[Bug middle-end/116503] wrong code with -O -fnon-call-exceptions -finstrument-functions -floop-nest-optimize -fno-tree-scev-cprop

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116503

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2024-08-28

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
[scheduler] original ast:
{
  S_21();
  for (int c0 = 0; c0 <= P_53 - P_95 + 6; c0 += 1)
    S_7(c0);
  S_8();
  for (int c0 = 0; c0 <= 3; c0 += 1)
    S_9(c0);
}

[scheduler] AST generated by isl:
{
  if (P_95 + 1 == P_53) {
    S_7(0);
    S_21();
  } else if (P_95 >= P_53 + 1) {
    S_8();
  }
  for (int c0 = P_53 + 1; c0 < P_95; c0 += 2)
    S_9((-P_53 + c0 - 1) / 2);
  if (P_95 >= P_53 + 1) {
    S_7(0);
    S_21();
    if ((P_53 - P_95 + 1) % 2 == 0)
      S_9((-P_53 + P_95 - 1) / 2);
  } else if (P_95 + 1 == P_53) {
    S_7(1);
    S_8();
  } else {
    S_7(0);
    S_21();
    S_8();
  }
  for (int c0 = max(P_53 + 1, P_95 + 1); c0 <= P_53 + 6; c0 += 1) {
    S_7(-P_95 + c0);
    if ((P_53 - c0 + 1) % 2 == 0)
      S_9((-P_53 + c0 - 1) / 2);
  }
  S_9(3);
}

weird.