private Dop findExpandedOpcodeForInsn(DalvInsn insn) {
    Dop result = findOpcodeForInsn(insn.getLowRegVersion(), insn.getOpcode());
    if (result == null) {
      throw new DexException("No expanded opcode for " + insn);
    }
    return result;
  }
Finds the proper opcode for the given instruction, ignoring register constraints.

@param insn {@code non-null;} the instruction in question
@return {@code non-null;} the opcode that fits
android/android_framework/dex-maker/src/main/java/com/android/dx/dex/code/OutputFinisher.java