Theoretical framework for compositional sequential hardware equivalence verification in presence of design constraints

Abstract

We are interested in sequential hardware equivalence (or alignability equivalence) verification of synchronous sequential circuits [Pix92]

A Compositional Approach to the Combination of Combinational and Sequential Equivalence Checking of Circuits Without Known Reset States

“…The most related work to ours is Khasidashvili and coworker's framework at Intel for alignability-based compositional equivalence checking [4]. However, there are a number of differences between our approach and theirs.…”

“…However, there are a number of differences between our approach and theirs. First of all, the work in [4] is centered around the use of manually added verification properties, whereas we focus on a flow that is completely automatic. Second, the framework in [4] uses computationally expensive alignability computations to check all subparts, whereas we apply combinational techniques wherever possible.…”

“…First of all, the work in [4] is centered around the use of manually added verification properties, whereas we focus on a flow that is completely automatic. Second, the framework in [4] uses computationally expensive alignability computations to check all subparts, whereas we apply combinational techniques wherever possible. Moreover, our notion of equivalence for a partition is easier to compute than alignability as we do not need the aligning sequence computation.…”

“…Second, since the equivalence checking is performed between whole designs, the inherent complexity of formal verification makes it vital to not ignore the known problem structure. In fact, the general sequential equivalence checking problem is so hard that, with the exception of some large semiconductor companies that have developed in-house tools tailored to their particular design styles [4,6], the industry standard is to either not use sequential optimizations, or to not verify them formally.…”

“…First of all, we define a notion of equivalence that is compositional, and that allows us to combine results from sequential and combinational analysis. Our equivalence notion is essentially a simpler version of the theoretical framework in [4] that does not rely on the use of manually added properties. We also discuss precisely in what sense our notion of equivalence implies correctness.…”