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Feb 10, 2020


Azure Pipelines Code Climate

A Lightweight LLVM Python Binding for Writing JIT Compilers

llvmlite is a project originally tailored for Numba's needs, using the following approach:

  • A small C wrapper around the parts of the LLVM C++ API we need that are not already exposed by the LLVM C API.
  • A ctypes Python wrapper around the C API.
  • A pure Python implementation of the subset of the LLVM IR builder that we need for Numba.

Why llvmlite

The old llvmpy binding exposes a lot of LLVM APIs but the mapping of C++-style memory management to Python is error prone. Numba and many JIT compilers do not need a full LLVM API. Only the IR builder, optimizer, and JIT compiler APIs are necessary.

Key Benefits

  • The IR builder is pure Python code and decoupled from LLVM's frequently-changing C++ APIs.
  • Materializing a LLVM module calls LLVM's IR parser which provides better error messages than step-by-step IR building through the C++ API (no more segfaults or process aborts).
  • Most of llvmlite uses the LLVM C API which is small but very stable (low maintenance when changing LLVM version).
  • The binding is not a Python C-extension, but a plain DLL accessed using ctypes (no need to wrestle with Python's compiler requirements and C++ 11 compatibility).
  • The Python binding layer has sane memory management.
  • llvmlite is quite faster than llvmpy's thanks to a much simpler architeture (the Numba test suite is twice faster than it was).

llvmpy Compatibility Layer

The llvmlite.llvmpy namespace provides a minimal llvmpy compatibility layer.


llvmlite works with Python 3.7 and greater.

As of version 0.37.0, llvmlite requires LLVM 11.x.x on all architectures

Historical compatibility table:

llvmlite versions compatible LLVM versions
0.37.0 - ... 11.x.x
0.34.0 - 0.36.0 10.0.x (9.0.x for aarch64 only)
0.33.0 9.0.x
0.29.0 - 0.32.0 7.0.x, 7.1.x, 8.0.x
0.27.0 - 0.28.0 7.0.x
0.23.0 - 0.26.0 6.0.x
0.21.0 - 0.22.0 5.0.x
0.17.0 - 0.20.0 4.0.x
0.16.0 - 0.17.0 3.9.x
0.13.0 - 0.15.0 3.8.x
0.9.0 - 0.12.1 3.7.x
0.6.0 - 0.8.0 3.6.x
0.1.0 - 0.5.1 3.5.x


You'll find the documentation at

Pre-built binaries

We recommend you use the binaries provided by the Numba team for the Conda package manager. You can find them in Numba's channel. For example:

$ conda install --channel=numba llvmlite

(or, simply, the official llvmlite package provided in the Anaconda distribution)

Other build methods

If you don't want to use our pre-built packages, you can compile and install llvmlite yourself. The documentation will teach you how: