ClearNonLiveTransitions indepedent of ContentArray

Review URL: https://chromiumcodereview.appspot.com/10387231

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11693 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects-inl.h

@@ -1943,6 +1943,12 @@ Object* DescriptorArray::GetValue(int descriptor_number) {
 }
 
 
+void DescriptorArray::SetNullValueUnchecked(int descriptor_number, Heap* heap) {
+  ASSERT(descriptor_number < number_of_descriptors());
+  GetContentArray()->set_null_unchecked(heap, ToValueIndex(descriptor_number));
+}
+
+
 PropertyDetails DescriptorArray::GetDetails(int descriptor_number) {
   ASSERT(descriptor_number < number_of_descriptors());
   Object* details = GetContentArray()->get(ToDetailsIndex(descriptor_number));
@@ -1950,6 +1956,12 @@ PropertyDetails DescriptorArray::GetDetails(int descriptor_number) {
 }
 
 
+void DescriptorArray::SetDetailsUnchecked(int descriptor_number, Smi* value) {
+  ASSERT(descriptor_number < number_of_descriptors());
+  GetContentArray()->set_unchecked(ToDetailsIndex(descriptor_number), value);
+}
+
+
 PropertyType DescriptorArray::GetType(int descriptor_number) {
   return GetDetails(descriptor_number).type();
 }

src/objects.cc

@@ -7440,23 +7440,20 @@ void Map::ClearNonLiveTransitions(Heap* heap) {
   if (d->IsEmpty()) return;
   Smi* NullDescriptorDetails =
     PropertyDetails(NONE, NULL_DESCRIPTOR).AsSmi();
-  FixedArray* contents = FixedArray::cast(
-      d->get(DescriptorArray::kContentArrayIndex));
-  ASSERT(contents->length() >= 2);
-  for (int i = 0; i < contents->length(); i += 2) {
+  for (int i = 0; i < d->number_of_descriptors(); ++i) {
     // If the pair (value, details) is a map transition, check if the target is
     // live. If not, null the descriptor. Also drop the back pointer for that
     // map transition, so that this map is not reached again by following a back
     // pointer from that non-live map.
     bool keep_entry = false;
-    PropertyDetails details(Smi::cast(contents->get(i + 1)));
+    PropertyDetails details(d->GetDetails(i));
     switch (details.type()) {
       case MAP_TRANSITION:
       case CONSTANT_TRANSITION:
-        ClearBackPointer(heap, contents->get(i), &keep_entry);
+        ClearBackPointer(heap, d->GetValue(i), &keep_entry);
         break;
       case ELEMENTS_TRANSITION: {
-        Object* object = contents->get(i);
+        Object* object = d->GetValue(i);
         if (object->IsMap()) {
           ClearBackPointer(heap, object, &keep_entry);
         } else {
@@ -7470,7 +7467,7 @@ void Map::ClearNonLiveTransitions(Heap* heap) {
         break;
       }
       case CALLBACKS: {
-        Object* object = contents->get(i);
+        Object* object = d->GetValue(i);
         if (object->IsAccessorPair()) {
           AccessorPair* accessors = AccessorPair::cast(object);
           if (ClearBackPointer(heap, accessors->getter(), &keep_entry)) {
@@ -7497,8 +7494,8 @@ void Map::ClearNonLiveTransitions(Heap* heap) {
     // What we *really* want to do here is removing this entry completely, but
     // for technical reasons we can't do this, so we zero it out instead.
     if (!keep_entry) {
-      contents->set_unchecked(i + 1, NullDescriptorDetails);
-      contents->set_null_unchecked(heap, i);
+      d->SetDetailsUnchecked(i, NullDescriptorDetails);
+      d->SetNullValueUnchecked(i, heap);
     }
   }
 }

src/objects.h

@@ -2451,7 +2451,9 @@ class DescriptorArray: public FixedArray {
   inline String* GetKey(int descriptor_number);
   inline Object* GetValue(int descriptor_number);
   inline Object** GetValueSlot(int descriptor_number);
+  inline void SetNullValueUnchecked(int descriptor_number, Heap* heap);
   inline PropertyDetails GetDetails(int descriptor_number);
+  inline void SetDetailsUnchecked(int descriptor_number, Smi* value);
   inline PropertyType GetType(int descriptor_number);
   inline int GetFieldIndex(int descriptor_number);
   inline JSFunction* GetConstantFunction(int descriptor_number);