where are caller-save addresses legitimized?

[Greg McGary]

reload() > setup_save_areas() > assign_stack_local_1() creates a mem 
address whose offset too large to fit into the machine insn's offset 
operand.  Later, reload() > save_call_clobbered_regs() > insert_save() > 
adjust_address_1() > change_address_1() asserts because the address is 
not legitimate.

My port defines all the address legitimizing target hooks, but none are 
called with the address in question.  Where/how is the address supposed 
to be fixed-up in this case?  Or, where/how does gcc avoid producing an 
illegitimate address in the first place?

G