[Bug tree-optimization/106663] New: FSM threading doesn't handle computed goto

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106663

            Bug ID: 106663
           Summary: FSM threading doesn't handle computed goto
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rguenth at gcc dot gnu.org
  Target Milestone: ---

For the following B->C isn't threaded but it seems the code is/was halfway
there.  With ranger we won't ever get &C as range for the goto destination
though, so whether the thread copier handles things correctly is unknown.

unsigned g;
void FSM (int start)
{
  void *states[] = { &&A, &&B, &&C, &&E };
  void *state = states[start];

  do {
  goto *state;

A:
  g += 1;
  state = g & 1 ? &&B : &&E;
  continue;

B:
  g += 2;
  state = &&C;
  continue;

C:
  g += 3;
  state = states[g & 3];
  continue;

E:
  break;
  } while (1);
}