Performance-Oriented Peephole Optimisation of Balsa Dual-Rail Circuits

The transparency and flexibility of the syntax-directed compilation technique, as used in the Tangram (now Haste) and Balsa synthesis systems, comes at the cost of performance overhead. Some control resynthesis and peephole optimisation techniques have been proposed to reduce this performance penalty. In this paper, we introduce new peephole optimisations for Balsa dual-rail circuits. The methods are oriented to remove redundant components and to increase the concurrency during return-to-zero phases. A novel control component, the ParSeq (a hybrid conditional parallel/sequencer controller) is also introduced. Simulations results using large, complex design examples, show substantial increases in performance with negligible area overhead.