[Bug tree-optimization/110540] [14 Regression] Dead Code Elimination Regression since r14-1163-gd8b058d3ca4

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110540

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2023-07-06
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

After threadfull2 we have:
  # VUSE <.MEM_17>
  _6 = *f.3_5;
  # VUSE <.MEM_17>
  _7 = *_6;
  if (_7 <= 0)
    goto <bb 3>; [5.50%]
  else
    goto <bb 6>; [94.50%]

  <bb 3> [local count: 55807731]:
  # .MEM_19 = VDEF <.MEM_17>
  *_6 = 0;
  # VUSE <.MEM_19>
  _10 = *f.3_5;
  if (_10 != 0B)
    goto <bb 5>; [0.00%]
  else
    goto <bb 4>; [100.00%]


But there is nothing which will optimize the load of *f.3_5 to be _6 before
vrp2 (which is the next pass).

There seems to be some other issues earlier on which gets us to that IR that
late but I am not sure how ...