CMake: Rewrite FindMKL.cmake (#7595)

* Rewrite FindMKL.cmake

* Report MKL BLACS interface; block mkl_threads with non-OpenMP build

* Remove cache variable MKL_THREADING

* Block MKL_BLACS auto-detection when cross-compiling

* Hide oneMKL internal result variables

* Use MKL_FOUND for oneMKL consumers

* CMake: Resolve DFT-D4 dependencies after math libraries

* Move MKL-BLACS report into MKL_FOUND if clause

Author: Growl1234

.github/workflows/build_test_cmake.yml

@@ -23,11 +23,11 @@ jobs:
 
           - tag: gnu
             external_toolchain_args: ""
-            build_args: "-DENABLE_LIBXC=ON -DENABLE_MLALGO=ON -DENABLE_LIBRI=ON"
+            build_args: "-DENABLE_LIBXC=ON -DENABLE_MLALGO=ON -DENABLE_LIBRI=ON -DENABLE_DFTD4=ON"
             name: "Build extra components with GNU toolchain"
           - tag: intel
             external_toolchain_args: "--with-intel"
-            build_args: "-DENABLE_LIBXC=ON -DENABLE_PEXSI=ON -DENABLE_MLALGO=ON -DENABLE_LIBRI=ON"
+            build_args: "-DENABLE_LIBXC=ON -DENABLE_PEXSI=ON -DENABLE_MLALGO=ON -DENABLE_LIBRI=ON -DENABLE_DFTD4=ON"
             name: "Build extra components with Intel toolchain"
 
           - tag: cuda

CMakeLists.txt

@@ -244,14 +244,10 @@ if(NOT DEFINED CMAKE_CXX_STANDARD)
 endif()
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
+# Enable DFT-D4 languages before finding OpenMP.
 if(ENABLE_DFTD4)
-  # DFTD4 requires enabling C and Fortran to work
   enable_language(C)
   enable_language(Fortran)
-  # Avoid custom-lapack fallback when resolving DFT-D4 dependencies
-  find_package(BLAS REQUIRED)
-  find_package(LAPACK REQUIRED)
-  find_package(dftd4 4.2.0 REQUIRED)
 endif()
 
 macro(set_if_higher VARIABLE VALUE)
@@ -341,6 +337,12 @@ if(DEBUG_INFO)
 endif()
 
 if(ENABLE_MPI)
+  if(NOT CMAKE_CROSSCOMPILING)
+    # FindMPI runs a probe executable to determine the MPI library version,
+    # which FindMKL.cmake uses to auto-detect the BLACS interface.
+    # When cross compiling, assume users know what they are doing.
+    set(MPI_DETERMINE_LIBRARY_VERSION TRUE)
+  endif()
   find_package(MPI COMPONENTS CXX REQUIRED)
   abacus_add_feature_definitions(__MPI)
 endif()
@@ -363,6 +365,44 @@ if(USE_OPENMP)
   find_package(OpenMP REQUIRED)
 endif()
 
+if(DEFINED ENV{MKLROOT} AND NOT DEFINED MKLROOT)
+  set(MKLROOT "$ENV{MKLROOT}")
+endif()
+if(USE_KML)
+  set(_kml_components BLAS LAPACK FFTW3)
+  if(ENABLE_MPI)
+    list(APPEND _kml_components ScaLAPACK)
+  endif()
+  if(ENABLE_FLOAT_FFTW)
+    list(APPEND _kml_components FFTW3_FLOAT)
+  endif()
+
+  find_package(KML REQUIRED COMPONENTS ${_kml_components})
+  abacus_add_feature_definitions(__KML)
+elseif(MKLROOT OR MKL_ROOT)
+  find_package(MKL REQUIRED)
+  abacus_add_feature_definitions(__MKL)
+elseif(NOT USE_SW)
+  find_package(Lapack REQUIRED)
+  # ScaLAPACK is a distributed-memory library and is only needed for the
+  # MPI build. A serial build (e.g. the native Windows serial version)
+  # must not require it.
+  if(ENABLE_MPI)
+    find_package(ScaLAPACK REQUIRED)
+  endif()
+  if(NOT CMAKE_CXX_COMPILER_ID MATCHES "GNU|Intel|Clang")
+    message(WARNING "Cannot determine the required Fortran runtime.")
+  endif()
+endif()
+
+if(NOT USE_KML AND NOT MKL_FOUND AND NOT USE_SW)
+  find_package(FFTW3 REQUIRED)
+endif()
+
+if(ENABLE_DFTD4)
+  find_package(dftd4 4.2.0 REQUIRED)
+endif()
+
 include(CheckLanguage)
 check_language(CUDA)
 if(CMAKE_CUDA_COMPILER)
@@ -534,42 +574,6 @@ if(ENABLE_ASAN)
   add_link_options(-fsanitize=address)
 endif()
 
-if(DEFINED ENV{MKLROOT} AND NOT DEFINED MKLROOT)
-  set(MKLROOT "$ENV{MKLROOT}")
-endif()
-if(USE_KML)
-  set(_kml_components BLAS LAPACK FFTW3)
-  if(ENABLE_MPI)
-    list(APPEND _kml_components ScaLAPACK)
-  endif()
-  if(ENABLE_FLOAT_FFTW)
-    list(APPEND _kml_components FFTW3_FLOAT)
-  endif()
-
-  find_package(KML REQUIRED COMPONENTS ${_kml_components})
-  abacus_add_feature_definitions(__KML)
-elseif(MKLROOT)
-  set(MKL_INTERFACE lp64)
-  set(ENABLE_SCALAPACK ON)
-  find_package(MKL REQUIRED)
-  abacus_add_feature_definitions(__MKL)
-elseif(NOT USE_SW)
-  find_package(Lapack REQUIRED)
-  # ScaLAPACK is a distributed-memory library and is only needed for the
-  # MPI build. A serial build (e.g. the native Windows serial version)
-  # must not require it.
-  if(ENABLE_MPI)
-    find_package(ScaLAPACK REQUIRED)
-  endif()
-  if(NOT CMAKE_CXX_COMPILER_ID MATCHES "GNU|Intel|Clang")
-    message(WARNING "Cannot determine the required Fortran runtime.")
-  endif()
-endif()
-
-if(NOT USE_KML AND NOT MKLROOT AND NOT USE_SW)
-  find_package(FFTW3 REQUIRED)
-endif()
-
 if(ENABLE_FLOAT_FFTW)
   abacus_add_feature_definitions(__ENABLE_FLOAT_FFTW)
 endif()

cmake/CollectBuildInfoVars.cmake

@@ -165,7 +165,7 @@ else()
     set(ABACUS_ELPA_VERSION "no")
 endif()
 
-if(MKLROOT)
+if(MKL_FOUND)
     set(ABACUS_MKL_SUPPORT "yes (version unknown)")
     find_path(MKL_VERSION_HEADER mkl_version.h PATHS ${MKL_INCLUDE} NO_DEFAULT_PATH)
     if(MKL_VERSION_HEADER)
@@ -190,9 +190,9 @@ else()
     set(ABACUS_LIBXC_VERSION "no")
 endif()
 
-if(NOT USE_SW AND NOT MKLROOT AND FFTW3_VERSION)
+if(NOT USE_SW AND NOT MKL_FOUND AND FFTW3_VERSION)
     set(ABACUS_FFTW_VERSION "yes (v${FFTW3_VERSION})")
-elseif(NOT USE_SW AND NOT MKLROOT)
+elseif(NOT USE_SW AND NOT MKL_FOUND)
     if(FFTW3_INCLUDE_DIR AND EXISTS "${FFTW3_INCLUDE_DIR}/fftw3.h")
         file(STRINGS "${FFTW3_INCLUDE_DIR}/fftw3.h" _fftw_ver_line REGEX "^#define[\t ]+FFTW_VERSION[\t ]+\"[^\"]+\"")
         if(_fftw_ver_line)

cmake/modules/FindKML.cmake

@@ -267,6 +267,18 @@ if(KML_FOUND)
   endif()
 endif()
 
+# Compatibility with packages that consume the standard CMake math targets.
+if(TARGET KML::BLAS AND NOT TARGET BLAS::BLAS)
+  add_library(BLAS::BLAS INTERFACE IMPORTED)
+  set_property(TARGET BLAS::BLAS PROPERTY
+               INTERFACE_LINK_LIBRARIES KML::BLAS)
+endif()
+if(TARGET KML::LAPACK AND NOT TARGET LAPACK::LAPACK)
+  add_library(LAPACK::LAPACK INTERFACE IMPORTED)
+  set_property(TARGET LAPACK::LAPACK PROPERTY
+               INTERFACE_LINK_LIBRARIES KML::LAPACK)
+endif()
+
 mark_as_advanced(
   KML_INCLUDE_DIR
   KML_RUNTIME_LIBRARY