Reproducer:

"""
$ cat sk.f
      program test
c         this program tests memory allocation

c     write(*,*)"Enter an interger higher than 0"
c     read(*,*)k
      k=1
      call  test_cray(k)
      end

      subroutine test_cray(k)
c        integer*8 ptrzz1
        pointer(ptrzz1 , zz1)
        ptrzz1=0
c        ptrzz1=loc(zz1)
        write(*,*)"   ptrzz1: ",ptrzz1
        if (ptrzz1 .ne. 0) then
          write(*,*)"   ptrzz1 ne zero in the calling routine"
        else
          write(*,*)"   ptrzz1 eq zero in the calling routine"
          call shape_cray(zz1)
          write(*,*)"*** Returning from shape_cray"
        end if
      end


      subroutine shape_cray(zz1)
        pointer(ptrzz , zz)
        ptrzz=loc(zz1)
        if (ptrzz .ne. 0) then
          write(*,*)"      ptrzz - loc(zz1)- ne zero in the called routine"
          write(*,*)"      ptrzz: ",ptrzz
        else
          write(*,*)"      ptrzz - loc(zz1) eq zero in the called routine"
          write(*,*)"      ptrzz: ",ptrzz
        end if
c        write(*,*)"   ptrzz: ",ptrzz
      end


$ gfortran -frecursive -fPIC -ffixed-line-length-132 -fautomatic -fcray-pointer -O1 -o test sk.f
$ ./test 
    ptrzz1:                     0
    ptrzz1 eq zero in the calling routine
       ptrzz - loc(zz1)- ne zero in the called routine
       ptrzz:                     0
 *** Returning from shape_cray
"""

  If compiled with -O0 it works as expected:
"""
$ gfortran -frecursive -fPIC -ffixed-line-length-132 -fautomatic -fcray-pointer -O0 -o test sk.f
$ ./test 
    ptrzz1:                     0
    ptrzz1 eq zero in the calling routine
       ptrzz - loc(zz1) eq zero in the called routine
       ptrzz:                     0
 *** Returning from shape_cray
"""