pytorch/cmake/Modules
Nathan John Sircombe 664126bab5 Enables build with oneDNN (MKL-DNN) on AArch64 (#50400)
Summary:
Since version 1.6, oneDNN has provided limited support for AArch64 builds.

This minor change is to detect an AArch64 CPU and permit the use of
`USE_MKLDNN` in that case.

Build flags for oneDNN are also modified accordingly.

Note: oneDNN on AArch64, by default, will use oneDNN's reference C++ kernels.
These are not optimised for AArch64, but oneDNN v1.7 onwards provides support
for a limited set of primitives based Arm Compute Library.
See: https://github.com/oneapi-src/oneDNN/pull/795
and: https://github.com/oneapi-src/oneDNN/pull/820
for more details. Support for ACL-based oneDNN primitives in PyTorch
will require some further modification,

Fixes #{issue number}

Pull Request resolved: https://github.com/pytorch/pytorch/pull/50400

Reviewed By: izdeby

Differential Revision: D25886589

Pulled By: malfet

fbshipit-source-id: 2c81277a28ad4528c2d2211381e7c6692d952bc1
2021-01-13 08:41:44 -08:00
..
FindARM.cmake Make PyTorch partially cross-compilable for Apple M1 (#49701) 2020-12-22 09:33:12 -08:00
FindAtlas.cmake
FindAVX.cmake
FindBenchmark.cmake
FindBLAS.cmake [cmake] clean up blas discovery (#47940) 2020-11-30 10:29:50 -08:00
FindCUB.cmake
FindFFmpeg.cmake
FindGloo.cmake
FindHiredis.cmake
FindLAPACK.cmake
FindLevelDB.cmake
FindLMDB.cmake
FindMAGMA.cmake
FindMatlabMex.cmake
FindMKL.cmake
FindMKLDNN.cmake Enables build with oneDNN (MKL-DNN) on AArch64 (#50400) 2021-01-13 08:41:44 -08:00
FindNCCL.cmake
FindNuma.cmake
FindNumPy.cmake
FindOpenBLAS.cmake
FindOpenMP.cmake
Findpybind11.cmake
FindRocksDB.cmake
FindSnappy.cmake
FindvecLib.cmake
FindVSX.cmake Vsx initial support issue27678 (#41541) 2020-12-10 13:42:39 -08:00
FindZMQ.cmake
README.md

This folder contains various custom cmake modules for finding libraries and packages. Details about some of them are listed below.

FindOpenMP.cmake

This is modified from the file included in CMake 3.13 release, with the following changes:

  • Replace VERSION_GREATER_EQUAL with NOT ... VERSION_LESS as VERSION_GREATER_EQUAL is not supported in CMake 3.5 (our min supported version).

  • Update the separate_arguments commands to not use NATIVE_COMMAND which is not supported in CMake 3.5 (our min supported version).

  • Make it respect the QUIET flag so that, when it is set, try_compile failures are not reported.

  • For AppleClang compilers, use -Xpreprocessor instead of -Xclang as the later is not documented.

  • For AppleClang compilers, an extra flag option is tried, which is -Xpreprocessor -openmp -I${DIR_OF_omp_h}, where ${DIR_OF_omp_h} is a obtained using find_path on omp.h with brew's default include directory as a hint. Without this, the compiler will complain about missing headers as they are not natively included in Apple's LLVM.

  • For non-GNU compilers, whenever we try a candidate OpenMP flag, first try it with directly linking MKL's libomp if it has one. Otherwise, we may end up linking two libomps and end up with this nasty error:

    OMP: Error #15: Initializing libomp.dylib, but found libiomp5.dylib already
    initialized.
    
    OMP: Hint This means that multiple copies of the OpenMP runtime have been
    linked into the program. That is dangerous, since it can degrade performance
    or cause incorrect results. The best thing to do is to ensure that only a
    single OpenMP runtime is linked into the process, e.g. by avoiding static
    linking of the OpenMP runtime in any library. As an unsafe, unsupported,
    undocumented workaround you can set the environment variable
    KMP_DUPLICATE_LIB_OK=TRUE to allow the program to continue to execute, but
    that may cause crashes or silently produce incorrect results. For more
    information, please see http://openmp.llvm.org/
    

    See NOTE [ Linking both MKL and OpenMP ] for details.