https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63359
--- Comment #12 from Richard Earnshaw <rearnsha at gcc dot gnu.org> --- We considered that, but it won't work. For example, in ILP32 address registers need to use the X form, but are still 32-bits in size. There are other cases as well where a W or X form is required but that is not the natural size of the object.
