This bug was previously mentioned in email from Denis. I have confirmed this on 4.5 (after long but educational tour of reload)
http://gcc.gnu.org/ml/gcc/2006-03/msg00783.html When stacks slots increase from zero in reload() (in my case due to setup_save_areas() ) the register elimination conditions can change. For example the AVR port has: get_frame_size () > 0 as part of frame_pointer_required_p thus FP->SP elimination can change. New slots do restart the spill and reload loop : /* If we allocated another stack slot, redo elimination bookkeeping. */ if (starting_frame_size != get_frame_size ()) continue; BUT update_eliminables is never called before calculate_needs_all_insns(), so the wrong reloads are calculated (in my case marking the FP to be spilled in the just added caller save insn !) As a consequence, a spill and reload failure occurs. The solution would seem to be to add update_eliminables before calculate_needs_all_insns (global); -- Summary: update_eliminables should be called in reload after something changes Product: gcc Version: 4.5.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: hutchinsonandy at gcc dot gnu dot org GCC host triplet: i686-pc-linux-gnu GCC target triplet: avr-unknown-none http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42204
