https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78516
--- Comment #10 from Vladimir Makarov <vmakarov at gcc dot gnu.org> --- (In reply to Peter Bergner from comment #8) > where "src" is the subreg:SI ..., so the new_reg mode will be SImode and we > then replace the whole SET_SRC (curr_insn_set) which is the subreg:SI > (reg:DF ...) which doesn't seem correct. > > Vlad, should we have never got this far into check_and_process_move() with > this type of insn? Adding an ugly hack that creates an early out for this > insn (ie, set (reg:SI) (subreg:SI (reg:DF))) seems to make us compile. > I believe we should process this insn in check_and_process_move. It is the single place to check secondary reload hooks and insns. > If we are supposed to still process this insn, then how about something like > the following patch that creates a new_reg with the mode of the src register > and not the subreg and then replacing that instead of the entire subreg src? > This too eliminates the SEGV/ICE. I think creating a new reg from the register instead of the sub-register is safer. Also it results in a better code too, if the subregister is a paradoxical one, So the patch idea is right. But I believe it is not finished. I am attaching a new version of the patch. If it is ok, I can commit it after your confirmation.
