Basics

Install Exo

We support Python versions 3.9 and above. If you're just using Exo, install it using pip:

$ pip install exo-lang

In case of ModuleNotFoundError: No module named 'attrs' please upgrade your attrs module by pip install --upgrade attrs.

Compile Exo

Exo files can be directly excuted with Python:

$ python exo_file.py

To generate generate C and header files, use exocc command:

$ exocc exo_file.py

Running the command will generate two files: exo_file.c and exo_file.h. These files will be created in a directory called exo_file/ by default. You can use optional arguments to customize the output:

• The -o argument allows you to specify a different directory name.
• The --stem argument allows you to specify custom names for the C file and header file.

Build Exo from source

We make active use of newer Python 3.x features. Please use Python 3.9 or 3.10 if you're getting errors about unsupported features.

Setting up Exo for development is like any other Python project. We strongly recommend you use a virtual environment.

$ git clone [email protected]:exo-lang/exo.git
$ cd exo/
$ git submodule update --init --recursive
$ python -m venv ~/.venv/exo
$ source ~/.venv/exo/bin/activate
(exo) $ python -m pip install -U pip setuptools wheel
(exo) $ python -m pip install -r requirements.txt
(exo) $ pre-commit install

This will make sure you have the submodules checked out and that the pre-commit scripts (that run an autoformatter, maybe other tools in the future) run.

Finally, you can build and install Exo.

(exo) $ python -m build .
(exo) $ pip install dist/*.whl

PySMT

Depending on your setup, getting PySMT to work correctly may be difficult. You need to independently install a solver such as Z3 or CVC4, and even then getting the PySMT library to correctly locate that solver may be difficult. We have included the z3-solver package as a requirement, which will hopefully avoid this issue, but you can also install z3 (or your choice of solver) independently.

Notes for Testing

Dependencies

Build system (required)

The Exo test harness generates C code and as such needs to compile and link using an unknown (i.e. system) compiler. To do this, it generates CMake build files and invokes CMake behind the scenes.

Therefore, you must have CMake 3.21 or newer installed.

By default, CMake will use Ninja as its backend, but this may be overridden by setting the environment variable CMAKE_GENERATOR to Unix Makefiles, in case you do not wish to install Ninja.

SDE (optional)

For testing x86 features on processors which don't support them (e.g., AVX-512 or AMX), we rely on the Intel Software Development Emulator as an optional dependency. Tests which rely on this (namely for AMX) look for sde64 either in the path defined by the SDE_PATH environment variable or in the system PATH, and are skipped if it is not available.

Running tests

To run the tests, simply type

pytest

in the root of the project.

Running Coverage Testing

To run pytest with coverage tests, execute

pytest --cov=./ --cov-report=html

Then, if you want to see annotated source files, open ./htmlcov/index.html.

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Learn about Exo

Take a look at the examples directory for scheduling examples and the documentation directory for various documentation about Exo.

Contact

Please contact [email protected] or [email protected] if you have any questions.

Publication

Exo's major contributions and ideas are published in the following two papers. The gist of its design principles and features is summarized in Design.md.

• Exocompilation for Productive Programming of Hardware Accelerators
  Yuka Ikarashi*, Gilbert Louis Bernstein*, Alex Reinking, Hasan Genc, Jonathan Ragan-Kelley
  PLDI 2022
  The full version with appendices can be found here.
• Exo 2: Growing a Scheduling Language
  Yuka Ikarashi, Kevin Qian, Samir Droubi, Alex Reinking, Gilbert Bernstein, Jonathan Ragan-Kelley
  ASPLOS 2025
  The full version with appendices can be found here.

If you use Exo, please cite both the compiler and the papers!