63a3bbbf5a
* Change VMMemoryDefinition::current_length to `usize` This commit changes the definition of `VMMemoryDefinition::current_length` to `usize` from its previous definition of `u32`. This is a pretty impactful change because it also changes the cranelift semantics of "dynamic" heaps where the bound global value specifier must now match the pointer type for the platform rather than the index type for the heap. The motivation for this change is that the `current_length` field (or bound for the heap) is intended to reflect the current size of the heap. This is bound by `usize` on the host platform rather than `u32` or` u64`. The previous choice of `u32` couldn't represent a 4GB memory because we couldn't put a number representing 4GB into the `current_length` field. By using `usize`, which reflects the host's memory allocation, this should better reflect the size of the heap and allows Wasmtime to support a full 4GB heap for a wasm program (instead of 4GB minus one page). This commit also updates the legalization of the `heap_addr` clif instruction to appropriately cast the address to the platform's pointer type, handling bounds checks along the way. The practical impact for today's targets is that a `uextend` is happening sooner than it happened before, but otherwise there is no intended impact of this change. In the future when 64-bit memories are supported there will likely need to be fancier logic which handles offsets a bit differently (especially in the case of a 64-bit memory on a 32-bit host). The clif `filetest` changes should show the differences in codegen, and the Wasmtime changes are largely removing casts here and there. Closes #3022 * Add tests for memory.size at maximum memory size * Add a dfg helper method
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.
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 - [C++] - the
wasmtime-cpprepository - 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.