c1b3962f7b
* Implement lowered-then-lifted functions This commit is a few features bundled into one, culminating in the implementation of lowered-then-lifted functions for the component model. It's probably not going to be used all that often but this is possible within a valid component so Wasmtime needs to do something relatively reasonable. The main things implemented in this commit are: * Component instances are now assigned a `RuntimeComponentInstanceIndex` to differentiate each one. This will be used in the future to detect fusion (one instance lowering a function from another instance). For now it's used to allocate separate `VMComponentFlags` for each internal component instance. * The `CoreExport<FuncIndex>` of lowered functions was changed to a `CoreDef` since technically a lowered function can use another lowered function as the callee. This ended up being not too difficult to plumb through as everything else was already in place. * A need arose to compile host-to-wasm trampolines which weren't already present. Currently wasm in a component is always entered through a host-to-wasm trampoline but core wasm modules are the source of all the trampolines. In the case of a lowered-then-lifted function there may not actually be any core wasm modules, so component objects now contain necessary trampolines not otherwise provided by the core wasm objects. This feature required splitting a new function into the `Compiler` trait for creating a host-to-wasm trampoline. After doing this core wasm compilation was also updated to leverage this which further enabled compiling trampolines in parallel as opposed to the previous synchronous compilation. * Review comments
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
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Fast. Wasmtime is built on the optimizing Cranelift code generator to quickly generate high-quality machine code either at runtime or ahead-of-time. Wasmtime's runtime is also optimized for cases such as efficient instantiation, low-overhead transitions between the embedder and wasm, and scalability of concurrent instances.
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Secure. Wasmtime's development is strongly focused on the correctness of its implementation with 24/7 fuzzing donated by Google's OSS Fuzz, leveraging Rust's API and runtime safety guarantees, careful design of features and APIs through an RFC process, a security policy in place for when things go wrong, and a release policy for patching older versions as well. We follow best practices for defense-in-depth and known protections and mitigations for issues like Spectre. Finally, we're working to push the state-of-the-art by collaborating with academic researchers to formally verify critical parts of Wasmtime and Cranelift.
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Configurable. Wastime supports a rich set of APIs and build time configuration to provide many options such as further means of restricting WebAssembly beyond its basic guarantees such as its CPU and Memory consumption. Wasmtime also runs in tiny environments all the way up to massive servers with many concurrent instances.
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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.