Use subfic (val - reg) and mulli (reg * val).

Use subfic (val - reg) and mulli (reg * val).

In the instruction list, put /* kills xer */ for sraw, srawi, subfic;
and correct the (now unused) "addi." and "lfdu".

Change MACHOPT_F from -m3 to -m2.  This changes the code for 15 * i
from

    slwi r3,r4,4
    subfic r5,r4,0
    add r3,r3,r5

to

    mulli r3,r4,15

If the sequence "slwi subfic addi" takes 3 cycles and 12 bytes, and
mulli takes 3 cycles and 4 bytes, then mulli is better.