verilog-auto-save-policy

verilog-auto-save-policy is a variable defined in `verilog-mode.el'.
Its value is

nil

Documentation:
Non-nil indicates action to take when saving a Verilog buffer with AUTOs.
A value of `force' will always do a M-x verilog-auto automatically if
needed on every save. A value of `detect' will do M-x verilog-auto
automatically when it thinks necessary. A value of `ask' will query the
user when it thinks updating is needed.

You should not rely on the 'ask or 'detect policies, they are safeguards
only. They do not detect when AUTOINSTs need to be updated because a
sub-module's port list has changed.

You can customize this variable.