Как получить количество активных ссылок на строку?

function GetAnsistringRefcount(const S: string): Cardinal;
asm
  or eax, eax
  jz @done
  sub eax, 8
  mov eax, dword ptr [eax]
  @done:
end;
 
procedure TForm1.Button1Click(Sender: TObject);
var
  S1, S2: string;
begin
  memo1.lines.Add(Format('Refcount at start: %d',
    [GetAnsistringRefcount(S1)]));
  S1 := StringOfChar('A', 10);
  memo1.lines.Add(Format('Refcount after assignment: %d',
    [GetAnsistringRefcount(S1)]));
  S2 := S1;
  memo1.lines.Add(Format('Refcount after S2:=S1: %d',
    [GetAnsistringRefcount(S1)]));
  S2 := S1 + S2;
  memo1.lines.Add(Format('Refcount after S2:=S1+S2: %d',
    [GetAnsistringRefcount(S1)]));
end;

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