Implement first D-specific optimization pass: -simplify-drtcalls. It uses the machinery of the standard -simplify-libcalls pass, but optimizes calls to the D runtime instead of calls to C libraries. At the moment, these optimizations are implemented by this pass: - Avoid the runtime call for `arr.length = newlen` if it can determine that the new length isn't longer than the old one. - Ditto for `cast(T[]) arr` if it will clearly always succeed. (e.g. if the length of the original array is zero, or if the old element size is a multiple of the new element size)

module qd1;
import qd;
void main() {
  screen(640, 480);
  sleep(1);

  cls(Red);
  sleep(1);

  cls(Green);
  sleep(1);

  cls(Blue);
  sleep(1);

//   pset(10, 10);
//   line(0, 0, 100, 100, Box, Back(Red~Black));
//   for (int i=0; i<=100; i+=10) {
//     line(i, 0, 100-i, 100);
//     line(0, i, 100, 100-i);
//   }
//   circle(100, 100, 50, 15, White~Black, Fill=White~Black);
//   paint(200, 200, Red, Back=White);
//   circle(100, 100, 50, 15, White);
//   paint(200, 200, Black);
//   pset(10, 11); pset(10, 11, Black);
//   pset(10, 10);
//   sleep(1);
}