RFC: Try to be much more careful with where we skip the write barrier by:...

src/objects-inl.h

 // Copyright 2006-2008 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 1331 matching lines @@
 
 
 void FixedArray::set(int index, Object* value) {
   ASSERT(index >= 0 && index < this->length());
   int offset = kHeaderSize + index * kPointerSize;
   WRITE_FIELD(this, offset, value);
   WRITE_BARRIER(this, offset);
 }
 
 
-WriteBarrierMode HeapObject::GetWriteBarrierMode() {
+WriteBarrierMode HeapObject::GetWriteBarrierMode(const AssertNoAllocation&) {
   if (Heap::InNewSpace(this)) return SKIP_WRITE_BARRIER;
   return UPDATE_WRITE_BARRIER;
 }
 
 
 void FixedArray::set(int index,
                      Object* value,
                      WriteBarrierMode mode) {
   ASSERT(index >= 0 && index < this->length());
   int offset = kHeaderSize + index * kPointerSize;
@@ skipping 178 matching lines @@
 
 uint32_t NumberDictionary::max_number_key() {
   ASSERT(!requires_slow_elements());
   Object* max_index_object = get(kMaxNumberKeyIndex);
   if (!max_index_object->IsSmi()) return 0;
   uint32_t value = static_cast<uint32_t>(Smi::cast(max_index_object)->value());
   return value >> kRequiresSlowElementsTagSize;
 }
 
 void NumberDictionary::set_requires_slow_elements() {
-  set(kMaxNumberKeyIndex,
-      Smi::FromInt(kRequiresSlowElementsMask),
-      SKIP_WRITE_BARRIER);
+  set(kMaxNumberKeyIndex, Smi::FromInt(kRequiresSlowElementsMask));
 }
 
 
 // ------------------------------------
 // Cast operations
 
 
 CAST_ACCESSOR(FixedArray)
 CAST_ACCESSOR(DescriptorArray)
 CAST_ACCESSOR(SymbolTable)
@@ skipping 1402 matching lines @@
   set_flag(Smi::FromInt(rest_value | AttributesField::encode(attributes)));
 }
 
 template<typename Shape, typename Key>
 void Dictionary<Shape, Key>::SetEntry(int entry,
                                       Object* key,
                                       Object* value,
                                       PropertyDetails details) {
   ASSERT(!key->IsString() || details.IsDeleted() || details.index() > 0);
   int index = HashTable<Shape, Key>::EntryToIndex(entry);
-  WriteBarrierMode mode = FixedArray::GetWriteBarrierMode();
+  AssertNoAllocation no_gc;
+  WriteBarrierMode mode = FixedArray::GetWriteBarrierMode(no_gc);
   FixedArray::set(index, key, mode);
   FixedArray::set(index+1, value, mode);
   FixedArray::fast_set(this, index+2, details.AsSmi());
 }
 
 
 void Map::ClearCodeCache() {
   // No write barrier is needed since empty_fixed_array is not in new space.
   // Please note this function is used during marking:
   //  - MarkCompactCollector::MarkUnmarkedObject
@@ skipping 13 matching lines @@
     // It's a performance benefit to keep a frequently used array in new-space.
   } else if (!Heap::new_space()->Contains(elts) &&
              required_size < kArraySizeThatFitsComfortablyInNewSpace) {
     // Expand will allocate a new backing store in new space even if the size
     // we asked for isn't larger than what we had before.
     Expand(required_size);
   }
 }
 
 
+void JSArray::set_length(Smi* length) {
+  set_length(static_cast<Object*>(length), SKIP_WRITE_BARRIER);
+}
+
+
 void JSArray::SetContent(FixedArray* storage) {
-  set_length(Smi::FromInt(storage->length()), SKIP_WRITE_BARRIER);
+  set_length(Smi::FromInt(storage->length()));
   set_elements(storage);
 }
 
 
 Object* FixedArray::Copy() {
   if (length() == 0) return this;
   return Heap::CopyFixedArray(this);
 }
 
 
@@ skipping 14 matching lines @@
 #undef WRITE_INT_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_