XL Fortran Enterprise Edition for AIX : User's Guide - IBM

Passing Fortran Files through the C Preprocessor
A common programming practice is to pass files through the C preprocessor (cpp).
cpp can include or omit lines from the output file based on user-specified
conditions (“conditional compilation”). It can also perform string substitution
(“macro expansion”).
XL Fortran can use cpp to preprocess a file before compiling it. If you are also
using one of the optimizing preprocessors, cpp is called before any of the other
preprocessors.
To call cpp for a particular file, use a file suffix of .F. If you specify the -d option,
each .F file filename.F is preprocessed into an intermediate file Ffilename.f, which is
then compiled. If you do not specify the -d option, the intermediate file name is
/tmpdir/F8xxxxxx, where x is an alphanumeric character and tmpdir is the contents
of the TMPDIR environment variable or, if you have not specified a value for
TMPDIR, /tmp. You can save the intermediate file by specifying the -d compiler
option; otherwise, the file is deleted. If you only want to preprocess and do not
want to produce object or executable files, specify the -qnoobject option also.
When XL Fortran uses cpp for a file, the preprocessor will emit #line directives
unless you also specify the -d option. The #line directive associates code that is
created by cpp or any other Fortran source code generator with input code that
you create. The preprocessor may cause lines of code to be inserted or deleted.
Therefore, the #line directives that it emits can be useful in error reporting and
debugging, because they identify the source statements found in the preprocessed
code by listing the line numbers that were used in the original source.
The _OPENMP C preprocessor macro can be used to conditionally include code.
This macro is defined when the C preprocessor is invoked and when you specify
the -qsmp=omp compiler option. An example of using this macro follows:
program par_mat_mul
implicit none
integer(kind=8)
integer(kind=8),parameter
integer(kind=8),dimension(N,N)
integer(kind=8)
#ifdef _OPENMP
integer omp_get_num_threads
#endif
::i,j,nthreads
::N=60
::Ai,Bi,Ci
::Sumi
!$OMP
common/data/ Ai,Bi,Ci
threadprivate (/data/)
!$omp parallel
forall(i=1:N,j=1:N) Ai(i,j) = (i-N/2)**2+(j+N/2)
forall(i=1:N,j=1:N) Bi(i,j) = 3-((i/2)+(j-N/2)**2)
!$omp master
#ifdef _OPENMP
nthreads=omp_get_num_threads()
#else
nthreads=8
#endif
!$omp end master
!$omp end parallel
!$OMP parallel default(private),copyin(Ai,Bi),shared(nthreads)
!$omp do
do i=1,nthreads
call imat_mul(Sumi)
enddo
40 XL Fortran Enterprise Edition for AIX : User’s Guide