"cycle advancing states" versus "cycle advancing arcs"

[Rafael Ávila de Espíndola <rafael dot espindola at gmail dot com>]

The finite automaton used in the pipeline hazard recognizer uses a cycle 
advancing arc in every state to represent a clock pulse. Bala(1) uses a 
different technique: All states were a instruction issue is not possible are 
marked as "cycle advancing" and the pipeline state is update to reflect a 
clock cycle. Every time the simulation gets to a cycle advancing state, it 
knows that it cannot issue another instruction in this cycle.

It appears to me that adding a cycle advance arc to every state has the 
potential of increasing the size of the automaton quite significantly. Is 
this true?

What is the advantage of the "cycle advancing arc"? It is simpler to 
understand, but the only use I can see is to represent a case were it was 
possible to issue a instruction but, instead of doing this, the pipeline 
advanced the clock. Does this happens in practice? 

1) V.Bala and N.Rubin, Efficient Instruction Scheduling Using Finite State 
Automata.

Thank you very much.
Rafael Ávila de Espíndola

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