Programming Languages Research Group

Towards Understanding the Costs of Avoiding Out-of-Thin-Air Results

Eliminating out-of-thin-air (OOTA) behaviors is an open problem with many existing programming language memory models including Java, C, and C++. OOTA behaviors are problematic in that they break both formal and informal modular reasoning about program behavior. Defining memory model semantics that are easily understood, allow existing optimizations, and forbid OOTA results remains very challenging. We explore two solutions to this problem that forbid OOTA results that enforce slightly stronger memory models. One solution is targeted towards C/C++-like memory models in which racing operations are explicitly labeled as atomic operations and a second solution is targeted towards Java-like languages in which all memory operations may create OOTA executions. We implement and evaluated both solutions in the LLVM compiler framework.

Getting Started

Our prototype compiler implementation that restricts OOTA behavior can be found here:

Our benchmarks can be accessed through the following links:

In case you want to grab a copy of how to build the version of Linux kernel and Ubuntu Filesystem images that we used, here’s a link to the documentation and the copies of images that we used:



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This material is based upon work supported by the National Science Foundation under Grant CCF-1319786, OAC-1740210 and CNS-1703598.

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.