Remove prototype checks for leaf maps in optimized code.

src/mark-compact.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 403 matching lines @@
   if (FLAG_verify_native_context_separation) {
     VerifyNativeContextSeparation(heap_);
   }
 #endif
 
 #ifdef VERIFY_HEAP
   if (FLAG_collect_maps && FLAG_weak_embedded_maps_in_optimized_code &&
       heap()->weak_embedded_maps_verification_enabled()) {
     VerifyWeakEmbeddedMapsInOptimizedCode();
   }
+  if (FLAG_collect_maps && FLAG_omit_prototype_checks_for_leaf_maps) {
+    VerifyOmittedPrototypeChecks();
+  }
 #endif
 
   Finish();
 
   if (marking_parity_ == EVEN_MARKING_PARITY) {
     marking_parity_ = ODD_MARKING_PARITY;
   } else {
     ASSERT(marking_parity_ == ODD_MARKING_PARITY);
     marking_parity_ = EVEN_MARKING_PARITY;
   }
@@ skipping 46 matching lines @@
   HeapObjectIterator code_iterator(heap()->code_space());
   for (HeapObject* obj = code_iterator.Next();
        obj != NULL;
        obj = code_iterator.Next()) {
     Code* code = Code::cast(obj);
     if (code->kind() != Code::OPTIMIZED_FUNCTION) continue;
     if (code->marked_for_deoptimization()) continue;
     code->VerifyEmbeddedMapsDependency();
   }
 }
+
+
+void MarkCompactCollector::VerifyOmittedPrototypeChecks() {
+  HeapObjectIterator iterator(heap()->map_space());
+  for (HeapObject* obj = iterator.Next();
+       obj != NULL;
+       obj = iterator.Next()) {
+    Map* map = Map::cast(obj);
+    map->VerifyOmittedPrototypeChecks();
+  }
+}
 #endif  // VERIFY_HEAP
 
 
 static void ClearMarkbitsInPagedSpace(PagedSpace* space) {
   PageIterator it(space);
 
   while (it.has_next()) {
     Bitmap::Clear(it.next());
   }
 }
@@ skipping 1785 matching lines @@
       // This map is used for inobject slack tracking and has been detached
       // from SharedFunctionInfo during the mark phase.
       // Since it survived the GC, reattach it now.
       map->unchecked_constructor()->unchecked_shared()->AttachInitialMap(map);
     }
 
     ClearNonLivePrototypeTransitions(map);
     ClearNonLiveMapTransitions(map, map_mark);
 
     if (map_mark.Get()) {
-      ClearNonLiveDependentCodes(map);
+      ClearNonLiveDependentCode(map);
     } else {
-      ClearAndDeoptimizeDependentCodes(map);
+      ClearAndDeoptimizeDependentCode(map);
     }
   }
 }
 
 
 void MarkCompactCollector::ClearNonLivePrototypeTransitions(Map* map) {
   int number_of_transitions = map->NumberOfProtoTransitions();
   FixedArray* prototype_transitions = map->GetPrototypeTransitions();
 
   int new_number_of_transitions = 0;
@@ skipping 49 matching lines @@
   // Follow back pointer, check whether we are dealing with a map transition
   // from a live map to a dead path and in case clear transitions of parent.
   bool current_is_alive = map_mark.Get();
   bool parent_is_alive = Marking::MarkBitFrom(parent).Get();
   if (!current_is_alive && parent_is_alive) {
     parent->ClearNonLiveTransitions(heap());
   }
 }
 
 
-void MarkCompactCollector::ClearAndDeoptimizeDependentCodes(Map* map) {
+void MarkCompactCollector::ClearAndDeoptimizeDependentCode(Map* map) {
   AssertNoAllocation no_allocation_scope;
-  DependentCodes* codes = map->dependent_codes();
-  int number_of_codes = codes->number_of_codes();
-  if (number_of_codes == 0) return;
-  for (int i = 0; i < number_of_codes; i++) {
-    Code* code = codes->code_at(i);
+  DependentCode* entries = map->dependent_code();
+  DependentCode::GroupStartIndexes starts(entries);
+  int number_of_entries = starts.number_of_entries();
+  if (number_of_entries == 0) return;
+  for (int i = 0; i < number_of_entries; i++) {
+    Code* code = entries->code_at(i);
     if (IsMarked(code) && !code->marked_for_deoptimization()) {
       code->set_marked_for_deoptimization(true);
     }
-    codes->clear_code_at(i);
+    entries->clear_code_at(i);
   }
-  map->set_dependent_codes(DependentCodes::cast(heap()->empty_fixed_array()));
+  map->set_dependent_code(DependentCode::cast(heap()->empty_fixed_array()));
 }
 
 
-void MarkCompactCollector::ClearNonLiveDependentCodes(Map* map) {
+void MarkCompactCollector::ClearNonLiveDependentCode(Map* map) {
   AssertNoAllocation no_allocation_scope;
-  DependentCodes* codes = map->dependent_codes();
-  int number_of_codes = codes->number_of_codes();
-  if (number_of_codes == 0) return;
-  int new_number_of_codes = 0;
-  for (int i = 0; i < number_of_codes; i++) {
-    Code* code = codes->code_at(i);
-    if (IsMarked(code) && !code->marked_for_deoptimization()) {
-      if (new_number_of_codes != i) {
-        codes->set_code_at(new_number_of_codes, code);
+  DependentCode* entries = map->dependent_code();
+  DependentCode::GroupStartIndexes starts(entries);
+  int number_of_entries = starts.number_of_entries();
+  if (number_of_entries == 0) return;
+  int new_number_of_entries = 0;
+  // Go through all groups, remove dead codes and compact.
+  for (int g = 0; g < DependentCode::kGroupCount; g++) {
+    int group_number_of_entries = 0;
+    for (int i = starts.at(g); i < starts.at(g + 1); i++) {
+      Code* code = entries->code_at(i);
+      if (IsMarked(code) && !code->marked_for_deoptimization()) {
+        if (new_number_of_entries + group_number_of_entries != i) {
+          entries->set_code_at(new_number_of_entries +
+                               group_number_of_entries, code);
+        }
+        Object** slot = entries->code_slot_at(new_number_of_entries +
+                                              group_number_of_entries);
+        RecordSlot(slot, slot, code);
+        group_number_of_entries++;
       }
-      Object** slot = codes->code_slot_at(new_number_of_codes);
-      RecordSlot(slot, slot, code);
-      new_number_of_codes++;
     }
+    entries->set_number_of_entries(
+        static_cast<DependentCode::DependencyGroup>(g),
+        group_number_of_entries);
+    new_number_of_entries += group_number_of_entries;
   }
-  for (int i = new_number_of_codes; i < number_of_codes; i++) {
-    codes->clear_code_at(i);
+  for (int i = new_number_of_entries; i < number_of_entries; i++) {
+    entries->clear_code_at(i);
   }
-  codes->set_number_of_codes(new_number_of_codes);
 }
 
 
 void MarkCompactCollector::ProcessWeakMaps() {
   Object* weak_map_obj = encountered_weak_maps();
   while (weak_map_obj != Smi::FromInt(0)) {
     ASSERT(MarkCompactCollector::IsMarked(HeapObject::cast(weak_map_obj)));
     JSWeakMap* weak_map = reinterpret_cast<JSWeakMap*>(weak_map_obj);
     ObjectHashTable* table = ObjectHashTable::cast(weak_map->table());
     Object** anchor = reinterpret_cast<Object**>(table->address());
@@ skipping 1656 matching lines @@
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 
 
 } }  // namespace v8::internal