Changing the order when generating a spill address

[Michael Hope]

Hi there.  The port that I'm working on has pointer registers backed
by a cache.  It's unusual as the cache changes immediately when the
pointer register is modified instead of later when it is deferenced.
This means that it is cheaper to copy a base address into the pointer
register, then add the offset as it is less likely that the cache row
will change.

Normal code such as this:
---
struct abc
{
  int a;
  char cc[64];
  int b;
};

int foo(struct abc *p)
{
  return p->a + p->b;
}
---
generates the correct code:
        LOADACC, R10
        STOREACC, X
        LOADLONG, #68
        ADD, X
        LOADACC, (X)

Code that saves or loads a value into a spill slot however does the opposite:
        LOADLONG, #16
        STOREACC, X
        LOADACC, R1E (the stack pointer)
        ADD, X
        LOADACC, R10
        STOREACC, (X)

I did a spot check on the bfin port and it does the same:
        P2 = -16 (X);
        P2 = P2 + FP;
        R0 = [P2];

Is there a way of setting the order that reload generates a spill slot
address?  I can work around it by implementing
LEGITIMIZE_RELOAD_ADDRESS but was wondering if there is a better way.

Thank you,

-- Michael