5aa9bdc7eb
regalloc2 is a bit pickier about critical edges than regalloc.rs was, because of how it inserts moves. In particular, if a branch has any arguments (e.g., a conditional branch or br_table), its successors must all have only one predecessor, so we can do edge moves at the top of successor blocks rather than at the end of this block. Otherwise, moves that semantically must come after the block's last uses (the branch's args) would be placed before it. This is almost always the case, because crit-edge splitting ensures that if we have more than one succ, all our succs will have only one pred. This is because branch kinds that take arguments (fixed args, not the blockparam args) tend to have more than one successor: conditionals and br_tables. However, a fuzzbug recently illuminated one corner case I had missed: a br_table can have *one* successor only, if it has a default target and an empty table. In this case, crit-edge splitting will happily skip a split and assume that we can insert edge moves at the end of the block with the br_table. But this will fail. regalloc2 explicitly checks this and bails with a panic, rather than continue, so no miscompilation is possible; but without this fix, we will get these panics on br_tables with empty tables.
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.
-
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.