private RegisterSpec getNextMoveResultPseudo() {
      int label = block.getPrimarySuccessor();

      if (label < 0) {
        return null;
      }

      Insn insn = method.getBlocks().labelToBlock(label).getInsns().get(0);

      if (insn.getOpcode().getOpcode() != RegOps.MOVE_RESULT_PSEUDO) {
        return null;
      } else {
        return insn.getResult();
      }
    }
Looks forward to the current block's primary successor, returning the RegisterSpec of the
result of the move-result-pseudo at the top of that block or null if none.

@return {@code null-ok;} result of move-result-pseudo at the beginning of primary successor
android/android_framework/dex-maker/src/main/java/com/android/dx/dex/code/RopTranslator.java