private void visit(Insn insn) {
      RegisterSpec result = insn.getResult();

      if (result != null) {
        processReg(result);
      }

      RegisterSpecList sources = insn.getSources();
      int sz = sources.size();

      for (int i = 0; i < sz; i++) {
        processReg(sources.get(i));
      }
    }
Helper for all the {@code visit*} methods.

@param insn {@code non-null;} instruction being visited
android/android_framework/dex-maker/src/main/java/com/android/dx/rop/code/BasicBlockList.java