The easiest way to build and test WAVM is using the dev.py script, which automatically downloads a compatible LLVM toolchain and builds WAVM:

# List available configurations for your platform
python3 Build/dev.py list-configs

# Build and test a specific configuration
python3 Build/dev.py test --config RelWithDebInfo-clang

# Build and test all configurations (takes a long time)
python3 Build/dev.py test

# Build and create packages (.tar.gz, .deb, .rpm on Linux)
python3 Build/dev.py package --config LTO-clang /path/to/output

The script stores downloaded LLVM toolchains and build artifacts in .working/ by default. You can override this with --work-dir or the WAVM_BUILD_TOOL_WORK_DIR environment variable.

# Check C/C++ source formatting (clang-format)
python3 Build/dev.py format

# Auto-fix C/C++ formatting
python3 Build/dev.py format --fix

# Run Python linters (ruff + ty)
python3 Build/dev.py lint

# Run clang-tidy
python3 Build/dev.py tidy

# Auto-fix clang-tidy issues
python3 Build/dev.py tidy --fix

If you prefer to configure the build manually, you'll need CMake and LLVM.

• CMake 3.16 or higher - On Linux, it is probably available via your package manager. For example, you can install it on Ubuntu with sudo apt install cmake. Otherwise, you can download it from the CMake website.

• Ninja (recommended) - Available via package managers or from the Ninja website.

• LLVM 20.0+ - LLVM 20 is the minimum supported version, but we recommend using WAVM-LLVM (LLVM 21.x with WAVM-specific patches). This is especially important on macOS, where upstream LLVM builds may have compatibility issues.

  • Recommended: Download pre-built WAVM-LLVM from the WAVM-LLVM releases.
  • On Ubuntu/Debian, upstream LLVM builds are available from the LLVM apt repo.
  • On other systems, you can download upstream LLVM from the LLVM download page.
  • To build LLVM from source, see Getting Started with the LLVM System and Building LLVM with CMake.

You can use Visual Studio 2022+ to compile WAVM. If you don't have Visual Studio, you can use the freely available Visual Studio C++ Build Tools or Visual Studio Community, both available from the Visual Studio download page. Visual Studio 2019 may also work, but has not been recently tested.

You'll need a C/C++ compiler. gcc and clang are known to compile WAVM correctly.

You'll need to install Xcode from the App Store.

# Create a build directory
mkdir build && cd build

# Configure with CMake (using Ninja)
cmake <path to WAVM source> -G Ninja -DLLVM_DIR=<path to LLVM>/lib/cmake/llvm

# Build
ninja

# Run tests
./bin/wavm test script ../Test/wavm/simd.wast

If CMake can't find your LLVM directory, set the LLVM_DIR CMake variable to point to your LLVM installation's lib/cmake/llvm directory.