TODO.rst

Graphviz:

• visualize exits
• apply toposort to joins
• select nice headport for blue edges
• visualize loops as clusters

Ideas for later:

• improve joins structuralization:

  • try to ensure the final join actually has an edge to after

  • try to ensure sequential blocks actually have edges between them

  • try to sort switch cases by value

  • for switches, try to maximize number of edges to the break block, or skip it entirely if after has lots of in-edges

  • make the join order deterministic

  • print unnatural loops specially somehow (at least note that they exist...)

  • emit more complex structures when useful?

    A:
    a();
    if (0) {
      B:
      b();
    }
    c();
    

• for joinless ifs, move the heavier branch out:

  if (x) {
    a();
    b();
    c();
    return;
  } else {
    d();
    return;
  }
  

  into:

  if (!x) {
    d();
    return;
  }
  a();
  b();
  c();
  return;
  

• loop improvements:

  • detect do while / for through single loop head jump
  • try detecting glued loop heads?
  • allow manually specifying loop breaks
  • improve loop break selection heuristics:
    • make it deterministic
    • like above, try to maximize break weight, all else being equal
    • if settling for a break at an exit, make sure it's actually used more than once
    • perhaps lower the priority of break-at-exit drastically, or remove it altogether? Just about the only useful case is connecting this loop's break to parent's break/continue...
    • consider long chains of blocks ending with a noreturn call as well (need to partially reverse half-structuralization for these?)

• if a return block contains no interesting instructions and has incoming gotos, just change them to a "return"

• convert if trees to switches [requires a better input format]

• maybe convert switches to ifs/subswitches when common exits are involved, eg.

  switch (x) {
    case 0:
      a();
      goto C;
    case 1:
      b();
    C:
      c();
      break;
    case 2:
      d();
      goto F;
    case 3:
      e();
    F:
      f();
      break;
  }
  

  into:

  if (x == 0 || x == 1) {
    if (x == 0) {
      a();
    } else {
      b();
    }
    c();
  } else if (x == 2 || x == 3) {
    if (x == 2) {
      d();
    } else if (x == 3) {
      e();
    }
    f();
  }
  

  or find another way to deal with common switch paths.