[Bug fortran/34053] New: -frecursive: No need to use the stack for local variables of the main program

[burnus at gcc dot gnu dot org]

Using -fopenmp or -frecursive, local variables are put on the stack. This makes
sense, but for the main program there is no need for the stack and the static
memory can be used. This seems to be done what sunf95 does (contrary to ifort
and gfortran).

The following example is based on the thread at
http://groups.google.com/group/comp.lang.fortran/browse_thread/thread/9a7daa8d75084b6b/
and using static memory should have no negative side effects.

Example: Run the following program with -fopenmp or -frecursive and
  ulimit -S -s 8192
Due to this low stack size, it will crash.

program sums
   implicit none
   integer, parameter :: sp = kind(1.0)
   integer, parameter :: dp = selected_real_kind(2*precision(1.0_sp))

   integer, parameter                      :: num_steps = 2000000
   real                                    :: t1, t2
   integer                                 :: i, j
   real(kind=dp), dimension(0:num_steps-1) :: y
   call cpu_time(t1)
   y = 0.0_dp
!$omp parallel do
   do j=0,num_steps-1
     do i=0,49
       y(j) = y(j) + 0.7_dp**i
     end do
   end do
!$omp end parallel do
   call cpu_time(t2)
   print *, "y(end) = ", y(num_steps-1)
   print *, "Reached result in ", t2-t1, " seconds processor time."
end program sums


-- 
           Summary: -frecursive: No need to use the stack for local
                    variables of the main program
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: burnus at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34053