Manual Pages for UNIX Darwin command on man mpif77

mpif77(1) Open MPI mpif77(1)

NAME

mpif77 - Open MPI Fortran 77 wrapper compiler

SSYYNNTTAAXX

mpif77 [-showme|-showme:compile|-showme:link] ...

OOPPTTIIOONNSS

-showme

Do not invoke the underlying compiler. Instead, show the com-

mand line that would be executed to compile the program. NNOOTTEE::

If a non-filename argument is passed on the command line, the

-showme option will not display any additional flags. For exam-

ple, both "mpif77 -showme" and "mpif77 -showme mysource.c"

will show all the wrapper-supplied flags. But "mpif77 -showme

-v" will only show the underlying compiler name and "-v".

-showme:compile

Do not invoke the underlying Fortran 77 compiler. Instead, show

the compiler flags that would be supplied to the Fortran 77 com-

piler.

-showme:link

Do not invoke the underlying Fortran 77 compiler. Instead, show

the linker flags that would be supplied to the Fortran 77 com-

piler. See the man page for your underlying compiler for other options that

can be passed through mpif77

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" compil-

ers because they do not actually compile or link applications them-

selves; they only add in command line flags and invoke the back-end

compiler. BBaacckkggrroouunndd 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 imple-

mentations.

The Fortran wrapper compilers for MPI (mpif77 and mpif90) will be inop-

erative and will return an error on use if Fortran 77 / Fortran 90 sup-

port was not built into the MPI layer. OOvveerrvviieeww

mpif77 is a convenience wrappers for the underlying Fortran 77 com-

piler. 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.

mpif77 passes its arguments to the underlying Fortran 77 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 forc-

ing changes to linker directives in users' Makefiles. Indeed, the spe-

cific 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 underly-

ing compiler, there are very, very few compelling reasons not to use

mpif77. 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 mympiprogram

NNOOTTEESS

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 dif-

ferent 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 cre-

ated by Open MPI and installed to $pkgdata/mpif77-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

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tion), or by setting selected environment variables of the form "OMPIvalue". 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