b438617e12
* Shrink the size of `FuncData` Before this commit on a 64-bit system the `FuncData` type had a size of 88 bytes and after this commit it has a size of 32 bytes. A `FuncData` is required for all host functions in a store, including those inserted from a `Linker` into a store used during linking. This means that instantiation ends up creating a nontrivial number of these types and pushing them into the store. Looking at some profiles there were some surprisingly expensive movements of `FuncData` from the stack to a vector for moves-by-value generated by Rust. Shrinking this type enables more efficient code to be generated and additionally means less storage is needed in a store's function array. For instantiating the spidermonkey and rustpython modules this improves instantiation by 10% since they each import a fair number of host functions and the speedup here is relative to the number of items imported. * Use `ptr::copy_nonoverlapping` during initialization Prevoiusly `ptr::copy` was used for copying imports into place which translates to `memmove`, but `ptr::copy_nonoverlapping` can be used here since it's statically known these areas don't overlap. While this doesn't end up having a performance difference it's something I kept noticing while looking at the disassembly of `initialize_vmcontext` so I figured I'd go ahead and implement. * Indirect shared signature ids in the VMContext This commit is a small improvement for the instantiation time of modules by avoiding copying a list of `VMSharedSignatureIndex` entries into each `VMContext`, instead building one inside of a module and sharing that amongst all instances. This involves less lookups at instantiation time and less movement of data during instantiation. The downside is that type-checks on `call_indirect` now involve an additionally load, but I'm assuming that these are somewhat pessimized enough as-is that the runtime impact won't be much there. For instantiation performance this is a 5-10% win with rustpyhon/spidermonky instantiation. This should also reduce the size of each `VMContext` for an instantiation since signatures are no longer stored inline but shared amongst all instances with one module. Note that one subtle change here is that the array of `VMSharedSignatureIndex` was previously indexed by `TypeIndex`, and now it's indexed by `SignaturedIndex` which is a deduplicated form of `TypeIndex`. This is done because we already had a list of those lying around in `Module`, so it was easier to reuse that than to build a separate array and store it somewhere. * Reserve space in `Store<T>` with `InstancePre` This commit updates the instantiation process to reserve space in a `Store<T>` for the functions that an `InstancePre<T>`, as part of instantiation, will insert into it. Using an `InstancePre<T>` to instantiate allows pre-computing the number of host functions that will be inserted into a store, and by pre-reserving space we can avoid costly reallocations during instantiation by ensuring the function vector has enough space to fit everything during the instantiation process. Overall this makes instantiation of rustpython/spidermonkey about 8% faster locally. * Fix tests * Use checked arithmetic
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.