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In [this comment](https://github.com/bytecodealliance/wasmtime/pull/3545#discussion_r756284757) I noted a potential subtle issue with the way that a few rules were written that is fine now but could cause some unexpected pain when we get around to verification. Specifically, a set of rules of the form ``` (rule (A (B _)) (C)) (rule (A _) (D)) ``` should, under any reasonable "default" rule ordering scheme, fire the more specific rule `(A (B _))` when applicable, in preference to the second "fallback" rule. However, for future verification-specific applications of ISLE, we want to ensure the property that a rule's meaning/validity is not dependent on being overridden by more specific rules. In other words, if a rule specifies a rewrite, that rewrite should always be correct; and choosing a more specific rule can give a *better* compilation (better generated code) but should not be necessary for correctness. This is an admittedly under-documented part of the language, though in the pending #3560 I added a note about rule ordering being a heuristic that should hopefully make this slightly clearer. Ultimately I want to have tests that choose non-default rule orderings and differentially fuzz in order to be sure that we're following this principle; and of course once we're actually doing verification, we'll catch issues like this upfront. Apologies for the subtle footgun here and hopefully the reasoning is clear enough :-)
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, 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 or usewasmtimeConan package - [C++] - the
wasmtime-cpprepository or usewasmtime-cppConan package - 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.