AC_OPENMP broken for IBM xl Fortran compilers

[Christian Rössel]

Hi,

AC_OPENMP returns "none needed" for the IBM xl Fortran compilers (xlf*,
bgxlf*, mpixlf*). This is wrong, you need to use -qsmp=omp.

configure tries to compile following program:

|       program main
|       call omp_get_num_threads
|       end

Compilation succeeds without specifying any OpenMP flag. If you modify
the test program to

      program main
      implicit none
!$    integer tid
      tid = 42
      call omp_set_num_threads(2)
      end

the correct flags are detected. See the attached patch where I also
added OpenMP flags for the Cray and NEC compilers. If you are happy with
this patch, please add Markus Geimer to THANKS, too.

BTW, the pgf* compilers also return "none needed", this patch might
solve this problem, too (untested).

Cheers,
Christian

openmp_fortran.patch
Description: Text Data