[GENERAL] What happens when a large table is alterted from UNLOGGED to LOGGED

In order to speed up loading a set of 12 tables, I have declared them as UNLOGGED.  As per documentation, an unlogged
tablewill also have unlogged indices.   

Question: When the table is converted back to logged, does PG rebuild all indices before marking them as logged.  Also
whatabout FKY constraints. Does it revalidate them ? 

thanks.