parse_multinomial.cpp

/*
 * The MIT License (MIT)
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 * Copyright (c) 2015-2023 Advanced Micro Devices, Inc. All rights reserved.
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 * of this software and associated documentation files (the "Software"), to deal
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 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
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 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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#include <migraphx/onnx/op_parser.hpp>
#include <migraphx/onnx/checks.hpp>
#include <migraphx/ranges.hpp>
#include <migraphx/instruction.hpp>
#include <migraphx/make_op.hpp>
#include <random>

namespace migraphx {
inline namespace MIGRAPHX_INLINE_NS {
namespace onnx {

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

    instruction_ref parse(const op_desc& /*opd*/,
                          const onnx_parser& /*parser*/,
                          const onnx_parser::node_info& info,
                          std::vector<instruction_ref> args) const
    {
        int dtype = 6;
        if(contains(info.attributes, "dtype"))
            dtype = info.attributes.at("dtype").i();
        shape::type_t output_type = get_type(dtype);

        size_t sample_size = 1;
        if(contains(info.attributes, "sample_size"))
            sample_size = info.attributes.at("sample_size").i();
        else
            MIGRAPHX_THROW("PARSE_MULTINOMIAL: sample_size not given");

        // Subtract the per-batch maximum log-probability, making the per-batch max 0
        auto maxes =
            info.add_instruction(migraphx::make_op("reduce_max", {{"axes", {1}}}), args[0]);
        auto cdf = info.add_common_op("sub", args[0], maxes);        
        // Take the element-wise exponent to get probabilities in the range (0, 1]
        cdf = info.add_instruction(migraphx::make_op("exp"), cdf);
        // Compute the cumulative density function
        cdf = info.add_instruction(
            migraphx::make_op("prefix_scan_sum", {{"axis", 1}, {"exclusive", false}}), cdf);


        // Make a shape that's the size of the sample set
        shape s0 = args[0]->get_shape();
        migraphx::shape dist_shape;

        instruction_ref rand_dummy;
        if(s0.dynamic())
        {
            dist_shape = {output_type, {s0.dyn_dims().front(), shape::dynamic_dimension({sample_size, sample_size})}};
            auto temp = info.add_instruction(make_op("dimensions_of", {{"start", 0}, {"end", s0.ndim() - 1}}), args[0]);

            auto asdf = temp->get_shape();

            rand_dummy = info.add_instruction(migraphx::make_op("multibroadcast", 
                {{"out_dyn_dims", migraphx::to_value(dist_shape)}}), args[0], temp);

            auto zap = rand_dummy->get_shape();
            printf("hello %d\n", zap.ndim());
        }
        else
        {
            // use literal
            size_t batch_size = s0.lens().front();
            dist_shape = {output_type, {batch_size, sample_size}};
            rand_dummy = info.add_literal(migraphx::literal{dist_shape, {batch_size, sample_size}});



            // mul_random = info.add_instruction(migraphx::make_op("multibroadcast", 
            //     {{"out_lens", migraphx::to_value(dist_shape)}}), args[0]);
            // migraphx::shape dist_shape{migraphx::shape::float_type, {batch_size, sample_size}};
        }



        // auto mul_random = info.add_instruction(migraphx::make_op("multibroadcast"
        // ,{{"out_dyn_dims", migraphx::to_value(b)}}
        // ), s0, dist_shape);

        uint32_t seed(0);
        if(contains(info.attributes, "seed"))
            seed = info.attributes.at("seed").i();

// how to populate data when dist_shape is dynamic?  Answer: just send dist_shape`
    // std::vector<float> data(dist_shape.elements(), 0.f);
    // auto dummy              = info.add_literal(migraphx::literal(dist_shape, data));
    auto randoms = info.add_instruction(migraphx::make_op("rand_uniform", {{"seed", seed}}), rand_dummy);
       

        return info.add_instruction(
            migraphx::make_op("multinomial", {{"dtype", output_type}}), cdf, randoms);
    }
};

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