...
while True do
begin
  op := Bytecode.Code[pc];
  Inc(pc);
  BIN_SUB:
    begin
      right := frame.Pop();
      frame.Top.SUB(right, bytecode.Variables[op.arg]);
      frame.SetTop(bytecode.Variables[op.arg]);
    end;
  BIN_MUL:
    begin
      right := frame.Pop();
      frame.Top.MUL(right, bytecode.Variables[op.arg]);
      frame.SetTop(bytecode.Variables[op.arg]);
    end;
...

procedure SetIntDest(var dest:TEpObject; constref value:epInt); inline;
begin
  if dest is TIntObject then
    TIntObject(dest).value := value
  else
  begin
    if not(dest is TNoneObject) then dest.Free;
    dest := TIntObject.Create(value);
  end;
end;

...

procedure TIntObject.MUL(other:TEpObject; var dest:TEpObject);
begin
  if (other is TIntObject) then
    SetIntDest(dest, self.value * TIntObject(other).value)
  else if (other is TFloatObject) then
    SetFloatDest(dest, self.value * TFloatObject(other).value)
  else
    inherited;
end;