On SAT-based Bounded Invariant Checking of Blackbox Designs

Abstract

Design verification by property checking is a mandatory task during circuit design. In this context, Bounded Model Checking (BMC) has become popular for falsifying erroneous designs. Additionally, the analysis of partial designs, i.e., circuits that are not fully specified, has recently gained attraction. In this work we analyze how BMC can be applied to such partial designs. Our experiments show that even with the most simple modelling scheme, namely 01X-simulation, a relevant number of errors can be detected. Additionally, we propose a SAT-solver that directly can handle 01X-logic.

Propositional approximations for bounded model checking of partial circuit designs

“…For the experimental comparison of the relation-oriented and function-oriented approach, we have implemented both approaches in the BMX-tool (bounded model checking using 01X-logic) that was already used in the relation-oriented style in [3], [4], [5]. As benchmark examples we used two model checking examples from the VIS-benchmark suite [22], PicoJava/biu and s1269, whereby both circuits were modified to contain blackboxes.…”

“…Since especially for s1269 the introduced error does not violate all properties, there are different numbers of examples available, see column '#benchmarks' in the following tables. For a more detailed description of these modified VIS-benchmarks, see [3], [4], [5].…”

“…The percentage is measured in gate equivalents. 3 The experiments were performed on an AMD Opteron Dual Processor 2.6 Ghz with 4 GB main memory, running a Debian Linux system. 4 And/Inverter-Graph, see [28], [29].…”

“…SAT-based BMC of partial circuit designs was investigated in a relational style in [3], [4], [5] where BMC was adapted to 01X-logic as well as to Quantified Boolean Formulas (QBFs). These works show the feasibility of 01X-BMC for a large number of relevant examples and hence served as starting point for our investigations.…”

On Combining 01X-Logic and QBF

“…Bounded model checking of blackbox designs was initially proposed in [3] by using 01X-logic, and was further extended in [2] to a more concise QBF formulation. The two-valued encoding approach for 01X-logic on which we rely on was presented in [4].…”