Gfortran Bug
Due to an apparent gfortran compiler bug, care must be
exercised with OpenMP directives' placement. For example,
program foo
implicit none
!$ integer :: IAM, NPROCS
!$ integer OMP_GET_NUM_THREADS, OMP_GET_THREAD_NUM, OMP_IN_PARALLEL
!$OMP PARALLEL DEFAULT(none) PRIVATE(IAM, NPROCS)
!$ IAM = OMP_GET_THREAD_NUM()
!$ NPROCS = OMP_GET_NUM_THREADS()
!$ print *, 'I AM processor ',IAM, ' (of ', NPROCS, ')'
!$ print *, 'Am I in a parallel region (T)? ', OMP_IN_PARALLEL()
!$OMP END PARALLEL
end program foo
In this example, since the OpenMP key word PARALLEL
starts two spaces to the right of !$OMP, the GNU gfortran compiler fails to recognize this to be an OpenMP directive !
Here is what happens when the above FORTRAN code is compiled with gfortran:
katana:~ % gfortran -fopenmp -o foo foo.f90
In file foo.f90:5
!$OMP PARALLEL DEFAULT(none) PRIVATE(IAM, NPROCS)
1
Error: Unclassifiable OpenMP directive at (1)
In file foo.f90:10
!$OMP END PARALLEL
1
Error: Unexpected !$OMP END PARALLEL statement at (1)
The above problem is restricted to gfortran. There is no similar problems for the GNU C compiler OpenMP
directives (i.e., #pramas).
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