code: private String getOptimization(final CommandLineCompilerConfiguration compilerConfig) {
      final String[] args = compilerConfig.getPreArguments();
      String opt = "0";
      for (final String arg : args) {
        if ("/Od".equals(arg)) {
          opt = "0";
        }
        if ("/O1".equals(arg)) {
          opt = "1";
        }
        if ("/O2".equals(arg)) {
          opt = "2";
        }
        if ("/Ox".equals(arg)) {
          opt = "3";
        }
      }
      return opt;
    }
docs: Get value of Optimization property.
  
  @param compilerConfig
  compiler configuration, may not be null.
  @return value of Optimization property.