FindBLAS.cmake

# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.

#.rst:
# FindBLAS
# --------
#
# Find Basic Linear Algebra Subprograms (BLAS) library
#
# This module finds an installed Fortran library that implements the
# BLAS linear-algebra interface (see http://www.netlib.org/blas/).
#
# The approach follows that taken for the ``autoconf`` macro file,
#``acx_blas.m4`` (distributed at
# http://ac-archive.sourceforge.net/ac-archive/acx_blas.html).
#
# Input Variables
# ^^^^^^^^^^^^^^^
#
# The following variables may be set to influence this module's behavior:
#
# ``BLA_STATIC``
#  if ``ON`` use static linkage
#
# ``BLA_VENDOR``
#  If set, checks only the specified vendor, if not set checks all the
#   possibilities.  List of vendors valid in this module:
#
#   * ``Goto``
#   * ``OpenBLAS``
#   * ``FLAME``
#   * ``ATLAS PhiPACK``
#   * ``CXML``
#   * ``DXML``
#   * ``SunPerf``
#   * ``SCSL``
#   * ``SGIMATH``
#   * ``IBMESSL``
#   * ``Intel10_32`` (intel mkl v10 32 bit)
#   * ``Intel10_64lp`` (intel mkl v10+ 64 bit, threaded code, lp64 model)
#   * ``Intel10_64lp_seq`` (intel mkl v10+ 64 bit, sequential code, lp64 model)
#   * ``Intel10_64ilp`` (intel mkl v10+ 64 bit, threaded code, ilp64 model)
#   * ``Intel10_64ilp_seq`` (intel mkl v10+ 64 bit, sequential code, ilp64 model)
#   * ``Intel10_64_dyn`` (intel mkl v10+ 64 bit, single dynamic library)
#   * ``Intel`` (obsolete versions of mkl 32 and 64 bit)
#   * ``ACML``
#   * ``ACML_MP``
#   * ``ACML_GPU``
#   * ``Apple``
#   * ``NAS``
#   * ``Arm``
#   * ``Arm_mp``
#   * ``Arm_ilp64``
#   * ``Arm_ilp64_mp``
#   * ``Generic``
#
# ``BLA_F95``
#   if ``ON`` tries to find the BLAS95 interfaces
#
# ``BLA_PREFER_PKGCONFIG``
#   if set ``pkg-config`` will be used to search for a BLAS library first
#   and if one is found that is preferred
#
# Result Variables
# ^^^^^^^^^^^^^^^^
#
# This module defines the following variables:
#
# ``BLAS_FOUND``
#   library implementing the BLAS interface is found
# ``BLAS_LINKER_FLAGS``
#   uncached list of required linker flags (excluding ``-l`` and ``-L``).
# ``BLAS_LIBRARIES``
#   uncached list of libraries (using full path name) to link against
#   to use BLAS (may be empty if compiler implicitly links BLAS)
# ``BLAS95_LIBRARIES``
#   uncached list of libraries (using full path name) to link against
#   to use BLAS95 interface
# ``BLAS95_FOUND``
#   library implementing the BLAS95 interface is found
#
# .. note::
#
#   C, CXX or Fortran must be enabled to detect a BLAS library.
#   C or CXX must be enabled to use Intel Math Kernel Library (MKL).
#
#   For example, to use Intel MKL libraries and/or Intel compiler:
#
#   .. code-block:: cmake
#
#     set(BLA_VENDOR Intel10_64lp)
#     find_package(BLAS)
#
# Hints
# ^^^^^
#
# Set the ``MKLROOT`` environment variable to a directory that contains an MKL
# installation, or add the directory to the dynamic library loader environment
# variable for your platform (``LIB``, ``DYLD_LIBRARY_PATH`` or
# ``LD_LIBRARY_PATH``).

# Check the language being used
if(NOT (CMAKE_C_COMPILER_LOADED OR CMAKE_CXX_COMPILER_LOADED OR CMAKE_Fortran_COMPILER_LOADED))
  if(BLAS_FIND_REQUIRED)
    message(FATAL_ERROR "FindBLAS requires Fortran, C, or C++ to be enabled.")
  else()
    message(STATUS "Looking for BLAS... - NOT found (Unsupported languages)")
    return()
  endif()
endif()

function(_add_blas_target)
  if(BLAS_FOUND AND NOT TARGET BLAS::BLAS)
    add_library(BLAS::BLAS INTERFACE IMPORTED)
    if(BLAS_LIBRARIES)
      set_target_properties(BLAS::BLAS PROPERTIES
        INTERFACE_LINK_LIBRARIES "${BLAS_LIBRARIES}"
      )
    endif()
    if(BLAS_LINKER_FLAGS)
      set_target_properties(BLAS::BLAS PROPERTIES
        INTERFACE_LINK_OPTIONS "${BLAS_LINKER_FLAGS}"
      )
    endif()
  endif()
endfunction()

if(CMAKE_Fortran_COMPILER_LOADED)
  include(${CMAKE_CURRENT_LIST_DIR}/CheckFortranFunctionExists.cmake)
else()
  include(CheckFunctionExists)
endif()
include(CMakePushCheckState)
include(FindPackageHandleStandardArgs)
cmake_push_check_state()
set(CMAKE_REQUIRED_QUIET ${BLAS_FIND_QUIETLY})

if(BLA_PREFER_PKGCONFIG)
  find_package(PkgConfig)
  pkg_check_modules(PKGC_BLAS blas)
  if(PKGC_BLAS_FOUND)
    set(BLAS_FOUND ${PKGC_BLAS_FOUND})
    set(BLAS_LIBRARIES "${PKGC_BLAS_LINK_LIBRARIES}")
    _add_blas_target()
    return()
  endif()
endif()

set(_blas_ORIG_CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES})
if(BLA_STATIC)
  if(WIN32)
    set(CMAKE_FIND_LIBRARY_SUFFIXES .lib ${CMAKE_FIND_LIBRARY_SUFFIXES})
  else()
    set(CMAKE_FIND_LIBRARY_SUFFIXES .a ${CMAKE_FIND_LIBRARY_SUFFIXES})
  endif()
else()
  if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
    # for ubuntu's libblas3gf and liblapack3gf packages
    set(CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES} .so.3gf)
  endif()
endif()

# TODO: move this stuff to a separate module

macro(CHECK_BLAS_LIBRARIES LIBRARIES _prefix _name _flags _list _threadlibs _addlibdir _subdirs)
  # This macro checks for the existence of the combination of fortran libraries
  # given by _list.  If the combination is found, this macro checks (using the
  # Check_Fortran_Function_Exists macro) whether can link against that library
  # combination using the name of a routine given by _name using the linker
  # flags given by _flags.  If the combination of libraries is found and passes
  # the link test, LIBRARIES is set to the list of complete library paths that
  # have been found.  Otherwise, LIBRARIES is set to FALSE.

  # N.B. _prefix is the prefix applied to the names of all cached variables that
  # are generated internally and marked advanced by this macro.
  # _addlibdir is a list of additional search paths. _subdirs is a list of path
  # suffixes to be used by find_library().

  set(_libraries_work TRUE)
  set(${LIBRARIES})
  set(_combined_name)

  set(_extaddlibdir "${_addlibdir}")
  if(WIN32)
    list(APPEND _extaddlibdir ENV LIB)
  elseif(APPLE)
    list(APPEND _extaddlibdir ENV DYLD_LIBRARY_PATH)
  else()
    list(APPEND _extaddlibdir ENV LD_LIBRARY_PATH)
  endif()
  list(APPEND _extaddlibdir "${CMAKE_C_IMPLICIT_LINK_DIRECTORIES}")

  foreach(_library ${_list})
    if(_library MATCHES "^-Wl,--(start|end)-group$")
      # Respect linker flags like --start/end-group (required by MKL)
      set(${LIBRARIES} ${${LIBRARIES}} "${_library}")
    else()
      set(_combined_name ${_combined_name}_${_library})
      if(NOT "${_threadlibs}" STREQUAL "")
        set(_combined_name ${_combined_name}_threadlibs)
      endif()
      if(_libraries_work)
        find_library(${_prefix}_${_library}_LIBRARY
          NAMES ${_library}
          PATHS ${_extaddlibdir}
          PATH_SUFFIXES ${_subdirs}
        )
        #message("DEBUG: find_library(${_library}) got ${${_prefix}_${_library}_LIBRARY}")
        mark_as_advanced(${_prefix}_${_library}_LIBRARY)
        set(${LIBRARIES} ${${LIBRARIES}} ${${_prefix}_${_library}_LIBRARY})
        set(_libraries_work ${${_prefix}_${_library}_LIBRARY})
      endif()
    endif()
  endforeach()

  if(_libraries_work)
    # Test this combination of libraries.
    set(CMAKE_REQUIRED_LIBRARIES ${_flags} ${${LIBRARIES}} ${_threadlibs})
    #message("DEBUG: CMAKE_REQUIRED_LIBRARIES = ${CMAKE_REQUIRED_LIBRARIES}")
    if(CMAKE_Fortran_COMPILER_LOADED)
      check_fortran_function_exists("${_name}" ${_prefix}${_combined_name}_WORKS)
    else()
      check_function_exists("${_name}_" ${_prefix}${_combined_name}_WORKS)
    endif()
    set(CMAKE_REQUIRED_LIBRARIES)
    set(_libraries_work ${${_prefix}${_combined_name}_WORKS})
  endif()

  if(_libraries_work)
    if("${_list}" STREQUAL "")
      set(${LIBRARIES} "${LIBRARIES}-PLACEHOLDER-FOR-EMPTY-LIBRARIES")
    else()
      set(${LIBRARIES} ${${LIBRARIES}} ${_threadlibs})
    endif()
  else()
    set(${LIBRARIES} FALSE)
  endif()
  #message("DEBUG: ${LIBRARIES} = ${${LIBRARIES}}")
endmacro()

set(BLAS_LINKER_FLAGS)
set(BLAS_LIBRARIES)
set(BLAS95_LIBRARIES)
if(NOT $ENV{BLA_VENDOR} STREQUAL "")
  set(BLA_VENDOR $ENV{BLA_VENDOR})
else()
  if(NOT BLA_VENDOR)
    set(BLA_VENDOR "All")
  endif()
endif()

# Implicitly linked BLAS libraries?
if(BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      ""
      ""
      ""
      ""
      ""
      )
  endif()
endif()

# BLAS in the Intel MKL 10+ library?
if(BLA_VENDOR MATCHES "Intel" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    if(CMAKE_C_COMPILER_LOADED OR CMAKE_CXX_COMPILER_LOADED)
      # System-specific settings
      if(WIN32)
        if(BLA_STATIC)
          set(BLAS_mkl_DLL_SUFFIX "")
        else()
          set(BLAS_mkl_DLL_SUFFIX "_dll")
        endif()
      else()
        if(BLA_STATIC)
          set(BLAS_mkl_START_GROUP "-Wl,--start-group")
          set(BLAS_mkl_END_GROUP "-Wl,--end-group")
        else()
          set(BLAS_mkl_START_GROUP "")
          set(BLAS_mkl_END_GROUP "")
        endif()
        # Switch to GNU Fortran support layer if needed (but not on Apple, where MKL does not provide it)
        if(CMAKE_Fortran_COMPILER_LOADED AND CMAKE_Fortran_COMPILER_ID STREQUAL "GNU" AND NOT APPLE)
          set(BLAS_mkl_INTFACE "gf")
          set(BLAS_mkl_THREADING "gnu")
          set(BLAS_mkl_OMP "gomp")
        else()
          set(BLAS_mkl_INTFACE "intel")
          set(BLAS_mkl_THREADING "intel")
          set(BLAS_mkl_OMP "iomp5")
        endif()
        set(BLAS_mkl_LM "-lm")
        set(BLAS_mkl_LDL "-ldl")
      endif()

      if(BLAS_FIND_QUIETLY OR NOT BLAS_FIND_REQUIRED)
        find_package(Threads)
      else()
        find_package(Threads REQUIRED)
      endif()

      if(BLA_VENDOR MATCHES "_64ilp")
        set(BLAS_mkl_ILP_MODE "ilp64")
      else()
        set(BLAS_mkl_ILP_MODE "lp64")
      endif()

      set(BLAS_SEARCH_LIBS "")

      if(BLA_F95)
        set(BLAS_mkl_SEARCH_SYMBOL "sgemm_f95")
        set(_LIBRARIES BLAS95_LIBRARIES)
        if(WIN32)
          # Find the main file (32-bit or 64-bit)
          set(BLAS_SEARCH_LIBS_WIN_MAIN "")
          if(BLA_VENDOR STREQUAL "Intel10_32" OR BLA_VENDOR STREQUAL "All")
            list(APPEND BLAS_SEARCH_LIBS_WIN_MAIN
              "mkl_blas95${BLAS_mkl_DLL_SUFFIX} mkl_intel_c${BLAS_mkl_DLL_SUFFIX}")
          endif()

          if(BLA_VENDOR MATCHES "^Intel10_64i?lp" OR BLA_VENDOR STREQUAL "All")
            list(APPEND BLAS_SEARCH_LIBS_WIN_MAIN
              "mkl_blas95_${BLAS_mkl_ILP_MODE}${BLAS_mkl_DLL_SUFFIX} mkl_intel_${BLAS_mkl_ILP_MODE}${BLAS_mkl_DLL_SUFFIX}")
          endif()

          # Add threading/sequential libs
          set(BLAS_SEARCH_LIBS_WIN_THREAD "")
          if(BLA_VENDOR MATCHES "^Intel10_64i?lp$" OR BLA_VENDOR STREQUAL "All")
            # old version
            list(APPEND BLAS_SEARCH_LIBS_WIN_THREAD
              "libguide40 mkl_intel_thread${BLAS_mkl_DLL_SUFFIX}")
            # mkl >= 10.3
            list(APPEND BLAS_SEARCH_LIBS_WIN_THREAD
              "libiomp5md mkl_intel_thread${BLAS_mkl_DLL_SUFFIX}")
          endif()
          if(BLA_VENDOR MATCHES "^Intel10_64i?lp_seq$" OR BLA_VENDOR STREQUAL "All")
            list(APPEND BLAS_SEARCH_LIBS_WIN_THREAD
              "mkl_sequential${BLAS_mkl_DLL_SUFFIX}")
          endif()

          # Cartesian product of the above
          foreach(MAIN ${BLAS_SEARCH_LIBS_WIN_MAIN})
            foreach(THREAD ${BLAS_SEARCH_LIBS_WIN_THREAD})
              list(APPEND BLAS_SEARCH_LIBS
                "${MAIN} ${THREAD} mkl_core${BLAS_mkl_DLL_SUFFIX}")
            endforeach()
          endforeach()
        else()
          if(BLA_VENDOR STREQUAL "Intel10_32" OR BLA_VENDOR STREQUAL "All")
            # old version
            list(APPEND BLAS_SEARCH_LIBS
              "mkl_blas95 mkl_${BLAS_mkl_INTFACE} mkl_${BLAS_mkl_THREADING}_thread mkl_core guide")

            # mkl >= 10.3
            list(APPEND BLAS_SEARCH_LIBS
              "${BLAS_mkl_START_GROUP} mkl_blas95 mkl_${BLAS_mkl_INTFACE} mkl_${BLAS_mkl_THREADING}_thread mkl_core ${BLAS_mkl_END_GROUP} ${BLAS_mkl_OMP}")
          endif()
          if(BLA_VENDOR MATCHES "^Intel10_64i?lp$" OR BLA_VENDOR STREQUAL "All")
            # old version
            list(APPEND BLAS_SEARCH_LIBS
              "mkl_blas95 mkl_${BLAS_mkl_INTFACE}_${BLAS_mkl_ILP_MODE} mkl_${BLAS_mkl_THREADING}_thread mkl_core guide")

            # mkl >= 10.3
            list(APPEND BLAS_SEARCH_LIBS
              "${BLAS_mkl_START_GROUP} mkl_blas95_${BLAS_mkl_ILP_MODE} mkl_${BLAS_mkl_INTFACE}_${BLAS_mkl_ILP_MODE} mkl_${BLAS_mkl_THREADING}_thread mkl_core ${BLAS_mkl_END_GROUP} ${BLAS_mkl_OMP}")
          endif()
          if(BLA_VENDOR MATCHES "^Intel10_64i?lp_seq$" OR BLA_VENDOR STREQUAL "All")
            list(APPEND BLAS_SEARCH_LIBS
              "${BLAS_mkl_START_GROUP} mkl_blas95_${BLAS_mkl_ILP_MODE} mkl_${BLAS_mkl_INTFACE}_${BLAS_mkl_ILP_MODE} mkl_sequential mkl_core ${BLAS_mkl_END_GROUP}")
          endif()
        endif()
      else()
        set(BLAS_mkl_SEARCH_SYMBOL sgemm)
        set(_LIBRARIES BLAS_LIBRARIES)
        if(WIN32)
          # Find the main file (32-bit or 64-bit)
          set(BLAS_SEARCH_LIBS_WIN_MAIN "")
          if(BLA_VENDOR STREQUAL "Intel10_32" OR BLA_VENDOR STREQUAL "All")
            list(APPEND BLAS_SEARCH_LIBS_WIN_MAIN
              "mkl_intel_c${BLAS_mkl_DLL_SUFFIX}")
          endif()
          if(BLA_VENDOR MATCHES "^Intel10_64i?lp" OR BLA_VENDOR STREQUAL "All")
            list(APPEND BLAS_SEARCH_LIBS_WIN_MAIN
              "mkl_intel_${BLAS_mkl_ILP_MODE}${BLAS_mkl_DLL_SUFFIX}")
          endif()

          # Add threading/sequential libs
          set(BLAS_SEARCH_LIBS_WIN_THREAD "")
          if(BLA_VENDOR MATCHES "^Intel10_64i?lp$" OR BLA_VENDOR STREQUAL "All")
            # old version
            list(APPEND BLAS_SEARCH_LIBS_WIN_THREAD
              "libguide40 mkl_intel_thread${BLAS_mkl_DLL_SUFFIX}")
            # mkl >= 10.3
            list(APPEND BLAS_SEARCH_LIBS_WIN_THREAD
              "libiomp5md mkl_intel_thread${BLAS_mkl_DLL_SUFFIX}")
          endif()
          if(BLA_VENDOR MATCHES "^Intel10_64i?lp_seq$" OR BLA_VENDOR STREQUAL "All")
            list(APPEND BLAS_SEARCH_LIBS_WIN_THREAD
              "mkl_sequential${BLAS_mkl_DLL_SUFFIX}")
          endif()

          # Cartesian product of the above
          foreach(MAIN ${BLAS_SEARCH_LIBS_WIN_MAIN})
            foreach(THREAD ${BLAS_SEARCH_LIBS_WIN_THREAD})
              list(APPEND BLAS_SEARCH_LIBS
                "${MAIN} ${THREAD} mkl_core${BLAS_mkl_DLL_SUFFIX}")
            endforeach()
          endforeach()
        else()
          if(BLA_VENDOR STREQUAL "Intel10_32" OR BLA_VENDOR STREQUAL "All")
            # old version
            list(APPEND BLAS_SEARCH_LIBS
              "mkl_${BLAS_mkl_INTFACE} mkl_${BLAS_mkl_THREADING}_thread mkl_core guide")

            # mkl >= 10.3
            list(APPEND BLAS_SEARCH_LIBS
              "${BLAS_mkl_START_GROUP} mkl_${BLAS_mkl_INTFACE} mkl_${BLAS_mkl_THREADING}_thread mkl_core ${BLAS_mkl_END_GROUP} ${BLAS_mkl_OMP}")
          endif()
          if(BLA_VENDOR MATCHES "^Intel10_64i?lp$" OR BLA_VENDOR STREQUAL "All")
            # old version
            list(APPEND BLAS_SEARCH_LIBS
              "mkl_${BLAS_mkl_INTFACE}_${BLAS_mkl_ILP_MODE} mkl_${BLAS_mkl_THREADING}_thread mkl_core guide")

            # mkl >= 10.3
            list(APPEND BLAS_SEARCH_LIBS
              "${BLAS_mkl_START_GROUP} mkl_${BLAS_mkl_INTFACE}_${BLAS_mkl_ILP_MODE} mkl_${BLAS_mkl_THREADING}_thread mkl_core ${BLAS_mkl_END_GROUP} ${BLAS_mkl_OMP}")
          endif()
          if(BLA_VENDOR MATCHES "^Intel10_64i?lp_seq$" OR BLA_VENDOR STREQUAL "All")
            list(APPEND BLAS_SEARCH_LIBS
              "${BLAS_mkl_START_GROUP} mkl_${BLAS_mkl_INTFACE}_${BLAS_mkl_ILP_MODE} mkl_sequential mkl_core ${BLAS_mkl_END_GROUP}")
          endif()

          #older vesions of intel mkl libs
          if(BLA_VENDOR STREQUAL "Intel" OR BLA_VENDOR STREQUAL "All")
            list(APPEND BLAS_SEARCH_LIBS
              "mkl")
            list(APPEND BLAS_SEARCH_LIBS
              "mkl_ia32")
            list(APPEND BLAS_SEARCH_LIBS
              "mkl_em64t")
          endif()
        endif()
      endif()

      if(BLA_VENDOR MATCHES "^Intel10_64_dyn$" OR BLA_VENDOR STREQUAL "All")
        # mkl >= 10.3 with single dynamic library
        list(APPEND BLAS_SEARCH_LIBS
          "mkl_rt")
      endif()

      # MKL uses a multitude of partially platform-specific subdirectories:
      if(BLA_VENDOR STREQUAL "Intel10_32")
        set(BLAS_mkl_ARCH_NAME "ia32")
      else()
        set(BLAS_mkl_ARCH_NAME "intel64")
      endif()
      if(WIN32)
        set(BLAS_mkl_OS_NAME "win")
      elseif(APPLE)
        set(BLAS_mkl_OS_NAME "mac")
      else()
        set(BLAS_mkl_OS_NAME "lin")
      endif()
      if(DEFINED ENV{MKLROOT})
        set(BLAS_mkl_MKLROOT "$ENV{MKLROOT}")
        # If MKLROOT points to the subdirectory 'mkl', use the parent directory instead
        # so we can better detect other relevant libraries in 'compiler' or 'tbb':
        get_filename_component(BLAS_mkl_MKLROOT_LAST_DIR "${BLAS_mkl_MKLROOT}" NAME)
        if(BLAS_mkl_MKLROOT_LAST_DIR STREQUAL "mkl")
            get_filename_component(BLAS_mkl_MKLROOT "${BLAS_mkl_MKLROOT}" DIRECTORY)
        endif()
      endif()
      set(BLAS_mkl_LIB_PATH_SUFFIXES
          "compiler/lib" "compiler/lib/${BLAS_mkl_ARCH_NAME}_${BLAS_mkl_OS_NAME}"
          "compiler/lib/${BLAS_mkl_ARCH_NAME}"
          "mkl/lib" "mkl/lib/${BLAS_mkl_ARCH_NAME}_${BLAS_mkl_OS_NAME}"
          "mkl/lib/${BLAS_mkl_ARCH_NAME}"
          "mkl/latest/lib" "mkl/latest/lib/${BLAS_mkl_ARCH_NAME}_${BLAS_mkl_OS_NAME}"
          "mkl/latest/lib/${BLAS_mkl_ARCH_NAME}"
          "lib/${BLAS_mkl_ARCH_NAME}_${BLAS_mkl_OS_NAME}")

      foreach(IT ${BLAS_SEARCH_LIBS})
        string(REPLACE " " ";" SEARCH_LIBS ${IT})
        if(NOT ${_LIBRARIES})
          check_blas_libraries(
            ${_LIBRARIES}
            BLAS
            ${BLAS_mkl_SEARCH_SYMBOL}
            ""
            "${SEARCH_LIBS}"
            "${CMAKE_THREAD_LIBS_INIT};${BLAS_mkl_LM};${BLAS_mkl_LDL}"
            "${BLAS_mkl_MKLROOT}"
            "${BLAS_mkl_LIB_PATH_SUFFIXES}"
            )
        endif()
      endforeach()

      unset(BLAS_mkl_ILP_MODE)
      unset(BLAS_mkl_INTFACE)
      unset(BLAS_mkl_THREADING)
      unset(BLAS_mkl_OMP)
      unset(BLAS_mkl_DLL_SUFFIX)
      unset(BLAS_mkl_LM)
      unset(BLAS_mkl_LDL)
      unset(BLAS_mkl_MKLROOT)
      unset(BLAS_mkl_MKLROOT_LAST_DIR)
      unset(BLAS_mkl_ARCH_NAME)
      unset(BLAS_mkl_OS_NAME)
      unset(BLAS_mkl_LIB_PATH_SUFFIXES)
    endif()
  endif()
endif()

if(BLA_F95)
  find_package_handle_standard_args(BLAS REQUIRED_VARS BLAS95_LIBRARIES)
  set(BLAS95_FOUND ${BLAS_FOUND})
  if(BLAS_FOUND)
    set(BLAS_LIBRARIES "${BLAS95_LIBRARIES}")
  endif()
endif()

# gotoblas? (http://www.tacc.utexas.edu/tacc-projects/gotoblas2)
if(BLA_VENDOR STREQUAL "Goto" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      ""
      "goto2"
      ""
      ""
      ""
      )
  endif()
endif()

# OpenBLAS? (http://www.openblas.net)
if(BLA_VENDOR STREQUAL "OpenBLAS" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      ""
      "openblas"
      ""
      ""
      ""
      )
  endif()
  if(NOT BLAS_LIBRARIES AND (CMAKE_C_COMPILER_LOADED OR CMAKE_CXX_COMPILER_LOADED))
    if(BLAS_FIND_QUIETLY OR NOT BLAS_FIND_REQUIRED)
      find_package(Threads)
    else()
      find_package(Threads REQUIRED)
    endif()
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      ""
      "openblas"
      "${CMAKE_THREAD_LIBS_INIT}"
      ""
      ""
      )
  endif()
endif()

# ArmPL blas library? (https://developer.arm.com/tools-and-software/server-and-hpc/compile/arm-compiler-for-linux/arm-performance-libraries)
if(BLA_VENDOR MATCHES "Arm" OR BLA_VENDOR STREQUAL "All")

   # Check for 64bit Integer support
   if(BLA_VENDOR MATCHES "_ilp64")
     set(BLAS_armpl_LIB "armpl_ilp64")
   else()
     set(BLAS_armpl_LIB "armpl_lp64")
   endif()

   # Check for OpenMP support, VIA BLA_VENDOR of Arm_mp or Arm_ipl64_mp
   if(BLA_VENDOR MATCHES "_mp")
     set(BLAS_armpl_LIB "${BLAS_armpl_LIB}_mp")
   endif()

   # Arm Performance Libraries contains Fortran code and must be linked against libgfortran for a GCC build.
   if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
     set(BLAS_armpl_LIB "${BLAS_armpl_LIB};gfortran")
   endif()

   # Link against libamath, provided with ArmPL, which contains AArch64 optimised implementations of math.h functions.
   set(BLAS_armpl_LIB "${BLAS_armpl_LIB};amath;m")

   if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      ""
      "${BLAS_armpl_LIB}"
      ""
      ""
      ""
      )
  endif()

endif()

# FLAME's blis library? (https://github.com/flame/blis)
if(BLA_VENDOR STREQUAL "FLAME" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      ""
      "blis"
      ""
      ""
      ""
      )
  endif()
endif()

# BLAS in the ATLAS library? (http://math-atlas.sourceforge.net/)
if(BLA_VENDOR STREQUAL "ATLAS" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      dgemm
      ""
      "blas;f77blas;atlas"
      ""
      ""
      ""
      )
  endif()
endif()

# BLAS in PhiPACK libraries? (requires generic BLAS lib, too)
if(BLA_VENDOR STREQUAL "PhiPACK" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      ""
      "sgemm;dgemm;blas"
      ""
      ""
      ""
      )
  endif()
endif()

# BLAS in Alpha CXML library?
if(BLA_VENDOR STREQUAL "CXML" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      ""
      "cxml"
      ""
      ""
      ""
      )
  endif()
endif()

# BLAS in Alpha DXML library? (now called CXML, see above)
if(BLA_VENDOR STREQUAL "DXML" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      ""
      "dxml"
      ""
      ""
      ""
      )
  endif()
endif()

# BLAS in Sun Performance library?
if(BLA_VENDOR STREQUAL "SunPerf" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      "-xlic_lib=sunperf"
      "sunperf;sunmath"
      ""
      ""
      ""
      )
    if(BLAS_LIBRARIES)
      set(BLAS_LINKER_FLAGS "-xlic_lib=sunperf")
    endif()
  endif()
endif()

# BLAS in SCSL library?  (SGI/Cray Scientific Library)
if(BLA_VENDOR STREQUAL "SCSL" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      ""
      "scsl"
      ""
      ""
      ""
      )
  endif()
endif()

# BLAS in SGIMATH library?
if(BLA_VENDOR STREQUAL "SGIMATH" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      ""
      "complib.sgimath"
      ""
      ""
      ""
      )
  endif()
endif()

# BLAS in IBM ESSL library? (requires generic BLAS lib, too)
if(BLA_VENDOR STREQUAL "IBMESSL" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      ""
      "essl;blas"
      ""
      ""
      ""
      )
  endif()
endif()

# BLAS in acml library?
if(BLA_VENDOR MATCHES "ACML" OR BLA_VENDOR STREQUAL "All")
  if(((BLA_VENDOR STREQUAL "ACML") AND (NOT BLAS_ACML_LIB_DIRS)) OR
    ((BLA_VENDOR STREQUAL "ACML_MP") AND (NOT BLAS_ACML_MP_LIB_DIRS)) OR
    ((BLA_VENDOR STREQUAL "ACML_GPU") AND (NOT BLAS_ACML_GPU_LIB_DIRS))
    )
  # try to find acml in "standard" paths
  if(WIN32)
    file(GLOB _ACML_ROOT "C:/AMD/acml*/ACML-EULA.txt")
  else()
    file(GLOB _ACML_ROOT "/opt/acml*/ACML-EULA.txt")
  endif()
  if(WIN32)
    file(GLOB _ACML_GPU_ROOT "C:/AMD/acml*/GPGPUexamples")
  else()
    file(GLOB _ACML_GPU_ROOT "/opt/acml*/GPGPUexamples")
  endif()
  list(GET _ACML_ROOT 0 _ACML_ROOT)
  list(GET _ACML_GPU_ROOT 0 _ACML_GPU_ROOT)
  if(_ACML_ROOT)
    get_filename_component(_ACML_ROOT ${_ACML_ROOT} PATH)
    if(SIZEOF_INTEGER EQUAL 8)
      set(_ACML_PATH_SUFFIX "_int64")
    else()
      set(_ACML_PATH_SUFFIX "")
    endif()
    if(CMAKE_Fortran_COMPILER_ID STREQUAL "Intel")
      set(_ACML_COMPILER32 "ifort32")
      set(_ACML_COMPILER64 "ifort64")
    elseif(CMAKE_Fortran_COMPILER_ID STREQUAL "SunPro")
      set(_ACML_COMPILER32 "sun32")
      set(_ACML_COMPILER64 "sun64")
    elseif(CMAKE_Fortran_COMPILER_ID STREQUAL "PGI")
      set(_ACML_COMPILER32 "pgi32")
      if(WIN32)
        set(_ACML_COMPILER64 "win64")
      else()
        set(_ACML_COMPILER64 "pgi64")
      endif()
    elseif(CMAKE_Fortran_COMPILER_ID STREQUAL "Open64")
      # 32 bit builds not supported on Open64 but for code simplicity
      # We'll just use the same directory twice
      set(_ACML_COMPILER32 "open64_64")
      set(_ACML_COMPILER64 "open64_64")
    elseif(CMAKE_Fortran_COMPILER_ID STREQUAL "NAG")
      set(_ACML_COMPILER32 "nag32")
      set(_ACML_COMPILER64 "nag64")
    else()
      set(_ACML_COMPILER32 "gfortran32")
      set(_ACML_COMPILER64 "gfortran64")
    endif()

    if(BLA_VENDOR STREQUAL "ACML_MP")
      set(_ACML_MP_LIB_DIRS
        "${_ACML_ROOT}/${_ACML_COMPILER32}_mp${_ACML_PATH_SUFFIX}/lib"
        "${_ACML_ROOT}/${_ACML_COMPILER64}_mp${_ACML_PATH_SUFFIX}/lib")
    else()
      set(_ACML_LIB_DIRS
        "${_ACML_ROOT}/${_ACML_COMPILER32}${_ACML_PATH_SUFFIX}/lib"
        "${_ACML_ROOT}/${_ACML_COMPILER64}${_ACML_PATH_SUFFIX}/lib")
    endif()
  endif()
elseif(BLAS_${BLA_VENDOR}_LIB_DIRS)
  set(_${BLA_VENDOR}_LIB_DIRS ${BLAS_${BLA_VENDOR}_LIB_DIRS})
endif()

if(BLA_VENDOR STREQUAL "ACML_MP")
  foreach(BLAS_ACML_MP_LIB_DIRS ${_ACML_MP_LIB_DIRS})
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      "" "acml_mp;acml_mv" "" ${BLAS_ACML_MP_LIB_DIRS} ""
      )
    if(BLAS_LIBRARIES)
      break()
    endif()
  endforeach()
elseif(BLA_VENDOR STREQUAL "ACML_GPU")
  foreach(BLAS_ACML_GPU_LIB_DIRS ${_ACML_GPU_LIB_DIRS})
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      "" "acml;acml_mv;CALBLAS" "" ${BLAS_ACML_GPU_LIB_DIRS} ""
      )
    if(BLAS_LIBRARIES)
      break()
    endif()
  endforeach()
else()
  foreach(BLAS_ACML_LIB_DIRS ${_ACML_LIB_DIRS})
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      "" "acml;acml_mv" "" ${BLAS_ACML_LIB_DIRS} ""
      )
    if(BLAS_LIBRARIES)
      break()
    endif()
  endforeach()
endif()

# Either acml or acml_mp should be in LD_LIBRARY_PATH but not both
if(NOT BLAS_LIBRARIES)
  check_blas_libraries(
    BLAS_LIBRARIES
    BLAS
    sgemm
    ""
    "acml;acml_mv"
    ""
    ""
    ""
    )
endif()
if(NOT BLAS_LIBRARIES)
  check_blas_libraries(
    BLAS_LIBRARIES
    BLAS
    sgemm
    ""
    "acml_mp;acml_mv"
    ""
    ""
    ""
    )
endif()
if(NOT BLAS_LIBRARIES)
  check_blas_libraries(
    BLAS_LIBRARIES
    BLAS
    sgemm
    ""
    "acml;acml_mv;CALBLAS"
    ""
    ""
    ""
    )
endif()
endif() # ACML

# Apple BLAS library?
if(BLA_VENDOR STREQUAL "Apple" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      dgemm
      ""
      "Accelerate"
      ""
      ""
      ""
      )
  endif()
endif()

# Apple NAS (vecLib) library?
if(BLA_VENDOR STREQUAL "NAS" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      dgemm
      ""
      "vecLib"
      ""
      ""
      ""
      )
  endif()
endif()

# Generic BLAS library?
if(BLA_VENDOR STREQUAL "Generic" OR BLA_VENDOR STREQUAL "All")
  if(NOT BLAS_LIBRARIES)
    check_blas_libraries(
      BLAS_LIBRARIES
      BLAS
      sgemm
      ""
      "blas"
      ""
      ""
      ""
      )
  endif()
endif()

if(NOT BLA_F95)
  find_package_handle_standard_args(BLAS REQUIRED_VARS BLAS_LIBRARIES)
endif()


# On compilers that implicitly link BLAS (such as ftn, cc, and CC on Cray HPC machines)
# we used a placeholder for empty BLAS_LIBRARIES to get through our logic above.
if(BLAS_LIBRARIES STREQUAL "BLAS_LIBRARIES-PLACEHOLDER-FOR-EMPTY-LIBRARIES")
  set(BLAS_LIBRARIES "")
endif()

cmake_pop_check_state()
set(CMAKE_FIND_LIBRARY_SUFFIXES ${_blas_ORIG_CMAKE_FIND_LIBRARY_SUFFIXES})

_add_blas_target()