protected function _renderFilters()
{
    if ($this->_isFiltersRendered) {
        return $this;
    }

    $this->_renderFiltersBefore(); // Hook for operations before rendering filters

    ....................
}

protected function _renderFiltersBefore() {
    $joinTable = $this->getTable('catalog_product_entity_varchar');
    $this->getSelect()->join($joinTable.' as cpev','main_table.entity_id = cpev.entity_id', array('*'));
    parent::_renderFiltersBefore();
}

<dataSource name="listing_name_data_source">
    <argument name="dataProvider" xsi:type="configurableObject">
        <argument name="class" xsi:type="string">UniqueNameGridDataProvider</argument>
        <argument name="name" xsi:type="string">listing_name_data_source</argument>