Add Intel SHMEM Python Bindings

[BenBrock]

Summary

This is a draft PR for an initial in-tree ishmem4py implementation. If Python bindings are enabled with -DBUILD_PYTHON_BINDINGS=ON, it will build a small shared object shim layer. The built Python package can then be installed from the build directory.

This draft currently only has basic functionality

• CPU-initiated communication
• basic init/finalize APIs
• shmem_malloc / shmem_free
• putmem / getmem
• simple examples and smoke tests

Architecture

The binding layer is built around a small in-tree runtime shim, _ishmem4py_runtime.so, rather than trying to bind directly to a stock Intel SHMEM install. If Intel SHMEM later adds a shared library build, we would likely use that directly.

The shim:

• is built as part of the normal ishmem CMake build
• links against ishmem-static
• exposes a stable extern "C" ABI for Python
• keeps the Python layer isolated from Intel SHMEM’s C++/template-heavy public interface

On the Python side, ishmem4py is currently a thin ctypes wrapper over that shim. For standard installs, the built runtime .so is bundled into the Python package; for editable/dev installs, the runtime can be overridden with ISHMEM4PY_RUNTIME_LIBRARY.

Building the bindings

The build should be performed as described in README.md, with the -DBUILD_PYTHON_BINDINGS=ON added. On my Ubuntu 24.04 system, I also needed -DENABLE_AOT_COMPILATION=OFF due to an outdated intel-ocloc package.

Then, it's usually easiest to install the Python package inside a conda environment. I also show the torch+xpu package install below. This is not strictly necessary, but the bindings will likely integrate with torch in the future.

conda create -n ishmem4py python=3.11 pip setuptools wheel

conda activate ishmem4py

# Recommended: install torch+xpu
python -m pip install torch --no-deps --index-url https://download.pytorch.org/whl/xpu

# Install the ishmem4py Python package built as part of Intel SHMEM.
python -m pip install --no-build-isolation $HOME/pkg/ishmem-2026-03-11-src/build/ishmem4py/python