trusty (1) mpicc.openmpi.1.gz

Provided by: libopenmpi-dev_1.6.5-8_amd64 bug

NAME

       mpicc -- Open MPI C wrapper compiler

SYNTAX

       mpicc [-showme|-showme:compile|-showme:link] ...

OPTIONS

       --showme
              This  option  comes  in  several different variants (see below).  None of the variants invokes the
              underlying compiler; they all provide information on how the underlying compiler would  have  been
              invoked had --showme not been used.  The basic --showme option outputs the command line that would
              be executed to compile the program.  NOTE: If a non-filename argument is  passed  on  the  command
              line,  the  -showme  option  will  not  display  any  additional  flags.  For example, both "mpicc
              --showme" and "mpicc --showme my_source.c" will show all the wrapper-supplied flags.   But  "mpicc
              --showme -v" will only show the underlying compiler name and "-v".

       --showme:compile
              Output the compiler flags that would have been supplied to the C compiler.

       --showme:link
              Output the linker flags that would have been supplied to the C compiler.

       --showme:command
              Outputs the underlying C compiler command (which may be one or more tokens).

       --showme:incdirs
              Outputs  a  space-delimited  (but  otherwise  undecorated)  list  of  directories that the wrapper
              compiler would have provided to the underlying C compiler to indicate where relevant header  files
              are located.

       --showme:libdirs
              Outputs  a  space-delimited  (but  otherwise  undecorated)  list  of  directories that the wrapper
              compiler would have provided to the underlying linker to indicate  where  relevant  libraries  are
              located.

       --showme:libs
              Outputs  a  space-delimited  (but  otherwise  undecorated)  list of library names that the wrapper
              compiler would have used to link an application.  For example: "mpi open-rte open-pal util".

       --showme:version
              Outputs the version number of Open MPI.

       See the man page for your underlying C compiler for other options that can be passed through mpicc.

DESCRIPTION

       Conceptually, the role of these commands is quite simple: transparently add relevant compiler and  linker
       flags  to the user's command line that are necessary to compile / link Open MPI programs, and then invoke
       the underlying compiler to actually perform the command.

       As such, these commands are frequently referred to as "wrapper" compilers because they  do  not  actually
       compile  or  link  applications  themselves;  they only add in command line flags and invoke the back-end
       compiler.

   Background
       Open MPI is comprised of three software layers: OPAL (Open Portable Access Layer),  ORTE  (Open  Run-Time
       Environment), and OMPI (Open MPI).  There are wrapper compilers for each layer; each layer's wrapper only
       links in the libraries relevant for that layer.  Specifically, each layer provides the following  wrapper
       compilers:

       OPAL
           opalcc and opalc++

       ORTE
           ortecc and ortec++

       OMPI
           mpicc,  mpic++,  mpicxx, mpiCC (only on systems with case-senstive file systems), mpif77, and mpif90.
           Note that mpic++, mpicxx, and mpiCC all invoke  the  same  underlying  C++  compiler  with  the  same
           options.  All are provided as compatibility with other MPI implementations.

       The Fortran wrapper compilers for MPI (mpif77 and mpif90) will be inoperative and will return an error on
       use if Fortran 77 / Fortran 90 support was not built into the MPI layer.

   Overview
       mpicc is a convenience wrappers for the underlying C  compiler.   Translation  of  an  Open  MPI  program
       requires  the  linkage  of  the  Open  MPI-specific libraries which may not reside in one of the standard
       search directories of ld(1).  It also often requires the inclusion of header files what may also  not  be
       found in a standard location.

       mpicc  passes its arguments to the underlying C compiler along with the -I, -L and -l options required by
       Open MPI programs.

       The Open MPI Team strongly encourages using the wrapper compilers instead of attempting to  link  to  the
       Open  MPI  libraries  manually.   This  allows  the specific implementation of Open MPI to change without
       forcing changes to linker directives in  users'  Makefiles.   Indeed,  the  specific  set  of  flags  and
       libraries  used by the wrapper compilers depends on how Open MPI was configured and built; the values can
       change between different installations of the same version of Open MPI.

       Indeed, since the wrappers are simply thin shells on top of an underlying compiler, there are very,  very
       few  compelling  reasons  not  to  use  mpicc.  When it is not possible to use the wrappers directly, the
       -showme:compile and -showme:link options should be used to determine what flags the wrappers  would  have
       used.  For example:

       shell$ cc -c file1.c `mpicc -showme:compile`

       shell$ cc -c file2.c `mpicc -showme:compile`

       shell$ cc file1.o file2.o `mpicc -showme:link` -o my_mpi_program

NOTES

       It  is  possible  to  make  the  wrapper  compilers multi-lib aware.  That is, the libraries and includes
       specified may differ based on the compiler flags specified (for example, with the GNU compilers on Linux,
       a  different  library  path may be used if -m32 is seen versus -m64 being seen).  This is not the default
       behavior in a standard build, but can be activated (for example, in a binary package  providing  both  32
       and 64 bit support).  More information can be found at:

         https://svn.open-mpi.org/trac/ompi/wiki/compilerwrapper3264

FILES

       The  string  that  the  wrapper  compilers  insert  into  the command line before invoking the underlying
       compiler are stored in a text file created by Open MPI and installed to  $pkgdata/mpicc-wrapper-data.txt,
       where  $pkgdata is typically $prefix/share/openmpi, and $prefix is the top installation directory of Open
       MPI.

       It is rarely necessary to edit this file, but it can be examined to gain  insight  into  what  flags  the
       wrappers are placing on the command line.

ENVIRONMENT VARIABLES

       By  default,  the  wrappers  use  the  compilers  that were selected when Open MPI was configured.  These
       compilers were either found automatically by Open MPI's "configure" script, or were selected by the  user
       in the CC, CXX, F77, and/or FC environment variables before "configure" was invoked.  Additionally, other
       arguments specific to the compiler may have been selected by configure.

       These values can be selectively overridden by either editing the text files containing this configuration
       information  (see  the  FILES  section),  or  by  setting  selected  environment  variables  of  the form
       "OMPI_value".

       Valid value names are:

       CPPFLAGS
              Flags added when invoking the preprocessor (C or C++)

       LDFLAGS
              Flags added when invoking the linker (C, C++, or Fortran)

       LIBS   Libraries added when invoking the linker (C, C++, or Fortran)

       CC     C compiler

       CFLAGS C compiler flags

       CXX    C++ compiler

       CXXFLAGS
              C++ compiler flags

       F77    Fortran 77 compiler

       FFLAGS Fortran 77 compiler flags

       FC     Fortran 90 compiler

       FCFLAGS
              Fortran 90 compiler flags