Building from Source

Installing Rustup

Building Wasmer from source requires Rust 1.45+.

The easiest way to install Rust on your system is via Rustup. To get Rustup on Linux and macOS, you can run the following:

curl https://sh.rustup.rs -sSf | sh

To install Rust on Windows, download and run rustup-init.exe, then follow the onscreen instructions.

Installing Additional Dependencies

Windows

Windows support is fully supported. WASI is fully supported, but Emscripten support is in the works.

1. Install Visual Studio

2. Install Rust for Windows

3. Install Git for Windows. Allow it to add git.exe to your PATH (default settings for the installer are fine).

4. (optional) Install LLVM 10.0

Building the Wasmer Runtime

Wasmer is built with Cargo, the Rust package manager.

First, let's clone Wasmer:

git clone https://github.com/wasmerio/wasmer.git
cd wasmer

Wasmer supports three different compilers at the moment:

Singlepass Compiler

Build Wasmer:

make build-wasmer

Note: you should see this as the first line in the console: Available compilers: singlepass

Cranelift Compiler

The Cranelift compiler will work if you are in a X86 or ARM machine, so you don't need to do anything in your system to enable it.

make build-wasmer

Note: should see this as the first line in the console: Available compilers: cranelift

LLVM Compiler

If you want support for the Wasmer LLVM compiler, then you will also need to ensure:

• Ensure that LLVM 10.0.x > is installed on your system

  • You can also download and use a prebuilt LLVM binary
• In case llvm-config is not accessible, set the correct environment variable for LLVM to access: For example, the environment variable for LLVM 10.0.x would be: LLVM_SYS_100_PREFIX=/path/to/unpacked/llvm-10.0

And create a Wasmer release

make build-wasmer

Note: you should see this as the first line in the console: Available compilers: llvm

All compilers

Once you have LLVM and Rust, you can just run:

make build-wasmer

Note: you should see this as the first line in the console: Available compilers: singlepass cranelift llvm

Running your Wasmer binary

Once you run the make build-wasmer command, you will have a new binary ready to be used!

./target/release/wasmer quickjs.wasm

Building Wasmer C-API from source

Wasmer provides a pre-compiled version for the C-API on its release page.

However, you can also compile the shared library from source:

make build-capi

This will generate the shared library (depending on your system):

• Windows: package/release/libwasmer_c_api.dll

• macOS: target/release/libwasmer_runtime_c_api.dylib

• Linux: target/release/libwasmer_runtime_c_api.so

If you want to generate the library and headers for using them easily, you can execute:

make package-capi

This command will generate a package directory, that you can then use easily in the Wasmer C API examples.

package/
  lib/
    libwasmer.so
  headers/
    wasm.h
    wasmer.h
    wasmer.hh
    wasmer_wasm.h

By default, the Wasmer C API shared library is built with Cranelift as the default compiler and JIT engine. You can generate the C-API for a specific compiler and engine with:

• Singlepass:

  • JIT: make build-capi-singlepass-jit

  • Native Engine: not yet available ⚠️

• Cranelift:

  • JIT: make build-capi-cranelift-jit

  • Native Engine: make build-capi-cranelift-native

• LLVM: make build-capi-llvm

  • JIT: make build-capi-llvm-jit

  • Native Engine: make build-capi-llvm-native