Testing the Compiler for a New-Born Programming Language: An Industrial Case Study (Experience Paper)

Due to the critical role of compilers, many compiler testing techniques have been proposed, two most notable categories among which are grammar-based and metamorphic-based techniques. All of them have been extensively studied for testing mature compilers. However, it is typical to develop a new compiler for a new-born programming language in practice. In this scenario, the existing techniques are hardly applicable due to some major reasons: (1) no reference compilers to support differential testing, (2) lack of program analysis tools to support most of metamorphic-based compiler testing, (3) substantial implementation effort incurred by different programming language features. Hence, it is unknown how the existing techniques perform in this new scenario. In this work, we conduct the first exploration (i.e., an industrial case study) to investigate the performance of the existing techniques in this new scenario with substantial adaptations. We adapted grammar-based compiler testing to this scenario by synthesizing new test programs based on code snippets and using compilation crash as test oracle due to the lack of reference compilers for differential testing. We also adapted metamorphic-based compiler testing to this scenario by constructing equivalent test programs under any inputs to relieve the dependence on program analysis tools. We call the adapted techniques SynFuzz and Meta-Fuzz, respectively. We evaluated both SynFuzz and MetaFuzz on two versions of a new compiler for a new-born programming language in a global IT company. By comparing with the testing practice adopted by the testing team and the general fuzzer (AFL), SynFuzz can detect more bugs during the same testing time, and both SynFuzz and