vhdl-align-group-separate

vhdl-align-group-separate is a variable defined in `vhdl-mode.el'.
Its value is

"^\\s-*$"

Documentation:
Regexp for matching a line that separates groups of lines for alignment.
Examples:
"^\s-*$": matches an empty line
"^\s-*\(--.*\)?$": matches an empty line or a comment-only line

You can customize this variable.