ewasm-cleanup
This tool transform WebAssembly S-expressions (WAST) code to an output conforming to the eWASM Contract Interface.
It is especially useful for using together clang to create eWASM contracts, because clang and C has a few limitations regarding WebAssembly currently.
Transformations
Exports
clang will export every global method, which is expected. For some reason making methods static or inline will not produce the proper results.
ewasm-cleanup will remove every export bar main and memory.
Imports
Ethereum module
Most of the current toolchains (clang for C and mir2wasm for Rust) do not support WebAssembly's two-level imports (namespace and method name). They mostly
hardcode env as the namespace.
ewasm-cleanup will transform these to imports matching the Ethereum Environment Interface.
libc methods
clang considers memset and memcpy special. It even detects patterns of them and replaces it with the internal memcpy and memset. Unfortunately
it isn't fully supported in the WebAssembly target and it ends up with memset and memcpy being an import.
ewasm-cleanup will insert an implementation of memset and memcpy.
Author
Alex Beregszaszi
License
MIT