Re: GNAT 4.9 - missing optimization feature?

[Victor Porton <porton@narod.ru>]

Victor Porton wrote:

> The below program, compiled with GNAT 4.9, calls Adjust two times when
> copying a T1 object.
> 
> But it does the same operations with a T2 object without calling Adjust.
> 
> So calling Adjust on a T1 object is here redundant and can be optimized
> away for greater performance. If I recall correctly, Ada Reference Manual
> allows this kind of optimization.
> 
> So GNAT is not as good as I expected, isn't it?
> 
> with Ada.Finalization;
> with Ada.Text_IO;
> 
> procedure Main is
> 
>    type T1 is new Ada.Finalization.Controlled with null record;
>    type T2 is new Ada.Finalization.Limited_Controlled with null record;
>    
>    overriding procedure Adjust(Object: in out T1) is
>    begin
>       Ada.Text_IO.Put_Line("Adjust");
>    end;
> 
>    function F return T1 is
>    begin
>       return (Ada.Finalization.Controlled with null record);
>    end;
>    
>    function F return T2 is
>    begin
>       return (Ada.Finalization.Limited_Controlled with null record);
>    end;
>    
>    X: T1 := F;
>    Y: T2 := F;
> 
> begin
>    null;
> end;

Is it true that this kind of optimization is legitimate accordingly ARM?

-- 
Victor Porton - http://portonvictor.org