Add WASI based WebAssembly support

[kateinoigakukun]

WebAssembly / WASI port of Ruby

How to cross-build

Requirement

• Ruby (the same version as the building target version) (baseruby)
• GNU make
• WASI SDK 14.0 or later
• Binaryen version 91
  • See also: Thread stack size of prebuilt binary for linux may not be enough WebAssembly/binaryen#4401
• Linux or macOS build machine

Steps

1. Download a prebuilt WASI SDK package from WASI SDK release page.
2. Set WASI_SDK_PATH environment variable to the root directory of the WASI SDK package.

$ export WASI_SDK_PATH=/path/to/wasi-sdk-X.Y

3. Download a prebuilt binaryen from Binaryen release page
4. Set PATH environment variable to lookup binaryen tools

$ export PATH=path/to/binaryen:$PATH

5. Configure

• You can select which extensions you want to build.
• If you got Out of bounds memory access while running the produced ruby, you may need to increase the maximum size of stack.

$ ./configure LDFLAGS="-Xlinker -zstack-size=16777216" \
  --host wasm32-unknown-wasi \
  --with-destdir=./ruby-wasm32-wasi \
  --with-static-linked-ext \
  --with-ext=ripper,monitor

6. Make

$ make install

Now you have a WASI compatible ruby binary. You can run it by any WebAssembly runtime like wasmtime, wasmer, Node.js, or browser with WASI polyfill.

Note: it may take a long time (~20 sec) for the first time for JIT compilation

$ wasmtime ruby-wasm32-wasi/usr/local/bin/ruby --mapdir /::./ruby-wasm32-wasi/ -- -e 'puts RUBY_PLATFORM'
wasm32-wasi

Current Limitation

• No Thread support for now.
• Spawning a new process is not supported. e.g. Kernel.spawn and Kernel.system

[shyouhei]

@ioquatix You might want to look at the coroutine implementation.

[KernelErr]

Nice work! Tested on WasmEdge. However, the required version of Binaryen seems should be 91 or others. For latest 105 version, there is an unsatisfiable import: asyncify::stop_unwind.

[supechicken]

Hello, I am trying to follow the build instruction in the comment, but I get the following error while running make install:

linking ruby
wasm-ld: error: ext/pty/pty.a(pty.o): undefined symbol: rb_fork_async_signal_safe
clang-14: error: linker command failed with exit code 1 (use -v to see invocation)

Output of ${WASI_SDK_PATH}/bin/clang --version (tried building from source and using prebuilt binaries):

clang version 14.0.0 (https://github.com/llvm/llvm-project 80e2c587498a7b2bf14dde47a33a058da6e88a9a)
Target: wasm32-unknown-wasi
Thread model: posix
InstalledDir: /usr/local/wasi/wasi-sdk/build/install/opt/bin/

Output of ./wasm-opt --version:

wasm-opt version 91 (version_91)

Does there any steps I have missed? Thanks!

[kateinoigakukun]

@supechicken It seems you're trying to build an unsupported ext pty for wasi. You need to select only supported exts by --with-ext. The list of supported exts is here https://github.com/kateinoigakukun/ruby.wasm/blob/75c4007d229786ae638510bcf39cafa08a932c23/Rakefile#L14

[hsbt]

@supechicken @eat4toast Can you file your question to https://bugs.ruby-lang.org/ ? This tracker is not support space.

[eat4toast]

@supechicken @eat4toast Can you file your question to https://bugs.ruby-lang.org/ ? This tracker is not support space.

Sorry, I will move the question.
Thank you.

[junaruga]

I think the instruction document below to run Ruby with WebAssembly support, created in this PR is useful for someone to try to do. So, let me put the link here.
https://github.com/ruby/ruby/blob/master/wasm/README.md

Because this PR URL is referred from the release note.
https://www.ruby-lang.org/en/news/2022/09/09/ruby-3-2-0-preview2-released/