.. _arch-pipeline:

=========================
Notes on Custom Pipelines
=========================

.. warning:: The custom pipeline feature is for expert use only.  Modifying
             the compiler behavior can invalidate internal assumptions in the
             numba source code.


For library developers looking for a way to extend or modify the compiler
behavior, you can do so by defining a custom compiler pipeline by inheriting
from ``numba.compiler.BasePipeline``.  The default numba pipeline is defined
as ``numba.compiler.Pipeline``, implementing the ``.define_pipelines()``
method, which adds the *nopython-mode*, *object-mode* and *interpreted-mode*
pipelines.  These three pipelines are defined in ``BasePipeline`` by the
methods ``.define_nopython_pipeline``, ``.define_objectmode_pipeline``
and ``.define_interpreted_pipeline``, respectively..

To use a custom subclass of ``BasePipeline``, supply it as the
``pipeline_class`` keyword argument to the ``@jit`` and ``@generated_jit``
decorators.  By doing so, the effect of the custom pipeline is limited to the
function being decorated.

Below are the common methods available to implementors of the ``BasePipeline``
class:

.. autoclass:: numba.compiler.BasePipeline
    :members: add_cleanup_stage, add_lowering_stage, add_optimization_stage,
              add_pre_typing_stage, add_preprocessing_stage, add_typing_stage,
              define_nopython_pipeline, define_objectmode_pipeline,
              define_interpreted_pipeline