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It does this by providing an implementation of the CLIF instructions `AtomicRmw`, `AtomicCas`, `AtomicLoad`, `AtomicStore` and `Fence`. The translation is straightforward. `AtomicCas` is translated into x64 `cmpxchg`, `AtomicLoad` becomes a normal load because x64-TSO provides adequate sequencing, `AtomicStore` becomes a normal store followed by `mfence`, and `Fence` becomes `mfence`. `AtomicRmw` is the only complex case: it becomes a normal load, followed by a loop which computes an updated value, tries to `cmpxchg` it back to memory, and repeats if necessary. This is a minimum-effort initial implementation. `AtomicRmw` could be implemented more efficiently using LOCK-prefixed integer read-modify-write instructions in the case where the old value in memory is not required. Subsequent work could add that, if required. The x64 emitter has been updated to emit the new instructions, obviously. The `LegacyPrefix` mechanism has been revised to handle multiple prefix bytes, not just one, since it is now sometimes necessary to emit both 0x66 (Operand Size Override) and F0 (Lock). In the aarch64 implementation of atomics, there has been some minor renaming for the sake of clarity, and for consistency with this x64 implementation.
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.
-
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.