Revision debug with non-linear version history in regression verification

Modern digital designs are relentlessly growing in complexity, making their verification a daunting task. Verification and debugging are the bottleneck, accounting for up to 70% of the design cycle. Most automated debugging tools target failures in isolation and rely solely on the current version of a design's RTL. A recently developed methodology targets multiple failures simultaneously while leveraging the revision history present in a version control system. It finds revisions likely to be responsible for the failures and ranks them such that higher ranked revisions are more likely to contain bugs. However, this technique treats the version history as a simple linear list of revisions rather than a graph structure. To address this limitation, this paper presents a technique that properly leverages the branching information in version control systems. It offers two-stage ranking with improved performance, allowing both branches and branch-local revisions to be ranked.