Make maps in monomorphic IC stubs weak.

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index f06b8be1d98246d3ea9b5f3237b7a96ae211572c..452e0f2232aad70ec379ccf61a28291e4ede9ca9 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -1719,180 +1719,6 @@ void Heap::UpdateReferencesInExternalStringTable(
 }
 
 
-template <class T>
-struct WeakListVisitor;
-
-
-template <class T>
-static Object* VisitWeakList(Heap* heap,
-                             Object* list,
-                             WeakObjectRetainer* retainer,
-                             bool record_slots) {
-  Object* undefined = heap->undefined_value();
-  Object* head = undefined;
-  T* tail = NULL;
-  MarkCompactCollector* collector = heap->mark_compact_collector();
-  while (list != undefined) {
-    // Check whether to keep the candidate in the list.
-    T* candidate = reinterpret_cast<T*>(list);
-    Object* retained = retainer->RetainAs(list);
-    if (retained != NULL) {
-      if (head == undefined) {
-        // First element in the list.
-        head = retained;
-      } else {
-        // Subsequent elements in the list.
-        ASSERT(tail != NULL);
-        WeakListVisitor<T>::SetWeakNext(tail, retained);
-        if (record_slots) {
-          Object** next_slot =
-            HeapObject::RawField(tail, WeakListVisitor<T>::WeakNextOffset());
-          collector->RecordSlot(next_slot, next_slot, retained);
-        }
-      }
-      // Retained object is new tail.
-      ASSERT(!retained->IsUndefined());
-      candidate = reinterpret_cast<T*>(retained);
-      tail = candidate;
-
-
-      // tail is a live object, visit it.
-      WeakListVisitor<T>::VisitLiveObject(
-          heap, tail, retainer, record_slots);
-    } else {
-      WeakListVisitor<T>::VisitPhantomObject(heap, candidate);
-    }
-
-    // Move to next element in the list.
-    list = WeakListVisitor<T>::WeakNext(candidate);
-  }
-
-  // Terminate the list if there is one or more elements.
-  if (tail != NULL) {
-    WeakListVisitor<T>::SetWeakNext(tail, undefined);
-  }
-  return head;
-}
-
-
-template <class T>
-static void ClearWeakList(Heap* heap,
-                          Object* list) {
-  Object* undefined = heap->undefined_value();
-  while (list != undefined) {
-    T* candidate = reinterpret_cast<T*>(list);
-    list = WeakListVisitor<T>::WeakNext(candidate);
-    WeakListVisitor<T>::SetWeakNext(candidate, undefined);
-  }
-}
-
-
-template<>
-struct WeakListVisitor<JSFunction> {
-  static void SetWeakNext(JSFunction* function, Object* next) {
-    function->set_next_function_link(next);
-  }
-
-  static Object* WeakNext(JSFunction* function) {
-    return function->next_function_link();
-  }
-
-  static int WeakNextOffset() {
-    return JSFunction::kNextFunctionLinkOffset;
-  }
-
-  static void VisitLiveObject(Heap*, JSFunction*,
-                              WeakObjectRetainer*, bool) {
-  }
-
-  static void VisitPhantomObject(Heap*, JSFunction*) {
-  }
-};
-
-
-template<>
-struct WeakListVisitor<Code> {
-  static void SetWeakNext(Code* code, Object* next) {
-    code->set_next_code_link(next);
-  }
-
-  static Object* WeakNext(Code* code) {
-    return code->next_code_link();
-  }
-
-  static int WeakNextOffset() {
-    return Code::kNextCodeLinkOffset;
-  }
-
-  static void VisitLiveObject(Heap*, Code*,
-                              WeakObjectRetainer*, bool) {
-  }
-
-  static void VisitPhantomObject(Heap*, Code*) {
-  }
-};
-
-
-template<>
-struct WeakListVisitor<Context> {
-  static void SetWeakNext(Context* context, Object* next) {
-    context->set(Context::NEXT_CONTEXT_LINK,
-                 next,
-                 UPDATE_WRITE_BARRIER);
-  }
-
-  static Object* WeakNext(Context* context) {
-    return context->get(Context::NEXT_CONTEXT_LINK);
-  }
-
-  static void VisitLiveObject(Heap* heap,
-                              Context* context,
-                              WeakObjectRetainer* retainer,
-                              bool record_slots) {
-    // Process the three weak lists linked off the context.
-    DoWeakList<JSFunction>(heap, context, retainer, record_slots,
-        Context::OPTIMIZED_FUNCTIONS_LIST);
-    DoWeakList<Code>(heap, context, retainer, record_slots,
-        Context::OPTIMIZED_CODE_LIST);
-    DoWeakList<Code>(heap, context, retainer, record_slots,
-        Context::DEOPTIMIZED_CODE_LIST);
-  }
-
-  template<class T>
-  static void DoWeakList(Heap* heap,
-                         Context* context,
-                         WeakObjectRetainer* retainer,
-                         bool record_slots,
-                         int index) {
-    // Visit the weak list, removing dead intermediate elements.
-    Object* list_head = VisitWeakList<T>(heap, context->get(index), retainer,
-        record_slots);
-
-    // Update the list head.
-    context->set(index, list_head, UPDATE_WRITE_BARRIER);
-
-    if (record_slots) {
-      // Record the updated slot if necessary.
-      Object** head_slot = HeapObject::RawField(
-          context, FixedArray::SizeFor(index));
-      heap->mark_compact_collector()->RecordSlot(
-          head_slot, head_slot, list_head);
-    }
-  }
-
-  static void VisitPhantomObject(Heap* heap, Context* context) {
-    ClearWeakList<JSFunction>(heap,
-        context->get(Context::OPTIMIZED_FUNCTIONS_LIST));
-    ClearWeakList<Code>(heap, context->get(Context::OPTIMIZED_CODE_LIST));
-    ClearWeakList<Code>(heap, context->get(Context::DEOPTIMIZED_CODE_LIST));
-  }
-
-  static int WeakNextOffset() {
-    return FixedArray::SizeFor(Context::NEXT_CONTEXT_LINK);
-  }
-};
-
-
 void Heap::ProcessWeakReferences(WeakObjectRetainer* retainer) {
   // We don't record weak slots during marking or scavenges.
   // Instead we do it once when we complete mark-compact cycle.
@@ -1918,66 +1744,6 @@ void Heap::ProcessNativeContexts(WeakObjectRetainer* retainer,
 }
 
 
-template<>
-struct WeakListVisitor<JSArrayBufferView> {
-  static void SetWeakNext(JSArrayBufferView* obj, Object* next) {
-    obj->set_weak_next(next);
-  }
-
-  static Object* WeakNext(JSArrayBufferView* obj) {
-    return obj->weak_next();
-  }
-
-  static void VisitLiveObject(Heap*,
-                              JSArrayBufferView* obj,
-                              WeakObjectRetainer* retainer,
-                              bool record_slots) {}
-
-  static void VisitPhantomObject(Heap*, JSArrayBufferView*) {}
-
-  static int WeakNextOffset() {
-    return JSArrayBufferView::kWeakNextOffset;
-  }
-};
-
-
-template<>
-struct WeakListVisitor<JSArrayBuffer> {
-  static void SetWeakNext(JSArrayBuffer* obj, Object* next) {
-    obj->set_weak_next(next);
-  }
-
-  static Object* WeakNext(JSArrayBuffer* obj) {
-    return obj->weak_next();
-  }
-
-  static void VisitLiveObject(Heap* heap,
-                              JSArrayBuffer* array_buffer,
-                              WeakObjectRetainer* retainer,
-                              bool record_slots) {
-    Object* typed_array_obj =
-        VisitWeakList<JSArrayBufferView>(
-            heap,
-            array_buffer->weak_first_view(),
-            retainer, record_slots);
-    array_buffer->set_weak_first_view(typed_array_obj);
-    if (typed_array_obj != heap->undefined_value() && record_slots) {
-      Object** slot = HeapObject::RawField(
-          array_buffer, JSArrayBuffer::kWeakFirstViewOffset);
-      heap->mark_compact_collector()->RecordSlot(slot, slot, typed_array_obj);
-    }
-  }
-
-  static void VisitPhantomObject(Heap* heap, JSArrayBuffer* phantom) {
-    Runtime::FreeArrayBuffer(heap->isolate(), phantom);
-  }
-
-  static int WeakNextOffset() {
-    return JSArrayBuffer::kWeakNextOffset;
-  }
-};
-
-
 void Heap::ProcessArrayBuffers(WeakObjectRetainer* retainer,
                                bool record_slots) {
   Object* array_buffer_obj =
@@ -1999,29 +1765,6 @@ void Heap::TearDownArrayBuffers() {
 }
 
 
-template<>
-struct WeakListVisitor<AllocationSite> {
-  static void SetWeakNext(AllocationSite* obj, Object* next) {
-    obj->set_weak_next(next);
-  }
-
-  static Object* WeakNext(AllocationSite* obj) {
-    return obj->weak_next();
-  }
-
-  static void VisitLiveObject(Heap* heap,
-                              AllocationSite* site,
-                              WeakObjectRetainer* retainer,
-                              bool record_slots) {}
-
-  static void VisitPhantomObject(Heap* heap, AllocationSite* phantom) {}
-
-  static int WeakNextOffset() {
-    return AllocationSite::kWeakNextOffset;
-  }
-};
-
-
 void Heap::ProcessAllocationSites(WeakObjectRetainer* retainer,
                                   bool record_slots) {
   Object* allocation_site_obj =
@@ -2660,6 +2403,7 @@ MaybeObject* Heap::AllocateMap(InstanceType instance_type,
   map->set_code_cache(empty_fixed_array(), SKIP_WRITE_BARRIER);
   map->set_dependent_code(DependentCode::cast(empty_fixed_array()),
                           SKIP_WRITE_BARRIER);
+  map->set_dependent_ic(undefined_value(), SKIP_WRITE_BARRIER);
   map->init_back_pointer(undefined_value());
   map->set_unused_property_fields(0);
   map->set_instance_descriptors(empty_descriptor_array());
@@ -2808,23 +2552,27 @@ bool Heap::CreateInitialMaps() {
   // Fix the instance_descriptors for the existing maps.
   meta_map()->set_code_cache(empty_fixed_array());
   meta_map()->set_dependent_code(DependentCode::cast(empty_fixed_array()));
+  meta_map()->set_dependent_ic(undefined_value());
   meta_map()->init_back_pointer(undefined_value());
   meta_map()->set_instance_descriptors(empty_descriptor_array());
 
   fixed_array_map()->set_code_cache(empty_fixed_array());
   fixed_array_map()->set_dependent_code(
       DependentCode::cast(empty_fixed_array()));
+  fixed_array_map()->set_dependent_ic(undefined_value());
   fixed_array_map()->init_back_pointer(undefined_value());
   fixed_array_map()->set_instance_descriptors(empty_descriptor_array());
 
   oddball_map()->set_code_cache(empty_fixed_array());
   oddball_map()->set_dependent_code(DependentCode::cast(empty_fixed_array()));
+  oddball_map()->set_dependent_ic(undefined_value());
   oddball_map()->init_back_pointer(undefined_value());
   oddball_map()->set_instance_descriptors(empty_descriptor_array());
 
   constant_pool_array_map()->set_code_cache(empty_fixed_array());
   constant_pool_array_map()->set_dependent_code(
       DependentCode::cast(empty_fixed_array()));
+  constant_pool_array_map()->set_dependent_ic(undefined_value());
   constant_pool_array_map()->init_back_pointer(undefined_value());
   constant_pool_array_map()->set_instance_descriptors(empty_descriptor_array());
 
@@ -4181,7 +3929,11 @@ MaybeObject* Heap::CreateCode(const CodeDesc& desc,
   code->set_ic_age(global_ic_age_);
   code->set_prologue_offset(prologue_offset);
   if (code->kind() == Code::OPTIMIZED_FUNCTION) {
-    code->set_marked_for_deoptimization(false);
+    ASSERT(!code->marked_for_deoptimization());
+  }
+  if (code->is_inline_cache_stub()) {
+    ASSERT(!code->is_weak_stub());
+    ASSERT(!code->is_invalidated_weak_stub());
   }
 
   if (FLAG_enable_ool_constant_pool) {