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Wasmer Features

The Wasmer WebAssembly runtime provides various features for users and developers:
  • Compilers: Wasmer supports multiple compilers: Singlepass, Cranelift and LLVM. Each of these have different tradeoffs of compilation speed vs runtime speed;
  • 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";
  • 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;
  • ABIs: it allows running different types of programs compiled to WebAssembly, with ABIs such as:
    • Emscripten
    • WASI

Support of features by Compiler

Runtime features:
Text
Singlepass
Cranelift
LLVM
Emscripten
WASI
WebAssembly features:
Text
Singlepass
Cranelift
LLVM
Bulk memory operations
Multi-value return
🔄
Import & export of mutable globals
Non-trapping float-to-int conversions
Sign-extension operations
Reference types
🔄
SIMD (Phase 4)
Threads (Phase 2)
🔄

Legend

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

Support by Operating System

Text
Linux
macOS
Windows
Cranelift
LLVM
Singlepass
WASI
✅*
* poll_fd is not fully implemented for Windows yet

Compiler Support by Chipset

Text
x86_64
arm64
x86
Cranelift
LLVM
Singlepass
🔄

Language Embeddings

Wasmer enables WebAssembly usage in a lot of different languages. Here are some of the features in each of those:
Text
Rust
C / C++
Go
Python
Ruby
Terminate in host call
WASI
WASI FS API
Serialize/Deserialize
Metering