Re: Allocation question

[Ludovic Brenta <ludovic@ludovic-brenta.org>]

Jacob Sparre Andersen wrote on comp.lang.ada:
> Is there something which prevents an Ada compiler from allocating
> large, local objects on the heap rather than on the stack?
>
> Would it be very complicated to introduce a rule in a compiler (not in
> the language), which makes local objects larger than some limit be
> allocated on the stack?

An interesting thought. I just re-read 3.11 and it only says that
declarative_parts are "elaborated". 3.3.1(18/2) is similarly terse on
object_declarations, saying only that "the object is created". The RM
doesn't seem to have a concept of a stack at all; this is left to the
implementation. So, I suppose you are correct that a compiler can
choose to allocate everything on the heap. In fact, I suspect that
that's what compilers targetting the Java virtual machine have to do.

For other targets, I guess it would make sense for some compilers to
introduce a pragma allowing the programmer to specify where the object
should be. For heap-allocated objects, I don't think it would be
overly difficult to replace an object_declaration with a synthetic
controlled object that encapsulates it in the manner I described
earlier.

--
Ludovic Brenta.