIsPrototypeOf(Hints const& value_hints);
   void ProcessHintsForRegExpTest(Hints const& regexp_hints);
   PropertyAccessInfo ProcessMapForRegExpTest(MapRef map);
   void ProcessHintsForFunctionCall(Hints const& target_hints);
@@ -1659,7 +1660,7 @@ void SerializerForBackgroundCompilation::ProcessBuiltinCall(
         ProcessHintsForPromiseResolve(resolution_hints);
       }
       break;
-    case Builtins::kRegExpPrototypeTest: {
+    case Builtins::kRegExpPrototypeTest:
       // For JSCallReducer::ReduceRegExpPrototypeTest.
       if (arguments.size() >= 1 &&
           speculation_mode != SpeculationMode::kDisallowSpeculation) {
@@ -1667,7 +1668,6 @@ void SerializerForBackgroundCompilation::ProcessBuiltinCall(
         ProcessHintsForRegExpTest(regexp_hints);
       }
       break;
-    }
     case Builtins::kFunctionPrototypeCall:
       if (arguments.size() >= 1 &&
           speculation_mode != SpeculationMode::kDisallowSpeculation) {
@@ -1675,6 +1675,11 @@ void SerializerForBackgroundCompilation::ProcessBuiltinCall(
         ProcessHintsForFunctionCall(target_hints);
       }
       break;
+    case Builtins::kObjectPrototypeIsPrototypeOf:
+      if (arguments.size() >= 2) {
+        ProcessHintsForObjectIsPrototypeOf(arguments[1]);
+      }
+      break;
     case Builtins::kFastFunctionPrototypeBind:
       if (arguments.size() >= 2 &&
           speculation_mode != SpeculationMode::kDisallowSpeculation) {
@@ -1687,6 +1692,26 @@ void SerializerForBackgroundCompilation::ProcessBuiltinCall(
   }
 }
 
+void SerializerForBackgroundCompilation::ProcessHintsForObjectIsPrototypeOf(
+    Hints const& value_hints) {
+  auto processMap = [&](Handle<Map> map_handle) {
+    MapRef map(broker(), map_handle);
+    while (map.IsJSObjectMap()) {
+      map.SerializePrototype();
+      map = map.prototype().map();
+    }
+  };
+
+  for (auto hint : value_hints.constants()) {
+    if (!hint->IsHeapObject()) continue;
+    Handle<HeapObject> object(Handle<HeapObject>::cast(hint));
+    processMap(handle(object->map(), broker()->isolate()));
+  }
+  for (auto map_hint : value_hints.maps()) {
+    processMap(map_hint);
+  }
+}
+
 void SerializerForBackgroundCompilation::ProcessHintsForPromiseResolve(
     Hints const& resolution_hints) {
   auto processMap = [&](Handle<Map> map) {
@@ -2213,6 +2238,38 @@ void SerializerForBackgroundCompilation::VisitTestIn(
   ProcessKeyedPropertyAccess(receiver, key, slot, AccessMode::kHas);
 }
 
+void SerializerForBackgroundCompilation::VisitTestInstanceOf(
+    BytecodeArrayIterator* iterator) {
+  Hints const& lhs =
+      environment()->register_hints(iterator->GetRegisterOperand(0));
+  Hints const& rhs = environment()->accumulator_hints();
+  FeedbackSlot slot = iterator->GetSlotOperand(1);
+
+  // Inspect feedback (about the rhs of the operator).
+  Handle<FeedbackVector> feedback_vector =
+      environment()->function().feedback_vector();
+  FeedbackNexus nexus(feedback_vector, slot);
+  VectorSlotPair rhs_feedback(feedback_vector, slot, nexus.ic_state());
+  Handle<JSObject> constructor;
+  if (rhs_feedback.IsValid() &&
+      nexus.GetConstructorFeedback().ToHandle(&constructor)) {
+    if (constructor->IsJSBoundFunction()) {
+      JSBoundFunctionRef(broker(), constructor).Serialize();
+    } else if (constructor->IsJSFunction()) {
+      JSFunctionRef(broker(), constructor).Serialize();
+    } else {
+      UNREACHABLE();
+    }
+  }
+
+  // TODO(neis): Support full instanceof semantics.
+
+  ProcessHintsForObjectIsPrototypeOf(lhs);
+
+  // TODO(neis): Process rhs hints.
+  USE(rhs);
+}
+
 void SerializerForBackgroundCompilation::VisitStaKeyedProperty(
     BytecodeArrayIterator* iterator) {
   Hints const& receiver =

test/mjsunit/compiler/object-isprototypeof.js

@@ -160,3 +160,16 @@
   %OptimizeFunctionOnNextCall(foo);
   assertTrue(foo());
 })();
+(function() {
+  function A() {}
+  A.prototype = {};
+  var a = {__proto__: new A, gaga: 42};
+
+  function foo() { a.gaga; return A.prototype.isPrototypeOf(a); }
+
+  %PrepareFunctionForOptimization(foo);
+  assertTrue(foo());
+  assertTrue(foo());
+  %OptimizeFunctionOnNextCall(foo);
+  assertTrue(foo());
+})();

test/mjsunit/compiler/regress-9041.js

@@ -5,19 +5,77 @@
 // Flags: --allow-natives-syntax
 
 (function() {
-class A {}
+  class A {};
 
-function foo(a, fn) {
+  function foo(a, fn) {
     const C = a.constructor;
     fn(a);
     return a instanceof C;
-};
-%PrepareFunctionForOptimization(foo);
-assertTrue(foo(new A(), a => {}));
-assertTrue(foo(new A(), a => {}));
-%OptimizeFunctionOnNextCall(foo);
-assertTrue(foo(new A(), a => {}));
-assertFalse(foo(new A(), a => {
-  a.__proto__ = {};
-}));
+  };
+
+  %PrepareFunctionForOptimization(foo);
+  assertTrue(foo(new A(), a => {}));
+  assertTrue(foo(new A(), a => {}));
+  %OptimizeFunctionOnNextCall(foo);
+  assertTrue(foo(new A(), a => {}));
+  assertFalse(foo(new A(), a => { a.__proto__ = {}; }));
+})();
+
+(function() {
+  class A {};
+  A.__proto__ = {};
+  A.prototype = {};
+
+  function foo() {
+    var x = Object.create(Object.create(Object.create(A.prototype)));
+    return x instanceof A;
+  };
+
+  %PrepareFunctionForOptimization(foo);
+  assertTrue(foo());
+  assertTrue(foo());
+  %OptimizeFunctionOnNextCall(foo);
+  assertTrue(foo());
+})();
+
+(function() {
+  class A {};
+  A.prototype = {};
+  A.__proto__ = {};
+  var a = {__proto__: new A, gaga: 42};
+
+  function foo() {
+    A.bla;  // Make A.__proto__ fast again.
+    a.gaga;
+    return a instanceof A;
+  };
+
+  %PrepareFunctionForOptimization(foo);
+  assertTrue(foo());
+  assertTrue(foo());
+  %OptimizeFunctionOnNextCall(foo);
+  assertTrue(foo());
+})();
+
+(function() {
+  class A {};
+  A.prototype = {};
+  A.__proto__ = {};
+  const boundA = Function.prototype.bind.call(A, {});
+  boundA.prototype = {};
+  boundA.__proto__ = {};
+  var a = {__proto__: new boundA, gaga: 42};
+
+  function foo() {
+    A.bla;  // Make A.__proto__ fast again.
+    boundA.bla;  // Make boundA.__proto__ fast again.
+    a.gaga;
+    return a instanceof boundA;
+  };
+
+  %PrepareFunctionForOptimization(foo);
+  assertTrue(foo());
+  assertTrue(foo());
+  %OptimizeFunctionOnNextCall(foo);
+  assertTrue(foo());
 })();