Source level optimisation of VHDL for behavioural synthesis

Optimisation in high level behavioural synthesis is usually performed by applying transforms to the datapath and control graphs. An alternative approach, however, is to apply transforms at a higher level in the process, specifically directly to the behavioural source description. This technique is analogous to the way in which the source code of a conventional sequential programming language may be processed by an optimising compiler. The application of this kind of preprocessing to a number of example behavioural VHDL source descriptions (which are then fed into a ‘conventional’ synthesis system) produces structural descriptions which are up to 32% smaller and 52% faster.