Since G_ICMP can be selected to a SUBS, we can fold shifts into such compares.
E.g.
cmp w1, w0, lsl #3 cmp w1, w0, lsr #3 cmp w1, w0, asr #3
This is done the same way as for adds and subtracts, using selectShiftedRegister.
This gives some minor code size savings on CTMark.