parse_gru.cpp

#include <migraphx/onnx/op_parser.hpp>
#include <migraphx/onnx/map_activation_functions.hpp>
#include <migraphx/op/common.hpp>
#include <migraphx/instruction.hpp>
#include <migraphx/ranges.hpp>
#include <migraphx/stringutils.hpp>
#include <migraphx/make_op.hpp>

namespace migraphx {
inline namespace MIGRAPHX_INLINE_NS {
namespace onnx {

struct parse_gru : op_parser<parse_gru>
{
    std::vector<op_desc> operators() const { return {{"GRU"}}; }

    std::vector<instruction_ref> parse(const op_desc& /*opd*/,
                                       const onnx_parser& parser,
                                       onnx_parser::node_info info,
                                       std::vector<instruction_ref> args) const
    {
        migraphx::shape input_shape = args[0]->get_shape();
        std::size_t hidden_size     = args[2]->get_shape().lens()[2];

        if(contains(info.attributes, "hidden_size"))
        {
            std::size_t hidden_size_att =
                parser.parse_value(info.attributes.at("hidden_size")).at<int>();
            if(hidden_size != hidden_size_att)
            {
                MIGRAPHX_THROW("GRU: hidden size mismatch in input and attribute");
            }
        }

        // Handling of direction to be added later
        std::string direction{"forward"};
        if(contains(info.attributes, "direction"))
        {
            direction = info.attributes.at("direction").s();
        }

        op::rnn_direction dirct = op::rnn_direction::forward;
        if(direction == "bidirectional")
        {
            dirct = op::rnn_direction::bidirectional;
        }
        else if(direction == "reverse")
        {
            dirct = op::rnn_direction::reverse;
        }

        std::vector<std::string> vec_names = {"sigmoid", "tanh"};
        if(contains(info.attributes, "activations"))
        {
            auto names = info.attributes.at("activations").strings();
            vec_names.clear();
            vec_names.resize(names.size());
            std::transform(names.begin(), names.end(), vec_names.begin(), [](auto name) {
                return to_lower(name);
            });
        }

        // need 4 activation functions
        if(dirct == op::rnn_direction::bidirectional)
        {
            // 4 activation functions are used in the bidirectional
            // scenario. No spec is provided in onnx::operator. we
            // use the algorithm that: if 1 actv function is provided,
            // repeat 1 four times. If 2 actv functins are provided,
            // assume forward and reverse use the same pair of actv
            // functions. For the case of 3 actv functions provided,
            // assume the 3rd one is repeated once and used by the
            // reverse direction.
            // This may need change later
            if(vec_names.size() == 1)
            {
                vec_names.insert(vec_names.end(), 3, vec_names.at(0));
            }
            else if(vec_names.size() == 2)
            {
                // repeat the activation functions
                vec_names.push_back(vec_names.at(0));
                vec_names.push_back(vec_names.at(1));
            }
            else if(vec_names.size() == 3)
            {
                vec_names.push_back(vec_names.at(2));
            }
        }
        else
        {
            if(vec_names.size() == 1)
            {
                vec_names.push_back(vec_names.at(0));
            }
        }

        auto name_it = std::find_if(vec_names.begin(), vec_names.end(), [&](auto& name) {
            return (map_activation_functions().count(name) == 0);
        });
        if(name_it != vec_names.end())
        {
            MIGRAPHX_THROW("GRU: activation function " + std::string(*name_it) + " not supported");
        }

        std::vector<operation> vec_actv_funcs(vec_names.size());
        std::transform(vec_names.begin(),
                       vec_names.end(),
                       vec_actv_funcs.begin(),
                       [&](const auto& name) { return map_activation_functions().at(name); });

        float clip = 0.0;
        if(contains(info.attributes, "clip"))
        {
            clip = parser.parse_value(info.attributes.at("clip")).at<float>();
        }

        int linear_before_reset = 0;
        if(contains(info.attributes, "linear_before_reset"))
        {
            linear_before_reset =
                parser.parse_value(info.attributes.at("linear_before_reset")).at<int>();
        }

        // append undefined opeator to make 6 arguments
        if(args.size() < 6)
        {
            auto ins = info.add_instruction(make_op("undefined"));
            args.insert(args.end(), 6 - args.size(), ins);
        }

        // first output for concatenation of hidden states
        auto hidden_states =
            info.add_instruction(make_op("gru",
                                         {{"hidden_size", hidden_size},
                                          {"actv_func", to_value(vec_actv_funcs)},
                                          {"direction", dirct},
                                          {"clip", clip},
                                          {"linear_before_reset", linear_before_reset}}),
                                 args);

        // second output for last gru output
        auto last_output = info.add_instruction(make_op("rnn_last_hs_output"), hidden_states);

        return {hidden_states, last_output};
    }
};

} // namespace onnx
} // namespace MIGRAPHX_INLINE_NS
} // namespace migraphx