8726eeefb3
* cranelift-isle: Add "partial" flag for constructors Instead of tying fallibility of constructors to whether they're either internal or pure, this commit assumes all constructors are infallible unless tagged otherwise with a "partial" flag. Internal constructors without the "partial" flag are not allowed to use constructors which have the "partial" flag on the right-hand side of any rules, because they have no way to report last-minute match failures. Multi-constructors should never be "partial"; they report match failures with an empty iterator instead. In turn this means you can't use partial constructors on the right-hand side of internal multi-constructor rules. However, you can use the same constructors on the left-hand side with `if` or `if-let` instead. In many cases, ISLE can already trivially prove that an internal constructor always returns `Some`. With this commit, those cases are largely unchanged, except for removing all the `Option`s and `Some`s from the generated code for those terms. However, for internal non-partial constructors where ISLE could not prove that, it now emits an `unreachable!` panic as the last-resort, instead of returning `None` like it used to do. Among the existing backends, here's how many constructors have these panic cases: - x64: 14% (53/374) - aarch64: 15% (41/277) - riscv64: 23% (26/114) - s390x: 47% (268/567) It's often possible to rewrite rules so that ISLE can tell the panic can never be hit. Just ensure that there's a lowest-priority rule which has no constraints on the left-hand side. But in many of these constructors, it's difficult to statically prove the unhandled cases are unreachable because that's only down to knowledge about how they're called or other preconditions. So this commit does not try to enforce that all terms have a last-resort fallback rule. * Check term flags while translating expressions Instead of doing it in a separate pass afterward. This involved threading all the term flags (pure, multi, partial) through the recursive `translate_expr` calls, so I extracted the flags to a new struct so they can all be passed together. * Validate multi-term usage Now that I've threaded the flags through `translate_expr`, it's easy to check this case too, so let's just do it. * Extract `ReturnKind` to use in `ExternalSig` There are only three legal states for the combination of `multi` and `infallible`, so replace those fields of `ExternalSig` with a three-state enum. * Remove `Option` wrapper from multi-extractors too If we'd had any external multi-constructors this would correct their signatures as well. * Update ISLE tests * Tag prelude constructors as pure where appropriate I believe the only reason these weren't marked `pure` before was because that would have implied that they're also partial. Now that those two states are specified separately we apply this flag more places. * Fix my changes to aarch64 `lower_bmask` and `imm` terms
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
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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.
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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.
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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.
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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, CMake orwasmtimeConan 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.