Avoid (some) symbol lookups at parse time if preparse data is available.

src/api.cc

 // Copyright 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 1118 matching lines @@
 
 ScriptData* ScriptData::PreCompile(v8::Handle<String> source) {
   i::Handle<i::String> str = Utils::OpenHandle(*source);
   return i::PreParse(str, NULL, NULL);
 }
 
 
 ScriptData* ScriptData::New(const char* data, int length) {
   // Return an empty ScriptData if the length is obviously invalid.
   if (length % sizeof(unsigned) != 0) {
-    return new i::ScriptDataImpl(i::Vector<unsigned>());
+    return new i::ScriptDataImpl();
   }
 
   // Copy the data to ensure it is properly aligned.
   int deserialized_data_length = length / sizeof(unsigned);
+  // If aligned, don't create a copy of the data.
+  if (reinterpret_cast<intptr_t>(data) % sizeof(unsigned) == 0) {
+    return new i::ScriptDataImpl(data, length);
+  }
+  // Copy the data to align it.
   unsigned* deserialized_data = i::NewArray<unsigned>(deserialized_data_length);
-  memcpy(deserialized_data, data, length);
+  i::MemCopy(deserialized_data, data, length);
 
   return new i::ScriptDataImpl(
       i::Vector<unsigned>(deserialized_data, deserialized_data_length));
 }
 
 
 // --- S c r i p t ---
 
 
 Local<Script> Script::New(v8::Handle<String> source,
@@ skipping 3695 matching lines @@
 
 
 char* HandleScopeImplementer::Iterate(ObjectVisitor* v, char* storage) {
   HandleScopeImplementer* thread_local =
       reinterpret_cast<HandleScopeImplementer*>(storage);
   thread_local->IterateThis(v);
   return storage + ArchiveSpacePerThread();
 }
 
 } }  // namespace v8::internal