Add macros to get opcode of instructions approriately

LoongArch: Add macros to get opcode and register of instructions appropriately

Currently, we get opcode of an instruction by manipulate the binary with
it's mask, it's a bit of a pain. Now a macro is defined to do this and a
macro to get the RD and RJ registers which is applicable to most instructions
of LoongArch are added.
4 files changed