e39b4aba1c
Previously, every call was lowered on AArch64 to a `call` instruction, which takes a signed 26-bit PC-relative offset. Including the 2-bit left shift, this gives a range of +/- 128 MB. Longer-distance offsets would cause an impossible relocation record to be emitted (or rather, a record that a more sophisticated linker would fix up by inserting a shim/veneer). This commit adds a notion of "relocation distance" in the MachInst backends, and provides this information for every call target and symbol reference. The intent is that backends on architectures like AArch64, where there are different offset sizes / addressing strategies to choose from, can either emit a regular call or a load-64-bit-constant / call-indirect sequence, as necessary. This avoids the need to implement complex linking behavior. The MachInst driver code provides this information based on the "colocated" bit in the CLIF symbol references, which appears to have been designed for this purpose, or at least a similar one. Combined with the `use_colocated_libcalls` setting, this allows client code to ensure that library calls can link to library code at any location in the address space. Separately, the `simplejit` example did not handle `Arm64Call`; rather than doing so, it appears all that is necessary to get its tests to pass is to set the `use_colocated_libcalls` flag to false, to make use of the above change. This fixes the `libcall_function` unit-test in this crate.
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, generate code blazingly fast with Lightbeam, 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.
-
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 - Python - the
wasmtimePyPI package - .NET - the
WasmtimeNuGet package - Go - the wasmtime-go repository
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.