ADDRESS_COST cleanups

[Michael Hayes]

Jan Hubicka writes:

 > I've rewrite it to function using decompose_address, but I've hit problem in
 > cse, that calls address_cost even for badly formed addresses.  It looks like
 > calling of problems here (also because currently cse will ignore correctly
 > formed ones when the badly formed one appears cheaper), so I've made new
 > function address_cost that calls ADDRESS_COST only for correct addresses and
 > gives high cost to the incorrect ones.

On many targets the address cost is dependent upon the choice of the
other operands within the instruction.  I wonder if we should add an
additional piece of context, such as the current insn, when
ADDRESS_COST is called?

Michael.