Syzygy: Dual Code-Test C to (safe) Rust Translation using LLMs and Dynamic Analysis

TL;DR

Syzygy is an automated method that combines large language models and dynamic analysis to translate complex C code into safe Rust, ensuring correctness and safety in a scalable way.

Contribution

This paper introduces a novel synergistic approach that integrates LLM-driven code translation with dynamic analysis for safe C to Rust conversion.

Findings

Successfully translated Zopfli library (~3000 lines, 98 functions)

Achieved largest automated, test-validated C to Rust translation to date

Validated translation correctness through equivalence testing

Abstract

Despite extensive usage in high-performance, low-level systems programming applications, C is susceptible to vulnerabilities due to manual memory management and unsafe pointer operations. Rust, a modern systems programming language, offers a compelling alternative. Its unique ownership model and type system ensure memory safety without sacrificing performance. In this paper, we present Syzygy, an automated approach to translate C to safe Rust. Our technique uses a synergistic combination of LLM-driven code and test translation guided by dynamic-analysis-generated execution information. This paired translation runs incrementally in a loop over the program in dependency order of the code elements while maintaining per-step correctness. Our approach exposes novel insights on combining the strengths of LLMs and dynamic analysis in the context of scaling and combining code generation with testing. We apply our approach to successfully translate Zopfli, a high-performance compression library with ~3000 lines of code and 98 functions. We validate the translation by testing equivalence with the source C program on a set of inputs. To our knowledge, this is the largest automated and test-validated C to safe Rust code translation achieved so far.