OPTIMIZATION EFFICIENCY IN BEHAVIORAL SYNTHESIS

Behavioural synthesis is the process whereby the mapping of system ope ration (behaviour) onto a physical circuit is essentially automated. I n general, there are many ways in which a given design can be realised and each alternative design will have different physical parameters ( area, speed and power dissipation being the most common). One of the k ey features of a good silicon compiler is that it allows-the user to e xplore the 'design space' corresponding to the behavioural description ; this means that the system must be capable of producing alternative (but behaviourally equivalent) designs relatively quickly. This paper describes the optimisation technique used in the MOODS (multiple objec tive optimisation behavioural synthesis) system and looks at the effic iency of the various subprocesses. The conclusions are that even for a large synthesis task, the time taken taken for MOODS to generate alte rnative designs,is sufficiently low that the user response (in evaluat ing alternative designs) is essentially the rate limiting step in the overall design process. Typically, MOODS can generate 35 designs/secon d for a behavioural description containing 41 primitive operations run ning on a Sun SPARCstation LX.