Intel oneAPI ============ .. toctree:: :maxdepth: 1 :caption: Contents: Supported versions ------------------ .. warning:: As of version 2024.0, Intel has discontinued the traditional compilers ``icc``, ``icpc``, and ``ifort``. We know that such a decision may affect many code projects that use those compilers and struggle switching to the new LLMV-based compilers ``icx``, ``icpx``, and ``ifx``. To make the transition from classic to LLVM-based compilers easier, we still host some older versions of Intel oneAPI compilers that include the classic compilers. 2023.2.1 is the latest such version. Check the document `Porting Guide for ICC Users to DPCPP or ICX`_ for more details about how to move from classic to LLVM-based compilers. .. warning:: **Do not use Intel MPI on Discoverer compute nodes.** That MPI library cannot scale to more than two nodes, and we do not have a clear explanation for that phenomena. To check which `Intel oneAPI`_ versions are currently supported on Discoverer, execute on the login node: .. code-block:: bash module load intel module avail and check the output in the section below ``/opt/software/intel/oneapi/modulefiles`` label. Accessing the compilers ----------------------- To obtain access to the latest Intel compilers, load the following environment modules: LLVM-based compilers .................... The access to the Intel LLVM-based compilers ``icx``, ``icpx``, ``ifx`` can be gained by loading the following sequence of environment modules: .. code:: bash module load intel module load tbb/latest module load compiler-rt/latest module load oclfpga/latest module load compiler/latest You may also specify the particular version of the modules instead of relying on their "latest" versions. LLVM base compilers (for experts) ................................. The Intel CPU and Intel GPU optimizing LLVM compilers and tools ``clang``, ``clang++``, ``clang-cl``, and ``clang-cpp`` are also available (though no ``flang`` is provided). To gain access to those compilers and tools load the following environment modules: .. code:: bash module load intel module load tbb/latest module load compiler-rt/latest module load oclfpga/latest module load compiler-intel-llvm/latest You may also specify the particular version of the modules instead of relying on their "latest" versions. .. warning:: **USE WITH CAUTION!** Load the access to those compilers only if there is not way to specify the use of ``icx`` and ``icpx``! Be aware that ``clang``, ``clang++``, ``clang-cl``, and ``clang-cpp`` binaries are not made accessible during environment setup (see "LLVM-based compilers" above) in order to reduce collisions with other toolchains. Classic compilers ................. .. warning:: **Intel has already discontinued and retired those compilers.** This implies that the Intel classic compilers will not receive any new or revised versions in the future. Therefore, if you require these compilers to compile outdated code, you have to adhere to the most recent version made available before their retirement. Consider switching to Intel's LLVM-based compilers as soon as possible (that may require to redesign your automake or CMake setups). The access to the classic Intel LLVM-based compilers ``icc``, ``icpc``, ``ifort`` can be gained by loading the following sequence of environment modules: .. code:: bash module load intel module load compiler/2023.2.1 .. note:: Version 2023.2.1 is the last version of Intel compilers that comes with ``icc``, ``icpc``, and ``ifort``. We will keep that version in our software repository until the second half of 2026. DPC++ compiler .............. .. note:: `Intel oneAPI Data Parallel C++ compiler`_ employs LLVM compiler drivers. To get access to the latest DPC++ compiler, load the LLVM-based compilers as mentioned above. Then instead or invoking the old ``dpcpp`` compiler (it is deprecated and will be removed in a future release), use: .. code:: bash icpx -fsycl Interoperability with GCC ------------------------- .. note:: For advanced users! You may need to load the latest `GCC`_ version to provide more recent C++ support to the Intel compilers: .. code:: bash module load gcc/latest module load intel ... Compiler flags for matching AMD Zen2 CPU microarchitecture ---------------------------------------------------------- .. note:: The compute nodes of Discoverer HPC are equipped with AMD EPYC 7H12 64-Core processors, which implies AMD Zen2 CPU microarchitecture. Refer to :doc:`resource_overview` for more details. The following compiler flags can be useful during the compile-time optimization of your binary code on AMD Zen2: .. code:: bash -march=znver2 -mtune=znver2 For example: .. code:: bash icx -march=znver2 -mtune=znver2 ... icpx -march=znver2 -mtune=znver2 ... ifx -march=znver2 -mtune=znver2 ... .. note:: The use of ``znver2`` CPU microarchitecture specifier implies the use of FMA! To pass the flags for the microarchitecture to the compilers one may add to the values of CFLAGS, CXXFLAGS, or FCFLAGS environmental variables the following: .. code:: bash CFLAGS+=" --march=znver2 -mtune=znver2" CXXFLAGS+=" --march=znver2 -mtune=znver2" FCFLAGS+=" --march=znver2 -mtune=znver2" You should be able to tune your code for using specific AVX2 SIMD instructions (i.e. the highest SIMD supported by AMD Zen2 kernel) by following the instructions given in `AMD EPYC™ 7xx2-series Processors Compiler Options Quick Reference Guide`_ See also: `Best Practice Guide - AMD EPYC`_. Interaction with CMake ---------------------- It is recommended to specify the compiler executables when invoking ``cmake`` tool: .. code:: bash -DCMAKE_C_COMPILER=icx -DCMAKE_CXX_COMPILER=icpx -DCMAKE_Fortran_COMPILER=ifx The corresponding optimization compiler flags can be passed to ``cmake`` as well: .. code:: bash -DCMAKE_C_FLAGS="-march=znver2 -mtune=znver2 ${CFLAGS}" -DCMAKE_CXX_FLAGS="-march=znver2 -mtune=znver2 ${CXXFLAGS}" -DCMAKE_Fortran_FLAGS="-march=znver2 -mtune=znver2 ${FCFLAGS}" Getting help ------------ See :doc:`help` .. _`Intel oneAPI Data Parallel C++ compiler`: https://www.intel.com/content/www/us/en/developer/tools/oneapi/dpc-compiler.html# .. _`Intel oneAPI`: https://www.intel.com/content/www/us/en/developer/tools/oneapi/overview.html .. _`Best Practice Guide - AMD EPYC`: https://prace-ri.eu/wp-content/uploads/Best-Practice-Guide_AMD.pdf .. _`GCC`: http://gcc.gnu.org .. _`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 .. _`Porting Guide for ICC Users to DPCPP or ICX`: https://www.intel.com/content/www/us/en/developer/articles/guide/porting-guide-for-icc-users-to-dpcpp-or-icx.html