https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99830
--- Comment #5 from Segher Boessenkool <segher at gcc dot gnu.org> --- (In reply to Jakub Jelinek from comment #3) > In normal insns such clobbers would be rejected by recog, but for > DEBUG_INSNs we don't have strict validity tests, but guess we need to throw > away at least the worst garbage. combine puts clobbers of const0_rtx in instructions precisely because those *should* be rejected; it does it to abort a combination attempt. So it isn't clear to me why we end up with this here? Papering over it (as the proposed patch does) is not a good idea imho.
