Building Wasmer from Source

Installing Rustup

Building Wasmer from source requires Rust (opens in a new tab) 1.67+.

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

Installing Additional Dependencies

Windows

Windows is fully supported by Wasmer. WASI is also fully supported, but Emscripten support is still experimental.

1. Install Visual Studio (opens in a new tab)
2. Install Rust for Windows (opens in a new tab)
3. Install Git for Windows (opens in a new tab). Allow it to add git.exe to your PATH (default settings for the installer are fine).
4. (optional) Install LLVM 11.0 (opens in a new tab)

Building the Wasmer Runtime

Wasmer is built with Cargo (opens in a new tab), 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 Enabled Compilers: singlepass in console.

You may disable Singlepass compiler with export ENABLE_SINGLEPASS=0.

Cranelift Compiler

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

make build-wasmer

Note: should see this as the first line in the console:
Enabled Compilers: cranelift

You may disable the Cranelift compiler with export ENABLE_CRANELIFT=0.

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 refer to LLVM install instructions (opens in a new tab)
  • You can also download and use a prebuilt LLVM binary (opens in a new tab)
• In case llvm-config is not accessible, set the correct environment variable for LLVM to access: For example, the environment variable for LLVM 11.0.x would be: LLVM_SYS_110_PREFIX=/path/to/unpacked/llvm-11.0

And create a Wasmer release

make build-wasmer

Note: you should see this in the console:
Enabled Compilers: llvm

You may disable the LLVM compiler with export ENABLE_LLVM=0.

All compilers

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

make build-wasmer

Note: you should see this in the console:
Enabled 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 (opens in a new tab).

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

make build-capi

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

• Windows: target/release/libwasmer_c_api.dll
• macOS: target/release/libwasmer_c_api.dylib
• Linux: target/release/libwasmer_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