https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68543
--- Comment #3 from ktkachov at gcc dot gnu.org --- After some discussion on IRC, WORD_REGISTER_OPERATIONS seems wrong for aarch64 since 32-bit operations i.e. in SImode operate like normal 32-bit operations because they use the 32-bit W-form of the registers. Thus they don't behave like word_mode operations, because word_mode is DImode on aarch64. So we may want to look at implementing the standard names after all
