glfft_wisdom.hpp

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/* Copyright (C) 2015 Hans-Kristian Arntzen <maister@archlinux.us>
 *
 * Permission is hereby granted, free of charge,
 * to any person obtaining a copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is 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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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#ifndef GLFFT_WISDOM_HPP__
#define GLFFT_WISDOM_HPP__

#include <unordered_map>
#include <utility>
#include <string>
#include "glfft_common.hpp"

namespace GLFFT
{

struct WisdomPass
{
    struct
    {
        unsigned Nx;
        unsigned Ny;
        unsigned radix;
        Mode mode;
        Target input_target;
        Target output_target;
        FFTOptions::Type type;
    } pass;

    double cost;

    bool operator==(const WisdomPass &other) const
    {
        return std::memcmp(&pass, &other.pass, sizeof(pass)) == 0;
    }
};

}

namespace std
{
    template<>
    struct hash<GLFFT::WisdomPass>
    {
        std::size_t operator()(const GLFFT::WisdomPass &params) const
        {
            std::size_t h = 0;
            hash<uint8_t> hasher;
            for (std::size_t i = 0; i < sizeof(params.pass); i++)
            {
                h ^= hasher(reinterpret_cast<const uint8_t*>(&params.pass)[i]);
            }

            return h;
        }
    };
}

namespace GLFFT
{

// Adds information which depends on the GPU vendor.
// This can speed up learning process, since there will be fewer "obviously wrong" settings to test.
struct FFTStaticWisdom
{
    enum Tristate { True = 1, False = 0, DontCare = -1 };

    unsigned min_workgroup_size = 1;
    unsigned min_workgroup_size_shared = 1;
    unsigned max_workgroup_size = 128; // GLES 3.1 mandates support for this.
    unsigned min_vector_size = 2;
    unsigned max_vector_size = 4;
    Tristate shared_banked = DontCare;
};

class FFTWisdom
{
    public:
        const std::pair<double, FFTOptions::Performance> learn_optimal_options(unsigned Nx, unsigned Ny, unsigned radix,
                Mode mode, Target input_target, Target output_target, const FFTOptions::Type &type);

        void learn_optimal_options_exhaustive(unsigned Nx, unsigned Ny,
                Type type, Target input_target, Target output_target, const FFTOptions::Type &fft_type);

        const std::pair<const WisdomPass, FFTOptions::Performance>* find_optimal_options(unsigned Nx, unsigned Ny, unsigned radix,
                Mode mode, Target input_target, Target output_target, const FFTOptions::Type &base_options) const;

        const FFTOptions::Performance& find_optimal_options_or_default(unsigned Nx, unsigned Ny, unsigned radix,
                Mode mode, Target input_target, Target output_target, const FFTOptions &base_options) const;

        void set_static_wisdom(FFTStaticWisdom static_wisdom) { this->static_wisdom = static_wisdom; }
        static FFTStaticWisdom get_static_wisdom_from_renderer(const char *renderer);

        void set_bench_params(unsigned warmup, unsigned iterations, unsigned dispatches,
                double timeout)
        {
            params.warmup = warmup;
            params.iterations = iterations;
            params.dispatches = dispatches;
            params.timeout = timeout;
        }

    private:
        std::unordered_map<WisdomPass, FFTOptions::Performance> library;

        std::pair<double, FFTOptions::Performance> study(const WisdomPass &pass, FFTOptions::Type options) const;

        double bench(GLuint output, GLuint input, const WisdomPass &pass, const FFTOptions &options,
                const std::shared_ptr<ProgramCache> &cache) const;

        FFTStaticWisdom static_wisdom;

        struct
        {
            unsigned warmup = 2;
            unsigned iterations = 20;
            unsigned dispatches = 50;
            double timeout = 1.0;
        } params;
};

}

#endif