KernelInterceptor: automating GPU kernel verification by intercepting kernels and their parameters

GPUVerify is a static analysis tool for verifying that GPU kernels are free from data races and barrier divergence. It is intended as an automatic tool, but its usability is impaired by the fact that the user must explicitly supply the kernel source code, the number of work items and work groups, and preconditions on key kernel arguments. Extracting this information from non-trivial OpenCL applications is laborious and error-prone. We describe an extension to GPUVerify, called KernelInterceptor, that automates the extraction of this information from a given OpenCL application. After recompiling the application having included an additional header file, and linking with an additional library, KernelInterceptor is able to detect each dynamic kernel launch and record the values of the various parameters in a series of log files. GPUVerify can then be invoked to examine these log files and verify each kernel instance. We explain how the interception mechanism works, and comment on the extent to which it improves the usability of GPUVerify.