https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83565
--- Comment #15 from Eric Botcazou <ebotcazou at gcc dot gnu.org> --- > Thanks Jim, that makes sense. It seems to me that WORD_REGISTER_OPERATIONS > should still be true on ia64 given the description in the documentation. I disagree, WORD_REGISTER_OPERATIONS means that the (general) registers are always modified as a whole by arithmetic operations. If that isn't the case, then the macro should not be defined (e.g Aarch64 doesn't define it although ARM does). > This regression was introduced in r242326, which added the `&& !REG_P > (SUBREG_REG (x))` to nonzero_bits1, thereby assuming that the high bits were > defined, which is a target-specific assumption. No, see above, WORD_REGISTER_OPERATIONS means that the bits are defined.
