--- Comment #22 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> So MIPS fundamentally needs this feature to work correctly; whether AArch64
> needs it or may just benefit from it depends on a lot of detailed knowledge
> of the ISA and architecture. Given Richard Sandiford is currently working on
> ARM ports but also fully understands the MIPS arch then he may be a good
> person to consult.
If "this feature" is WORD_REGISTER_OPERATIONS, then I don't think that any
target, including MIPS, really needs it. Defining the macro is only an
optimization and a way to convey multiple properties of the target with only
one setting. And, for MIPS, the implementation of the sign-extension invariant
is done by other means.