CirCA: Aligning Credit Assignment with Circuit Semantics via Atomic Logic Blocks for RTL Generation

Lei Huang, Rui Zhang, Jiaming Guo, Yang Zhang, Di Huang, Zidong Du, Xing Hu, Qi Guo, Yunji Chen


Abstract
Reinforcement learning (RL) post-training has emerged as a promising paradigm for LLM-based Verilog generation. However, existing RL credit assignment methods are either overly coarse (sequence-level GRPO) or fragmented (line-level methods), leading to severe misattribution as they ignore the characteristics of Verilog designs that are fundamentally structured through concurrent constructs and procedural control flows. To bridge this gap, we propose CirCA, a novel RL framework that performs credit assignment based on Atomic Logic Blocks (ALBs), the smallest semantically complete units of circuit logic. CirCA decomposes Verilog into ALBs, derives reliable rewards from signal-level feedback, and then constructs logic-enhanced signal dependency cones to localize erroneous ALBs, whose localized responsibilities are further incorporated into GRPO through asymmetric advantage correction. Extensive experiments show CirCA establishes a new state-of-the-art across multiple benchmarks among non-reasoning models, and even surpasses some cutting-edge reasoning models on complex tasks.
Anthology ID:
2026.emnlp-main.1450
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:
33112–33128
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1450/
DOI:
Bibkey:
Cite (ACL):
Lei Huang, Rui Zhang, Jiaming Guo, Yang Zhang, Di Huang, Zidong Du, Xing Hu, Qi Guo, and Yunji Chen. 2026. CirCA: Aligning Credit Assignment with Circuit Semantics via Atomic Logic Blocks for RTL Generation. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 33112–33128, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
CirCA: Aligning Credit Assignment with Circuit Semantics via Atomic Logic Blocks for RTL Generation (Huang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1450.pdf