Debugging WebAssembly - Put Some Whamm on It!

Explore Whamm, an innovative instrumentation framework for WebAssembly that addresses critical challenges in debugging and monitoring WebAssembly applications through this 16-minute conference presentation from OOPSLA 2025. Learn how this framework tackles three major problems in the WebAssembly ecosystem: tooling fragmentation across different instrumentation techniques, prohibitive overhead of general-purpose frameworks, and the complexity of implementing high-performance low-level mechanisms. Discover Whamm's unique approach using engine-level probing with bytecode rewriting fallback to ensure portability across different WebAssembly environments. Examine the framework's key features including fully-programmable instrumentation with declarative match rules, static and dynamic predication, automatic state reporting, and comprehensive user library support. Understand how Whamm achieves high performance through compiler and engine optimizations, particularly through its engine API that allows instrumentation to be provided as WebAssembly code, enabling existing engine optimizations and unlocking new ones like intrinsification to minimize overhead. Gain insights into the framework's innovative approach of explicitly requesting program state in match rules rather than using reflection, which enables engines to efficiently bundle arguments and inline compiled probe logic. See how Whamm streamlines tooling efforts through its bytecode-rewriting target that can run instrumented programs universally, reducing fragmentation and advancing engine support capabilities. Review case studies demonstrating the framework's expressiveness, power, and efficiency in implementing non-trivial monitors for dynamic analysis, instrumentation, and debugging of WebAssembly applications.