Passing function arguments in registers

[Michael P. Hayes]

The c4x port I have been working on requires a weird function argument
passing model to be compatible with the vendor's compiler.  The order
that registers are allocated depends on the number of floating point
arguments passed.  To date, I have hacked calls.c and function.c to
include a macro FUNCTION_ARG_PRESCAN, which is used during a first
pass scan to allow the backend to determine the types of arguments to
expect.  Can someone suggest a better strategy or have I missed
something obvious?

Michael.