@Override
 public void process(Node externs, Node root) {
   if (!passes.isEmpty()) {
     SimpleDefinitionFinder defFinder = new SimpleDefinitionFinder(compiler);
     compiler.setSimpleDefinitionFinder(defFinder);
     defFinder.process(externs, root);
     for (CallGraphCompilerPass pass : passes) {
       pass.process(externs, root, defFinder);
     }
   }
 }