REG_ALLOC_ORDER
If this macro is not defined, registers are used lowest numbered first (all else being equal).
One use of this macro is on machines where the highest numbered
registers must always be saved and the save-multiple-registers
instruction supports only sequences of consecutive registers. On such
machines, define REG_ALLOC_ORDER
to be an initializer that lists
the highest numbered allocatable register first.
ORDER_REGS_FOR_LOCAL_ALLOC
Store the desired register order in the array reg_alloc_order
.
Element 0 should be the register to allocate first; element 1, the next
register; and so on.
The macro body should not assume anything about the contents of
reg_alloc_order
before execution of the macro.
On most machines, it is not necessary to define this macro.