Merge branch 'improvement.cmake.libraries' into 'master.dev'

[improvement.cmake.libraries] Detect libraries present on the system, set CMake defaults accordingly See merge request piclas/piclas!922
piclas-framework · Mar 23, 2024 · 31d376e · 31d376e
2 parents d55cef4 + 35810da
commit 31d376e
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Showing 11 changed files with 350 additions and 195 deletions.
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -1,6 +1,7 @@
 # =========================================================================
 # CMake configuration
 # =========================================================================
+MESSAGE(STATUS "Generating with [cmake] (${CMAKE_VERSION})")
 # NOTE: use minimum CMake version required
 CMAKE_MINIMUM_REQUIRED(VERSION 3.6.3)
 # Policies (see https://cmake.org/cmake/help/v3.13/manual/cmake-policies.7.html)
@@ -63,32 +64,72 @@ INCLUDE(CMakeDependentOption)
 OPTION(PICLAS_PERFORMANCE "Enable performance optimizations (e.g. PGO for GNU)" OFF)
 
 # =========================================================================
-# Check gold support
-# =========================================================================
-EXECUTE_PROCESS(COMMAND ld.gold --version COMMAND grep "^GNU gold" COMMAND sed "s/^.* //g" OUTPUT_VARIABLE GNU_GOLD_VERSION)
-IF (DEFINED GNU_GOLD_VERSION  AND NOT "${GNU_GOLD_VERSION}" STREQUAL "")
-  STRING(STRIP "${GNU_GOLD_VERSION}" GNU_GOLD_VERSION)
-  MESSAGE(STATUS "Setting linker to [gold] (v${GNU_GOLD_VERSION})")
-  # Shift responsibility of driving the final stages of compilation from collect2 to gold via the linker plugin
-  # More information at: https://gcc.gnu.org/wiki/LinkTimeOptimization
-  IF(CMAKE_VERSION VERSION_GREATER_EQUAL 3.13)
-    ADD_LINK_OPTIONS("-fuse-ld=gold")
-    # Make it abundantly clear we want to use gold
-    FIND_PROGRAM(CMAKE_GOLD_LINKER NAMES ${_CMAKE_TOOLCHAIN_PREFIX}ld.gold${_CMAKE_TOOLCHAIN_SUFFIX} HINTS ${_CMAKE_TOOLCHAIN_LOCATION})
-    SET (CMAKE_LINKER "${CMAKE_GOLD_LINKER}" CACHE FILEPATH "" FORCE)
-    MARK_AS_ADVANCED(FORCE CMAKE_GOLD_LINKER)
+# Check lld / gold support
+# =========================================================================
+# EXECUTE_PROCESS(COMMAND ld.lld --version COMMAND grep "^LLD" COMMAND grep -Eo "[0-9]+\.[0-9]+\.[0-9]+" OUTPUT_VARIABLE LLD_VERSION)
+# # lld should be faster than gold
+# IF (DEFINED LLD_VERSION  AND NOT "${LLD_VERSION}" STREQUAL "")
+#   STRING(STRIP "${LLD_VERSION}" LLD_VERSION)
+#   MESSAGE(STATUS "Setting linker to [lld] (v${LLD_VERSION})")
+#   # Shift responsibility of driving the final stages of compilation from collect2 to gold via the linker plugin
+#   # More information at: https://gcc.gnu.org/wiki/LinkTimeOptimization
+#   IF(CMAKE_VERSION VERSION_GREATER_EQUAL 3.13)
+#     ADD_LINK_OPTIONS("-fuse-ld=lld")
+#     # Make it abundantly clear we want to use lld
+#     FIND_PROGRAM(LLD_LINKER NAMES ${_CMAKE_TOOLCHAIN_PREFIX}ld.lld${_CMAKE_TOOLCHAIN_SUFFIX} HINTS ${_CMAKE_TOOLCHAIN_LOCATION})
+#     SET (CMAKE_LINKER "${LLD_LINKER}" CACHE FILEPATH "" FORCE)
+#     MARK_AS_ADVANCED(FORCE LLD_LINKER)
+#   ELSE()
+#     SET (CMAKE_EXE_LINKER_FLAGS    "${CMAKE_EXE_LINKER_FLAGS}    -fuse-ld=lld")
+#     SET (CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -fuse-ld=lld")
+#     SET (CMAKE_STATIC_LINKER_FLAGS "${CMAKE_STATIC_LINKER_FLAGS} -fuse-ld=lld")
+#     SET (CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} -fuse-ld=lld")
+#     # Make it abundantly clear we want to use lld
+#     FIND_PROGRAM(LLD_LINKER NAMES ${_CMAKE_TOOLCHAIN_PREFIX}ld.lld${_CMAKE_TOOLCHAIN_SUFFIX} HINTS ${_CMAKE_TOOLCHAIN_LOCATION})
+#     SET (CMAKE_LINKER "${LLD_LINKER}" CACHE FILEPATH "" FORCE)
+#     MARK_AS_ADVANCED(FORCE LLD_LINKER)
+#   ENDIF()
+# # gold should be faster than GNU ld
+# ELSE()
+  EXECUTE_PROCESS(COMMAND ld.gold --version COMMAND grep "^GNU gold" COMMAND sed "s/^.* //g" OUTPUT_VARIABLE GNU_GOLD_VERSION)
+  IF (DEFINED GNU_GOLD_VERSION  AND NOT "${GNU_GOLD_VERSION}" STREQUAL "")
+    STRING(STRIP "${GNU_GOLD_VERSION}" GNU_GOLD_VERSION)
+    MESSAGE(STATUS "Linking with [gold] (v${GNU_GOLD_VERSION})")
+    # Shift responsibility of driving the final stages of compilation from collect2 to gold via the linker plugin
+    # More information at: https://gcc.gnu.org/wiki/LinkTimeOptimization
+    IF(CMAKE_VERSION VERSION_GREATER_EQUAL 3.13)
+      ADD_LINK_OPTIONS("-fuse-ld=gold")
+      # Make it abundantly clear we want to use gold
+      FIND_PROGRAM(CMAKE_GOLD_LINKER NAMES ${_CMAKE_TOOLCHAIN_PREFIX}ld.gold${_CMAKE_TOOLCHAIN_SUFFIX} HINTS ${_CMAKE_TOOLCHAIN_LOCATION})
+      SET (CMAKE_LINKER "${CMAKE_GOLD_LINKER}" CACHE FILEPATH "" FORCE)
+      MARK_AS_ADVANCED(FORCE CMAKE_GOLD_LINKER)
+    ELSE()
+      SET (CMAKE_EXE_LINKER_FLAGS    "${CMAKE_EXE_LINKER_FLAGS}    -fuse-ld=gold")
+      SET (CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -fuse-ld=gold")
+      # This currently breaks ar (binutils archiver)
+      # SET (CMAKE_STATIC_LINKER_FLAGS "${CMAKE_STATIC_LINKER_FLAGS} -fuse-ld=gold")
+      SET (CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} -fuse-ld=gold")
+      # Make it abundantly clear we want to use gold
+      FIND_PROGRAM(CMAKE_GOLD_LINKER NAMES ${_CMAKE_TOOLCHAIN_PREFIX}ld.gold${_CMAKE_TOOLCHAIN_SUFFIX} HINTS ${_CMAKE_TOOLCHAIN_LOCATION})
+      SET (CMAKE_LINKER "${CMAKE_GOLD_LINKER}" CACHE FILEPATH "" FORCE)
+      MARK_AS_ADVANCED(FORCE CMAKE_GOLD_LINKER)
+    ENDIF()
+# Found neither lld nor gold, output GNU ld
   ELSE()
-    SET (CMAKE_EXE_LINKER_FLAGS    "${CMAKE_EXE_LINKER_FLAGS}    -fuse-ld=gold")
-    SET (CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -fuse-ld=gold")
-    # This currently breaks ar (binutils archiver)
-    # SET (CMAKE_STATIC_LINKER_FLAGS "${CMAKE_STATIC_LINKER_FLAGS} -fuse-ld=gold")
-    SET (CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} -fuse-ld=gold")
-    # Make it abundantly clear we want to use gold
-    FIND_PROGRAM(CMAKE_GOLD_LINKER NAMES ${_CMAKE_TOOLCHAIN_PREFIX}ld.gold${_CMAKE_TOOLCHAIN_SUFFIX} HINTS ${_CMAKE_TOOLCHAIN_LOCATION})
-    SET (CMAKE_LINKER "${CMAKE_GOLD_LINKER}" CACHE FILEPATH "" FORCE)
-    MARK_AS_ADVANCED(FORCE CMAKE_GOLD_LINKER)
+    EXECUTE_PROCESS(COMMAND ld --version OUTPUT_VARIABLE GNU_LD_STRING)
+    # Check if we actually got GNU ld
+    IF (GNU_LD_STRING MATCHES "^GNU ld")
+      EXECUTE_PROCESS(COMMAND ld --version COMMAND grep "^GNU ld" COMMAND sed "s/^.* //g" OUTPUT_VARIABLE GNU_LD_VERSION)
+      STRING(STRIP "${GNU_LD_VERSION}" GNU_LD_VERSION)
+      MESSAGE(STATUS "Linking with [ld] (v${GNU_LD_VERSION})")
+    # ... or if we are running mold
+    ELSEIF (GNU_LD_STRING MATCHES "^mold")
+      EXECUTE_PROCESS(COMMAND ld --version COMMAND grep "^mold" COMMAND grep -Eo "[0-9]+\.[0-9]+\.[0-9]+ " OUTPUT_VARIABLE GNU_MOLD_VERSION)
+      STRING(STRIP "${GNU_MOLD_VERSION}" GNU_MOLD_VERSION)
+      MESSAGE(STATUS "Linking with [mold] (v${GNU_MOLD_VERSION})")
+    ENDIF()
   ENDIF()
-ENDIF()
+# ENDIF()
 
 # =========================================================================
 # code development
@@ -212,6 +253,7 @@ ELSE()
     ENDIF()
   ENDIF()
 ENDIF()
+MESSAGE(STATUS "Compiling with [${BUILD_TYPE_LC}] build type")
 
 # =========================================================================
 # Location of binary and filenames
@@ -248,12 +290,12 @@ endfunction()
 # A function to get all user defined variables with a specified prefix
 SET(configuration ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/configuration.cmake)
 FILE(WRITE ${configuration} "")
-GETLISTOFVARSSTARTINGWITH("PICLAS_" piclasVars)
+GETLISTOFVARSSTARTINGWITH("PICLAS_" piclasVars1)
 GETLISTOFVARSSTARTINGWITH("HDF5_"   piclasVars2)
 GETLISTOFVARSSTARTINGWITH("CMAKE_"  piclasVars3)
 GETLISTOFVARSSTARTINGWITH("POSTI_"  piclasVars4)
 GETLISTOFVARSSTARTINGWITH("LIBS_"   piclasVars5)
-FOREACH (_var IN LISTS piclasVars piclasVars2 piclasVars3 piclasVars4 piclasVars5)
+FOREACH (_var IN LISTS piclasVars1 piclasVars2 piclasVars3 piclasVars4 piclasVars5)
   GET_PROPERTY(currentHelpString CACHE "${_var}" PROPERTY HELPSTRING)
   # Skip empty variables
   IF(NOT ${${_var}} STREQUAL "")

diff --git a/CMakeListsLib.txt b/CMakeListsLib.txt
@@ -44,8 +44,19 @@ ENDIF()
 # =========================================================================
 # MPI
 # =========================================================================
-OPTION(LIBS_USE_MPI "Compile SINGLE or MPI version" ON)
+# Try to find system MPI
+SET(MPI_DETERMINE_LIBRARY_VERSION TRUE)
+FIND_PACKAGE(MPI QUIET)
+IF (MPI_FOUND)
+  MESSAGE (STATUS "[MPI] found in system libraries")
+  OPTION(LIBS_USE_MPI "Compile SINGLE or MPI version" ON)
+ELSE()
+  MESSAGE (STATUS "[MPI] not found in system libraries")
+  OPTION(LIBS_USE_MPI "Compile SINGLE or MPI version" OFF)
+ENDIF()
+
 IF(LIBS_USE_MPI)
+  # If library is specifically requested, it is required
   SET(MPI_DETERMINE_LIBRARY_VERSION TRUE)
   FIND_PACKAGE(MPI REQUIRED)
 
@@ -89,6 +100,13 @@ IF(LIBS_USE_MPI)
 
   MESSAGE(STATUS "Compiling with [${LIBS_MPI_NAME}] (v${MPI_C_LIBRARY_VERSION})")
   ADD_DEFINITIONS(-DUSE_MPI=1)
+
+  # LUMI needs even more help here
+  IF("${CMAKE_FQDN_HOST}" MATCHES ".can")
+    SET(MPI_C_COMPILER       cc)
+    SET(MPI_CXX_COMPILER     CC)
+    SET(MPI_Fortran_COMPILER ftn)
+  ENDIF()
 ELSE()
   ADD_DEFINITIONS(-DUSE_MPI=0)
 ENDIF()
@@ -97,7 +115,28 @@ ENDIF()
 # =========================================================================
 # HDF5 library
 # =========================================================================
-SET(LIBS_BUILD_HDF5 OFF CACHE BOOL "Compile and build HDF5 library")
+# Try to find system HDF5 using CMake
+SET(LIBS_HDF5_CMAKE TRUE)
+FIND_PACKAGE(HDF5 NAMES hdf5 COMPONENTS C Fortran ${SEARCH_TYPE} QUIET PATH_SUFFIXES share/cmake)
+# Try to find the configure version
+SET(LIBS_HDF5_CMAKE FALSE)
+FIND_PACKAGE(HDF5 COMPONENTS C Fortran QUIET)
+# Hide all the HDF5 libs paths
+MARK_AS_ADVANCED(FORCE HDF5_DIR)
+# CMake version found
+IF (HDF5_FOUND)
+  IF(${CMAKE_VERSION} VERSION_LESS "3.10.0")
+    MESSAGE (WARNING "HDF5 built with CMake was found! This feature is only supported for CMake 3.10+ and HDF5 1.10.2+!")
+  ENDIF()
+  MESSAGE (STATUS "HDF5 C libs:${HDF5_FOUND} static:${HDF5_static_C_FOUND} and shared:${HDF5_shared_C_FOUND}")
+  MESSAGE (STATUS "HDF5 Fortran libs: static:${HDF5_static_Fortran_FOUND} and shared:${HDF5_shared_Fortran_FOUND}")
+  MESSAGE (STATUS "h5diff found:${HDF5_DIFF_EXECUTABLE}")
+  MESSAGE (STATUS "[HDF5] found in system libraries")
+  SET(LIBS_BUILD_HDF5 OFF CACHE BOOL "Compile and build HDF5 library")
+ELSE()
+  MESSAGE (STATUS "[HDF5] not found in system libraries")
+  SET(LIBS_BUILD_HDF5 ON  CACHE BOOL "Compile and build HDF5 library")
+ENDIF()
 
 # Set type of library to look up, STATIC/SHARED
 SET(LIB_TYPE STATIC)
@@ -134,7 +173,7 @@ IF(NOT LIBS_BUILD_HDF5)
     # In case CMake did not find HDF5 here, it will generate an error by itself
   ENDIF()
   # Hide all the HDF5 libs paths
-  MARK_AS_ADVANCED(FORCE HDF5_DIR)
+  # MARK_AS_ADVANCED(FORCE HDF5_DIR)
   MARK_AS_ADVANCED(FORCE HDF5_C_LIBRARY_dl)
   MARK_AS_ADVANCED(FORCE HDF5_C_LIBRARY_hdf5)
   MARK_AS_ADVANCED(FORCE HDF5_C_LIBRARY_m)
@@ -147,6 +186,7 @@ IF(NOT LIBS_BUILD_HDF5)
   MARK_AS_ADVANCED(FORCE HDF5_Fortran_LIBRARY_sz)
   MARK_AS_ADVANCED(FORCE HDF5_Fortran_LIBRARY_z)
 
+  SET(HDF5_BUILD_STATUS "system")
   # Build HDF5 in PICLas
 ELSE()
   # Origin pointing to Github
@@ -179,11 +219,11 @@ ELSE()
         SET (HDF5_TAG "hdf5-1_10_6" CACHE STRING   "HDF5 version tag")
         SET (HDF5_VERSION "1.10"    CACHE INTERNAL "HDF5 version number")
       ENDIF()
-    MESSAGE (STATUS "Setting HDF5 to tag ${HDF5_TAG} to be compatible with detected [${LIBS_MPI_NAME}] (v${MPI_C_LIBRARY_VERSION})")
+    MESSAGE (STATUS "Setting [HDF5] to tag ${HDF5_TAG} to be compatible with detected [${LIBS_MPI_NAME}] (v${MPI_C_LIBRARY_VERSION})")
   ELSE()
     SET (HDF5_TAG "hdf5-1_12_0" CACHE STRING   "HDF5 version tag")
     SET (HDF5_VERSION "1.12"    CACHE INTERNAL "HDF5 version number")
-    MESSAGE (STATUS "Setting HDF5 to tag ${HDF5_TAG} as no MPI support was requested")
+    MESSAGE (STATUS "Setting [HDF5] to tag ${HDF5_TAG} as no MPI support was requested")
   ENDIF()
   MARK_AS_ADVANCED(FORCE HDF5_TAG)
 
@@ -269,6 +309,8 @@ ELSE()
   # Add ZLIB to include paths for HDF5 data compression
   FIND_LIBRARY(HDF5_z_LIBRARY_RELEASE z)
   LIST(APPEND HDF5_LIBRARIES ${HDF5_hdf5_fortran_LIBRARY_RELEASE} ${HDF5_hdf5_LIBRARY_RELEASE} ${HDF5_z_LIBRARY_RELEASE} -ldl)
+
+  SET(HDF5_BUILD_STATUS "self-built")
 ENDIF()
 
 # HDF5 1.14 references build directory
@@ -286,9 +328,9 @@ IF(LIBS_HDF5_CMAKE)
 ELSE()
   INCLUDE_DIRECTORIES (${HDF5_INCLUDE_DIR_FORTRAN} ${HDF5_INCLUDE_DIR})
   IF(${HDF5_IS_PARALLEL})
-    MESSAGE(STATUS "Compiling with [HDF5] (v${HDF5_VERSION}) with parallel support")
+    MESSAGE(STATUS "Compiling with ${HDF5_BUILD_STATUS} [HDF5] (v${HDF5_VERSION}) with parallel support")
   ELSE()
-    MESSAGE(STATUS "Compiling with [HDF5] (v${HDF5_VERSION}) without parallel support")
+    MESSAGE(STATUS "Compiling with ${HDF5_BUILD_STATUS} [HDF5] (v${HDF5_VERSION}) without parallel support")
   ENDIF()
   LIST(APPEND linkedlibs ${HDF5_LIBRARIES} )
 ENDIF()
@@ -297,36 +339,39 @@ ENDIF()
 # =========================================================================
 # Math libary
 # =========================================================================
-SET(LIBS_BUILD_MATH_LIB OFF CACHE BOOL "Compile and build math library")
+# Try to find system LAPACK/OpenBLAS
+FIND_PACKAGE(LAPACK QUIET)
+IF (LAPACK_FOUND)
+  LIST(APPEND linkedlibs ${LAPACK_LIBRARIES})
+  MESSAGE (STATUS "[BLAS/Lapack] found in system libraries")
+  SET(LIBS_BUILD_MATH_LIB OFF CACHE BOOL "Compile and build math library")
+ELSE()
+  MESSAGE (STATUS "[BLAS/Lapack] not found in system libraries")
+  SET(LIBS_BUILD_MATH_LIB ON  CACHE BOOL "Compile and build math library")
+ENDIF()
 
 # Check if Intel MKL is requested instead of BLAS/LAPACK
-CMAKE_DEPENDENT_OPTION(LIBS_USE_MKL "Use system MKL libraries instead of system BLAS/LAPACK" OFF
-                                    "NOT LIBS_BUILD_MATH_LIB" OFF)
+# CMAKE_DEPENDENT_OPTION(LIBS_USE_MKL "Use system MKL libraries instead of system BLAS/LAPACK" OFF
+#                                     "NOT LIBS_BUILD_MATH_LIB" OFF)
 
 # Use system LAPACK/MKL
 IF(NOT LIBS_BUILD_MATH_LIB)
-  IF (LIBS_USE_MKL)
-    SET(BLA_VENDOR "Intel10_64lp") #search only for Intel BLAS (=MKL)
-  ENDIF()
+  # IF (LIBS_USE_MKL)
+  #   SET(BLA_VENDOR "Intel10_64lp") #search only for Intel BLAS (=MKL)
+  # ENDIF()
 
   # Use Lapack/Blas for GNU
+  # If library is specifically requested, it is required
   FIND_PACKAGE(LAPACK REQUIRED)
   IF (LAPACK_FOUND)
     LIST(APPEND linkedlibs ${LAPACK_LIBRARIES})
     MESSAGE(STATUS "Compiling with system [BLAS/Lapack]")
   ENDIF()
 
   # VDM inverse, replace lapack with analytical solution
-  # HLRS HAWK / SuperMUC + DEBUG
-  IF (CMAKE_BUILD_TYPE MATCHES "Debug" AND "${CMAKE_HOSTNAME}" MATCHES "login")
-    # HAWK and SuperMUC name their login nodes identically, so use the Fully Qualified Domain Name (FQDN) to identify
-    CMAKE_HOST_SYSTEM_INFORMATION(RESULT FQDN QUERY FQDN)
-    MARK_AS_ADVANCED(FORCE FQDN)
-    # HLRS HAWK
-    IF ("${FQDN}" MATCHES "hawk.hww.hlrs.de")
-      MESSAGE(STATUS "Compiling PICLas in debug mode on Hawk with system math lib. Setting VDM inverse to analytical solution")
-      ADD_DEFINITIONS(-DVDM_ANALYTICAL)
-    ENDIF()
+  IF (CMAKE_BUILD_TYPE MATCHES "Debug" AND CMAKE_FQDN_HOST MATCHES "hawk\.hww\.hlrs\.de$")
+    MESSAGE(STATUS "Compiling PICLas in debug mode on Hawk with system math lib. Setting VDM inverse to analytical solution")
+    ADD_DEFINITIONS(-DVDM_ANALYTICAL)
   ENDIF()
 
 # Build LAPACK/OpenBLAS in FLEXI
@@ -554,24 +599,35 @@ ENDIF()
 #  ENDIF()
 
 
-#  # =========================================================================
-#  # OPENMP library
-#  # =========================================================================
-#  OPTION(LIBS_USE_OPENMP "Enable OpenMP" OFF)
-#  IF(LIBS_USE_OPENMP)
-#    IF ("${CMAKE_VERSION}" VERSION_LESS 3.1.0)
-#      MESSAGE(WARNING "For finding OpenMP Fortran flags at least CMake version 3.1.0 is required. Please specify flags manually or use newer CMake version.")
-#    ENDIF()
-#    FIND_PACKAGE(OpenMP REQUIRED)
-#    SET (CMAKE_Fortran_FLAGS_DEBUG   "${CMAKE_Fortran_FLAGS_DEBUG}   ${OpenMP_Fortran_FLAGS}")
-#    SET (CMAKE_Fortran_FLAGS_RELEASE "${CMAKE_Fortran_FLAGS_RELEASE} ${OpenMP_Fortran_FLAGS}")
-#    SET (CMAKE_CXX_FLAGS_DEBUG       "${CMAKE_CXX_FLAGS_DEBUG}       ${OpenMP_CXX_FLAGS}")
-#    SET (CMAKE_CXX_FLAGS_RELEASE     "${CMAKE_CXX_FLAGS_RELEASE}     ${OpenMP_CXX_FLAGS}")
-#    SET (CMAKE_EXE_LINKER_FLAGS      "${CMAKE_EXE_LINKER_FLAGS}      ${OpenMP_EXE_LINKER_FLAGS}")
-#    ADD_DEFINITIONS(-DUSE_OPENMP=1)
-#  ELSE()
-#    ADD_DEFINITIONS(-DUSE_OPENMP=0)
-#  ENDIF()
+# # =========================================================================
+# # OPENMP library
+# # =========================================================================
+# # Try to find system OpenMP
+# FIND_PACKAGE(OpenMP QUIET)
+# IF (OpenMP_FOUND)
+#   MESSAGE (STATUS "[OpenMP] found in system libraries")
+#   OPTION(LIBS_USE_OPENMP "Enable OpenMP" ON)
+# ELSE()
+#   MESSAGE (STATUS "[OpenMP] not found in system libraries")
+#   OPTION(LIBS_USE_OPENMP "Enable OpenMP" OFF)
+# ENDIF()
+#
+# IF(LIBS_USE_OPENMP)
+#   IF ("${CMAKE_VERSION}" VERSION_LESS 3.1.0)
+#     MESSAGE(WARNING "For finding OpenMP Fortran flags at least CMake version 3.1.0 is # required. Please specify flags manually or use newer CMake version.")
+#   ENDIF()
+#   # If library is specifically requested, it is required
+#   FIND_PACKAGE(OpenMP REQUIRED)
+#   SET (CMAKE_Fortran_FLAGS_DEBUG   "${CMAKE_Fortran_FLAGS_DEBUG}   ${OpenMP_Fortran_FLAGS}")
+#   SET (CMAKE_Fortran_FLAGS_RELEASE "${CMAKE_Fortran_FLAGS_RELEASE} ${OpenMP_Fortran_FLAGS}")
+#   SET (CMAKE_CXX_FLAGS_DEBUG       "${CMAKE_CXX_FLAGS_DEBUG}       ${OpenMP_CXX_FLAGS}")
+#   SET (CMAKE_CXX_FLAGS_RELEASE     "${CMAKE_CXX_FLAGS_RELEASE}     ${OpenMP_CXX_FLAGS}")
+#   SET (CMAKE_EXE_LINKER_FLAGS      "${CMAKE_EXE_LINKER_FLAGS}      ${OpenMP_EXE_LINKER_FLAGS}")
+#   ADD_DEFINITIONS(-DUSE_OPENMP=1)
+#   MESSAGE(STATUS "Compiling with [OpenMP] (v${OpenMP_Fortran_VERSION})")
+# ELSE()
+#   ADD_DEFINITIONS(-DUSE_OPENMP=0)
+# #  ENDIF()
 
 #=========================================================================
 # PETSc