mpicxx

Compiles and links MPI programs written in C++

Description

This command can be used to compile and link MPI programs written in C++. It provides the options and any special libraries that are needed to compile and link MPI programs.

It is important to use this command, particularly when linking programs, as it provides the necessary libraries.

Command line arguments

-show: Show the commands that would be used without running them
-help: Give short help
-cxx=name: Use compiler name instead of the default choice. Use this only if the compiler is compatible with the MPICH library (see below)
-config=name: Load a configuration file for a particular compiler. This allows a single mpicxx command to be used with multiple compilers.
-compile_info: Show the steps for compiling a program. This option can be used to see what options and include paths are used by mpicxx.
-link_info: Show the steps for linking a program. This option can be used to see what options and libraries are used by mpicxx.
-profile=name: Use the MPI profiling given by name. See below for details
-echo: Show exactly what this program is doing. This option should normally not be used.
others: are passed to the compiler or linker. For example, \-ccauses files to be compiled, \-g selects compilation with debugging on most systems, and \-o name causes linking with the output executable given the name name.

Environment Variables

The environment variables MPICH_CXX may be used to select different C++ compiler and linker. Note that since MPICH is built with a particular C and Fortran compiler, changing the compilers used can cause problems. Use this only if you could intermix code compiled with the different compilers.

The environment variable MPICC_PROFILE specifies a profile library and has the same effect as if \-profile=$MPICC_PROFILE were used as an argument to mpicc. See the discussion of \-profile below for more details.

Compatible Compilers

The MPI library may be used with any compiler that uses the same lengths for basic data objects (such as long double) and that uses compatible run-time libraries. On many systems, the various compilers are compatible and may be used interchangably. There are exceptions; if you use the MPICH_CXX environment variable or the \-cxx=name command-line argument to override the choice of compiler and encounter problems, try reconfiguring MPICH with the new compiler, and installing MPICH in a separate location. See the installation manual for more details.

Examples

To compile a single file foo.c, use

   mpicxx -c foo.cxx

To link the output and make an executable, use

   mpicxx -o foo foo.o

Combining compilation and linking in a single command

   mpicxx -o foo foo.cxx

is a convenient way to build simple programs.

Selecting a Profiling Library

The \-profile=name argument allows you to specify an MPI profiling library to be used. name can have two forms:

A library in the same directory as the MPI library
The name of a profile configuration file

If name is a library, then this library is included before the MPI library. This allows the simple use of libraries that make use of the MPI profiling interface and that are installed in the same directory as the MPI library.

If name.conf is the name of a file in the sysconfdir directory, then this is read and may define the following variables:

PROFILE_PRELIB: Libraries (and paths) to include before the MPI library
PROFILE_POSTLIB: Libraries to include after the MPI library
PROFILE_INCPATHS: C preprocessor arguments for any include files For example, to add /usr/local/myprof/include to the include path and the library libmyprof.a in /usr/local/myprof/lib to the link step, you could create the file myprof.conf with the lines

    PROFILE_PRELIB="-L/usr/local/myprof/lib -lmyprof"
    PROFILE_INCPATHS="-I/usr/local/myprof/include"

and place it in the sysconfdir directory (this directory is set at configure time when MPICH is built). Then using the command-line argument \-profile=myprof will cause these definitions to be added to the relevant compile commands.