void addSSE(inout vector3 v1, inout vector3 v2) {
  writefln(v1.x, "-", v2.x);
  asm {
    movups XMM0, v1;
    movups XMM1, v2;
    addps XMM0, XMM1;
    movups [v1], XMM0;
  }
  writefln(v1.x, "-", v2.x);
}