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As part of a Wasm JIT update, SpiderMonkey is changing its internal WebAssembly function ABI. The new ABI's frame format includes "caller TLS" and "callee TLS" slots. The details of where these come from are not important; from Cranelift's point of view, the only relevant requirement is that we have two on-stack args that are always present (offsetting other on-stack args), and that we define special argument purposes so that we can supply values for these slots. Note that this adds a *new* ABI (a variant of the Baldrdash ABI) because we do not want to tightly couple the landing of this PR to the landing of the changes in SpiderMonkey; it's better if both the old and new behavior remain available in Cranelift, so SpiderMonkey can continue to vendor Cranelift even if it does not land (or backs out) the ABI change. Furthermore, note that this needs to be a Cranelift-level change (i.e. cannot be done purely from the translator environment implementation) because the special TLS arguments must always go on the stack, which would not otherwise happen with the usual argument-placement logic; and there is no primitive to push a value directly in CLIF code (the notion of a stack frame is a lower-level concept).
wasmtime
A standalone runtime for WebAssembly
A Bytecode Alliance project
Guide | Contributing | Website | Chat
Installation
The Wasmtime CLI can be installed on Linux and macOS with a small install script:
$ curl https://wasmtime.dev/install.sh -sSf | bash
Windows or otherwise interested users can download installers and binaries directly from the GitHub Releases page.
Example
If you've got the Rust compiler installed then you can take some Rust source code:
fn main() {
println!("Hello, world!");
}
and compile/run it with:
$ rustup target add wasm32-wasi
$ rustc hello.rs --target wasm32-wasi
$ wasmtime hello.wasm
Hello, world!
Features
-
Lightweight. Wasmtime is a standalone runtime for WebAssembly that scales with your needs. It fits on tiny chips as well as makes use of huge servers. Wasmtime can be embedded into almost any application too.
-
Fast. Wasmtime is built on the optimizing Cranelift code generator to quickly generate high-quality machine code at runtime.
-
Configurable. Whether you need to precompile your wasm ahead of time, generate code blazingly fast with Lightbeam, or interpret it at runtime, Wasmtime has you covered for all your wasm-executing needs.
-
WASI. Wasmtime supports a rich set of APIs for interacting with the host environment through the WASI standard.
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Standards Compliant. Wasmtime passes the official WebAssembly test suite, implements the official C API of wasm, and implements future proposals to WebAssembly as well. Wasmtime developers are intimately engaged with the WebAssembly standards process all along the way too.
Language Support
You can use Wasmtime from a variety of different languages through embeddings of the implementation:
- Rust - the
wasmtimecrate - C - the
wasm.h,wasi.h, andwasmtime.hheaders - Python - the
wasmtimePyPI package - .NET - the
WasmtimeNuGet package - Go - the
wasmtime-gorepository
Documentation
📚 Read the Wasmtime guide here! 📚
The wasmtime guide is the best starting point to learn about what Wasmtime can do for you or help answer your questions about Wasmtime. If you're curious in contributing to Wasmtime, it can also help you do that!.
It's Wasmtime.