Alex Crichton 0b4263333b Fuzz cranelift cpu flag settings with Wasmtime (#3800)
* Fuzz cranelift cpu flag settings with Wasmtime

This commit updates the `Config` fuzz-generator to consume some of the
input as configuration settings for codegen flags we pass to cranelift.
This should allow for ideally some more coverage where settings are
disabled or enabled, ideally finding possible bugs in feature-specific
implementations or generic implementations that are rarely used if the
feature-specific ones almost always take precedent.

The technique used in this commit is to weight selection of codegen
settings less frequently than using the native settings. Afterwards each
listed feature is individually enabled or disabled depending on the
input fuzz data, and if a feature is enabled but the host doesn't
actually support it then the fuzz input is rejected with a log message.
The goal here is to still have many fuzz inputs accepted but also ensure
determinism across hosts. If there's a bug specifically related to
enabling a flag then running it on a host without the flag should
indicate that the flag isn't supported rather than silently leaving it
disabled and reporting the fuzz case a success.

* Use built-in `Unstructured::ratio` method

* Tweak macro

* Bump arbitrary dep version
2022-02-15 14:27:55 -06:00
2022-02-14 15:29:28 +01:00
2020-02-28 09:16:05 -08:00
2021-12-17 12:00:11 -08:00
2021-09-27 12:27:19 -05:00
2022-02-07 19:16:26 -06:00

wasmtime

A standalone runtime for WebAssembly

A Bytecode Alliance project

build status zulip chat supported rustc stable Documentation Status

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:

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.

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