My research interests broadly span compiler systems, operating systems, and software engineering, especially language virtual machines, optimizing compilers, and Android systems. I'm now working on leveraging large language models to facilitate compiler optimization and fuzzing, for example, fuzzing the JIT compilers of modern language virtual machines such as Java Virtual Machines (HotSpot, OpenJ9, etc.) and JavaScript Engines (V8, JavaScriptCore, etc.). Feel free to drop an email if you are interested.
Address: Ant A Space, Hangzhou, China
Email: connglli # outlook.com
Open Source Contributions
My research has actively contributed to the compiler community.
Artemis: On the one hand, I'm active around JVMs and received thanks from HotSpot's and OpenJ9's JIT complier teams. My work was also liked by Mark Reinhold, the Chief Architect of the Java Platform Group at Oracle. Specifically, I've found 80+ JIT compiler bugs in four widely-used production JVMs, namely HotSpot, OpenJ9, Graal, and the Android Runtime (ART), where 50+ have been confirmed or fixed. These bugs are diverse ranging from segmentation faults (SIGSEGV), fatal arithmetic error (SIGFPE), emergency abort (SIGABRT), assertion failures, mis-compilations, to performance issues. The following lists some selected JIT compiler bugs that I found:
- HotSpot: JDK-8287223, JDK-8290781, JDK-8293996, JDK-8289043, JDK-8288975, etc.
- OpenJ9: 15305, 15319, 15335, 15369, 15338, etc.
- ART: 227382489, 229134124, 230079540, 230635320, etc.
- Graal: 4754, 6350, 6351, etc.
MetaMut: Beyond that, I'm also active in ensuring the correctness of other optimizing compilers like GCC and LLVM. Below are some bugs that my collaborators and I have found:
Selected Publications (All)
- Validating JIT Compilers via Compilation Space Exploration (Extension)
Cong Li, Yanyan Jiang, Chang Xu, and Zhendong Su
In: ACM Transactions on Computer Systems (TOCS '25; to appear)
TOCS '25
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CCF-A
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Preprint
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Tool: Artemis
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Tool: Apollo
- Understanding Code Changes Practically with Small-Scale Language Models
Cong Li, Zhaogui Xu, Peng Di, Dongxia Wang, Zheng Li, and Qian Zheng
In: Proceedings of the 2024 IEEE/ACM International Conference on Automated Software Engineering (ASE '24) ASE '24
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CCF-A
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Core-A*
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PDF
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Tool: HQCM
- The Mutators Reloaded: Fuzzing Compilers with Large Language Model Generated Mutation Operators
Xianfei Ou, Cong Li, Yanyan Jiang, and Chang Xu
In: Proceedings of the 2024 ACM International Conference on Architectural Support for Programming Languages and Operating Systems (ASPLOS '24; to appear) ASPLOS '24
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CCF-A
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Core-A*
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Preprint
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Tool: MetaMut
- Best Paper Award Validating JIT Compilers via Compilation Space Exploration
Cong Li, Yanyan Jiang, Chang Xu, and Zhendong Su
In: Proceedings of the 2023 ACM Symposium on Operating Systems Principles (SOSP '23) SOSP '23
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CCF-A
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Core-A*
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PDF
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Supplementary Material
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Slides
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Tool: Artemis
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Video
- Cross-Device Record and Replay for Android Apps
Cong Li, Yanyan Jiang, and Chang Xu
In: Proceedings of the 2022 ACM Joint European Software Engineering Conference and Symposium on the Foundations of Software Engineering (ESEC/FSE '22) ESEC/FSE '22
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CCF-A
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Core-A*
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PDF
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Tool: Rx
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Video
- Push-Button Synthesis of Watch Companions for Android Apps
Cong Li, Yanyan Jiang, and Chang Xu
In: Proceedings of the 2022 Internaltional Conference on Software Engineering (ICSE '22) ICSE '22
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CCF-A
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Core-A*
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PDF
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Artifact: Jigsaw
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Video
Education
- Visit
10.2021 − 10.2022
ETH Zurich, Institute for Programming Languages and Systems, Advanced Software Technologies Lab
Advisor: Prof. Zhendong Su- Ph.D
09.2018 − 06.2023
Nanjing University, State Key Lab for Novel Software Technology, Institute of Computer Software
Advisors: Prof. Yanyan Jiang and Prof. Chang Xu- B.Sc
09.2014 − 06.2018
Nanjing University, Department of Computer Science and Technology
Advisors: Prof. Lili Wei and Prof. Chang Xu
Experiences
- Ant Group
08.2023 – Present
Researcher (LLMs for Sys/SE/PL and vice versa), Software Engineer- Alibaba
(Intern) 07.2017 − 09.2017
Software Engineer (HTML5, JavaScript, and JsBridge)
Honors & Awards
- 2025, Excellent Star Youth, Ant Group (in Chinese: 蚂蚁集团卓越星青年)
- 2024, Distinguished Dissertation Award, JSCS (in Chinese: 江苏省计算机学会优秀博士论文)
- 2024, Distinguished Dissertation Award, ACM Nanjing (in Chinese: ACM南京分会优秀博士论文)
- 2024, Distinguished Dissertation Award, CCF Systems Software (in Chinese: CCF系统软件优秀博士论文)
- 2024, Distinguished Dissertation Award, NJU (in Chinese: 南京大学优秀博士论文)
- 2023, Best Paper Award, SOSP '2023 (in Chinese: SOSP'23 最佳论文奖)
- 2023, Ant Star, Ant Star Program '2023, Ant Group (in Chinese: 蚂蚁集团蚂蚁星)
- 2023, Outstanding Graduate, NJU (in Chinese: 南京大学优秀毕业生)
- 2022, National Scholarship, China (in Chinese: 国家奖学金)
- 2022, Pacemaker to Excellent Postgraduate Student, NJU (in Chinese: 南京大学优秀研究生标兵)
- 2021, Joint Ph.D Student Scholarship, CSC (in Chinese: 国家留学基金委博士研究生联合培养奖学金)
- 2019, The Elite Scholarship First Class, China (in Chinese: 博士研究生英才奖学金, 一等)
- 2018, President Scholarship for Doctoral Students, NJU (in Chinese: 博士研究生校长特别奖学金)
- 2018, Outstanding Graduate, NJU (in Chinese: 南京大学优秀毕业生)
- 2017, HUAWEI Scholarship (in Chinese: 华为奖学金)
Teaching
- Spring 2021, TA, Principles and Techniques of Compilers, NJU
- Spring 2020, TA, Principles and Techniques of Compilers, NJU
Hobbies
On my spare time, I like reading Japanese and Chinese mangas (and animes). Specifically, I'm a BIG FAN of One Piece, Bleach, and Hunter × Hunter. I prefer Dragon Ball, Yo Yo Hakusho, Demon Slayer: Kimetsu no Yaiba, Haikyu!!, and many Shonen mangas for Japanese. I love The Legend of Qin as for Chinese. Some Korean ones also fit my tastes like Noblesse and Tower of God.