[Bug fortran/70950] New: ICE with -O0 in simplify_subreg, at simplify-rtx.c:5895

["gerhard dot steinmetz dot fortran at t-online dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70950

            Bug ID: 70950
           Summary: ICE with -O0 in simplify_subreg, at
                    simplify-rtx.c:5895
           Product: gcc
           Version: 6.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gerhard.steinmetz.fortran@t-online.de
  Target Milestone: ---

This error message is generated with optimization level -O0 :
(affects older gfortran versions too)


$ cat z1.f90
program p
   type t1
   end type
   type t2
      type(t1), pointer :: q => null()
   end type
   type(t1), pointer :: a, b
   type(t2) :: c

   allocate(a)
   call s(a, c)
   print *, 'a', associated(a, f(c))

   b => f(c)
   print *, 'b', associated(a, b)

contains

   subroutine s(x, y)
      type(t1), pointer :: x
      type(t2), intent(out) :: y
      y%q => x
   end

   function f(x) result (z)
      type(t2), intent(in) :: x
      class(t1), pointer :: z
      z => x%q
   end
end


$ gfortran-6 -O0 z1.f90
z1.f90:12:0:

    print *, 'a', associated(a, f(c))

internal compiler error: in simplify_subreg, at simplify-rtx.c:5895