A fast two-pass HDL simulation with on-demand dump

Simulation-based functional verification is characterized by two inherently conflicting targets: the signal visibility and simulation performance. Achieving a proper trade-off between these two targets is of paramount importance. Even though HDL simulators are the most widely used verification platform at the RTL and gate level, their major drawback is the low performance in verifying complex SOCs, especially when the high visibility over the design under verification is required. This paper presents a new, fast simulation method as an effective way to achieve both high simulation speed and full signal visibility. It is based on an original two-pass simulation approach. During the 1^st pass, with the simulation running at full speed, a set of design states is saved periodically at predetermined checkpoints. During the 2^nd pass, another simulation is performed, using any of saved checkpoints and providing 100% signal visibility for debugging. Our method differs from the traditional simulation snapshot approach in the amount and the way the design state is saved. Experimental results show significant speed-up compared to existing traditional simulation methods while maintaining 100% visibility.