https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91274
--- Comment #4 from Bill Schmidt <wschmidt at gcc dot gnu.org> --- The short answer is history. Those others were inherited from the old Altivec PIM. Having splat-immediates with different names for different sizes and signedness isn't consistent with the rest of the vector architecture, which uses overloading to accomplish the same thing with fewer names to remember. So it wasn't deemed necessary to require all compilers to add yet another redundant interface when VSX came along. We could add the interfaces you request to GCC, but using them would be non-portable across compilers, and therefore they wouldn't be recommended. Adding to the list of interfaces to be supported by all compilers can be done, but will take time to propagate everywhere, and until then they would still not be recommended. So I'm not sure you really want to go that way. But if you do, feel free to re-open this as a feature request.
