Translate WASM modules into JVM class files

This is a library and CLI for converting any single WASM module into several JVM class files (usually packaged into a JAR).

$ cargo run --bin wasm2jar foo.wasm --output-class 'me/Foo' --jar foo.jar

Building and testing

The usual cargo commands apply for building and unit tests:

$ cargo build      # Compile everything
$ cargo test       # Run unit tests

Since the specification tests for WebAssembly is encoded in .wast files, there is also a way to run against a bunch of .wast files at once. This assumes that javac and java are installed.

$ cargo run --bin wast2jar -- tests/loop.wast   # Run the tests in `tests/loop.wast`
$ cargo run --bin wast2jar -- tests             # Run all `*.wast` tests in `tests`

Debugging

Some handy tools/techniques for debugging

• wat2wasm and wasm2wat (from WABT) for inspecting/manipulating WASM
• javap (in JDK) for inspecting generated class files
• jshell (in JDK 9+) for running the output (jshell --class-path foo.jar)
• cfr for decompiling JVM bytecode into Java code
• hexdump or xxd for debugging serialized class files

References

• WebAssembly Core Specification
• Specification repo (spec tests are here)
• JVM specification