VSync: push-button verification and optimization for synchronization primitives on weak memory models
Jonas Oberhauser, Rafael Lourenco de Lima Chehab, Diogo Behrens, Ming Fu, Antonio Paolillo, Lilith Oberhauser, Koustubha Bhat, Yuzhong Wen, Haibo Chen, Jaeho Kim, Viktor Vafeiadis
Abstract
Implementing highly efficient and correct synchronization primitives on modern Weak Memory Model (WMM) architectures, such as ARM and RISC-V, is very difficult even for human experts. We introduce VSync, a framework to assist in optimizing and verifying synchronization primitives on WMM architectures. VSync automatically detects missing and overly-constrained barriers, while ensuring essential safety and liveness properties. VSync relies on two novel techniques: 1) Adaptive Linear Relaxation (ALR), which utilizes barrier monotonicity and speculation to quickly find a correct maximally-relaxed barrier combination; and 2) Await Model Checking (AMC), which for the first time makes it possible to check termination of await loops on WMMs.