https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122663
--- Comment #17 from rguenther at suse dot de <rguenther at suse dot de> --- On Thu, 13 Nov 2025, pinskia at gcc dot gnu.org wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122663 > > --- Comment #11 from Andrew Pinski <pinskia at gcc dot gnu.org> --- > (In reply to Andrew Pinski from comment #9) > > (In reply to Richard Biener from comment #7) > > > this shows that the way to discover the "unused leaf" does not handle > > > cycles > > > properly, as would simple_dce_from_worklist. We have > > > > > > m_9 = _7 | m_8; > > > ... > > > # m_8 = PHI <2(4), m_9(5)> > > > > > > here. > > > > yes simple_dce_from_worklist only handles the simpliest cycle case (the ssa > > name used in its own phi definition which was added with > > r14-712-g3e8f8ab5237002). Expanding it to handle the one statement case > > might be fast enough still (I wonder if this is now missed in ccp1 after > > r14-569-g21e2ef2dc25de3; I didn't see it at the time though). > > Filed pR 122678 for that. There are more cylces it does not handle than that; > but I am not sure we want to cause a huge slow down on cycle detection :). I don't think so, it's called simple for a reason.
