[Bug fortran/68769] New: [fortran] annotate omp data pointers with restrict for -fno-cray-pointers

["vries at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68769

            Bug ID: 68769
           Summary: [fortran] annotate omp data pointers with restrict for
                    -fno-cray-pointers
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vries at gcc dot gnu.org
  Target Milestone: ---

Consider the following program:
...
program main
  implicit none
  integer, parameter         :: n = 1024
  integer, dimension (0:n-1) :: a, b
  integer                    :: i

  do i = 0, n - 1
     a(i) = i * 2
  end do

  do i = 0, n -1
     b(i) = i * 4
  end do

!$omp parallel do                                                            
  do i = 0, n - 1
     a(i) = b(i) + b(i)
  end do

  do i = 0, n - 1
     if (a(i) .ne. b(i) + b(i)) call abort
  end do

end program main
...

when compiling with -fno-cray-pointers, I think we can annotate the pointers to
a and b in omp_data_i (the argument to the resulting thread function) as
restrict. Without pointers, there's no way to introduce an alias for a and b.