if (trip_count <= 0) return failure();

    // TODO(fengliuai): use loopUnrollByFactor once the iter_arg is supported

    Block *single_block = for_op.getBody();
    IRMapping mapping;
    Value iv = for_op.getInductionVar();
    for (auto iter_op :
         llvm::zip(for_op.getRegionIterArgs(), for_op.getInitArgs())) {
      mapping.map(std::get<0>(iter_op), std::get<1>(iter_op));
    }
    mapping.map(iv, for_op.getLowerBound());