/* List the order in which to allocate registers.  Each register must be
listed once, even those in FIXED_REGISTERS.

We allocate in the following order:
$f10-$f15        (nonsaved floating-point register)
$f22-$f30        (likewise)
$f21-$f16        (likewise, but input args)
$f0          (nonsaved, but return value)
$f1          (nonsaved, but immediate before saved)
$f2-$f9      (saved floating-point registers)                               
$1-$8        (nonsaved integer registers)
$22-$25      (likewise)
$28          (likewise)
$0           (likewise, but return value)
$21-$16      (likewise, but input args)
$27          (procedure value in OSF, nonsaved in NT)
$9-$14       (saved integer registers)
$26          (return PC)
$15          (frame pointer)
$29          (global pointer)
$30, $31, $f31   (stack pointer and always zero/ap & fp)  */

