Building from Source#

Local Environment#



  • If building LLVM from source, either of these is highly recommended:

Linux (Ubuntu)#

Install python and libs:

sudo apt-get install -y --no-install-recommends python3-dev python3-pip
python3 -m pip install --user -U pip
python3 -m pip install --user maturin

Install Rust from rustup.


Install Python 3.7+ from one of the following and make sure it is added to the path.

In a command prompt:

python -m pip install --user maturin

Install Rust from rustup.


Install Python 3.7+ from

or brew:

brew install 'python@3.9'
python -m pip install --user maturin

Install Rust from rustup.

Installing Clang and Ninja#

You can install Clang manually:

  • Linux (Ubuntu 22.04)

    apt-get update
    apt-get install -y clang-13 lldb-13 lld-11 clangd-13
    apt-get install -y --no-install-recommends ninja-build clang-tidy-13 build-essential
  • Windows

    • Download and install the LLVM-13.0.1-win64.exe from the 13.0.1 Release page.

    • This package only contains the Clang components. There is no package that contains Clang and LLVM.

  • MacOS

    • Should be preinstalled.

Installing LLVM#

The build scripts will automatically download an LLVM toolchain which is detailed in the Development section. The build installs the toolchain to target/llvm-<version>.


To initialize your local environment and build the solution, run


This will compile qirlib and its dependencies with the appropriate environment variables set for their build scripts. After this is run, the build commands below can be used instead of build.ps1.

The Environment Variables section details ways to change this behavior.

Within each project folder, the build can be run specifically for that project.

For any of these commands, the LLVM version must be added via features. For maturin, they must be added to the cargo-extra-args option.

  • <features> is a placeholder for --features (llvm11-0 | llvm12-0 | llvm13-0 | llvm14-0)

Build commands:

  • maturin build --cargo-extra-args="<features>": Build the crate into python packages

  • maturin build --release --cargo-extra-args="<features>": Build and pass –release to cargo

  • maturin build --help: to view more options

  • maturin develop --cargo-extra-args="<features>": Installs the crate as module in the current virtualenv

  • maturin develop --cargo-extra-args="<features>" && pytest: Installs the crate as module in the current virtualenv and runs the Python tests

If you do not wish to package and test the Python wheels, cargo can be used to build the project and run Rust tests.

  • cargo build <features>: Build the Rust cdylib

  • cargo build --release <features>: Build the Rust cdylib in release mode

  • cargo test <features>: Build and run the Rust cdylib tests

  • cargo test --release <features>: Build and run the Rust cdylib tests in release mode

Environment Variables#

For those directly consuming qirlib, refer to the Environment variables section of it’s README as the following constraints do not apply.

The Python PyQIR projects require LLVM to already be installed prior to build. The PowerShell scripts will look at the the qirlib Environment variables and locate, build, or install LLVM as specified by the environment. The default order is:

  • Use specific LLVM installation if specified

  • Locate existing LLVM installation on PATH

  • Build LLVM from source

  • Download LLVM if allowed from specified source

Afterward, the build configures the LLVM_SYS_*_PREFIX environment variable according to what the environment has configured. This will allow LLVM to be linked into the rest of the build.


The build.ps1, maturin builds all generate Python wheels to the target/wheels folder. The default Python3 installation will be used targeting Python ABI 3.7.