Revisit Reconvergence Issue in Simulation-based Observability and Testability, and its Rectification

This paper presents a highly efficient and accurate approach for detecting observability and assessing testability in contemporary logic circuits with growing size and heightened complexity, especially for MCUs or SoCs used in the automotive industry. The algorithm incorporated in this methodology also mitigates the accuracy loss caused by reconvergent fan-outs. The proposed observability correction method results in a significant improvement in rectifying erroneous node observability calculations compared to existing algorithms while achieving faster execution times. In the context of simulation-based testability and observability evaluations, we also introduce a constant folding algorithm that enables rapid MFFC calculation. By incorporating levelized data parallelism in a two-phase computation process (comprising forward and backward propagation), our approach achieves a performance speedup of more than two orders of magnitude compared to mainstream SAT solver-based techniques and is 50× faster than the fault injection engine of a commercial tool.