Method optimize_fwd_graph

src/opr/impl/loop/forward.cpp:430–493

}

void Loop::optimize_fwd_graph(int level, FwdDesc& desc) {
    // setup endpoints
    VarNodeArray endpoints;
    endpoints.reserve(desc.all_inputs().size() + desc.output_record_spec().size());
    for (auto i : desc.all_inputs()) {
        if (i->param().has_assign) {
            endpoints.push_back(i->assignor());
        }
    }
    for (auto&& i : desc.output_record_spec()) {
        endpoints.push_back(i.var_sub());
    }
    auto cond = desc.loop_cond_manager().var();
    mgb_throw_if(!cond.node(), GraphError, "loop condition not set");
    endpoints.push_back(cond.node());

    // optimize also extra_vardeps
    size_t nr_extra_deps = 0;
    auto&& extra_deps = desc.sub_graph()->options().extra_vardeps;
    {
        auto on_opr = [&](OperatorNodeBase* opr) {
            for (auto i : opr->output()) {
                auto&& iter = extra_deps.find(i);
                if (iter != extra_deps.end()) {
                    nr_extra_deps += iter->second.size();
                    endpoints.insert(
                            endpoints.end(), iter->second.begin(), iter->second.end());
                    extra_deps.erase(iter);
                }
            }
        };
        cg::DepOprIter opr_iter{on_opr};
        for (size_t i = 0; i < endpoints.size(); ++i) {
            opr_iter.add(endpoints[i]->owner_opr());
        }
    }

    // apply opt and reset vars
    gopt::GraphOptimizer()
            .add_preset_passes()
            .verbosity(0)
            .enable_check_result(level < 0)
            .apply_inplace(endpoints);

    auto ep_iter = endpoints.begin();
    for (auto i : desc.all_inputs()) {
        if (i->param().has_assign) {
            i->set_assignor(*(ep_iter++));
        }
    }
    for (auto&& i : desc.output_record_spec()) {
        const_cast<OutputRecordSpecItem&>(i).var_sub(*(ep_iter++));
    }
    desc.loop_cond_manager().setup(*(ep_iter++));

    auto&& cond_deps = extra_deps[desc.loop_cond_manager().var().node()];
    for (size_t i = 0; i < nr_extra_deps; ++i) {
        cond_deps.push_back(*(ep_iter++));