75ae976adc
In the provided test case in #5716, the result of a call was then added to 0. We have a rewrite rule that sets the remat-bit on any add of a value and a constant, because these frequently appear (e.g. from address offset calculations) and this can frequently reduce register pressure (one long-lived base vs. many long-lived base+offset values). Separately, we have an algebraic rule that `x+0` rewrites to `x`. The result of this was that we had an eclass with the remat bit set on the add, but the add was also union'd into the call. We pick the latter during extraction, because it's cheaper not to do the add at all; but we still get the remat bit, and try to remat a call (!), which blows up later. This PR fixes the logic to look up the "best value" for a value (i.e., whatever extraction determined), and look up the remat bit on *that* node, not the canonical node. (Why did the canonical node become the iadd and not the call? Because the former had a lower value-number, as an accident of IR construction; we don't impose any requirements on the input CLIF's value-number ordering, and I don't think this breaks any of the important acyclic properties, even though there is technically a dependence from a lower-numbered to a higher-numbered node. In essence one can think of them as having "virtual numbers" in any true topologically-sorted order, and the only place the actual integer indices matter should be in choosing the "canonical ID", which is just used for dedup'ing, modulo this bug.) Fixes #5716.
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 (locally) 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
-
Fast. Wasmtime is built on the optimizing Cranelift code generator to quickly generate high-quality machine code either at runtime or ahead-of-time. Wasmtime is optimized for efficient instantiation, low-overhead calls between the embedder and wasm, and scalability of concurrent instances.
-
Secure. Wasmtime's development is strongly focused on correctness and security. Building on top of Rust's runtime safety guarantees, each Wasmtime feature goes through careful review and consideration via an RFC process. Once features are designed and implemented, they undergo 24/7 fuzzing donated by Google's OSS Fuzz. As features stabilize they become part of a release, and when things go wrong we have a well-defined security policy in place to quickly mitigate and patch any issues. We follow best practices for defense-in-depth and integrate protections and mitigations for issues like Spectre. Finally, we're working to push the state-of-the-art by collaborating with academic researchers to formally verify critical parts of Wasmtime and Cranelift.
-
Configurable. Wasmtime uses sensible defaults, but can also be configured to provide more fine-grained control over things like CPU and memory consumption. Whether you want to run Wasmtime in a tiny environment or on massive servers with many concurrent instances, we've got you covered.
-
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.
Languages supported by the Bytecode Alliance:
- Rust - the
wasmtimecrate - C - the
wasm.h,wasi.h, andwasmtime.hheaders, CMake orwasmtimeConan package - C++ - the
wasmtime-cpprepository or usewasmtime-cppConan package - Python - the
wasmtimePyPI package - .NET - the
WasmtimeNuGet package - Go - the
wasmtime-gorepository - Ruby - the
wasmtimegem
Languages supported by the community:
- Elixir - the
wasmexhex package
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.