The Vivado synthesis flags INFO messages in the log file, giving information about Finite State Machine (FSM) components and their encoding. The following are example messages:
INFO: [Synth 8-802] inferred FSM for state register 'state_reg' in module 'fsm_test'
INFO: [Synth 8-3354] encoded FSM with state register 'state_reg' using encoding 'sequential' in module 'fsm_test'