SYNTAX

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

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

       oshc++ [--showme | --showme:compile | --showme:link] ...

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

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

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

       shmemc++ [--showme | --showme:compile | --showme:link] ...

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

OPTIONS

       The options below apply to all of the wrapper compilers:

       • --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 "oshcc --showme and oshcc --showme my_source.c will show all the
            wrapper-supplied flags. But oshcc --showme -v will only show the underlying compiler name and -v.

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

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

       • --showme:command: Outputs the underlying 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 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-pal util.

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

       • --showme:help: Output a brief usage help message.

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

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 OpenSHMEM 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 provides wrapper compilers for several languages:

       • oshcc, shmemcc: C

       • oshc++, oshcxx, shmemc++, shmemcxx`:: C++

       • oshfort, shmemfort: Fortran

       The  wrapper  compilers  for  each  of the languages are identical; they can be use interchangeably.  The
       different names are provided solely for backwards compatibility.

FORTRAN NOTES

       The Fortran wrapper compiler for OpenSHMEM  (oshfort  and  shmemfort)  can  compile  and  link  OpenSHMEM
       applications that use any/all of the OpenSHMEM Fortran bindings.

       Note,  however,  that  the  Fortran  compiler  may  require  additional command-line options to enforce a
       specific Fortran dialect. For example, in some versions  of  the  IBM  XLF  compiler,  if  xlf90  is  the
       underlying Fortran compiler, -qfixed may be necessary to compile fixed-format Fortran source files.

       Finally, note that oshfort will be inoperative and will return an error on use if Fortran support was not
       built into the OpenSHMEM layer.

OVERVIEW

       oshcc  and  shmemcc  are convenience wrappers for the underlying C compiler.  Translation of an OpenSHMEM
       program requires the linkage of the OpenSHMEM-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.

       oshcc and shmemcc pass their arguments to the underlying C compiler along with the -I, -L and -l  options
       required by OpenSHMEM programs.

       The same is true for all the other language wrapper compilers.

       The  OpenSHMEM  Team strongly encourages using the wrapper compilers instead of attempting to link to the
       OpenSHMEM libraries manually. This allows the specific implementation  of  OpenSHMEM  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 OpenSHMEM was configured and built; the values can change
       between different installations of the same version of OpenSHMEM.

       Indeed, since the wrappers are simply thin shells on top of an underlying compiler, there are very,  very
       few  compelling  reasons  not  to  use  oshcc.  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 `shmemcc --showme:compile`

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

          shell$ cc file1.o file2.o `shmemcc --showme:link` -o my_oshmem_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 here.

FILES

       The  strings  that  the  wrapper  compilers  insert  into the command line before invoking the underlying
       compiler are stored in a text file created by OpenSHMEM and installed to  $pkgdata/NAME-wrapper-data.txt,
       where:

       • $pkgdata is typically $prefix/share/openmpi

       • $prefix is the top installation directory of OpenSHMEM

       • NAME is the name of the wrapper compiler (e.g., $pkgdata/shmemcc-wrapper-data.txt)

       It  is rarely necessary to edit these files, but they 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  OpenSHMEM  was  configured.  These
       compilers  were either found automatically by Open MPI’s “configure” script, or were selected by the user
       in the CC, CXX, 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
       oshmem_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

       • FC: Fortran compiler

       • FCFLAGS: Fortran compiler flags

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                        OSHMEM-WRAPPER-COMPILER(1)