c84d6be6f4
This PR propagates "value labels" all the way from CLIF to DWARF metadata on the emitted machine code. The key idea is as follows: - Translate value-label metadata on the input into "value_label" pseudo-instructions when lowering into VCode. These pseudo-instructions take a register as input, denote a value label, and semantically are like a "move into value label" -- i.e., they update the current value (as seen by debugging tools) of the given local. These pseudo-instructions emit no machine code. - Perform a dataflow analysis *at the machine-code level*, tracking value-labels that propagate into registers and into [SP+constant] stack storage. This is a forward dataflow fixpoint analysis where each storage location can contain a *set* of value labels, and each value label can reside in a *set* of storage locations. (Meet function is pairwise intersection by storage location.) This analysis traces value labels symbolically through loads and stores and reg-to-reg moves, so it will naturally handle spills and reloads without knowing anything special about them. - When this analysis converges, we have, at each machine-code offset, a mapping from value labels to some number of storage locations; for each offset for each label, we choose the best location (prefer registers). Note that we can choose any location, as the symbolic dataflow analysis is sound and guarantees that the value at the value_label instruction propagates to all of the named locations. - Then we can convert this mapping into a format that the DWARF generation code (wasmtime's debug crate) can use. This PR also adds the new-backend variant to the gdb tests on CI.
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.
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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 - 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.