CktEvo: Repository-Level RTL Code Benchmark for Design Evolution

TL;DR

CktEvo introduces a repository-level RTL benchmark and framework that enables iterative, function-preserving PPA improvements across complete IP cores using LLMs and toolchain feedback.

Contribution

It provides the first repository-scale RTL benchmark with a closed-loop framework for LLM-assisted, cross-file, iterative RTL optimization.

Findings

Achieves PPA improvements without human intervention

Supports cross-file modifications in real-world RTL repositories

Establishes a foundation for LLM-assisted RTL design evolution

Abstract

Register-Transfer Level (RTL) coding is an iterative, repository-scale process in which Power, Performance, and Area (PPA) emerge from interactions across many files and the downstream toolchain. While large language models (LLMs) have recently been applied to hardware design, most efforts focus on generation or debugging from natural-language prompts, where ambiguity and hallucinations necessitate expert review. A separate line of work begins from formal inputs, yet typically optimizes high-level synthesis or isolated modules and remains decoupled from cross-file dependencies. In this work, we present CktEvo, a benchmark and reference framework for repo-level RTL evolution. Unlike prior benchmarks consisting of isolated snippets, our benchmark targets complete IP cores where PPA emerges from cross-file dependencies. Our benchmark packages several high-quality Verilog repositories from real-world designs. We formalize the task as: given an initial repository, produce edits that preserve functional behavior while improving PPA. We also provide a closed-loop framework that couples LLM-proposed edits with toolchain feedback to enable cross-file modifications and iterative repair at repository scale. Our experiments demonstrate that the reference framework realizes PPA improvements without any human interactions. CktEvo establishes a rigorous and executable foundation for studying LLM-assisted RTL optimization that matters for engineering practice: repository-level, function-preserving, and PPA-driven.