Towards a Highly Interactive Design-Debug-Verification Cycle

Taking a hardware design from concept to silicon is along and complicated process, partly due to very long-running simulations. After modifying a Register Transfer Level (RTL) design, it is typically handed off to the simulator, which then simulates the full design for a given amount of time. If a bug is discovered, there is no way to adjust the design while still in the context of the simulation. Instead, all simulation results are thrown away, and the entire cycle must be restarted from the beginning. In this paper, we argue that it is worth breaking up this strict separation between design languages, analysis languages, verification languages,and simulators. We present virtual signals, a methodology to inject new logic in to existing wave forms. Virtual signals are based on WAL, an open-source waveform analysis language, and can therefore use the capabilities of WAL for debugging, fixing, analyzing, and verifying a design. All this enables an interactive and fast response design-debug-verification cycle. To demonstrate the benefits of our methodology, we present a case-study in which we show how the technique improves debugging and design analysis.