Make embedded maps in optimized code weak.

src/objects.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 9666 matching lines @@
 
 
 void Map::ZapPrototypeTransitions() {
   FixedArray* proto_transitions = GetPrototypeTransitions();
   MemsetPointer(proto_transitions->data_start(),
                 GetHeap()->the_hole_value(),
                 proto_transitions->length());
 }
 
 
+Handle<DependentCodes> DependentCodes::Append(Handle<DependentCodes> codes,
+                                              Handle<Code> value) {
+  int append_index = codes->number_of_codes();
+  if (append_index > 0 && codes->code_at(append_index - 1) == *value) {
+    // Do not append the code if it is already in the array.
+    // It is sufficient to just check only the last element because
+    // we process embedded maps of an optimized code in one batch.
+    return codes;
+  }
+  if (codes->length() < kCodesOffset + append_index + 1) {
+    Factory* factory = codes->GetIsolate()->factory();
+    int capacity = kCodesOffset + append_index + 1;
+    if (capacity > 5) capacity = capacity * 5 / 4;
+    Handle<DependentCodes> new_codes =
+        Handle<DependentCodes>::cast(factory->NewFixedArray(capacity));
+    // The number of codes can change after GC.
+    append_index = codes->number_of_codes();
+    new_codes->set_number_of_codes(append_index + 1);
+    for (int i = 0; i < append_index; i++) {
+      new_codes->set_code_at(i, codes->code_at(i));
+      codes->clear_code_at(i);
+    }

[Michael Starzinger, 2013/01/21 10:31:48]

This resizing is already implemented in Factory::CopySizeFixedArray, if you
change your sentinel value from Smi(0) to undefined you could reuse all of that
code. I'll leave that up to you.

[ulan, 2013/01/21 13:11:57]

Done.

+    new_codes->set_code_at(append_index, *value);
+    for (int i = append_index + 1; kCodesOffset + i < capacity; i++) {
+      new_codes->clear_code_at(i);
+    }
+    return new_codes;
+  }
+  codes->set_code_at(append_index, *value);
+  codes->set_number_of_codes(append_index + 1);
+  return codes;
+}
+
+
 MaybeObject* JSReceiver::SetPrototype(Object* value,
                                       bool skip_hidden_prototypes) {
 #ifdef DEBUG
   int size = Size();
 #endif
 
   Heap* heap = GetHeap();
   // Silently ignore the change if value is not a JSObject or null.
   // SpiderMonkey behaves this way.
   if (!value->IsJSReceiver() && !value->IsNull()) return value;
@@ skipping 4330 matching lines @@
   set_year(Smi::FromInt(year), SKIP_WRITE_BARRIER);
   set_month(Smi::FromInt(month), SKIP_WRITE_BARRIER);
   set_day(Smi::FromInt(day), SKIP_WRITE_BARRIER);
   set_weekday(Smi::FromInt(weekday), SKIP_WRITE_BARRIER);
   set_hour(Smi::FromInt(hour), SKIP_WRITE_BARRIER);
   set_min(Smi::FromInt(min), SKIP_WRITE_BARRIER);
   set_sec(Smi::FromInt(sec), SKIP_WRITE_BARRIER);
 }
 
 } }  // namespace v8::internal