Re: segfault with large-ish array with GNAT

[Jerry <lanceboyle@qwest.net>]

On Mar 18, 3:23 am, Ludovic Brenta <ludo...@ludovic-brenta.org> wrote:
> Jeffrey Creem wrote on comp.lang.ada:
<snip>
> > If you want the memory to come from the heap, you need to declare the
> > variables inside of packages instead of inside procedures. You can then
> > avoid using access types.
<snip>
> > package do_stuff is
> >     procedure no_bomb;
> > end do_stuff;
>
> > package body do_stuff is
> >       type Float_Array_Type is array (Integer range <>) of Long_Float;
> >       -- 1_048_343 causes segmentation fault, 1_048_342  does not.
> >       x : Float_Array_Type(1 .. 1_048_343);
>
> >      procedure No_bomb is
>
> >      begin
> >        x(1) := 1.0;
> >      end No_bomb;
> > end do_stuff;
>
> > with do_stuff;
> > procedure stuff is
>
> > begin
> >     do_stuff.No_Bomb;
> > end stuff;
>
> No, the array is not in the heap in this case; it is in the executable
> program's data segment. This may increase the size of the binary file.
>
> To ensure that the array is on the heap, it is necessary to use an
> access type and an allocator, e.g.:
>
> type Float_Array_Access_Type is access Float_Array_Type;
> x : Float_Array_Access_Type := new Float_Array_Type (1 .. 1_048_343);
>
> --
> Ludovic Brenta.

This (using a package) works. I made two Long_Float arrays of
100_000_000 length. The binary size is 292 KB (I included Text_IO)
regardless of the size of the arrays.

I'm not sure if I like the programming style better than using access
variables. I would have to essentially embed my entire program in a
package. And it seems to become impossible to selectively release
memory as is possible with access types. But it does solve my problem.

I programmed Pascal on Mac OS < 10 for years using pointers to arrays.
IIRC the stack was 32 KB.

Jerry