Industrial Deployment of Compiler Fuzzing Techniques for Two GPU Shading Languages

We report on our experience at Google deploying a variety of coverage-guided and black-box fuzzers to find bugs in compilers for two graphics shading languages: the WebGPU Shading Language (WGSL) and Standard Portable Intermediate Representation (SPIR-V). We discuss the deployment of coverage-guided fuzzing on ClusterFuzz and OSS-Fuzz using libFuzzer’s built-in mutators, and a number of custom mutators that exploit knowledge of the syntax and semantics of WGSL and SPIR-V. We also discuss the deployment of several black box fuzzers on ClusterFuzz, including two that are based on new randomised program generators for WGSL, which we have also used in a targeted fashion for end-to-end testing of WebGPU implementations. We discuss a series of insights arising from our experience that we hope will be valuable to practitioners and researchers interested in applying fuzzing to industrial problems.