Custom wasm runtime

All WebAssembly modules must execute in a highly performant and fully deterministic WebAssembly virtual machine. The WebAssembly specification has made some non-deterministic design choices, because of which the default runtimes are insufficient for a blockchain use-case.

Psibase therefore defines a custom WebAssembly run-time based on a battle-tested and deterministic runtime called EOS VM. The psibase VM specification adds further requirements above and beyond the EOS VM implementation.

Goals

• Support bulk memory operations
• Support sign extension operators
• Better generated code optimization
• Add non-trapping float-to-int conversions
• Support 128-bit SIMD instructions to accelerate some wasm computation such as cryptographic operations
• Support using the latest WASI SDK (Currently wasi-sdk-20)
• Maintain full determinism developed for EOS VM

Reference implementation

The reference implementation for the custom Psibase WebAssembly runtime currently satisfies all goals. It can be found here.