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xgboost/cub/cub/agent/agent_rle.cuh  view on Meta::CPAN

#include "../block/block_scan.cuh"
#include "../block/block_exchange.cuh"
#include "../block/block_discontinuity.cuh"
#include "../grid/grid_queue.cuh"
#include "../iterator/cache_modified_input_iterator.cuh"
#include "../iterator/constant_input_iterator.cuh"
#include "../util_namespace.cuh"

/// Optional outer namespace(s)
CUB_NS_PREFIX

/// CUB namespace
namespace cub {


/******************************************************************************
 * Tuning policy types
 ******************************************************************************/

/**
 * Parameterizable tuning policy type for AgentRle
 */
template <
    int                         _BLOCK_THREADS,                 ///< Threads per thread block
    int                         _ITEMS_PER_THREAD,              ///< Items per thread (per tile of input)
    BlockLoadAlgorithm          _LOAD_ALGORITHM,                ///< The BlockLoad algorithm to use
    CacheLoadModifier           _LOAD_MODIFIER,                 ///< Cache load modifier for reading input elements
    bool                        _STORE_WARP_TIME_SLICING,       ///< Whether or not only one warp's worth of shared memory should be allocated and time-sliced among block-warps during any store-related data transpositions (versus each warp having its...
    BlockScanAlgorithm          _SCAN_ALGORITHM>                ///< The BlockScan algorithm to use
struct AgentRlePolicy
{
    enum
    {
        BLOCK_THREADS           = _BLOCK_THREADS,               ///< Threads per thread block
        ITEMS_PER_THREAD        = _ITEMS_PER_THREAD,            ///< Items per thread (per tile of input)
        STORE_WARP_TIME_SLICING = _STORE_WARP_TIME_SLICING,     ///< Whether or not only one warp's worth of shared memory should be allocated and time-sliced among block-warps during any store-related data transpositions (versus each warp having its...
    };

    static const BlockLoadAlgorithm     LOAD_ALGORITHM          = _LOAD_ALGORITHM;      ///< The BlockLoad algorithm to use
    static const CacheLoadModifier      LOAD_MODIFIER           = _LOAD_MODIFIER;       ///< Cache load modifier for reading input elements
    static const BlockScanAlgorithm     SCAN_ALGORITHM          = _SCAN_ALGORITHM;      ///< The BlockScan algorithm to use
};





/******************************************************************************
 * Thread block abstractions
 ******************************************************************************/

/**
 * \brief AgentRle implements a stateful abstraction of CUDA thread blocks for participating in device-wide run-length-encode 
 */
template <
    typename    AgentRlePolicyT,        ///< Parameterized AgentRlePolicyT tuning policy type
    typename    InputIteratorT,         ///< Random-access input iterator type for data
    typename    OffsetsOutputIteratorT, ///< Random-access output iterator type for offset values
    typename    LengthsOutputIteratorT, ///< Random-access output iterator type for length values
    typename    EqualityOpT,            ///< T equality operator type
    typename    OffsetT>                ///< Signed integer type for global offsets
struct AgentRle
{
    //---------------------------------------------------------------------
    // Types and constants
    //---------------------------------------------------------------------

    /// The input value type
    typedef typename std::iterator_traits<InputIteratorT>::value_type T;

    /// The lengths output value type
    typedef typename If<(Equals<typename std::iterator_traits<LengthsOutputIteratorT>::value_type, void>::VALUE),   // LengthT =  (if output iterator's value type is void) ?
        OffsetT,                                                                                                    // ... then the OffsetT type,
        typename std::iterator_traits<LengthsOutputIteratorT>::value_type>::Type LengthT;                           // ... else the output iterator's value type

    /// Tuple type for scanning (pairs run-length and run-index)
    typedef KeyValuePair<OffsetT, LengthT> LengthOffsetPair;

    /// Tile status descriptor interface type
    typedef ReduceByKeyScanTileState<LengthT, OffsetT> ScanTileStateT;

    // Constants
    enum
    {
        WARP_THREADS            = CUB_WARP_THREADS(PTX_ARCH),
        BLOCK_THREADS           = AgentRlePolicyT::BLOCK_THREADS,
        ITEMS_PER_THREAD        = AgentRlePolicyT::ITEMS_PER_THREAD,
        WARP_ITEMS              = WARP_THREADS * ITEMS_PER_THREAD,
        TILE_ITEMS              = BLOCK_THREADS * ITEMS_PER_THREAD,
        WARPS                   = (BLOCK_THREADS + WARP_THREADS - 1) / WARP_THREADS,

        /// Whether or not to sync after loading data
        SYNC_AFTER_LOAD         = (AgentRlePolicyT::LOAD_ALGORITHM != BLOCK_LOAD_DIRECT),

        /// Whether or not only one warp's worth of shared memory should be allocated and time-sliced among block-warps during any store-related data transpositions (versus each warp having its own storage)
        STORE_WARP_TIME_SLICING = AgentRlePolicyT::STORE_WARP_TIME_SLICING,
        ACTIVE_EXCHANGE_WARPS   = (STORE_WARP_TIME_SLICING) ? 1 : WARPS,
    };


    /**
     * Special operator that signals all out-of-bounds items are not equal to everything else,
     * forcing both (1) the last item to be tail-flagged and (2) all oob items to be marked
     * trivial.
     */
    template <bool LAST_TILE>
    struct OobInequalityOp
    {
        OffsetT         num_remaining;
        EqualityOpT      equality_op;

        __device__ __forceinline__ OobInequalityOp(
            OffsetT     num_remaining,
            EqualityOpT  equality_op)
        :
            num_remaining(num_remaining),
            equality_op(equality_op)
        {}

        template <typename Index>
        __device__ __forceinline__ bool operator()(T first, T second, Index idx)

xgboost/cub/cub/agent/agent_rle.cuh  view on Meta::CPAN

    //---------------------------------------------------------------------

    /**
     * Scan of allocations
     */
    __device__ __forceinline__ void WarpScanAllocations(
        LengthOffsetPair    &tile_aggregate,
        LengthOffsetPair    &warp_aggregate,
        LengthOffsetPair    &warp_exclusive_in_tile,
        LengthOffsetPair    &thread_exclusive_in_warp,
        LengthOffsetPair    (&lengths_and_num_runs)[ITEMS_PER_THREAD])
    {
        // Perform warpscans
        unsigned int warp_id = ((WARPS == 1) ? 0 : threadIdx.x / WARP_THREADS);
        int lane_id = LaneId();

        LengthOffsetPair identity;
        identity.key = 0;
        identity.value = 0;

        LengthOffsetPair thread_inclusive;
        LengthOffsetPair thread_aggregate = ThreadReduce(lengths_and_num_runs, scan_op);
        WarpScanPairs(temp_storage.warp_scan[warp_id]).Scan(
            thread_aggregate,
            thread_inclusive,
            thread_exclusive_in_warp,
            identity,
            scan_op);

        // Last lane in each warp shares its warp-aggregate
        if (lane_id == WARP_THREADS - 1)
            temp_storage.warp_aggregates.Alias()[warp_id] = thread_inclusive;

        CTA_SYNC();

        // Accumulate total selected and the warp-wide prefix
        warp_exclusive_in_tile          = identity;
        warp_aggregate                  = temp_storage.warp_aggregates.Alias()[warp_id];
        tile_aggregate                  = temp_storage.warp_aggregates.Alias()[0];

        #pragma unroll
        for (int WARP = 1; WARP < WARPS; ++WARP)
        {
            if (warp_id == WARP)
                warp_exclusive_in_tile = tile_aggregate;

            tile_aggregate = scan_op(tile_aggregate, temp_storage.warp_aggregates.Alias()[WARP]);
        }
    }


    //---------------------------------------------------------------------
    // Utility methods for scattering selections
    //---------------------------------------------------------------------

    /**
     * Two-phase scatter, specialized for warp time-slicing
     */
    template <bool FIRST_TILE>
    __device__ __forceinline__ void ScatterTwoPhase(
        OffsetT             tile_num_runs_exclusive_in_global,
        OffsetT             warp_num_runs_aggregate,
        OffsetT             warp_num_runs_exclusive_in_tile,
        OffsetT             (&thread_num_runs_exclusive_in_warp)[ITEMS_PER_THREAD],
        LengthOffsetPair    (&lengths_and_offsets)[ITEMS_PER_THREAD],
        Int2Type<true>      is_warp_time_slice)
    {
        unsigned int warp_id = ((WARPS == 1) ? 0 : threadIdx.x / WARP_THREADS);
        int lane_id = LaneId();

        // Locally compact items within the warp (first warp)
        if (warp_id == 0)
        {
            WarpExchangePairs(temp_storage.exchange_pairs[0]).ScatterToStriped(lengths_and_offsets, thread_num_runs_exclusive_in_warp);
        }

        // Locally compact items within the warp (remaining warps)
        #pragma unroll
        for (int SLICE = 1; SLICE < WARPS; ++SLICE)
        {
            CTA_SYNC();

            if (warp_id == SLICE)
            {
                WarpExchangePairs(temp_storage.exchange_pairs[0]).ScatterToStriped(lengths_and_offsets, thread_num_runs_exclusive_in_warp);
            }
        }

        // Global scatter
        #pragma unroll
        for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
        {
            if ((ITEM * WARP_THREADS) < warp_num_runs_aggregate - lane_id)
            {
                OffsetT item_offset =
                    tile_num_runs_exclusive_in_global +
                    warp_num_runs_exclusive_in_tile +
                    (ITEM * WARP_THREADS) + lane_id;

                // Scatter offset
                d_offsets_out[item_offset] = lengths_and_offsets[ITEM].key;

                // Scatter length if not the first (global) length
                if ((!FIRST_TILE) || (ITEM != 0) || (threadIdx.x > 0))
                {
                    d_lengths_out[item_offset - 1] = lengths_and_offsets[ITEM].value;
                }
            }
        }
    }


    /**
     * Two-phase scatter
     */
    template <bool FIRST_TILE>
    __device__ __forceinline__ void ScatterTwoPhase(
        OffsetT             tile_num_runs_exclusive_in_global,
        OffsetT             warp_num_runs_aggregate,
        OffsetT             warp_num_runs_exclusive_in_tile,
        OffsetT             (&thread_num_runs_exclusive_in_warp)[ITEMS_PER_THREAD],
        LengthOffsetPair    (&lengths_and_offsets)[ITEMS_PER_THREAD],
        Int2Type<false>     is_warp_time_slice)
    {
        unsigned int warp_id = ((WARPS == 1) ? 0 : threadIdx.x / WARP_THREADS);
        int lane_id = LaneId();

        // Unzip
        OffsetT run_offsets[ITEMS_PER_THREAD];
        LengthT run_lengths[ITEMS_PER_THREAD];

        #pragma unroll
        for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
        {
            run_offsets[ITEM] = lengths_and_offsets[ITEM].key;
            run_lengths[ITEM] = lengths_and_offsets[ITEM].value;
        }

        WarpExchangeOffsets(temp_storage.exchange_offsets[warp_id]).ScatterToStriped(run_offsets, thread_num_runs_exclusive_in_warp);

        WARP_SYNC(0xffffffff);

        WarpExchangeLengths(temp_storage.exchange_lengths[warp_id]).ScatterToStriped(run_lengths, thread_num_runs_exclusive_in_warp);

        // Global scatter
        #pragma unroll
        for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
        {
            if ((ITEM * WARP_THREADS) + lane_id < warp_num_runs_aggregate)
            {
                OffsetT item_offset =
                    tile_num_runs_exclusive_in_global +
                    warp_num_runs_exclusive_in_tile +
                    (ITEM * WARP_THREADS) + lane_id;

                // Scatter offset
                d_offsets_out[item_offset] = run_offsets[ITEM];

                // Scatter length if not the first (global) length
                if ((!FIRST_TILE) || (ITEM != 0) || (threadIdx.x > 0))
                {
                    d_lengths_out[item_offset - 1] = run_lengths[ITEM];
                }
            }
        }
    }


    /**
     * Direct scatter
     */
    template <bool FIRST_TILE>
    __device__ __forceinline__ void ScatterDirect(
        OffsetT             tile_num_runs_exclusive_in_global,
        OffsetT             warp_num_runs_aggregate,
        OffsetT             warp_num_runs_exclusive_in_tile,
        OffsetT             (&thread_num_runs_exclusive_in_warp)[ITEMS_PER_THREAD],
        LengthOffsetPair    (&lengths_and_offsets)[ITEMS_PER_THREAD])
    {
        #pragma unroll
        for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ++ITEM)
        {
            if (thread_num_runs_exclusive_in_warp[ITEM] < warp_num_runs_aggregate)
            {
                OffsetT item_offset =
                    tile_num_runs_exclusive_in_global +
                    warp_num_runs_exclusive_in_tile +
                    thread_num_runs_exclusive_in_warp[ITEM];

                // Scatter offset
                d_offsets_out[item_offset] = lengths_and_offsets[ITEM].key;

                // Scatter length if not the first (global) length
                if (item_offset >= 1)
                {
                    d_lengths_out[item_offset - 1] = lengths_and_offsets[ITEM].value;
                }
            }
        }
    }


    /**
     * Scatter
     */
    template <bool FIRST_TILE>
    __device__ __forceinline__ void Scatter(
        OffsetT             tile_num_runs_aggregate,
        OffsetT             tile_num_runs_exclusive_in_global,
        OffsetT             warp_num_runs_aggregate,
        OffsetT             warp_num_runs_exclusive_in_tile,
        OffsetT             (&thread_num_runs_exclusive_in_warp)[ITEMS_PER_THREAD],
        LengthOffsetPair    (&lengths_and_offsets)[ITEMS_PER_THREAD])
    {
        if ((ITEMS_PER_THREAD == 1) || (tile_num_runs_aggregate < BLOCK_THREADS))
        {
            // Direct scatter if the warp has any items
            if (warp_num_runs_aggregate)
            {
                ScatterDirect<FIRST_TILE>(
                    tile_num_runs_exclusive_in_global,
                    warp_num_runs_aggregate,
                    warp_num_runs_exclusive_in_tile,
                    thread_num_runs_exclusive_in_warp,
                    lengths_and_offsets);
            }
        }
        else
        {
            // Scatter two phase
            ScatterTwoPhase<FIRST_TILE>(
                tile_num_runs_exclusive_in_global,
                warp_num_runs_aggregate,
                warp_num_runs_exclusive_in_tile,
                thread_num_runs_exclusive_in_warp,
                lengths_and_offsets,
                Int2Type<STORE_WARP_TIME_SLICING>());
        }
    }



    //---------------------------------------------------------------------
    // Cooperatively scan a device-wide sequence of tiles with other CTAs
    //---------------------------------------------------------------------

    /**
     * Process a tile of input (dynamic chained scan)
     */
    template <
        bool                LAST_TILE>
    __device__ __forceinline__ LengthOffsetPair ConsumeTile(
        OffsetT             num_items,          ///< Total number of global input items
        OffsetT             num_remaining,      ///< Number of global input items remaining (including this tile)
        int                 tile_idx,           ///< Tile index
        OffsetT             tile_offset,       ///< Tile offset
        ScanTileStateT       &tile_status)       ///< Global list of tile status
    {
        if (tile_idx == 0)
        {
            // First tile

            // Load items
            T items[ITEMS_PER_THREAD];
            if (LAST_TILE)
                BlockLoadT(temp_storage.load).Load(d_in + tile_offset, items, num_remaining, T());
            else
                BlockLoadT(temp_storage.load).Load(d_in + tile_offset, items);

            if (SYNC_AFTER_LOAD)
                CTA_SYNC();

            // Set flags
            LengthOffsetPair    lengths_and_num_runs[ITEMS_PER_THREAD];

            InitializeSelections<true, LAST_TILE>(
                tile_offset,
                num_remaining,
                items,
                lengths_and_num_runs);

            // Exclusive scan of lengths and runs
            LengthOffsetPair tile_aggregate;
            LengthOffsetPair warp_aggregate;
            LengthOffsetPair warp_exclusive_in_tile;
            LengthOffsetPair thread_exclusive_in_warp;

            WarpScanAllocations(
                tile_aggregate,
                warp_aggregate,
                warp_exclusive_in_tile,
                thread_exclusive_in_warp,
                lengths_and_num_runs);

            // Update tile status if this is not the last tile
            if (!LAST_TILE && (threadIdx.x == 0))
                tile_status.SetInclusive(0, tile_aggregate);

            // Update thread_exclusive_in_warp to fold in warp run-length
            if (thread_exclusive_in_warp.key == 0)
                thread_exclusive_in_warp.value += warp_exclusive_in_tile.value;

            LengthOffsetPair    lengths_and_offsets[ITEMS_PER_THREAD];
            OffsetT             thread_num_runs_exclusive_in_warp[ITEMS_PER_THREAD];
            LengthOffsetPair    lengths_and_num_runs2[ITEMS_PER_THREAD];

            // Downsweep scan through lengths_and_num_runs
            ThreadScanExclusive(lengths_and_num_runs, lengths_and_num_runs2, scan_op, thread_exclusive_in_warp);

            // Zip

            #pragma unroll
            for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
            {
                lengths_and_offsets[ITEM].value         = lengths_and_num_runs2[ITEM].value;
                lengths_and_offsets[ITEM].key        = tile_offset + (threadIdx.x * ITEMS_PER_THREAD) + ITEM;
                thread_num_runs_exclusive_in_warp[ITEM] = (lengths_and_num_runs[ITEM].key) ?
                                                                lengths_and_num_runs2[ITEM].key :         // keep
                                                                WARP_THREADS * ITEMS_PER_THREAD;            // discard
            }

            OffsetT tile_num_runs_aggregate              = tile_aggregate.key;
            OffsetT tile_num_runs_exclusive_in_global    = 0;
            OffsetT warp_num_runs_aggregate              = warp_aggregate.key;
            OffsetT warp_num_runs_exclusive_in_tile      = warp_exclusive_in_tile.key;

            // Scatter
            Scatter<true>(
                tile_num_runs_aggregate,
                tile_num_runs_exclusive_in_global,
                warp_num_runs_aggregate,
                warp_num_runs_exclusive_in_tile,
                thread_num_runs_exclusive_in_warp,
                lengths_and_offsets);

            // Return running total (inclusive of this tile)
            return tile_aggregate;
        }
        else
        {
            // Not first tile

            // Load items
            T items[ITEMS_PER_THREAD];
            if (LAST_TILE)
                BlockLoadT(temp_storage.load).Load(d_in + tile_offset, items, num_remaining, T());
            else
                BlockLoadT(temp_storage.load).Load(d_in + tile_offset, items);

            if (SYNC_AFTER_LOAD)
                CTA_SYNC();

            // Set flags
            LengthOffsetPair    lengths_and_num_runs[ITEMS_PER_THREAD];

            InitializeSelections<false, LAST_TILE>(
                tile_offset,
                num_remaining,
                items,
                lengths_and_num_runs);

            // Exclusive scan of lengths and runs
            LengthOffsetPair tile_aggregate;
            LengthOffsetPair warp_aggregate;
            LengthOffsetPair warp_exclusive_in_tile;
            LengthOffsetPair thread_exclusive_in_warp;

            WarpScanAllocations(
                tile_aggregate,
                warp_aggregate,
                warp_exclusive_in_tile,
                thread_exclusive_in_warp,
                lengths_and_num_runs);

            // First warp computes tile prefix in lane 0
            TilePrefixCallbackOpT prefix_op(tile_status, temp_storage.prefix, Sum(), tile_idx);
            unsigned int warp_id = ((WARPS == 1) ? 0 : threadIdx.x / WARP_THREADS);
            if (warp_id == 0)
            {
                prefix_op(tile_aggregate);
                if (threadIdx.x == 0)
                    temp_storage.tile_exclusive = prefix_op.exclusive_prefix;
            }

            CTA_SYNC();

            LengthOffsetPair tile_exclusive_in_global = temp_storage.tile_exclusive;

            // Update thread_exclusive_in_warp to fold in warp and tile run-lengths
            LengthOffsetPair thread_exclusive = scan_op(tile_exclusive_in_global, warp_exclusive_in_tile);
            if (thread_exclusive_in_warp.key == 0)
                thread_exclusive_in_warp.value += thread_exclusive.value;

            // Downsweep scan through lengths_and_num_runs
            LengthOffsetPair    lengths_and_num_runs2[ITEMS_PER_THREAD];
            LengthOffsetPair    lengths_and_offsets[ITEMS_PER_THREAD];
            OffsetT             thread_num_runs_exclusive_in_warp[ITEMS_PER_THREAD];

            ThreadScanExclusive(lengths_and_num_runs, lengths_and_num_runs2, scan_op, thread_exclusive_in_warp);

            // Zip
            #pragma unroll
            for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ITEM++)
            {
                lengths_and_offsets[ITEM].value         = lengths_and_num_runs2[ITEM].value;
                lengths_and_offsets[ITEM].key        = tile_offset + (threadIdx.x * ITEMS_PER_THREAD) + ITEM;
                thread_num_runs_exclusive_in_warp[ITEM] = (lengths_and_num_runs[ITEM].key) ?
                                                                lengths_and_num_runs2[ITEM].key :         // keep
                                                                WARP_THREADS * ITEMS_PER_THREAD;            // discard
            }

            OffsetT tile_num_runs_aggregate              = tile_aggregate.key;
            OffsetT tile_num_runs_exclusive_in_global    = tile_exclusive_in_global.key;
            OffsetT warp_num_runs_aggregate              = warp_aggregate.key;
            OffsetT warp_num_runs_exclusive_in_tile      = warp_exclusive_in_tile.key;

            // Scatter
            Scatter<false>(
                tile_num_runs_aggregate,
                tile_num_runs_exclusive_in_global,
                warp_num_runs_aggregate,
                warp_num_runs_exclusive_in_tile,
                thread_num_runs_exclusive_in_warp,
                lengths_and_offsets);

            // Return running total (inclusive of this tile)
            return prefix_op.inclusive_prefix;
        }
    }


    /**
     * Scan tiles of items as part of a dynamic chained scan
     */
    template <typename NumRunsIteratorT>            ///< Output iterator type for recording number of items selected
    __device__ __forceinline__ void ConsumeRange(
        int                 num_tiles,              ///< Total number of input tiles
        ScanTileStateT&     tile_status,            ///< Global list of tile status
        NumRunsIteratorT    d_num_runs_out)         ///< Output pointer for total number of runs identified
    {
        // Blocks are launched in increasing order, so just assign one tile per block
        int     tile_idx        = (blockIdx.x * gridDim.y) + blockIdx.y;    // Current tile index
        OffsetT tile_offset     = tile_idx * TILE_ITEMS;                  // Global offset for the current tile
        OffsetT num_remaining   = num_items - tile_offset;                  // Remaining items (including this tile)

        if (tile_idx < num_tiles - 1)
        {
            // Not the last tile (full)
            ConsumeTile<false>(num_items, num_remaining, tile_idx, tile_offset, tile_status);
        }
        else if (num_remaining > 0)
        {
            // The last tile (possibly partially-full)
            LengthOffsetPair running_total = ConsumeTile<true>(num_items, num_remaining, tile_idx, tile_offset, tile_status);

            if (threadIdx.x == 0)
            {
                // Output the total number of items selected
                *d_num_runs_out = running_total.key;

                // The inclusive prefix contains accumulated length reduction for the last run
                if (running_total.key > 0)
                    d_lengths_out[running_total.key - 1] = running_total.value;
            }
        }
    }
};


}               // CUB namespace
CUB_NS_POSTFIX  // Optional outer namespace(s)



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