[Bug middle-end/67005] [5/6 Regression] ICE: in verify_loop_structure, at cfgloop.c:1647 (loop with header n not in loop tree)

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67005

--- Comment #7 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
(In reply to Marek Polacek from comment #6)
> Hm, adding || (e2->flags & EDGE_IRREDUCIBLE_LOOP) doesn't work; the E2 edge
> doesn't have the EDGE_IRREDUCIBLE_LOOP flag, even if I recompute that flag
> via mark_irreducible_loops.  So maybe set LOOPS_NEED_FIXUP every time we
> remove an edge?

I did some measurements on a GCC regtest.  The edge removal was triggered
~13000 times, but for only ~4000 out of that was "loop_exit_edge_p
(bb->loop_father, e)" true -- setting LOOPS_NEED_FIXUP unconditionally would be
maybe too expensive thus.