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UVMarvel: an Automated LLM-aided UVM Machine for Subsystem-level RTL Verification

Authors
Junhao Ye, Dingrong Pan, Hanyuan Liu, Yuchen Hu, Jie Zhou, Ke Xu, et al.
Source
arXiv
Published
Collection
Software Intelligence
Rtl VerificationUvm AutomationCode IntelligenceLLM AgentsHardware Engineering
Open arXivMarkdown source

Summary

UVMarvel automates subsystem-level RTL verification by using LLMs to build UVM testbenches and refine stimuli. It claims 95.65% average code coverage and a 4.5-hour run to 90% coverage on industrial-style subsystem benchmarks.

Problem

  • RTL verification consumes nearly 70% of IC front-end effort, and subsystem-level UVM testbench construction still needs expert manual coding.
  • Prior LLM and template-based UVM flows work mainly at IP level and struggle with bus timing, inter-IP dependencies, protocol semantics, and long corner-case sequences.
  • Initial LLM-generated stimuli can average below 40% coverage because they repeat simple patterns and miss multi-step subsystem behavior.

Approach

  • UVMarvel converts specs and RTL into a five-part IR: module name, interface description, register configuration, timing characteristics, and functional description.
  • A Bus Protocol Library supplies UVM skeletons for interfaces, drivers, monitors, and agents across APB, AHB, AXI, P-Channel, and Q-Channel, while the LLM fills DUT-specific fields.
  • A Coverage Analyser extracts uncovered and partially covered items from simulator coverage reports and feeds compact targets to the LLMs.
  • A Signal Tracker traces uncovered signals through Verilog files to find related statements and controllable top-level I/O paths.
  • A Verilog Patcher rebuilds minimal valid RTL slices around those statements, then GPT-4.1, Claude 4.5, and Gemini 2.5 Pro generate or repair new UVM sequences.

Results

  • UVMarvel reports 95.65% average code coverage across six subsystem benchmarks: Watchdog, Pwrctrl, Cordic, IdleControl, LPctrl, and Busremap.
  • Per-design code coverage is 98.84% on Watchdog, 93.66% on Pwrctrl, 100% on Cordic, 94.90% on IdleControl, 90.83% on LPctrl, and 95.66% on Busremap.
  • Functional coverage is 100% on Watchdog, 90.64% on Pwrctrl, 100% on Cordic, 96.12% on IdleControl, 89.33% on LPctrl, and 98.27% on Busremap.
  • The benchmark set covers APB, AHB, AXI, Q-Channel, and P-Channel designs with 3 to 10 modules and about 800 to 3000+ RTL lines per design.
  • The paper claims UVMarvel reaches 90% code coverage in 4.5 hours, 20.17x faster than an expert manual flow, excluding the human IR and test-planning phase.

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