Method scn_do_execute

src/opr/impl/loop/grad.cpp:237–268

}

void LoopGrad::AssignorGradOpr::scn_do_execute() {
    if (should_fwd()) {
        rofwd_execute();
        return;
    }
    auto&& prev_gsum = m_state->prev_gsum;
    auto&& dest = output(0)->dev_tensor();
    if (prev_gsum.empty()) {
        // first execution in a loop

        if (m_assignor_grad) {
            auto&& src = m_assignor_grad->dev_tensor();
            if (dest.raw_ptr() != src.raw_ptr()) {
                dest.copy_from_fixlayout(src);
            } else {
                mgb_assert(dest.layout().eq_layout(src.layout()));
            }
        } else {
            fill_zero_dev_tensor(dest);
        }
        return;
    }
    if (m_assignor_grad) {
        auto&& src = m_assignor_grad->dev_tensor();
        opr::Elemwise::perform(
                opr::Elemwise::Mode::ADD, const_cast<DeviceTensorND&>(dest),
                {src, prev_gsum}, m_state->accum_state.adder);
    } else {
        dest.copy_from_fixlayout(prev_gsum);
    }
    m_state->accum_state.reset();
}

cg::OperatorNodeBase* LoopGrad::AssignorGradOpr::shallow_copy(
        const VarNodeArray& inputs, const OperatorNodeConfig& config) const {