chance of undefined logic states is reduced and (3) the synthesis
software will not have a problem with your VHDL!
What is being synthesized?
Overall design structure
The basic approach for synthesizing digital circuits is to consider
every design block as a combination of a controller and a data path.
The controller is generally a Finite State Machine (FSM), clocked,
and the data path is usually combinatorial logic, but there may also
be storage in there and so a clock may also be required. The basic
outline is shown in Figure 35.
Controller
The controller is producing the control signals for the data path
logic and may also have external control signals, ...