Updates MPI setup in Axom export to optionally depend on Fortran

[kennyweiss]

Summary

• This PR tweaks Axom's exported config related to MPI setup.
• We now only require Fortran for MPI when Axom was configured with it.
• This is in support of a user configuration that required Fortran (ENABLE_FORTRAN=TRUE) and MPI (ENABLE_MPI=TRUE), but did not have a compatible MPI Fortran wrapper.
• This PR depends on a blt PR -- Adds BLT_ALLOW_MISSING_MPI_WRAPPER option to allow Fortran configs with MPI to not have an MPI_Fortran_COMPILER blt#755 -- and updates our blt submodule
  • I will update the submodule to blt@develop once that PR is merged.

[kennyweiss]

Looks like our installing-with-blt example worked with this change, but not our installing-with-cmake, so I'll need to fix that.

[cyrush]

Does axom need to use fortran mpi targets at all?

[kennyweiss]

@cyrush -- we use Fortran+MPI in our quest shroud bindings and in our our quest inout interface examples

axom/src/axom/quest/examples/CMakeLists.txt

Lines 601 to 648 in 5ce7042

	if (ENABLE_FORTRAN)
	set(quest_fortran_examples quest_signed_distance_interface)
	if("${AXOM_CONFIG_NAME}" STREQUAL "GNU-Debug-shared-mpi-openmp")
	# The gcc-11 docker image does not work, turning off for now
	set(_has_inout_fortran_example FALSE)
	elseif("${CMAKE_Fortran_COMPILER}" MATCHES "amdflang$" AND
	CMAKE_BUILD_TYPE MATCHES "(Debug|RelWithDebInfo)")
	# The inout Fortran example fails to compile with hipcc/amdflang in debug configurations
	set(_has_inout_fortran_example FALSE)
	else()
	set(_has_inout_fortran_example TRUE)
	blt_list_append(TO quest_fortran_examples ELEMENTS quest_inout_interface)
	endif()
	foreach(_t ${quest_fortran_examples})
	set(_example_name "${_t}_F_ex")
	axom_add_executable(
	NAME ${_example_name}
	SOURCES ${_t}.F
	OUTPUT_DIR ${EXAMPLE_OUTPUT_DIRECTORY}
	DEPENDS_ON ${quest_example_depends}
	FOLDER axom/quest/examples)
	# When CUDA is enabled, BLT will determine the correct linker, so don't override it here
	if(NOT AXOM_ENABLE_CUDA)
	if ("${CMAKE_Fortran_COMPILER_ID}" STREQUAL "Intel" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "IntelLLVM")
	set_target_properties(${_example_name}
	PROPERTIES LINKER_LANGUAGE Fortran)
	else()
	set_target_properties(${_example_name}
	PROPERTIES LINKER_LANGUAGE CXX)
	endif()
	endif()
	endforeach()
	if(AXOM_ENABLE_TESTS AND AXOM_DATA_DIR AND ${_has_inout_fortran_example})
	set(_num_ranks 1)
	if(AXOM_ENABLE_MPI)
	set(_num_ranks 2)
	endif()
	axom_add_test(
	NAME quest_inout_interface_F_test
	COMMAND quest_inout_interface_F_ex ${quest_data_dir}/sphere_binary.stl
	NUM_MPI_TASKS ${_num_ranks})
	endif()
	endif()