[Bug tree-optimization/80617] [missed optimization] Storing constant in two possibly-aliased locations

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80617

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
So we end up with

void disassemble_me(A&, A&) (struct A & a, struct A & b)
{
  void * __old_val;
  void * __old_val;
  void * _7;
  void * _8;

  <bb 2> [100.00%]:
  __old_val_5 = MEM[(void * &)a_2(D)];
  MEM[(void * &)a_2(D)] = 0B;
  __old_val_6 = MEM[(void * &)b_3(D)];
  MEM[(void * &)b_3(D)] = 0B;
  _7 = MEM[(void * &)a_2(D)];
  MEM[(void * &)a_2(D)] = __old_val_6;
  if (_7 != 0B)
    goto <bb 3>; [53.47%]
  else
    goto <bb 4>; [46.53%]

  <bb 3> [53.47%]:
  free (_7);
...

which shows this issue.  I believe there's a duplicate PR for this somewhere...
(I even remember writing a patch for this).