AI 中文总结
该研究提出以契约为核心的规约驱动硬件演化方法，将硬件演化分为四阶段，经评估可推动遗留RTL向新版本功能收敛，为硬件版本迭代提供新方案。
AI 中文摘要
硬件开发本质上是演化性的：重大修订通常始于变更预期行为，随后更新先前已验证的实现，而非从头生成RTL。然而，多数近期基于大语言模型（LLM）的硬件研究仍将该任务主要视为提示词到RTL的生成，对可信遗留设计的语义版本演化支持有限。我们提出规约驱动的硬件演化，这是一种以契约为核心的RTL版本迭代形式化方法。我们不将新功能请求视为RTL生成的直接提示，而是将其精化为下一版本的经审查可执行契约。该契约通过行为级参考及显式观察与检查语义，指定了外部可见事务级必须满足的条件，同时将变更如何在RTL中实现留待演化过程完成。基于此形式化方法，我们将硬件演化组织为四个阶段：规约制定、规划、实现与验证。契约获批后，后续阶段自动进行：规划借助基于变异的语义探测，推导跨版本语义差异并定位受影响的RTL区域；实现与验证则在证明引导的检查与迭代修复下，执行感知遗留代码的RTL更新。我们在一个代表性TPU数据通路模块在数据格式变更下的受控版本演化案例研究中评估了该框架。结果表明契约驱动硬件演化的可行性，并证明所提出的后端工作流可在经审查的可执行契约下，有效推动已验证的遗留RTL向新版本功能收敛。可复现的匿名工件可在该https URL获取。
英文摘要
Hardware development is inherently evolutionary: major revisions typically begin by changing intended behavior and then updating a previously validated implementation, rather than regenerating RTL from scratch. Yet most recent LLM-based hardware research still frames the task primarily as prompt-to-RTL generation, offering limited support for semantic version evolution of trusted legacy designs. We present spec-driven hardware evolution, a contract-centered formulation for RTL version iteration. Instead of treating a new feature request as a direct prompt for RTL generation, we refine it into a reviewed executable contract for the next version. This contract specifies what must hold at the externally visible transactional level through a behavior-level reference together with explicit observation and checking semantics, while leaving how the change is realized in RTL to the evolution process. Based on this formulation, we organize hardware evolution into four stages: Specify, Plan, Implement, and Validate. After contract approval, the remaining stages proceed automatically: Plan derives cross-version semantic deltas and localizes affected RTL regions, aided by mutation-based semantic probing; Implement and Validate then perform legacy-aware RTL update under proof-guided checking and iterative repair. We evaluate the framework on a controlled version-evolution case study of a representative TPU datapath block under data-format changes. The results support the feasibility of contract-driven hardware evolution and demonstrate that the proposed backend workflow can effectively drive validated legacy RTL toward next-version functional convergence under a reviewed executable contract. An anonymous artifact for reproducibility is available at https://anonymous.4open.science/r/SDHE-3A6C.
