digraph heron {
  //node [shape=circle,regular=1,style=filled,fillcolor=white];
  edge [arrowhead=odot];
  graph [overlap=scale];
  subgraph {
    edge [weight=3];
    C0 -> C1 -> C2 -> C3 -> C4 -> C5 -> C6 -> C7 -> C8 -> C9 [minlen=3.5];
  }

  // variables & constants
  mem_0         [label="mem[0]"];
  mem_i         [label="mem[i]"];
  mem_i2        [label="mem[i]",shape="box"];
  i             [label="i"];
  1             [              ];
  "1a"          [label="1"     ];
  "1b"          [label="1"     ];
  "1c"          [label="1"     ];
  "1d"          [label="1"     ];
  Finish        [label="Finish"];

  // operands
  s_shift_1 [label=">>",];
  i_lt_0   [label=">",];

  // i <= mem[0]
  mem_0 -> i:n [label="C0",style=dotted];

  0 -> i_lt_0;
  i -> i_lt_0;
  { rank=same; C0; i}
  { rank=same; C1; i_lt_0; }

  // if (i <= mem[0]) ->
  i_lt_0 -> mem_s_gte_1  [style=dotted, arrowhead=normal,label="True"];
  // else
  i_lt_0 -> Finish  [style=dotted, arrowhead=normal,label="False"];
  { rank=same; C9; Finish;}

  subgraph i_lt_0 {
    mem_s_gte_1     [label=">"];

    s_div_x         [label="/",];
    new_x           [label="+",];
    s_div_x_shift_1 [label=">>",];
    x_shift_1       [label=">>",];
    old_x_lte_new_x [label=">=",];
    dec_i           [label="-",];

    // (s > 1)
    mem_i -> mem_s_gte_1;
    "1d" -> mem_s_gte_1;
    { rank=same; C2; mem_s_gte_1}

    // if (s > 1)
    mem_s_gte_1 -> s_shift_1 [style=dotted,arrowhead=normal,label="True"];
    // else
    mem_s_gte_1 -> dec_i [style=dotted,arrowhead=normal,label="False"];

    subgraph if_mem_i_gte_1 {
      // x = s >> 1
      mem_i -> s_shift_1;
      1 -> s_shift_1;
      s_shift_1 -> x [style=dotted,arrowhead=normal,label="C2->C3"];
      { rank=same; C3; s_shift_1; x}

      // (x >> 1)
      x [shape="box"];
      x -> x_shift_1;
      "1a" -> x_shift_1;
      // (s/x)
      mem_i -> s_div_x;
      x -> s_div_x;
      { rank=same; C4; x_shift_1; s_div_x}

      // ((s/x) >> 1)
      s_div_x -> s_div_x_shift_1;
      "1b" -> s_div_x_shift_1;
      { rank=same; C5; s_div_x_shift_1}

      // (x >> 1) + ((s/x) >> 1);
      x_shift_1 -> new_x;
      s_div_x_shift_1 -> new_x;
      { rank=same; C6; new_x;}

      // (old_x <= X)
      x -> old_x_lte_new_x;
      new_x -> old_x_lte_new_x;
      new_x -> x [style=dotted,label="C7->C3"];

      { rank=same; C7; old_x_lte_new_x;}

      // if (old_x <= X)
      old_x_lte_new_x -> dec_i [style=dotted,arrowhead=normal,label="True"];
      // else
      old_x_lte_new_x -> x [style=dotted,arrowhead=normal,label="False"];

      "1c" -> dec_i;
      i -> dec_i:ne;
      dec_i:s -> i:s;
      new_x -> mem_i2 [label="C7->C8", style=dotted];
      { rank=same; C8; dec_i; mem_i2};
    }
  }
}