Synthesis of wiring signature-invariant equivalence class circuit mutants and applications to benchmarking

Abstract

This paper formalizes the synthesis process of wiring signature-invariant (WSI) combinational circuit mutants. The signature /spl sigma//sub 0/ is defined by a reference circuit /spl eta//sub 0/, which itself is modeled as a canonical form of a directed bipartite graph. A wiring perturbation /spl gamma/ induces a perturbed reference circuit /spl eta//sub /spl gamma//. A number of mutant circuits /spl eta//sub /spl gamma/i/ can be resynthesized from the perturbed circuit /spl eta//sub /spl gamma//. The mutants of interest are the ones that belong to the wiring-signature-invariant equivalence class N/sub /spl sigma/0/, i.e. the mutants /spl eta//sub /spl gamma/i//spl isin/N/sub /spl sigma/0/. Circuit mutants /spl eta//sub /spl gamma/i//spl isin/N/sub /spl sigma/0/ have a number of useful properties. For any wiring perturbation /spl gamma/, the size of the wiring-signature-invariant equivalence class is huge. Notably, circuits in this class are not random, although for unbiased testing and benchmarking purposes, mutant selections from this class are typically random. For each reference circuit, we synthesized eight equivalence subclasses of circuit mutants, based on 0 to 100% perturbation. Each subclass contains 100 randomly chosen mutant circuits, each listed in a different random order. The 14,400 benchmarking experiments with 3200 mutants in 4 equivalence classes, covering 13 typical EDA algorithms, demonstrate that an unbiased random selection of such circuits can lead to statistically meaningful differentiation and improvements of existing and new algorithms.