ENH: add new version of FindMPI, fix it to work with MPICH2 on windows

Modules/FindMPI.cmake

-# - Find MPI
-# This module looks for MPI (Message Passing Interface) support
-# it will define the following values
-#  MPI_INCLUDE_PATH = where mpi.h can be found
-#  MPI_LIBRARY    = the library to link in (mpi mpich etc)
-
-FIND_PATH(MPI_INCLUDE_PATH NAMES mpi.h 
-          PATH_SUFFIXES mpi mpi/include
-          PATHS
-          "$ENV{ProgramFiles}/MPICH/SDK/Include"
-          "$ENV{ProgramFiles}/MPICH2/include"
-          "C:/Program Files/MPICH/SDK/Include" 
-)
-
-FIND_LIBRARY(MPI_LIBRARY 
-             NAMES mpich2 mpi mpich mpich.rts
-             PATH_SUFFIXES mpi/lib
-             PATHS
-             "$ENV{ProgramFiles}/MPICH/SDK/Lib"
-             "$ENV{ProgramFiles}/MPICH2/Lib"
-             "C:/Program Files/MPICH/SDK/Lib" 
-)
-
-FIND_LIBRARY(MPI_EXTRA_LIBRARY 
-             NAMES mpi++
-             PATH_SUFFIXES mpi/lib
-             PATHS
-             "$ENV{ProgramFiles}/MPICH/SDK/Lib"
-             "C:/Program Files/MPICH/SDK/Lib" 
-             DOC "If a second mpi library is necessary, specify it here.")
+# This module looks for the Message Passing Interface (MPI).
+#
+# This module will set the following variables:
+#   MPI_FOUND                  TRUE if we have found MPI
+#   MPI_COMPILE_FLAGS          Compilation flags for MPI programs
+#   MPI_INCLUDE_PATH           Include path for MPI header
+#   MPI_LINK_FLAGS             Linking flags for MPI programs
+#   MPI_LIBRARIES              Libraries to link MPI programs against
+#   MPI_LIBRARY                Deprecated; first MPI library to link against
+#   MPI_EXTRA_LIBRARY          Deprecated; second MPI library to link against
+#   MPIEXEC                    Executable for running MPI programs
+#
+# This module will attempt to auto-detect these settings, first by
+# looking for a C++ MPI driver (e.g., mpic++, mpiCC, or mpicxx; set by
+# MPICXX) and later by checking common MPI paths and library names.
 
-# on BlueGene/L the MPI lib is named libmpich.rts.a, there also these additional libs are required
-IF("${MPI_LIBRARY}" MATCHES "mpich.rts")
-   SET(MPI_EXTRA_LIBRARY msglayer.rts devices.rts rts.rts devices.rts CACHE STRING "Additional MPI libs" FORCE)
-ENDIF("${MPI_LIBRARY}" MATCHES "mpich.rts")
+# Try to find the MPI driver program
+find_program(MPICXX 
+  NAMES mpic++ mpicxx mpiCC
+  DOC "MPI C++ compiler. Used only to detect MPI compilation flags.")
+mark_as_advanced(MPICXX)
+
+find_program(MPIEXEC
+  NAMES mpiexec mpirun
+  DOC "Executable for running MPI programs.")
+mark_as_advanced(MPIEXEC)
+
+if (NOT OLD_MPICXX STREQUAL MPICXX)
+  set(MPI_FORCE_RECONFIGURE TRUE)
+  set(OLD_MPICXX ${MPICXX} CACHE INTERNAL "Previous value of MPICXX" FORCE)
+endif (NOT OLD_MPICXX STREQUAL MPICXX)
+  
+if (NOT MPICXX)
+  # If there is no MPI C++ compiler, we force ourselves to configure
+  # MPI the old way.
+  set(MPI_FORCE_RECONFIGURE TRUE)
+endif (NOT MPICXX)
+
+if (MPICXX)
+  # Check whether the -showme:compile option works. This indicates
+  # that we have either Open MPI or a newer version of LAM-MPI, and
+  # implies that -showme:link will also work.
+  exec_program(${MPICXX} 
+    ARGS -showme:compile 
+    OUTPUT_VARIABLE MPI_COMPILE_CMDLINE
+    RETURN_VALUE MPICXX_RETURN)
+
+  if (MPICXX_RETURN EQUAL 0)
+    # If we appear to have -showme:compile, then we should also have
+    # -showme:link. Try it.
+    exec_program(${MPICXX} 
+      ARGS -showme:link
+      OUTPUT_VARIABLE MPI_LINK_CMDLINE
+      RETURN_VALUE MPICXX_RETURN)
+  endif (MPICXX_RETURN EQUAL 0)
+
+  if (MPICXX_RETURN EQUAL 0)
+    # Do nothing: we have our command lines now
+  else (MPICXX_RETURN EQUAL 0)
+    # Older versions of LAM-MPI have "-showme". Try it.
+    exec_program(${MPICXX} 
+      ARGS -showme
+      OUTPUT_VARIABLE MPI_COMPILE_CMDLINE
+      RETURN_VALUE MPICXX_RETURN)
+  endif (MPICXX_RETURN EQUAL 0)  
+
+  if (MPICXX_RETURN EQUAL 0)
+    # Do nothing: we have our command lines now
+  else (MPICXX_RETURN EQUAL 0)
+    # MPICH uses "-show". Try it.
+    exec_program(${MPICXX} 
+      ARGS -show
+      OUTPUT_VARIABLE MPI_COMPILE_CMDLINE
+      RETURN_VALUE MPICXX_RETURN)
+  endif (MPICXX_RETURN EQUAL 0)  
+
+  if (MPICXX_RETURN EQUAL 0)
+    # We have our command lines, but we might need to copy
+    # MPI_COMPILE_CMDLINE into MPI_LINK_CMDLINE, if the underlying
+    if (NOT MPI_LINK_CMDLINE)
+      SET(MPI_LINK_CMDLINE ${MPI_COMPILE_CMDLINE})
+    endif (NOT MPI_LINK_CMDLINE)
+  else (MPICXX_RETURN EQUAL 0)
+    message(STATUS "Unable to determine MPI from MPI driver ${MPICXX}")
+  endif (MPICXX_RETURN EQUAL 0)
+endif (MPICXX)
+
+if (NOT MPI_FORCE_RECONFIGURE)
+  # We don't actually have to reconfigure anything
+elseif (MPI_COMPILE_CMDLINE)
+  # Extract compile flags from the compile command line.
+  string(REGEX MATCHALL "-D([^\" ]+|\"[^\"]+\")" MPI_ALL_COMPILE_FLAGS ${MPI_COMPILE_CMDLINE})
+  set(MPI_COMPILE_FLAGS_WORK)
+  foreach(FLAG ${MPI_ALL_COMPILE_FLAGS})
+    if (MPI_COMPILE_FLAGS_WORK)
+      set(MPI_COMPILE_FLAGS_WORK "${MPI_COMPILE_FLAGS_WORK} ${FLAG}")
+    else(MPI_COMPILE_FLAGS_WORK)
+      set(MPI_COMPILE_FLAGS_WORK ${FLAG})
+    endif(MPI_COMPILE_FLAGS_WORK)
+  endforeach(FLAG)
+
+  # Extract include paths from compile command line
+  string(REGEX MATCH "-I([^\" ]+|\"[^\"]+\")" MPI_INCLUDE_PATH ${MPI_COMPILE_CMDLINE})
+  string(REGEX REPLACE "^-I" "" MPI_INCLUDE_PATH ${MPI_INCLUDE_PATH})
+  string(REGEX REPLACE "//" "/" MPI_INCLUDE_PATH ${MPI_INCLUDE_PATH})
+
+  # Extract linker paths from the link command line
+  string(REGEX MATCH "-L([^\" ]+|\"[^\"]+\")" MPI_LINK_PATH ${MPI_LINK_CMDLINE})
+  string(REGEX REPLACE "^-L" "" MPI_LINK_PATH ${MPI_LINK_PATH})
+  string(REGEX REPLACE "//" "/" MPI_LINK_PATH ${MPI_LINK_PATH})
 
-INCLUDE(FindPackageHandleStandardArgs)
+  # Extract linker flags from the link command line
+  string(REGEX MATCHALL "-Wl,([^\" ]+|\"[^\"]+\")" MPI_ALL_LINK_FLAGS ${MPI_LINK_CMDLINE})
+  set(MPI_LINK_FLAGS_WORK)
+  foreach(FLAG ${MPI_ALL_LINK_FLAGS})
+    if (MPI_LINK_FLAGS_WORK)
+      set(MPI_LINK_FLAGS_WORK "${MPI_LINK_FLAGS_WORK} ${FLAG}")
+    else(MPI_LINK_FLAGS_WORK)
+      set(MPI_LINK_FLAGS_WORK ${FLAG})
+    endif(MPI_LINK_FLAGS_WORK)
+  endforeach(FLAG)
+
+  # Extract the set of libraries to link against from the link command
+  # line
+  string(REGEX MATCHALL "-l([^\" ]+|\"[^\"]+\")" MPI_LIBNAMES ${MPI_LINK_CMDLINE})
+
+  # Determine full path names for all of the libraries that one needs
+  # to link against in an MPI program
+  set(MPI_LIBRARIES)
+  foreach(LIB ${MPI_LIBNAMES})
+    string(REGEX REPLACE "^-l" "" LIB ${LIB})
+    set(MPI_LIB "MPI_LIB-NOTFOUND" CACHE FILEPATH "Cleared" FORCE)
+    find_library(MPI_LIB ${LIB} PATHS ${MPI_LINK_PATH})
+    if (MPI_LIB)
+      list(APPEND MPI_LIBRARIES ${MPI_LIB})
+    else (MPI_LIB)
+      status(ERROR "Unable to find MPI library ${LIB}")
+    endif (MPI_LIB)
+  endforeach(LIB)
+  set(MPI_LIB "MPI_LIB-NOTFOUND" CACHE INTERNAL "Scratch variable for MPI detection" FORCE)
+
+  # Chop MPI_LIBRARIES into the old-style MPI_LIBRARY and
+  # MPI_EXTRA_LIBRARY.
+  list(LENGTH MPI_LIBRARIES MPI_NUMLIBS)
+  if (MPI_NUMLIBS GREATER 0)
+    list(GET MPI_LIBRARIES 0 MPI_LIBRARY)
+  else (MPI_NUMLIBS GREATER 0)
+    set(MPI_LIBRARY "MPI_LIBRARY-NOTFOUND")
+  endif (MPI_NUMLIBS GREATER 0)
+  if (MPI_NUMLIBS GREATER 1)
+    cdr(MPI_EXTRA_LIBRARY ${MPI_LIBRARIES})
+  else (MPI_NUMLIBS GREATER 1)
+    set(MPI_EXTRA_LIBRARY "MPI_EXTRA_LIBRARY-NOTFOUND")
+  endif (MPI_NUMLIBS GREATER 1)
+
+  # Set up all of the appropriate cache entries
+  set(MPI_FOUND TRUE CACHE INTERNAL "Whether MPI was found" FORCE)
+
+  if (NOT MPI_FORCE_RECONFIGURE)
+    set(MPI_COMPILE_FLAGS ${MPI_COMPILE_FLAGS_WORK} CACHE STRING "MPI compilation flags")
+    set(MPI_INCLUDE_PATH ${MPI_INCLUDE_PATH} CACHE STRING "MPI include path")
+    set(MPI_LINK_FLAGS ${MPI_LINK_FLAGS_WORK} CACHE STRING "MPI linking flags")
+    set(MPI_LIBRARIES ${MPI_LIBRARIES} CACHE STRING "MPI libraries to link against, separated by semicolons")
+  else (NOT MPI_FORCE_RECONFIGURE)
+    set(MPI_COMPILE_FLAGS ${MPI_COMPILE_FLAGS_WORK} CACHE STRING "MPI compilation flags" FORCE)
+    set(MPI_INCLUDE_PATH ${MPI_INCLUDE_PATH} CACHE STRING "MPI include path" FORCE)
+    set(MPI_LINK_FLAGS ${MPI_LINK_FLAGS_WORK} CACHE STRING "MPI linking flags" FORCE)
+    set(MPI_LIBRARIES ${MPI_LIBRARIES} CACHE STRING "MPI libraries to link against, separated by semicolons" FORCE)
+  endif (NOT MPI_FORCE_RECONFIGURE)
+else (MPI_COMPILE_CMDLINE)
+  find_path(MPI_INCLUDE_PATH mpi.h 
+    /usr/local/include 
+    /usr/include 
+    /usr/include/mpi
+    /usr/local/mpi/include
+    "C:/Program Files/MPICH/SDK/Include" 
+    "$ENV{SystemDrive}/Program Files/MPICH2/include"
+    "C:/Program Files/Microsoft Compute Cluster Pack/Include"
+    )
+  
+  # TODO: How do we know whether we're building 32-bit vs. 64-bit?
+  find_library(MPI_LIBRARY 
+    NAMES mpi mpich
+    PATHS /usr/lib /usr/local/lib /usr/local/mpi/lib
+    "C:/Program Files/MPICH/SDK/Lib" 
+    "$ENV{SystemDrive}/Program Files/MPICH/SDK/Lib"
+    "C:/Program Files/Microsoft Compute Cluster Pack/Lib/i386"
+    )
+  find_library(MPI_LIBRARY 
+    NAMES mpich2
+    PATHS
+    "$ENV{SystemDrive}/Program Files/MPICH2/Lib")
+
+  find_library(MPI_EXTRA_LIBRARY 
+    NAMES mpi++
+    PATHS /usr/lib /usr/local/lib /usr/local/mpi/lib
+    "C:/Program Files/MPICH/SDK/Lib" 
+    "C:/Program Files/Microsoft Compute Cluster Pack/Lib/i386"
+    DOC "If a second MPI library is necessary, specify it here.")
+
+  set(MPI_COMPILE_FLAGS "" CACHE STRING "MPI compilation flags")
+  set(MPI_LINK_FLAGS "" CACHE STRING "MPI linking flags")
+
+  if (MPI_EXTRA_LIBRARY)
+    set(MPI_LIBRARIES "${MPI_LIBRARY};${MPI_EXTRA_LIBRARY}" CACHE STRING "MPI libraries to link against, separated by semicolons")
+  else (MPI_EXTRA_LIBRARY)
+    set(MPI_LIBRARIES ${MPI_LIBRARY} CACHE STRING "MPI libraries to link against, separated by semicolons")
+  endif (MPI_EXTRA_LIBRARY)
+
+  if (MPI_LIBRARY)
+    set(MPI_FOUND TRUE CACHE INTERNAL "Whether MPI was found" FORCE)
+  else (MPI_LIBRARY)
+    set(MPI_FOUND FALSE CACHE INTERNAL "Whether MPI was found" FORCE)
+  endif (MPI_LIBRARY)
+endif (NOT MPI_FORCE_RECONFIGURE)
+
+# on BlueGene/L the MPI lib is named libmpich.rts.a, there also these additional libs are required
+if("${MPI_LIBRARY}" MATCHES "mpich.rts")
+   set(MPI_EXTRA_LIBRARY ${MPI_EXTRA_LIBRARY} msglayer.rts devices.rts rts.rts devices.rts)
+   set(MPI_LIBRARY ${MPI_LIBRARY}  msglayer.rts devices.rts rts.rts devices.rts)
+endif("${MPI_LIBRARY}" MATCHES "mpich.rts")
 
-# handle the QUIETLY and REQUIRED arguments and set LIBXML2_FOUND to TRUE if 
-# all listed variables are TRUE
-FIND_PACKAGE_HANDLE_STANDARD_ARGS(MPI DEFAULT_MSG MPI_LIBRARY MPI_INCLUDE_PATH)
+set(MPI_LIBRARY ${MPI_LIBRARY} CACHE INTERNAL "MPI library to link against. Deprecated: use MPI_LIBRARIES instead")
+set(MPI_EXTRA_LIBRARY ${MPI_EXTRA_LIBRARY} CACHE INTERNAL "Second MPI library to link against. Deprecated: use MPI_LIBRARIES instead")
 
-MARK_AS_ADVANCED(MPI_INCLUDE_PATH MPI_LIBRARY MPI_EXTRA_LIBRARY)
+include(FindPackageHandleStandardArgs)
+# handle the QUIETLY and REQUIRED arguments 
+find_package_handle_standard_args(MPI DEFAULT_MSG MPI_LIBRARY MPI_INCLUDE_PATH)
+mark_as_advanced(MPI_INCLUDE_PATH MPI_COMPILE_FLAGS MPI_LINK_FLAGS MPI_LIBRARIES)