[Bug fortran/81416] OpenMP craches if large arrays passed

["bz0815 at tirol dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81416

--- Comment #4 from bz0815 at tirol dot com ---
(In reply to Andrew Pinski from comment #3)
> >  DOUBLE PRECISION,DIMENSION(n) :: b
> 
> This array is on the stack.

So

  DOUBLE PRECISION,DIMENSION(n) :: b

is put on the stack if it is passed as an argument but put on heap if it isn't?

If it is passed as argument even small dimensions cause a segmentation fault:

PROGRAM Prog
  USE Mod
  USE OMP_LIB
  IMPLICIT NONE

  INTEGER :: nthreads
  INTEGER,PARAMETER :: n = 262144
  DOUBLE PRECISION,DIMENSION(n) :: b

  nthreads = 4

  CALL OMP_SET_NUM_THREADS(nthreads)

  PRINT *,omp_get_num_procs()
  PRINT *,omp_get_max_threads()
  PRINT *,omp_get_num_threads()

  CALL Print_Info(b)

END PROGRAM Prog

$ make
$ gfortran -Wl,--stack,2097152 -fopenmp -c mod.f08 -o mod.o
$ gfortran -Wl,--stack,2097152 -fopenmp  -o prog mod.o prog.f08

$ ./prog
Segmentation fault (core dumped)

However, if array b is not passed as an argument even dimensions greater than
stack limit work fine: 

PROGRAM Prog
  USE Mod
  USE OMP_LIB
  IMPLICIT NONE

  INTEGER :: nthreads
  INTEGER,PARAMETER :: n = 134217728
  DOUBLE PRECISION,DIMENSION(n) :: b

  nthreads = 4

  CALL OMP_SET_NUM_THREADS(nthreads)

  PRINT *,omp_get_num_procs()
  PRINT *,omp_get_max_threads()
  PRINT *,omp_get_num_threads()

!  CALL Print_Info(b)

END PROGRAM Prog

$ gfortran -Wl,--stack,2097152 -fopenmp -c mod.f08 -o mod.o
$ gfortran -Wl,--stack,2097152 -fopenmp  -o prog mod.o prog.f08

$ ./prog
           8
           4
           1

Anyway, many thanks for the hint. My program is now up and running.