GRPO with State Mutations: Improving LLM-Based Hardware Test Plan Generation

Fuente: arXiv
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Main Authors: Kochar, Dimple Vijay, Pinckney, Nathaniel, Liu, Guan-Ting, Ho, Chia-Tung, Deng, Chenhui, Ren, Haoxing, Khailany, Brucek
Format: Preprint
Published: 2026
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author Kochar, Dimple Vijay
Pinckney, Nathaniel
Liu, Guan-Ting
Ho, Chia-Tung
Deng, Chenhui
Ren, Haoxing
Khailany, Brucek
author_facet Kochar, Dimple Vijay
Pinckney, Nathaniel
Liu, Guan-Ting
Ho, Chia-Tung
Deng, Chenhui
Ren, Haoxing
Khailany, Brucek
contents RTL design often relies heavily on ad-hoc testbench creation early in the design cycle. While large language models (LLMs) show promise for RTL code generation, their ability to reason about hardware specifications and generate targeted test plans remains largely unexplored. We present the first systematic study of LLM reasoning capabilities for RTL verification stimuli generation, establishing a two-stage framework that decomposes test plan generation from testbench execution. Our benchmark reveals that state-of-the-art models, including DeepSeek-R1 and Claude-4.0-Sonnet, achieve only 15.7-21.7% success rates on generating stimuli that pass golden RTL designs. To improve LLM generated stimuli, we develop a comprehensive training methodology combining supervised fine-tuning with a novel reinforcement learning approach, GRPO with State Mutation (GRPO-SMu), which enhances exploration by varying input mutations. Our approach leverages a tree-based branching mutation strategy to construct training data comprising equivalent and mutated trees, moving beyond linear mutation approaches to provide rich learning signals. Training on this curated dataset, our 7B parameter model achieves a 33.3% golden test pass rate and a 13.9% mutation detection rate, representing a 17.6% absolute improvement over baseline and outperforming much larger general-purpose models. These results demonstrate that specialized training methodologies can significantly enhance LLM reasoning capabilities for hardware verification tasks, establishing a foundation for automated sub-unit testing in semiconductor design workflows.
format Preprint
id arxiv_https___arxiv_org_abs_2601_07593
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle GRPO with State Mutations: Improving LLM-Based Hardware Test Plan Generation
Kochar, Dimple Vijay
Pinckney, Nathaniel
Liu, Guan-Ting
Ho, Chia-Tung
Deng, Chenhui
Ren, Haoxing
Khailany, Brucek
Hardware Architecture
Computation and Language
Machine Learning
RTL design often relies heavily on ad-hoc testbench creation early in the design cycle. While large language models (LLMs) show promise for RTL code generation, their ability to reason about hardware specifications and generate targeted test plans remains largely unexplored. We present the first systematic study of LLM reasoning capabilities for RTL verification stimuli generation, establishing a two-stage framework that decomposes test plan generation from testbench execution. Our benchmark reveals that state-of-the-art models, including DeepSeek-R1 and Claude-4.0-Sonnet, achieve only 15.7-21.7% success rates on generating stimuli that pass golden RTL designs. To improve LLM generated stimuli, we develop a comprehensive training methodology combining supervised fine-tuning with a novel reinforcement learning approach, GRPO with State Mutation (GRPO-SMu), which enhances exploration by varying input mutations. Our approach leverages a tree-based branching mutation strategy to construct training data comprising equivalent and mutated trees, moving beyond linear mutation approaches to provide rich learning signals. Training on this curated dataset, our 7B parameter model achieves a 33.3% golden test pass rate and a 13.9% mutation detection rate, representing a 17.6% absolute improvement over baseline and outperforming much larger general-purpose models. These results demonstrate that specialized training methodologies can significantly enhance LLM reasoning capabilities for hardware verification tasks, establishing a foundation for automated sub-unit testing in semiconductor design workflows.
title GRPO with State Mutations: Improving LLM-Based Hardware Test Plan Generation
topic Hardware Architecture
Computation and Language
Machine Learning
url https://arxiv.org/abs/2601.07593