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This paper presents CirFix, a framework for automatically repairing defects in hardware designs implemented in languages like Verilog. We propose a novel fault localization approach based on assignments to wires and registers, and a fitness function tailored to the hardware domain to bridge the gap between software-level automated program repair and hardware descriptions. We also present a benchmark suite of 32 defect scenarios corresponding to a variety of hardware projects. Overall, CirFix produces plausible repairs for 21/32 and correct repairs for 16/32 of the defect scenarios. This repair rate is comparable to that of successful program repair approaches for software, indicating CirFix is effective at bringing over the benefits of automated program repair to the hardware domain for the first time. 

Distributed systems are hard to design and implement correctly. Recent work has tried to use formal verification techniques to provide rigorous correctness guarantees. These works present a hard choice, though. One must either opt for the power of refinement-based approaches like IronFleet and Verdi, at the cost of large amounts of manual effort; or choose the more automated approach of I4, IC3PO, SWISS and DistAI which give up the ability to prove refinement and the power and scalability that come with it. We propose an alternative approach, Sift, that combines the power of refinement with the ability to automate proofs. Sift is a two-tier methodology that uses a new technique, refinement-guided automation, to leverage automation in a refinement proof and a divide-and-conquer technique to split a system into more refinement layers when necessary. This combination advances the frontier of what systems can be proven correct using a high degree of automation. Contrary to what was possible before, our evaluation shows that our novel approach allows us to prove the correctness of a number of systems with little manual effort, and to extend our proofs to include not just the protocols, but also an executable distributed implementation of these systems.