242     if (Occupied.is_null() && Unused.is_null() && Known.is_null() &&  in checkConsistency()
243         Written.is_null())  in checkConsistency()
246     assert(!Occupied.is_null() || !Unused.is_null());  in checkConsistency()
247     assert(!Known.is_null());  in checkConsistency()
248     assert(!Written.is_null());  in checkConsistency()
251     if (Occupied.is_null() || Unused.is_null())  in checkConsistency()
277     return (Occupied.is_null() || Unused.is_null()) && !Known.is_null() &&  in isUsable()
278            !Written.is_null();  in isUsable()
284       if (!Occupied.is_null())  in print()
288       if (!Unused.is_null())  in print()
302     assert(!Unused.is_null() && !That.Occupied.is_null());  in learnFrom()
304         That.Unused.is_null() &&  in learnFrom()
306     assert(Occupied.is_null() && "This function does not implement "  in learnFrom()
339     assert(!Existing.Unused.is_null());  in isConflicting()
340     assert(!Proposed.Occupied.is_null());  in isConflicting()
343     if (!Existing.Occupied.is_null() && !Proposed.Unused.is_null()) {  in isConflicting()
874     if (PerPHIWrites.is_null()) {  in tryMapPHI()
1210     if (EltUnused.is_null() || EltKnown.is_null() || EltWritten.is_null()) {  in computeZone()