Approximate Logic Synthesis Via Iterative SMT-Based Subcircuit Rewriting

Morteza Rezaalipour

doi:10.1109/TCAD.2025.3638267

Approximate Logic Synthesis Via Iterative SMT-Based Subcircuit Rewriting

2025-12-01

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George A. Constantinides

L

Laura Pozzi

DOI：10.1109/TCAD.2025.3638267

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This article presents a novel iterative approach to achieve effective and efficient approximate logic synthesis (ALS). The core idea is to perform circuit rewriting in a way that is both local, i.e., is applied piecewise to selected subcircuits, and extensive, i.e., systematically explores the design space for good solutions. Concretely, we propose SubXPAT, a new Boolean rewriting framework which iteratively uses satisfiability modulo theories (SMT) solving to select and approximate key parts of a circuit. Selection aims at finding subcircuits that at the same time include a significant number of gates and can be efficiently approximated, which is done by searching for large convex subcircuits with a limited number of inputs and outputs. Approximation is guided by the use of a parametric template, structured as a sum of products, which allows for fine-grained control over the subcircuit characteristics. SubXPAT was implemented as an open-source tool and compared against other ALS tools implementing state-of-the-art techniques. Our experimental evaluation used a broad range of arithmetic circuits with different bit-widths, and our results indicate that SubXPAT generates approximate circuits that are more area-efficient than those generated by state-of-the-art techniques in 72% of the cases.

Keywords:

Approximate computing

Boolean rewriting

local analysis

satisfiability modulo theories (SMT) solving

Approximate Logic Synthesis Via Iterative SMT-Based Subcircuit Rewriting

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