https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123914
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- Yeah, having both *_BIT* and *_UNIT* is inconsistent across tree and RTL. But I guess consistency within tree and RTL would be very much appreciated. There's also GET_MODE_UNIT_SIZE, while GET_MODE_SIZE is byte size. We do not have any non-byte BITS_PER_UNIT target left, but unless we want to scrap that I'd say GET_MODE_SIZE should be GET_MODE_BYTE_SIZE, it's even more confusing to have a non-UNIT scaled size anywhere.
