Compiler Testing With Relaxed Memory Models

It is critical that compilers are correct! Finding bugs is one aspect of testing the correctness of compilers in wide use today. A compiler is correct if every compiled program behaves as allowed by the semantics of its source code - else there is a bug. Memory consistency models define the semantics of concurrent programs. We focus on how to detect concurrency bugs introduced by compilers, as identified using memory models. We seek a testing technique that automatically covers concurrency bugs up to fixed bounds on program sizes and that scales to find bugs in compiled programs with many lines of code. Otherwise, a testing technique can miss bugs. Unfortunately, the state-of-the-art techniques are yet to satisfy all of these properties. We present the T\'el\'echat compiler testing tool for concurrent programs. T\'el\'echat finds a concurrency bug when the behaviour of a compiled program, as allowed by its architecture memory model, is not a behaviour of the source program under its source model. We make three claims: T\'el\'echat improves the state-of-the-art at finding bugs in code generation for multi-threaded execution, it is the first public description of a compiler testing tool for concurrency that is deployed in industry, and it is the first tool that takes a significant step towards the desired properties. We provide experimental evidence suggesting T\'el\'echat finds bugs missed by other state-of-the-art techniques, case studies indicating that T\'el\'echat satisfies the properties, and reports of our experience deploying T\'el\'echat in industry.