code: private String getUsePrecompiledHeader(final CommandLineCompilerConfiguration compilerConfig) {
      String usePCH = "0";
      final String[] args = compilerConfig.getPreArguments();
      for (final String arg : args) {
        if ("/Yc".equals(arg)) {
          usePCH = "1";
        }
        if ("/Yu".equals(arg)) {
          usePCH = "2";
        }
      }
      return usePCH;
    }
docs: Get value of UsePrecompiledHeader property.
  
  @param compilerConfig
  compiler configuration.
  @return value of UsePrecompiledHeader property.