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ortecc

NAME

ortecc -- OpenRTE C wrapper compiler

SYNTAX

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

-showme:compile

Do not invoke the underlying C compiler. Instead, show the compiler flags that would be supplied to the C compiler.

-showme:link

Do not invoke the underlying C compiler. Instead, show the linker flags that would be supplied to the C compiler.

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

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 OpenRTE 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

ortecc is a convenience wrappers for the underlying C compiler. Translation of an OpenRTE program requires the linkage of the OpenRTE-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.

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

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

Indeed, since the wrappers are simply thin shells on top of an underlying compiler, there are very, very few compelling reasons not to use ortecc. 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 OpenRTE and installed to $pkgdata/ortecc-wrapper-data.txt, where $pkgdata is typically $prefix/share/openmpi, and $prefix is the top installation directory of OpenRTE.

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 OpenRTE 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 "ORTE_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