> P.S.: if code that is missing prototypes for stdarg functions is of no > concern, > there is another ABI alternative that might give good code density for > architectures like ARC that have pre-decrement addressing modes and allow > immediates to be pushed: > > You could put all unnamed arguments on the stack (thus simplifying varargs > processing), and leave all registers not used for argument passing call-saved. > Thus, the callers wouldn't have to worry about saving these registers or > reloading their values from the stack. > > For gcc, this would require making the call fusage really work - probably > involving a hook to tell the middle-end that the port really wants that - or a > kludge to make affected call insn not look like call insns, similar to the > sfuncs.
Unfortunately, we need to be compatible with the previous ABI for the time being. I am now investigating passing the DI like modes in non even-odd registers. The biggest challenge is how to pass such a mode partially, without introducing odd/even register classes.
