verilog-auto-arg-format

verilog-auto-arg-format is a variable defined in `verilog-mode.el'.
Its value is

packed

• This variable is safe as a file local variable if its value
  satisfies the predicate `(lambda (x) (memq x (quote (packed single))))'.

Documentation:
Formatting to use for AUTOARG signal names.
If 'packed', then as many inputs and outputs that fit within
`fill-column' will be put onto one line.

If 'single', then a single input or output will be put onto each
line.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 25.1 of Emacs.