Formal Verification on the RT Level Computing One-To-One Design Abstractions by Signal Width Reduction
Peer Johannsen, Rolf Drechsler · 2001
Digital circuit designs are usually given as Register-Transfer-Level (RTL) specifications, but most of today’s hardware verification tools are based on bit-level methods, using SAT or BDD-based techniques. RTL specifications contain more explicite structural information than bit-level descriptions. This paper presents a new approach to scale down design sizes before verification by exploiting wordlevel information. We introduce a one-to-one abstraction technique for RTL property checking, which computes a scaled-down abstract model of a design, in which signal widths are reduced with respect to a property. The property holds for the abstract RTL if and only if it holds for the original RTL. If the property fails, counterexamples for the original design are computed from counterexamples found on the reduced model. The verification task is completely carried out on the scaled-down version of the design; falsenegatives cannot occur. Linear signal width reductions result in exponentially smaller state spaces and have a significant impact on the runtimes of verification tools. Experimental results on large industrial circuits have demonstrated the applicability and efficiency of our method. 1