AMD Optimized Compiler Collection (AOCC)
========================================

.. toctree::
   :maxdepth: 1
   :caption: Contents:

Supported versions
------------------

To check which `AMD AOCC`_ versions are currently supported on Discoverer, execute on the login node:

.. code-block:: bash

 module avail amd/aocc/

Loading
-------

To obtain access to the latest AMD AOCC load the environment module ``aocc/latest``:

.. code:: bash

 module load amd/aocc/latest

otherwise replace ``latest`` with the version you need.

LLVM compilers
--------------

.. warning:: AOCC provides LLVM compilers only!

.. code:: bash

 clang
 clang++
 flang

Compiler optimization flags for AMD Zen2 CPU
--------------------------------------------

.. note:: The compute nodes of Discoverer HPC are equipped with AMD EPYC 7H12 64-Core processors, which implies AMD Zen2 CPU architecture.

The following compiler flags can be useful during the compile-time optimization of your binary code on AMD Zen2:

.. code:: bash

 -march=znver2 -mtune=native

For example:

.. code:: bash

 clang -march=znver2 -mtune=native ...
 clang++ -march=znver2 -mtune=native ...
 flang -march=znver2 -mtune=native ...

More on the supported compiler flags: `AMD EPYC™ 7xx2-series Processors Compiler Options Quick Reference Guide`_

Interaction with CMake
----------------------

It is recommended to specify the compiler executables when invoking ``cmake`` tool:

.. code:: bash

 -DCMAKE_C_COMPILER=clang
 -DCMAKE_CXX_COMPILER=clang++
 -DCMAKE_Fortran_COMPILER=flang

The corresponding optimization compiler flags can be passed to ``cmake`` as well:

.. code:: bash

 -DCMAKE_C_FLAGS="-march=znver2 -mtune=native"
 -DCMAKE_CXX_FLAGS="-march=znver2 -mtune=native"
 -DCMAKE_Fortran_FLAGS="-march=znver2 -mtune=native"

Getting help
------------

See :doc:`help`

.. _`AMD AOCC`: https://developer.amd.com/amd-aocc
.. _`AMD EPYC™ 7xx2-series Processors Compiler Options Quick Reference Guide`: https://developer.amd.com/wordpress/media/2020/04/Compiler%20Options%20Quick%20Ref%20Guide%20for%20AMD%20EPYC%207xx2%20Series%20Processors.pdf