Re: [Patch 1/2, Fortran, pr60322] [OOP] Incorrect bounds on polymorphic dummy array

[Andre Vehreschild <vehre@gmx.de>]

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Hi Mikael,

thanks for looking at the patch. Please note, that Paul has sent an addendum to
the patches for 60322, which I deliberately have attached.

>  26/02/2015 18:17, Andre Vehreschild a écrit :
> > This first patch is only preparatory and does not change any of the
> > semantics of gfortran at all.
> Sure?

With the counterexample you found below, this of course is a wrong statement.
 
> > diff --git a/gcc/fortran/expr.c b/gcc/fortran/expr.c
> > index ab6f7a5..d28cf77 100644
> > --- a/gcc/fortran/expr.c
> > +++ b/gcc/fortran/expr.c
> > @@ -4059,10 +4060,10 @@ gfc_lval_expr_from_sym (gfc_symbol *sym)
> >    lval->symtree = gfc_find_symtree (sym->ns->sym_root, sym->name);
> >  
> >    /* It will always be a full array.  */
> > -  lval->rank = sym->as ? sym->as->rank : 0;
> > +  as = sym->as;
> > +  lval->rank = as ? as->rank : 0;
> >    if (lval->rank)
> > -    gfc_add_full_array_ref (lval, sym->ts.type == BT_CLASS ?
> > -			    CLASS_DATA (sym)->as : sym->as);
> > +    gfc_add_full_array_ref (lval, as);
> 
> This is a change of semantics.  Or do you know that sym->ts.type !=
> BT_CLASS?

You are completely right. I have made a mistake here. I have to tell the truth,
I never ran a regtest with only part 1 of the patches applied. The second part
of the patch will correct this, by setting the variable as depending on whether
type == BT_CLASS or not. Sorry for the mistake.

> > diff --git a/gcc/fortran/trans-decl.c b/gcc/fortran/trans-decl.c
> > index 3664824..e571a17 100644
> > --- a/gcc/fortran/trans-decl.c
> > +++ b/gcc/fortran/trans-decl.c
> > @@ -1013,16 +1017,24 @@ gfc_build_dummy_array_decl (gfc_symbol * sym, tree
> > dummy) tree decl;
> >    tree type;
> >    gfc_array_spec *as;
> > +  symbol_attribute *array_attr;
> >    char *name;
> >    gfc_packed packed;
> >    int n;
> >    bool known_size;
> >  
> > -  if (sym->attr.pointer || sym->attr.allocatable
> > -      || (sym->as && sym->as->type == AS_ASSUMED_RANK))
> > +  /* Use the array as and attr.  */
> > +  as = sym->as;
> > +  array_attr = &sym->attr;
> > +
> > +  /* The pointer attribute is always set on a _data component, therefore
> > check
> > +     the sym's attribute only.  */
> > +  if (sym->attr.pointer || array_attr->allocatable
> > +      || (as && as->type == AS_ASSUMED_RANK))
> >      return dummy;
> >  
> Any reason to sometimes use array_attr, sometimes not, like here?
> By the way, the comment is misleading: for classes, there is the
> class_pointer attribute (and it is a pain, I know).

Yes, and a good one. Array_attr is sometimes sym->attr and sometimes
CLASS_DATA(sym)->attr aka sym->ts.u.derived->components->attr. In the later
case .pointer is always set to 1 in the _data component's attr. I.e., the above
if, would always yield true for a class_array, which is not intended, but rather
destructive. I know about the class_pointer attribute, but I figured, that it
is not relevant here. Any idea how to formulate the comment better, to reflect
what I just explained?

Regards,
	Andre
-- 
Andre Vehreschild * Email: vehre ad gmx dot de 

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Dear Andre and Dominique,

I have found that LOC is returning the address of the class container
rather than the _data component for class scalars. See the source
below, which you will recognise! A fix is attached.

Note that the scalar allocate fails with MOLD= and so I substituted SOURCE=.

Cheers

Paul

    class(*), allocatable :: a(:), e ! Change 'e' to an array and
second memcpy works correctly
                                     ! Problem is with loc(e), which
returns the address of the
                                     ! class container.
    allocate (e, source = 99.0)
    allocate (a(2), source = [1.0, 2.0])
    call add_element_poly (a,e)
    select type (a)
      type is (real)
        print *, a
    end select

contains

    subroutine add_element_poly(a,e)
      use iso_c_binding
      class(*),allocatable,intent(inout),target :: a(:)
      class(*),intent(in),target :: e
      class(*),allocatable,target :: tmp(:)
      type(c_ptr) :: dummy

      interface
        function memcpy(dest,src,n) bind(C,name="memcpy") result(res)
          import
          type(c_ptr) :: res
          integer(c_intptr_t),value :: dest
          integer(c_intptr_t),value :: src
          integer(c_size_t),value :: n
        end function
      end interface

      if (.not.allocated(a)) then
        allocate(a(1), source=e)
      else
        allocate(tmp(size(a)),source=a)
        deallocate(a)
        allocate(a(size(tmp)+1),source=e) ! mold gives a segfault
        dummy = memcpy(loc(a(1)),loc(tmp),sizeof(tmp))
        dummy = memcpy(loc(a(size(tmp)+1)),loc(e),sizeof(e))
      end if
    end subroutine
end

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Index: gcc/fortran/trans-intrinsic.c
===================================================================
*** gcc/fortran/trans-intrinsic.c	(revision 221500)
--- gcc/fortran/trans-intrinsic.c	(working copy)
*************** gfc_conv_intrinsic_loc (gfc_se * se, gfc
*** 7080,7086 ****

    arg_expr = expr->value.function.actual->expr;
    if (arg_expr->rank == 0)
!     gfc_conv_expr_reference (se, arg_expr);
    else
      gfc_conv_array_parameter (se, arg_expr, true, NULL, NULL, NULL);
    se->expr = convert (gfc_get_int_type (gfc_index_integer_kind), se->expr);
--- 7080,7091 ----

    arg_expr = expr->value.function.actual->expr;
    if (arg_expr->rank == 0)
!     {
!       if (arg_expr->symtree->n.sym->ts.type == BT_CLASS
! 	  && !CLASS_DATA (arg_expr->symtree->n.sym)->as)
! 	gfc_add_component_ref (arg_expr, "_data");
!       gfc_conv_expr_reference (se, arg_expr);
!     }
    else
      gfc_conv_array_parameter (se, arg_expr, true, NULL, NULL, NULL);
    se->expr = convert (gfc_get_int_type (gfc_index_integer_kind), se->expr);