predicated code motion (in lim)

[Evgeniya Maenkova]

Hi,
could anyone clarify about predicated code motion in lim?

After reading a TODO in /tree-ssa-loop-im.c (see [1]) I tried several
examples, say [2]. However, in all of them the code was moved out of
the loop successfully (either by pre or by lim, as in [2]).

So my question is: what the author of this code did mean by
"predicated code motion"? (what is the TODO)

Thanks,

Evgeniya

[1]
TODO:  Support for predicated code motion.  I.e.

   while (1)
     {
       if (cond)
         {
           a = inv;
           something;
         }
     }

[2]

void foo(int cond, int inv)
{

    int a;
    int i = 0;
    int j = 0;
    while (j++ < 100) {
        while (i++ < 2000)
         {
           if (j % 2)
            {
                a = 528*j;
                printf("Hey1%d %d", a, i);//something;
             }
        }

     }
}

lim:

;; Function foo (foo, funcdef_no=0, decl_uid=1394, cgraph_uid=0, symbol_order=0)

foo (int cond, int inv)
{
  int j;
  int i;
  int a;
  unsigned int j.0_12;
  unsigned int _13;
  unsigned int _18;
  unsigned int _21;

  <bb 2>:
  goto <bb 8>;

  <bb 3>:
  if (_13 != 0)
    goto <bb 4>;
  else
    goto <bb 10>;

  <bb 10>:
  goto <bb 5>;

  <bb 4>:
  printf ("Hey1%d %d", a_14, i_11);

  <bb 5>:

  <bb 6>:
  # i_1 = PHI <i_22(8), i_11(5)>
  i_11 = i_1 + 1;
  if (i_1 <= 1999)
    goto <bb 3>;
  else
    goto <bb 7>;

  <bb 7>:
  # i_20 = PHI <i_11(6)>
  j_9 = j_23 + 1;
  if (j_23 != 100)
    goto <bb 11>;
  else
    goto <bb 9>;

  <bb 11>:

  <bb 8>:
  # i_22 = PHI <i_20(11), 0(2)>
  # j_23 = PHI <j_9(11), 1(2)>
  j.0_12 = (unsigned int) j_23;
  _13 = j.0_12 & 1;
  _21 = (unsigned int) j_23;
  _18 = _21 * 528;
  a_14 = (int) _18;
  goto <bb 6>;

  <bb 9>:
  return;

}


However, in loopinit (the optimization before lim) there was no motion
(So this was done by lim:
  <bb 4>:
  a_14 = j_23 * 528;
  printf ("Hey1%d %d", a_14, i_11);