3e2be43502
* Refactor wasmtime_runtime::Export Instead of an enumeration with variants that have data fields have an enumeration where each variant has a struct, and each struct has the data fields. This allows us to store the structs in the `wasmtime` API and avoid lots of `panic!` calls and various extraneous matches. * Pre-generate trampoline functions The `wasmtime` crate supports calling arbitrary function signatures in wasm code, and to do this it generates "trampoline functions" which have a known ABI that then internally convert to a particular signature's ABI and call it. These trampoline functions are currently generated on-the-fly and are cached in the global `Store` structure. This, however, is suboptimal for a few reasons: * Due to how code memory is managed each trampoline resides in its own 64kb allocation of memory. This means if you have N trampolines you're using N * 64kb of memory, which is quite a lot of overhead! * Trampolines are never free'd, even if the referencing module goes away. This is similar to #925. * Trampolines are a source of shared state which prevents `Store` from being easily thread safe. This commit refactors how trampolines are managed inside of the `wasmtime` crate and jit/runtime internals. All trampolines are now allocated in the same pass of `CodeMemory` that the main module is allocated into. A trampoline is generated per-signature in a module as well, instead of per-function. This cache of trampolines is stored directly inside of an `Instance`. Trampolines are stored based on `VMSharedSignatureIndex` so they can be looked up from the internals of the `ExportFunction` value. The `Func` API has been updated with various bits and pieces to ensure the right trampolines are registered in the right places. Overall this should ensure that all trampolines necessary are generated up-front rather than lazily. This allows us to remove the trampoline cache from the `Compiler` type, and move one step closer to making `Compiler` threadsafe for usage across multiple threads. Note that as one small caveat the `Func::wrap*` family of functions don't need to generate a trampoline at runtime, they actually generate the trampoline at compile time which gets passed in. Also in addition to shuffling a lot of code around this fixes one minor bug found in `code_memory.rs`, where `self.position` was loaded before allocation, but the allocation may push a new chunk which would cause `self.position` to be zero instead. * Pass the `SignatureRegistry` as an argument to where it's needed. This avoids the need for storing it in an `Arc`. * Ignore tramoplines for functions with lots of arguments Co-authored-by: Dan Gohman <sunfish@mozilla.com>
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.
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Fast. Wasmtime is built on the optimizing Cranelift code generator to quickly generate high-quality machine code at runtime.
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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.
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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.
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.