Noisy Test-Time Reinforcement Learning for Code LLMs

Xikai Yang, Hieu Trung Nguyen, Dunyuan Xu, Yuzhi Zhao, Jinpeng Li, Wenao Ma, Pheng-Ann Heng


Abstract
Large language models (LLMs) have demonstrated remarkable performance across various code-related tasks. However, unlike carefully curated datasets that are typically high-quality and error-free, real-world user instructions are often vague and error-prone, posing significant challenges to the robustness of code LLMs. Furthermore, robustness-oriented fine-tuning relies on paired clean-noisy samples, which are costly to curate and require sophisticated noisy simulation techniques. To address these challenges, we propose the Noisy Test-time Reinforcement Learning framework (NTRL-Code), which enables robust self-evolution of code LLMs using only unlabeled noisy data during the testing stage. Specifically, NTRL-Code uses conservative self-denoising to obtain a cleaner semantic anchor for target estimation, and employs an abstract-syntax-tree (AST)-based structural aggregation mechanism to estimate a proxy target from multiple candidate programs. The policy is then optimized on the original noisy prompts with a hybrid reward that combines format validity, code similarity, and anti-repetition signals. Extensive experiments on three benchmarks, each incorporating character-level, word-level, and paragraph-level perturbations, demonstrate that NTRL-Code yields robust and consistent improvements, stabilizing the predictions of various base models. Our code is available at https://github.com/Xikai97/NTRL-Code.
Anthology ID:
2026.emnlp-main.848
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
19656–19677
Language:
URL:
https://aclanthology.org/2026.emnlp-main.848/
DOI:
Bibkey:
Cite (ACL):
Xikai Yang, Hieu Trung Nguyen, Dunyuan Xu, Yuzhi Zhao, Jinpeng Li, Wenao Ma, and Pheng-Ann Heng. 2026. Noisy Test-Time Reinforcement Learning for Code LLMs. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 19656–19677, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Noisy Test-Time Reinforcement Learning for Code LLMs (Yang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.848.pdf