F77(3) User Contributed Perl Documentation F77(3)NAME
ExtUtils::F77 - Simple interface to F77 libs
DESCRIPTION
This module tries to figure out how to link C programs with Fortran subroutines on your system. Basically one must add a list of Fortran
runtime libraries. The problem is their location and name varies with each OS/compiler combination!
This module tries to implement a simple 'rule-of-thumb' database for various flavours of UNIX systems. A simple self-documenting Perl
database of knowledge/code for figuring out how to link for various combinations of OS and compiler is embedded in the modules Perl code.
Please help save the world by sending database entries for your system to karl_pgplot@mac.com
The library list which the module returns can be explicitly overridden by setting the environment variable F77LIBS, e.g.
% setenv F77LIBS "-lfoo -lbar"
% perl Makefile.PL
...
SYNOPSIS
use ExtUtils::F77; # Automatic guess
use ExtUtils::F77 qw(sunos); # Specify system
use ExtUtils::F77 qw(linux g77); # Specify system and compiler
$fortranlibs = ExtUtils::F77->runtime;
METHODS
The following methods are provided:
o runtime
Returns a list of F77 runtime libraries.
$fortranlibs = ExtUtils::F77->runtime;
o runtimeok
Returns TRUE only if runtime libraries have been found successfully.
o trail_
Returns true if F77 names have trailing underscores.
o compiler
Returns command to execute the compiler (e.g. 'f77').
o cflags
Returns compiler flags.
o testcompiler
Test to see if compiler actually works.
More methods will probably be added in the future.
AUTHOR
Karl Glazebrook (kgb@aaoepp.aao.GOV.AU).
perl v5.12.1 2007-04-02 F77(3)
Check Out this Related Man Page
mpif77(1) Open MPI mpif77(1)NAME
mpif77 -- Open MPI Fortran 77 wrapper compiler
SYNTAX
mpif77 [-showme|-showme:compile|-showme:link] ...
OPTIONS -showme
Do not invoke the underlying compiler. Instead, show 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
"mpif77 --showme" and "mpif77 --showme my_source.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 compiler.
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" compilers because they do not actually compile or link applications them-
selves; 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 implementa-
tions.
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
mpif77 is a convenience wrappers for the underlying Fortran 77 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.
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 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
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 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 com-
piler 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 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 automati-
cally by Open MPI's "configure" script, or were selected by the user in the CC, CXX, F77, and/or FC environment variables before "config-
ure" 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 sec-
tion), 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
OMPI Open MPI mpif77(1)