[2603.20075] Agentic Harness for Real-World Compilers

Computer Science > Software Engineering arXiv:2603.20075 (cs) [Submitted on 20 Mar 2026] Title:Agentic Harness for Real-World Compilers Authors:Yingwei Zheng, Cong Li, Shaohua Li, Yuqun Zhang, Zhendong Su View a PDF of the paper titled Agentic Harness for Real-World Compilers, by Yingwei Zheng and 4 other authors View PDF HTML (experimental) Abstract:Compilers are critical to modern computing, yet fixing compiler bugs is difficult. While recent large language model (LLM) advancements enable automated bug repair, compiler bugs pose unique challenges due to their complexity, deep cross-domain expertise requirements, and sparse, non-descriptive bug reports, necessitating compiler-specific tools. To bridge the gap, we introduce llvm-autofix, the first agentic harness designed to assist LLM agents in understanding and fixing compiler bugs. Our focus is on LLVM, one of the most widely used compiler infrastructures. Central to llvm-autofix are agent-friendly LLVM tools, a benchmark llvm-bench of reproducible LLVM bugs, and a tailored minimal agent llvm-autofix-mini for fixing LLVM bugs. Our evaluation demonstrates a performance decline of 60% in frontier models when tackling compiler bugs compared with common software bugs. Our minimal agent llvm-autofix-mini also outperforms the state-of-the-art by approximately 22%. This emphasizes the necessity for specialized harnesses like ours to close the loop between LLMs and compiler engineering. We believe this work establishes a founda...