Adding hidden values always turned the object slow case because the

hidden symbol is not an identifier.  Make sure to keep objects fast
case when adding hidden values if possible.
Review URL: http://codereview.chromium.org/93004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1758 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects.cc

@@ -1129,9 +1129,10 @@ Object* JSObject::AddFastPropertyUsingMap(Map* new_map,
 Object* JSObject::AddFastProperty(String* name,
                                   Object* value,
                                   PropertyAttributes attributes) {
-  // Normalize the object if the name is not a real identifier.
+  // Normalize the object if the name is an actual string (not the
+  // hidden symbols) and is not a real identifier.
   StringInputBuffer buffer(name);
-  if (!Scanner::IsIdentifier(&buffer)) {
+  if (!Scanner::IsIdentifier(&buffer) && name != Heap::hidden_symbol()) {
     Object* obj = NormalizeProperties(CLEAR_INOBJECT_PROPERTIES);
     if (obj->IsFailure()) return obj;
     return AddSlowProperty(name, value, attributes);
@@ -5172,19 +5173,15 @@ bool JSObject::HasLocalElement(uint32_t index) {
 Object* JSObject::GetHiddenProperties(bool create_if_needed) {
   String* key = Heap::hidden_symbol();
   if (this->HasFastProperties()) {
-    // If the object has fast properties, check whether the first slot in the
-    // descriptor array matches the hidden symbol. Since the hidden symbols
-    // hash code is zero it will always occupy the first entry if present.
+    // If the object has fast properties, check whether the first slot
+    // in the descriptor array matches the hidden symbol. Since the
+    // hidden symbols hash code is zero (and no other string has hash
+    // code zero) it will always occupy the first entry if present.
     DescriptorArray* descriptors = this->map()->instance_descriptors();
-    if (descriptors->number_of_descriptors() > 0) {
-      if (descriptors->GetKey(0) == key) {
-#ifdef DEBUG
-        PropertyDetails details(descriptors->GetDetails(0));
-        ASSERT(details.type() == FIELD);
-#endif  // DEBUG
-        Object* value = descriptors->GetValue(0);
-        return FastPropertyAt(Descriptor::IndexFromValue(value));
-      }
+    DescriptorReader r(descriptors);
+    if (!r.eos() && (r.GetKey() == key) && r.IsProperty()) {
+      ASSERT(r.type() == FIELD);
+      return FastPropertyAt(r.GetFieldIndex());
     }
   }