Generalize map dependent codes array to allow multiple dependency groups.

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 2351 matching lines @@
   bool parent_is_alive = Marking::MarkBitFrom(parent).Get();
   if (!current_is_alive && parent_is_alive) {
     parent->ClearNonLiveTransitions(heap());
   }
 }
 
 
 void MarkCompactCollector::ClearAndDeoptimizeDependentCodes(Map* map) {
   AssertNoAllocation no_allocation_scope;
   DependentCodes* codes = map->dependent_codes();
-  int number_of_codes = codes->number_of_codes();
+  DependentCodes::GroupStartIndexes starts;
+  codes->ComputeGroupStartIndexes(starts);
+  int number_of_codes = starts[DependentCodes::kGroupCount];
   if (number_of_codes == 0) return;
   for (int i = 0; i < number_of_codes; i++) {
     Code* code = codes->code_at(i);
     if (IsMarked(code) && !code->marked_for_deoptimization()) {
       code->set_marked_for_deoptimization(true);
     }
     codes->clear_code_at(i);
   }
   map->set_dependent_codes(DependentCodes::cast(heap()->empty_fixed_array()));
 }
 
 
 void MarkCompactCollector::ClearNonLiveDependentCodes(Map* map) {
   AssertNoAllocation no_allocation_scope;
   DependentCodes* codes = map->dependent_codes();
-  int number_of_codes = codes->number_of_codes();
+  DependentCodes::GroupStartIndexes starts;
+  codes->ComputeGroupStartIndexes(starts);
+  int number_of_codes = starts[DependentCodes::kGroupCount];
   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);
+  // Go through all groups, remove dead codes and compact.
+  for (int g = 0; g < DependentCodes::kGroupCount; g++) {
+    int group_number_of_codes = 0;
+    for (int i = starts[g]; i < starts[g + 1]; i++) {
+      Code* code = codes->code_at(i);
+      if (IsMarked(code) && !code->marked_for_deoptimization()) {
+        if (new_number_of_codes + group_number_of_codes != i) {
+          codes->set_code_at(new_number_of_codes + group_number_of_codes, code);
+        }
+        Object** slot = codes->code_slot_at(new_number_of_codes +
+                                            group_number_of_codes);
+        RecordSlot(slot, slot, code);
+        group_number_of_codes++;
       }
-      Object** slot = codes->code_slot_at(new_number_of_codes);
-      RecordSlot(slot, slot, code);
-      new_number_of_codes++;
     }
+    codes->set_number_of_codes(static_cast<DependentCodes::DependencyGroup>(g),
+                               group_number_of_codes);
+    new_number_of_codes += group_number_of_codes;
   }
   for (int i = new_number_of_codes; i < number_of_codes; i++) {
     codes->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