Track ascii-ness of data in externalized strings.

src/objects.cc

 // Copyright 2006-2009 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 660 matching lines @@
       cs->set_second(Heap::empty_string());
       return result;
     }
     default:
       return this;
   }
 }
 
 
 bool String::MakeExternal(v8::String::ExternalStringResource* resource) {
+  // Externalizing twice leaks the external resouce, so it's
+  // prohibited by the API.
+  ASSERT(!this->IsExternalString());
 #ifdef DEBUG
   if (FLAG_enable_slow_asserts) {
     // Assert that the resource and the string are equivalent.
     ASSERT(static_cast<size_t>(this->length()) == resource->length());
     ScopedVector<uc16> smart_chars(this->length());
     String::WriteToFlat(this, smart_chars.start(), 0, this->length());
     ASSERT(memcmp(smart_chars.start(),
                   resource->data(),
                   resource->length() * sizeof(smart_chars[0])) == 0);
   }
 #endif  // DEBUG
 
   int size = this->Size();  // Byte size of the original string.
   if (size < ExternalString::kSize) {
     // The string is too small to fit an external String in its place. This can
     // only happen for zero length strings.
     return false;
   }
   ASSERT(size >= ExternalString::kSize);
+  bool is_ascii = this->IsAsciiRepresentation();
   bool is_symbol = this->IsSymbol();
   int length = this->length();
   int hash_field = this->hash_field();
 
   // Morph the object to an external string by adjusting the map and
   // reinitializing the fields.
-  this->set_map(Heap::external_string_map());
+  this->set_map(is_ascii ?
+                Heap::external_string_with_ascii_data_map() :
+                Heap::external_string_map());
   ExternalTwoByteString* self = ExternalTwoByteString::cast(this);
   self->set_length(length);
   self->set_hash_field(hash_field);
   self->set_resource(resource);
   // Additionally make the object into an external symbol if the original string
   // was a symbol to start with.
   if (is_symbol) {
     self->Hash();  // Force regeneration of the hash value.
     // Now morph this external string into a external symbol.
-    this->set_map(Heap::external_symbol_map());
+    this->set_map(is_ascii ?
+                  Heap::external_symbol_with_ascii_data_map() :
+                  Heap::external_symbol_map());
   }
 
   // Fill the remainder of the string with dead wood.
   int new_size = this->Size();  // Byte size of the external String object.
   Heap::CreateFillerObjectAt(this->address() + new_size, size - new_size);
   return true;
 }
 
 
 bool String::MakeExternal(v8::String::ExternalAsciiStringResource* resource) {
@@ skipping 7995 matching lines @@
   if (break_point_objects()->IsUndefined()) return 0;
   // Single beak point.
   if (!break_point_objects()->IsFixedArray()) return 1;
   // Multiple break points.
   return FixedArray::cast(break_point_objects())->length();
 }
 #endif
 
 
 } }  // namespace v8::internal