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.. _porting:
Porting GlobalISel to A New Target
There are four major classes to implement by the target:
* :ref:`CallLowering <translator-call-lower>` --- lower calls, returns, and
arguments according to the ABI.
* :ref:`RegisterBankInfo <api-registerbankinfo>` --- describe
:ref:`gmir-regbank` coverage, cross-bank copy cost, and the mapping of
operands onto banks for each instruction.
* :ref:`LegalizerInfo <api-legalizerinfo>` --- describe what is legal, and how
to legalize what isn't.
* :ref:`InstructionSelector <api-instructionselector>` --- select generic MIR
to target-specific MIR.
* ``TargetPassConfig`` --- create the passes constituting the pipeline,
including additional passes not included in the :ref:`pipeline`.
We'd recommend watching `this tutorial
<>`_ from the 2017 LLVM DevMeeting
which gave an overview of how to bring up a new backend in GlobalISel.