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

[Paul Richard Thomas <paul.richard.thomas@gmail.com>]

Dear Andre,

Dominique pointed out to me that the 'loc' patch causes a ICE in the
testsuite. It seems that 'loc' should provide the address of the class
container in some places and the address of the data in others. I will
put my thinking cap on tonight :-)

Cheers

Paul

On 23 March 2015 at 13:43, Andre Vehreschild <vehre@gmx.de> wrote:
> 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
>
>
> ---------- Forwarded message ----------
> From: Paul Richard Thomas <paul.richard.thomas@gmail.com>
> To: Andre Vehreschild <vehre@gmx.de>, Dominique Dhumieres <dominiq@lps.ens.fr>
> Cc:
> Date: Sun, 22 Mar 2015 21:20:20 +0100
> Subject: Bug in intrinsic LOC for scalar class objects
> 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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