Enzyme-JAX

Custom bindings for Enzyme automatic differentiation tool and interfacing with JAX. Currently this is set up to allow you to automatically import, and automatically differentiate (both jvp and vjp) external C++ code into JAX. As Enzyme is language-agnostic, this can be extended for arbitrary programming languages (Julia, Swift, Fortran, Rust, and even Python)!

You can use

from enzyme_ad.jax import cpp_call

# Forward-mode C++ AD example

@jax.jit
def something(inp):
    y = cpp_call(inp, out_shapes=[jax.core.ShapedArray([2, 3], jnp.float32)], source="""
        template<std::size_t N, std::size_t M>
        void myfn(enzyme::tensor<float, N, M>& out0, const enzyme::tensor<float, N, M>& in0) {
        out0 = 56.0f + in0(0, 0);
        }
        """, fn="myfn")
    return y

ones = jnp.ones((2, 3), jnp.float32)
primals, tangents = jax.jvp(something, (ones,), (ones,) )

# Reverse-mode C++ AD example

primals, f_vjp = jax.vjp(something, ones)
(grads,) = f_vjp((x,))

Installation

The easiest way to install is using pip.

# The project is available on PyPi and installable like
# a usual python package (https://pypi.org/project/enzyme-ad/)
pip install enzyme-ad

Building from source

Requirements: bazel-6.5, clang++, python, python-virtualenv, python3-dev.

Build our extension with:

# Will create a whl in bazel-bin/enzyme_ad-VERSION-SYSTEM.whl
bazel build :wheel

Finally, install the built library with:

pip install bazel-bin/enzyme_ad-VERSION-SYSTEM.whl

Note that you cannot run code from the root of the git directory. For instance, in the code below, you have to first run cd test before running test.py.

Running the test

To run tests, you can simply execute the following bazel commands (this does not require building or installing the wheel).

bazel test //test/...

Alternatively, if you have installed the wheel, you can manually invoke the tests as follows

cd test && python test.py