a916788ab4
This fixes two problems: minimum symbol alignment for the LARL instruction, and alignment requirements for LRL/LGRL etc. The first problem is that the LARL instruction used to load a symbol address (PC relative) requires that the target symbol is at least 2-byte aligned. This is always guaranteed for code symbols (all instructions must be 2-aligned anyway), but not necessarily for data symbols. Other s390x compilers fix this problem by ensuring that all global symbols are always emitted with a minimum 2-byte alignment. This patch introduces an equivalent mechanism for cranelift: - Add a symbol_alignment routine to TargetIsa, similar to the existing code_section_alignment routine. - Respect symbol_alignment as minimum alignment for all symbols emitted in the object backend (code and data). The second problem is that PC-relative instructions that directly *access* data (like LRL/LGRL, STRL/STGRL etc.) not only have the 2-byte requirement like LARL, but actually require that their memory operand is *naturally* aligned (i.e. alignment is at least the size of the access). This property (natural alignment for memory accesses) is supposed to be provided by the "aligned" flag in MemFlags; however, this is not implemented correctly at the moment. To fix this, this patch: - Only emits PC-relative memory access instructions if the "aligned" flag is set in the associated MemFlags. - Fixes a bug in emit_small_memory_copy and emit_small_memset which currently set the aligned flag unconditionally, ignoring the actual alignment info passed by their caller. Tested with wasmtime and cg_clif.
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
-
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's runtime is also optimized for cases such as efficient instantiation, low-overhead transitions between the embedder and wasm, and scalability of concurrent instances.
-
Secure. Wasmtime's development is strongly focused on the correctness of its implementation with 24/7 fuzzing donated by Google's OSS Fuzz, leveraging Rust's API and runtime safety guarantees, careful design of features and APIs through an RFC process, a security policy in place for when things go wrong, and a release policy for patching older versions as well. We follow best practices for defense-in-depth and known 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. Wastime supports a rich set of APIs and build time configuration to provide many options such as further means of restricting WebAssembly beyond its basic guarantees such as its CPU and Memory consumption. Wasmtime also runs in tiny environments all the way up to massive servers with many concurrent instances.
-
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, 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.