Optimal Reads-From Consistency Checking for C11-Style Memory Models

Over the years, several memory models have been proposed to capture subtle concurrency semantics of C/C++. One most fundamental problems associated with a model M is consistency checking: given an execution X , consistent ? This problem lies at heart numerous applications, including specification testing and litmus tests, stateless checking, dynamic analyses. As such, it has explored extensively its complexity well-understood for traditional like SC TSO. However, less known variants C/C++, which becomes challenging due intricacies their primitives. In this work we study checking popular C11 model, in particular, RC 20 release-acquire ( RA ) fragment, strong weak SRA WRA ), as well Relaxed fragment 20. Motivated by applications focus on reads-from checking. The input specifying set events, program order relation, task decide existence modification writes that makes model. We draw rich landscape problem; our results include (i) nearly-linear-time algorithms certain variants, improve over prior results, (ii) fine-grained optimality (iii) matching upper lower bounds (NP-hardness) other variants. To knowledge, first characterize models. implemented inside TruSt checker C11Tester tool. Experiments standard benchmarks show new often significant margin.