sh1add     rd rs1 rs2 31..25=16 14..12=2 6..2=0x0C 1..0=3
sh2add     rd rs1 rs2 31..25=16 14..12=4 6..2=0x0C 1..0=3
sh3add     rd rs1 rs2 31..25=16 14..12=6 6..2=0x0C 1..0=3