# A Load-Buffer Semantics for Total Store Ordering

## TL;DR

This paper introduces a load-buffer semantics for TSO that simplifies safety verification, significantly improves efficiency and scalability, and enables parametric verification for systems with an arbitrary number of processes.

## Contribution

It proposes an alternative semantics using load buffers, making TSO safety analysis more efficient and extendable to parametric verification, which was difficult with previous store-buffer based methods.

## Key findings

- Simplifies TSO safety analysis
- Achieves significant efficiency and scalability improvements
- Enables parametric verification for arbitrary process counts

## Abstract

We address the problem of verifying safety properties of concurrent programs running over the Total Store Order (TSO) memory model. Known decision procedures for this model are based on complex encodings of store buffers as lossy channels. These procedures assume that the number of processes is fixed. However, it is important in general to prove the correctness of a system/algorithm in a parametric way with an arbitrarily large number of processes. In this paper, we introduce an alternative (yet equivalent) semantics to the classical one for the TSO semantics that is more amenable to efficient algorithmic verification and for the extension to parametric verification. For that, we adopt a dual view where load buffers are used instead of store buffers. The flow of information is now from the memory to load buffers. We show that this new semantics allows (1) to simplify drastically the safety analysis under TSO, (2) to obtain a spectacular gain in efficiency and scalability compared to existing procedures, and (3) to extend easily the decision procedure to the parametric case, which allows obtaining a new decidability result, and more importantly, a verification algorithm that is more general and more efficient in practice than the one for bounded instances.