Wasmer Runtime Features

Wasmer is powered by WebAssembly .

Wasmer supports many different backends, depending on your needs:

Wasmer Native Backends:
- Singlepass: incredibly fast compilation times, ideal for Blockchain Smart Contracts
- Cranelift: normal compilation times, good performance
- LLVM: slow compilation times, great performance
Other Backends:
- V8: ideal for iOS, Android and development.
- Browser: make your Rust code using Wasmer run in the browser

Each of these backends supports different features and has varying support for operating systems and chipsets.

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;

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”;
Profiling: generate profiling data for WebAssembly code to analyze performance using tools like Linux perf;

Support of features by backend

WebAssembly features:

	Singlepass	Cranelift	LLVM
Bulk memory operations	✅	✅	✅
Multi-value return	✅¹	✅¹	✅
Import & export of mutable globals	✅	✅	✅
Non-trapping float-to-int conversions	✅	✅	✅
Sign-extension operations	✅	✅	✅
Wide Arithmetic	❌	✅	✅
Reference types	🔄	✅	✅
SIMD	✅	✅	✅
Relaxed SIMD	❌	✅	✅
Threads	✅	✅	✅
Exceptions	🔄	✅	✅
Async Functions	✅	✅	✅
Extended Constant Expressions	✅	✅	✅
Tail Call	❌	❌	✅

Wasmer features:

Features	Singlepass	Cranelift	LLVM
Caching	✅	✅	✅
Metering	✅	✅	✅
Profiling	✅	✅	✅

	Linux	macOS	Windows	iOS	Android	Browser
Cranelift	✅	✅	✅	❌	✅	❌
LLVM	✅	✅	✅	❌	✅	❌
Singlepass	✅	✅	✅	❌	✅	❌
V8	✅	✅	✅	✅	✅	❌
Browser	✅	✅	✅	✅	✅	✅

	x86_64	arm64	riscv64gc	riscv32gc	loongarch64
Cranelift	✅	✅	✅	❌	❌
LLVM	✅	✅	✅	✅	✅
Singlepass	✅	✅	✅	❌	❌
V8	✅	✅	✅	✅	✅
Browser	✅	✅	✅	✅	✅