[Bug ada/62042] New: Missing optimization of copying non-limited objects

["porton at narod dot ru" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62042

            Bug ID: 62042
           Summary: Missing optimization of copying non-limited objects
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: ada
          Assignee: unassigned at gcc dot gnu.org
          Reporter: porton at narod dot ru

The below program, compiled with GNAT 4.9, calls Adjust two times whenÂ
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 awayÂ
for greater performance. Ada Reference Manual allowsÂthis 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

ÂÂÂtype T1 is new Ada.Finalization.Controlled with null record;
ÂÂÂtype T2 is new Ada.Finalization.Limited_Controlled with null record;

ÂÂÂoverriding procedure Adjust(Object: in out T1) is
ÂÂÂbegin
ÂÂÂÂÂÂAda.Text_IO.Put_Line("Adjust");
ÂÂÂend;

ÂÂÂfunction F return T1 is
ÂÂÂbegin
ÂÂÂÂÂÂreturn (Ada.Finalization.Controlled with null record);
ÂÂÂend;

ÂÂÂfunction F return T2 is
ÂÂÂbegin
ÂÂÂÂÂÂreturn (Ada.Finalization.Limited_Controlled with null record);
ÂÂÂend;

ÂÂÂX: T1 := F;
ÂÂÂY: T2 := F;

begin
ÂÂÂnull;
end;