src/operator/subgraph/static_shape_subgraph_property.cc

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

#include "./common.h"
#include "./subgraph_property.h"
#include "../../imperative/cached_op.h"

namespace mxnet {
namespace op {

/*!
 * This selects nodes for a subgraph that only contains static shape operators
 * and it visits nodes via both input and output links.
 */
class StaticShapeOpSelector : public SubgraphSelector {
 public:
  // select nodes with FInferShape attribute
  bool Select(const nnvm::Node& seed_node) override {
    const auto& infershape = nnvm::Op::GetAttr<mxnet::FInferShape>("FInferShape");
    return !seed_node.is_variable() && infershape.count(seed_node.op()) &&
           !unsupported_op_names_.count(seed_node.op()->name);
  }

  bool SelectInput(const nnvm::Node& cur_node, const nnvm::Node& input_node) override {
    return Select(input_node);
  }

  bool SelectOutput(const nnvm::Node& cur_node, const nnvm::Node& output_node) override {
    return Select(output_node);
  }

  // reject single node subgraph
  std::vector<nnvm::Node*> Filter(const std::vector<nnvm::Node*>& candidates) override {
    if (candidates.size() == 1) {
      return std::vector<nnvm::Node*>();
    }
    return candidates;
  }

 private:
  // Rejecte the ops that have FInferShape registered but return true by CheckDynamicShapeExists()
  std::unordered_set<std::string> unsupported_op_names_{"_npi_dstack", "_npi_hstack"};
};

/*!
 * This subgraph property finds a subgraph whose nodes have only static shape operators.
 * The operators in the subgraph will be executed by _CachedOp.
 */
class StaticShapeSubgraphProperty : public SubgraphProperty {
 public:
  StaticShapeSubgraphProperty() {
    // flag to ensure subgraph CachedOp has at least one external input
    // as required by CachedOp::Forward
    attrs_["require_subgraph_inputs"] = std::make_shared<dmlc::any>(true);
  }
  static SubgraphPropertyPtr Create() {
    return std::make_shared<StaticShapeSubgraphProperty>();
  }

  SubgraphSelectorPtr CreateSubgraphSelector() const override {
    return std::make_shared<StaticShapeOpSelector>();
  }

  void PrePartition(const nnvm::Graph& g,
                    const std::unordered_map<std::string, std::string>& options_map) override {
    options_map_.clear();
    param_name_set_.clear();
    const auto& indexed_graph = g.indexed_graph();
    for (auto& kv : options_map) {
      // update static_alloc and static_shape flags
      if (kv.first == "static_alloc" || kv.first == "static_shape") {
        if (kv.second == "True") {
          options_map_.emplace_back(kv.first, "true");
        } else {
          options_map_.emplace_back(kv.first, "false");
        }
        // update param_name_set_ for data_indices and param_indices
      } else if (kv.first == "param_indices") {
        std::string param_str = kv.second;
        int temp              = 0;
        for (int i = 0; param_str[i] != '\0'; i++) {
          if (param_str[i] == ',' || param_str[i] == '[') {
            continue;
          }
          if (param_str[i] == ' ' || param_str[i] == ']') {
            auto nid     = indexed_graph.input_nodes()[temp];
            nnvm::Node n = *(indexed_graph[nid].source);
            param_name_set_.emplace(n.attrs.name);
            temp = 0;
          } else {
            temp = temp * 10 + (param_str[i] - 48);
          }
        }
      }
    }
  }

  void InitSubgraphInputs(std::vector<nnvm::NodeEntry*>* input_entries,
                          std::vector<nnvm::NodeEntry>* orig_input_entries) const override {
    for (size_t i = 0; i < input_entries->size(); ++i) {
      nnvm::NodeEntry* e    = input_entries->at(i);
      nnvm::NodeEntry& orig = orig_input_entries->at(i);
      // set attribute for subgraph input nodes
      if (orig.node->is_variable()) {
        // get name of original output entry
        nnvm::Symbol sym;
        sym.outputs.push_back(orig);
        const auto output_names = sym.ListOutputNames();
        CHECK_EQ(output_names.size(), 1U);
        const std::string& var_name    = output_names[0];
        e->node->attrs.dict["isArg"]   = "True";
        e->node->attrs.dict["argName"] = var_name;
      } else {
        e->node->attrs.dict["isArg"] = "False";
      }
    }
  }

  nnvm::ObjectPtr CreateSubgraphNode(const nnvm::Symbol& sym,
                                     const int subgraph_id = 0) const override {
    std::vector<std::pair<std::string, std::string>> flags;
    _set_cachedop_flags(sym, &flags);
    nnvm::ObjectPtr n = nnvm::Node::Create();
    n->attrs.op       = Op::Get("_CachedOp");
    n->attrs.name     = "_static_shape_CachedOp" + std::to_string(subgraph_id);
    n->attrs.subgraphs.push_back(std::make_shared<nnvm::Symbol>(sym));
    n->attrs.parsed = std::make_shared<CachedOp>(sym, flags);
    return n;
  }

 private:
  // generate data_indices and param_indices for subgraph CachedOp node
  void _set_cachedop_flags(nnvm::Symbol symbol,
                           std::vector<std::pair<std::string, std::string>>* flags) const {
    std::vector<nnvm::ObjectPtr> inputs = symbol.ListInputs(nnvm::Symbol::ListInputOption(0));
    std::string data_indices            = "[";
    std::string param_indices           = "[";
    for (int i = 0; i < inputs.size(); i++) {
      nnvm::ObjectPtr node = inputs[i];
      if (node->attrs.dict["isArg"] == "True" &&
          param_name_set_.count(node->attrs.dict["argName"]) > 0) {
        if (param_indices.compare("[") == 0) {
          param_indices += std::to_string(i);
        } else {
          param_indices += ", " + std::to_string(i);
        }
      } else {
        if (data_indices.compare("[") == 0) {
          data_indices += std::to_string(i);
        } else {
          data_indices += ", " + std::to_string(i);
        }
      }
    }
    data_indices  = data_indices + "]";
    param_indices = param_indices + "]";
    for (auto kv : options_map_) {
      flags->emplace_back(kv);
    }
    flags->emplace_back("data_indices", data_indices);
    flags->emplace_back("param_indices", param_indices);
  }

  std::vector<std::pair<std::string, std::string>> options_map_;
  std::set<std::string> param_name_set_;
};

MXNET_REGISTER_SUBGRAPH_BACKEND(static_shape);
MXNET_REGISTER_SUBGRAPH_PROPERTY(static_shape, StaticShapeSubgraphProperty);

}  // namespace op
}  // namespace mxnet