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tools/cub-1.8.0/cub/device/device_select.cuh 18.4 KB
8dcb6dfcb   Yannick Estève   first commit
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  /******************************************************************************
   * Copyright (c) 2011, Duane Merrill.  All rights reserved.
   * Copyright (c) 2011-2018, NVIDIA CORPORATION.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *     * Redistributions of source code must retain the above copyright
   *       notice, this list of conditions and the following disclaimer.
   *     * Redistributions in binary form must reproduce the above copyright
   *       notice, this list of conditions and the following disclaimer in the
   *       documentation and/or other materials provided with the distribution.
   *     * Neither the name of the NVIDIA CORPORATION nor the
   *       names of its contributors may be used to endorse or promote products
   *       derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL NVIDIA CORPORATION BE LIABLE FOR ANY
   * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   ******************************************************************************/
  
  /**
   * \file
   * cub::DeviceSelect provides device-wide, parallel operations for compacting selected items from sequences of data items residing within device-accessible memory.
   */
  
  #pragma once
  
  #include <stdio.h>
  #include <iterator>
  
  #include "dispatch/dispatch_select_if.cuh"
  #include "../util_namespace.cuh"
  
  /// Optional outer namespace(s)
  CUB_NS_PREFIX
  
  /// CUB namespace
  namespace cub {
  
  
  /**
   * \brief DeviceSelect provides device-wide, parallel operations for compacting selected items from sequences of data items residing within device-accessible memory. ![](select_logo.png)
   * \ingroup SingleModule
   *
   * \par Overview
   * These operations apply a selection criterion to selectively copy
   * items from a specified input sequence to a compact output sequence.
   *
   * \par Usage Considerations
   * \cdp_class{DeviceSelect}
   *
   * \par Performance
   * \linear_performance{select-flagged, select-if, and select-unique}
   *
   * \par
   * The following chart illustrates DeviceSelect::If
   * performance across different CUDA architectures for \p int32 items,
   * where 50% of the items are randomly selected.
   *
   * \image html select_if_int32_50_percent.png
   *
   * \par
   * The following chart illustrates DeviceSelect::Unique
   * performance across different CUDA architectures for \p int32 items
   * where segments have lengths uniformly sampled from [1,1000].
   *
   * \image html select_unique_int32_len_500.png
   *
   * \par
   * \plots_below
   *
   */
  struct DeviceSelect
  {
      /**
       * \brief Uses the \p d_flags sequence to selectively copy the corresponding items from \p d_in into \p d_out.  The total number of items selected is written to \p d_num_selected_out. ![](select_flags_logo.png)
       *
       * \par
       * - The value type of \p d_flags must be castable to \p bool (e.g., \p bool, \p char, \p int, etc.).
       * - Copies of the selected items are compacted into \p d_out and maintain their original relative ordering.
       * - \devicestorage
       *
       * \par Snippet
       * The code snippet below illustrates the compaction of items selected from an \p int device vector.
       * \par
       * \code
       * #include <cub/cub.cuh>       // or equivalently <cub/device/device_select.cuh>
       *
       * // Declare, allocate, and initialize device-accessible pointers for input, flags, and output
       * int  num_items;              // e.g., 8
       * int  *d_in;                  // e.g., [1, 2, 3, 4, 5, 6, 7, 8]
       * char *d_flags;               // e.g., [1, 0, 0, 1, 0, 1, 1, 0]
       * int  *d_out;                 // e.g., [ ,  ,  ,  ,  ,  ,  ,  ]
       * int  *d_num_selected_out;    // e.g., [ ]
       * ...
       *
       * // Determine temporary device storage requirements
       * void     *d_temp_storage = NULL;
       * size_t   temp_storage_bytes = 0;
       * cub::DeviceSelect::Flagged(d_temp_storage, temp_storage_bytes, d_in, d_flags, d_out, d_num_selected_out, num_items);
       *
       * // Allocate temporary storage
       * cudaMalloc(&d_temp_storage, temp_storage_bytes);
       *
       * // Run selection
       * cub::DeviceSelect::Flagged(d_temp_storage, temp_storage_bytes, d_in, d_flags, d_out, d_num_selected_out, num_items);
       *
       * // d_out                 <-- [1, 4, 6, 7]
       * // d_num_selected_out    <-- [4]
       *
       * \endcode
       *
       * \tparam InputIteratorT       <b>[inferred]</b> Random-access input iterator type for reading input items \iterator
       * \tparam FlagIterator         <b>[inferred]</b> Random-access input iterator type for reading selection flags \iterator
       * \tparam OutputIteratorT      <b>[inferred]</b> Random-access output iterator type for writing selected items \iterator
       * \tparam NumSelectedIteratorT  <b>[inferred]</b> Output iterator type for recording the number of items selected \iterator
       */
      template <
          typename                    InputIteratorT,
          typename                    FlagIterator,
          typename                    OutputIteratorT,
          typename                    NumSelectedIteratorT>
      CUB_RUNTIME_FUNCTION __forceinline__
      static cudaError_t Flagged(
          void*               d_temp_storage,                ///< [in] %Device-accessible allocation of temporary storage.  When NULL, the required allocation size is written to \p temp_storage_bytes and no work is done.
          size_t                      &temp_storage_bytes,            ///< [in,out] Reference to size in bytes of \p d_temp_storage allocation
          InputIteratorT              d_in,                           ///< [in] Pointer to the input sequence of data items
          FlagIterator                d_flags,                        ///< [in] Pointer to the input sequence of selection flags
          OutputIteratorT             d_out,                          ///< [out] Pointer to the output sequence of selected data items
          NumSelectedIteratorT         d_num_selected_out,                 ///< [out] Pointer to the output total number of items selected (i.e., length of \p d_out)
          int                         num_items,                      ///< [in] Total number of input items (i.e., length of \p d_in)
          cudaStream_t                stream             = 0,         ///< [in] <b>[optional]</b> CUDA stream to launch kernels within.  Default is stream<sub>0</sub>.
          bool                        debug_synchronous  = false)     ///< [in] <b>[optional]</b> Whether or not to synchronize the stream after every kernel launch to check for errors.  May cause significant slowdown.  Default is \p false.
      {
          typedef int                     OffsetT;         // Signed integer type for global offsets
          typedef NullType                SelectOp;       // Selection op (not used)
          typedef NullType                EqualityOp;     // Equality operator (not used)
  
          return DispatchSelectIf<InputIteratorT, FlagIterator, OutputIteratorT, NumSelectedIteratorT, SelectOp, EqualityOp, OffsetT, false>::Dispatch(
              d_temp_storage,
              temp_storage_bytes,
              d_in,
              d_flags,
              d_out,
              d_num_selected_out,
              SelectOp(),
              EqualityOp(),
              num_items,
              stream,
              debug_synchronous);
      }
  
  
      /**
       * \brief Uses the \p select_op functor to selectively copy items from \p d_in into \p d_out.  The total number of items selected is written to \p d_num_selected_out. ![](select_logo.png)
       *
       * \par
       * - Copies of the selected items are compacted into \p d_out and maintain their original relative ordering.
       * - \devicestorage
       *
       * \par Performance
       * The following charts illustrate saturated select-if performance across different
       * CUDA architectures for \p int32 and \p int64 items, respectively.  Items are
       * selected with 50% probability.
       *
       * \image html select_if_int32_50_percent.png
       * \image html select_if_int64_50_percent.png
       *
       * \par
       * The following charts are similar, but 5% selection probability:
       *
       * \image html select_if_int32_5_percent.png
       * \image html select_if_int64_5_percent.png
       *
       * \par Snippet
       * The code snippet below illustrates the compaction of items selected from an \p int device vector.
       * \par
       * \code
       * #include <cub/cub.cuh>   // or equivalently <cub/device/device_select.cuh>
       *
       * // Functor type for selecting values less than some criteria
       * struct LessThan
       * {
       *     int compare;
       *
       *     CUB_RUNTIME_FUNCTION __forceinline__
       *     LessThan(int compare) : compare(compare) {}
       *
       *     CUB_RUNTIME_FUNCTION __forceinline__
       *     bool operator()(const int &a) const {
       *         return (a < compare);
       *     }
       * };
       *
       * // Declare, allocate, and initialize device-accessible pointers for input and output
       * int      num_items;              // e.g., 8
       * int      *d_in;                  // e.g., [0, 2, 3, 9, 5, 2, 81, 8]
       * int      *d_out;                 // e.g., [ ,  ,  ,  ,  ,  ,  ,  ]
       * int      *d_num_selected_out;    // e.g., [ ]
       * LessThan select_op(7);
       * ...
       *
       * // Determine temporary device storage requirements
       * void     *d_temp_storage = NULL;
       * size_t   temp_storage_bytes = 0;
       * cub::DeviceSelect::If(d_temp_storage, temp_storage_bytes, d_in, d_out, d_num_selected_out, num_items, select_op);
       *
       * // Allocate temporary storage
       * cudaMalloc(&d_temp_storage, temp_storage_bytes);
       *
       * // Run selection
       * cub::DeviceSelect::If(d_temp_storage, temp_storage_bytes, d_in, d_out, d_num_selected_out, num_items, select_op);
       *
       * // d_out                 <-- [0, 2, 3, 5, 2]
       * // d_num_selected_out    <-- [5]
       *
       * \endcode
       *
       * \tparam InputIteratorT       <b>[inferred]</b> Random-access input iterator type for reading input items \iterator
       * \tparam OutputIteratorT      <b>[inferred]</b> Random-access output iterator type for writing selected items \iterator
       * \tparam NumSelectedIteratorT  <b>[inferred]</b> Output iterator type for recording the number of items selected \iterator
       * \tparam SelectOp             <b>[inferred]</b> Selection operator type having member <tt>bool operator()(const T &a)</tt>
       */
      template <
          typename                    InputIteratorT,
          typename                    OutputIteratorT,
          typename                    NumSelectedIteratorT,
          typename                    SelectOp>
      CUB_RUNTIME_FUNCTION __forceinline__
      static cudaError_t If(
          void*               d_temp_storage,                ///< [in] %Device-accessible allocation of temporary storage.  When NULL, the required allocation size is written to \p temp_storage_bytes and no work is done.
          size_t                      &temp_storage_bytes,            ///< [in,out] Reference to size in bytes of \p d_temp_storage allocation
          InputIteratorT              d_in,                           ///< [in] Pointer to the input sequence of data items
          OutputIteratorT             d_out,                          ///< [out] Pointer to the output sequence of selected data items
          NumSelectedIteratorT         d_num_selected_out,                 ///< [out] Pointer to the output total number of items selected (i.e., length of \p d_out)
          int                         num_items,                      ///< [in] Total number of input items (i.e., length of \p d_in)
          SelectOp                    select_op,                      ///< [in] Unary selection operator
          cudaStream_t                stream             = 0,         ///< [in] <b>[optional]</b> CUDA stream to launch kernels within.  Default is stream<sub>0</sub>.
          bool                        debug_synchronous  = false)     ///< [in] <b>[optional]</b> Whether or not to synchronize the stream after every kernel launch to check for errors.  May cause significant slowdown.  Default is \p false.
      {
          typedef int                     OffsetT;         // Signed integer type for global offsets
          typedef NullType*               FlagIterator;   // FlagT iterator type (not used)
          typedef NullType                EqualityOp;     // Equality operator (not used)
  
          return DispatchSelectIf<InputIteratorT, FlagIterator, OutputIteratorT, NumSelectedIteratorT, SelectOp, EqualityOp, OffsetT, false>::Dispatch(
              d_temp_storage,
              temp_storage_bytes,
              d_in,
              NULL,
              d_out,
              d_num_selected_out,
              select_op,
              EqualityOp(),
              num_items,
              stream,
              debug_synchronous);
      }
  
  
      /**
       * \brief Given an input sequence \p d_in having runs of consecutive equal-valued keys, only the first key from each run is selectively copied to \p d_out.  The total number of items selected is written to \p d_num_selected_out. ![](unique_logo.png)
       *
       * \par
       * - The <tt>==</tt> equality operator is used to determine whether keys are equivalent
       * - Copies of the selected items are compacted into \p d_out and maintain their original relative ordering.
       * - \devicestorage
       *
       * \par Performance
       * The following charts illustrate saturated select-unique performance across different
       * CUDA architectures for \p int32 and \p int64 items, respectively.  Segments have
       * lengths uniformly sampled from [1,1000].
       *
       * \image html select_unique_int32_len_500.png
       * \image html select_unique_int64_len_500.png
       *
       * \par
       * The following charts are similar, but with segment lengths uniformly sampled from [1,10]:
       *
       * \image html select_unique_int32_len_5.png
       * \image html select_unique_int64_len_5.png
       *
       * \par Snippet
       * The code snippet below illustrates the compaction of items selected from an \p int device vector.
       * \par
       * \code
       * #include <cub/cub.cuh>       // or equivalently <cub/device/device_select.cuh>
       *
       * // Declare, allocate, and initialize device-accessible pointers for input and output
       * int  num_items;              // e.g., 8
       * int  *d_in;                  // e.g., [0, 2, 2, 9, 5, 5, 5, 8]
       * int  *d_out;                 // e.g., [ ,  ,  ,  ,  ,  ,  ,  ]
       * int  *d_num_selected_out;    // e.g., [ ]
       * ...
       *
       * // Determine temporary device storage requirements
       * void     *d_temp_storage = NULL;
       * size_t   temp_storage_bytes = 0;
       * cub::DeviceSelect::Unique(d_temp_storage, temp_storage_bytes, d_in, d_out, d_num_selected_out, num_items);
       *
       * // Allocate temporary storage
       * cudaMalloc(&d_temp_storage, temp_storage_bytes);
       *
       * // Run selection
       * cub::DeviceSelect::Unique(d_temp_storage, temp_storage_bytes, d_in, d_out, d_num_selected_out, num_items);
       *
       * // d_out                 <-- [0, 2, 9, 5, 8]
       * // d_num_selected_out    <-- [5]
       *
       * \endcode
       *
       * \tparam InputIteratorT       <b>[inferred]</b> Random-access input iterator type for reading input items \iterator
       * \tparam OutputIteratorT      <b>[inferred]</b> Random-access output iterator type for writing selected items \iterator
       * \tparam NumSelectedIteratorT  <b>[inferred]</b> Output iterator type for recording the number of items selected \iterator
       */
      template <
          typename                    InputIteratorT,
          typename                    OutputIteratorT,
          typename                    NumSelectedIteratorT>
      CUB_RUNTIME_FUNCTION __forceinline__
      static cudaError_t Unique(
          void*               d_temp_storage,                ///< [in] %Device-accessible allocation of temporary storage.  When NULL, the required allocation size is written to \p temp_storage_bytes and no work is done.
          size_t                      &temp_storage_bytes,            ///< [in,out] Reference to size in bytes of \p d_temp_storage allocation
          InputIteratorT              d_in,                           ///< [in] Pointer to the input sequence of data items
          OutputIteratorT             d_out,                          ///< [out] Pointer to the output sequence of selected data items
          NumSelectedIteratorT         d_num_selected_out,             ///< [out] Pointer to the output total number of items selected (i.e., length of \p d_out)
          int                         num_items,                      ///< [in] Total number of input items (i.e., length of \p d_in)
          cudaStream_t                stream             = 0,         ///< [in] <b>[optional]</b> CUDA stream to launch kernels within.  Default is stream<sub>0</sub>.
          bool                        debug_synchronous  = false)     ///< [in] <b>[optional]</b> Whether or not to synchronize the stream after every kernel launch to check for errors.  May cause significant slowdown.  Default is \p false.
      {
          typedef int                     OffsetT;         // Signed integer type for global offsets
          typedef NullType*               FlagIterator;   // FlagT iterator type (not used)
          typedef NullType                SelectOp;       // Selection op (not used)
          typedef Equality                EqualityOp;     // Default == operator
  
          return DispatchSelectIf<InputIteratorT, FlagIterator, OutputIteratorT, NumSelectedIteratorT, SelectOp, EqualityOp, OffsetT, false>::Dispatch(
              d_temp_storage,
              temp_storage_bytes,
              d_in,
              NULL,
              d_out,
              d_num_selected_out,
              SelectOp(),
              EqualityOp(),
              num_items,
              stream,
              debug_synchronous);
      }
  
  };
  
  /**
   * \example example_device_select_flagged.cu
   * \example example_device_select_if.cu
   * \example example_device_select_unique.cu
   */
  
  }               // CUB namespace
  CUB_NS_POSTFIX  // Optional outer namespace(s)