Wasmer Runtime Features

The Wasmer WebAssembly runtime supports different backends:

• Native backends: Singlepass, Cranelift and LLVM Each of these have different tradeoffs of compilation speed vs runtime speed;
• Other runtimes: JavascriptCore and Browser;

Each of this backends support different features, and have different support for Operating Systems and Chipsets.

WebAssembly Features

• Bulk-memory operations: e.g. instructions with behavior similar to C's memmove and memset in WebAssembly;
• Multi-value return: return multiple values from functions making data transfer between host and guest simpler;
• Import & export of mutable globals: adds ability to import and export mutable globals;
• Non-trapping float-to-int conversions: this proposal would establish a convention for saturating operations, to avoid introducing trapping;
• Sign-extension operations: adds five new integer instructions for sign-extending 8-bit, 16-bit, and 32-bit values;
• Reference types: easier and more efficient interop with host environment;
• SIMD: Single Instruction, Multiple data: do heavy number crunching more quickly and/or with lower power usage.
• Threads: adds a new shared linear memory type and some new operations for atomic memory access;

Wasmer features

• Caching: compiled WebAssembly modules can be reused so subsequent runs of a Wasm file will have very little start up time;
• Metering: computation time and other resources can be monitored and limits set to control how the Wasm code runs. This is also known as "gas metering";

Support of features by backend

WebAssembly features:

Wasmer features:

Legend:

• ✅ Supported
• 🔄 In the works
• ❌ Not yet supported (please ping us if you need this feature!)

Backend support by Operating System

Backend support by Chipset