Blame view
tools/cub-1.8.0/cub/agent/agent_select_if.cuh
28.9 KB
8dcb6dfcb
first commit
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 |
/******************************************************************************
* 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::AgentSelectIf implements a stateful abstraction of CUDA thread blocks for participating in device-wide select.
*/
#pragma once
#include <iterator>
#include "single_pass_scan_operators.cuh"
#include "../block/block_load.cuh"
#include "../block/block_store.cuh"
#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 "../util_namespace.cuh"
/// Optional outer namespace(s)
CUB_NS_PREFIX
/// CUB namespace
namespace cub {
/******************************************************************************
* Tuning policy types
******************************************************************************/
/**
* Parameterizable tuning policy type for AgentSelectIf
*/
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
BlockScanAlgorithm _SCAN_ALGORITHM> ///< The BlockScan algorithm to use
struct AgentSelectIfPolicy
{
enum
{
BLOCK_THREADS = _BLOCK_THREADS, ///< Threads per thread block
ITEMS_PER_THREAD = _ITEMS_PER_THREAD, ///< Items per thread (per tile of input)
};
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 AgentSelectIf implements a stateful abstraction of CUDA thread blocks for participating in device-wide selection
*
* Performs functor-based selection if SelectOpT functor type != NullType
* Otherwise performs flag-based selection if FlagsInputIterator's value type != NullType
* Otherwise performs discontinuity selection (keep unique)
*/
template <
typename AgentSelectIfPolicyT, ///< Parameterized AgentSelectIfPolicy tuning policy type
typename InputIteratorT, ///< Random-access input iterator type for selection items
typename FlagsInputIteratorT, ///< Random-access input iterator type for selections (NullType* if a selection functor or discontinuity flagging is to be used for selection)
typename SelectedOutputIteratorT, ///< Random-access input iterator type for selection_flags items
typename SelectOpT, ///< Selection operator type (NullType if selections or discontinuity flagging is to be used for selection)
typename EqualityOpT, ///< Equality operator type (NullType if selection functor or selections is to be used for selection)
typename OffsetT, ///< Signed integer type for global offsets
bool KEEP_REJECTS> ///< Whether or not we push rejected items to the back of the output
struct AgentSelectIf
{
//---------------------------------------------------------------------
// Types and constants
//---------------------------------------------------------------------
// The input value type
typedef typename std::iterator_traits<InputIteratorT>::value_type InputT;
// The output value type
typedef typename If<(Equals<typename std::iterator_traits<SelectedOutputIteratorT>::value_type, void>::VALUE), // OutputT = (if output iterator's value type is void) ?
typename std::iterator_traits<InputIteratorT>::value_type, // ... then the input iterator's value type,
typename std::iterator_traits<SelectedOutputIteratorT>::value_type>::Type OutputT; // ... else the output iterator's value type
// The flag value type
typedef typename std::iterator_traits<FlagsInputIteratorT>::value_type FlagT;
// Tile status descriptor interface type
typedef ScanTileState<OffsetT> ScanTileStateT;
// Constants
enum
{
USE_SELECT_OP,
USE_SELECT_FLAGS,
USE_DISCONTINUITY,
BLOCK_THREADS = AgentSelectIfPolicyT::BLOCK_THREADS,
ITEMS_PER_THREAD = AgentSelectIfPolicyT::ITEMS_PER_THREAD,
TILE_ITEMS = BLOCK_THREADS * ITEMS_PER_THREAD,
TWO_PHASE_SCATTER = (ITEMS_PER_THREAD > 1),
SELECT_METHOD = (!Equals<SelectOpT, NullType>::VALUE) ?
USE_SELECT_OP :
(!Equals<FlagT, NullType>::VALUE) ?
USE_SELECT_FLAGS :
USE_DISCONTINUITY
};
// Cache-modified Input iterator wrapper type (for applying cache modifier) for items
typedef typename If<IsPointer<InputIteratorT>::VALUE,
CacheModifiedInputIterator<AgentSelectIfPolicyT::LOAD_MODIFIER, InputT, OffsetT>, // Wrap the native input pointer with CacheModifiedValuesInputIterator
InputIteratorT>::Type // Directly use the supplied input iterator type
WrappedInputIteratorT;
// Cache-modified Input iterator wrapper type (for applying cache modifier) for values
typedef typename If<IsPointer<FlagsInputIteratorT>::VALUE,
CacheModifiedInputIterator<AgentSelectIfPolicyT::LOAD_MODIFIER, FlagT, OffsetT>, // Wrap the native input pointer with CacheModifiedValuesInputIterator
FlagsInputIteratorT>::Type // Directly use the supplied input iterator type
WrappedFlagsInputIteratorT;
// Parameterized BlockLoad type for input data
typedef BlockLoad<
OutputT,
BLOCK_THREADS,
ITEMS_PER_THREAD,
AgentSelectIfPolicyT::LOAD_ALGORITHM>
BlockLoadT;
// Parameterized BlockLoad type for flags
typedef BlockLoad<
FlagT,
BLOCK_THREADS,
ITEMS_PER_THREAD,
AgentSelectIfPolicyT::LOAD_ALGORITHM>
BlockLoadFlags;
// Parameterized BlockDiscontinuity type for items
typedef BlockDiscontinuity<
OutputT,
BLOCK_THREADS>
BlockDiscontinuityT;
// Parameterized BlockScan type
typedef BlockScan<
OffsetT,
BLOCK_THREADS,
AgentSelectIfPolicyT::SCAN_ALGORITHM>
BlockScanT;
// Callback type for obtaining tile prefix during block scan
typedef TilePrefixCallbackOp<
OffsetT,
cub::Sum,
ScanTileStateT>
TilePrefixCallbackOpT;
// Item exchange type
typedef OutputT ItemExchangeT[TILE_ITEMS];
// Shared memory type for this thread block
union _TempStorage
{
struct
{
typename BlockScanT::TempStorage scan; // Smem needed for tile scanning
typename TilePrefixCallbackOpT::TempStorage prefix; // Smem needed for cooperative prefix callback
typename BlockDiscontinuityT::TempStorage discontinuity; // Smem needed for discontinuity detection
};
// Smem needed for loading items
typename BlockLoadT::TempStorage load_items;
// Smem needed for loading values
typename BlockLoadFlags::TempStorage load_flags;
// Smem needed for compacting items (allows non POD items in this union)
Uninitialized<ItemExchangeT> raw_exchange;
};
// Alias wrapper allowing storage to be unioned
struct TempStorage : Uninitialized<_TempStorage> {};
//---------------------------------------------------------------------
// Per-thread fields
//---------------------------------------------------------------------
_TempStorage& temp_storage; ///< Reference to temp_storage
WrappedInputIteratorT d_in; ///< Input items
SelectedOutputIteratorT d_selected_out; ///< Unique output items
WrappedFlagsInputIteratorT d_flags_in; ///< Input selection flags (if applicable)
InequalityWrapper<EqualityOpT> inequality_op; ///< T inequality operator
SelectOpT select_op; ///< Selection operator
OffsetT num_items; ///< Total number of input items
//---------------------------------------------------------------------
// Constructor
//---------------------------------------------------------------------
// Constructor
__device__ __forceinline__
AgentSelectIf(
TempStorage &temp_storage, ///< Reference to temp_storage
InputIteratorT d_in, ///< Input data
FlagsInputIteratorT d_flags_in, ///< Input selection flags (if applicable)
SelectedOutputIteratorT d_selected_out, ///< Output data
SelectOpT select_op, ///< Selection operator
EqualityOpT equality_op, ///< Equality operator
OffsetT num_items) ///< Total number of input items
:
temp_storage(temp_storage.Alias()),
d_in(d_in),
d_flags_in(d_flags_in),
d_selected_out(d_selected_out),
select_op(select_op),
inequality_op(equality_op),
num_items(num_items)
{}
//---------------------------------------------------------------------
// Utility methods for initializing the selections
//---------------------------------------------------------------------
/**
* Initialize selections (specialized for selection operator)
*/
template <bool IS_FIRST_TILE, bool IS_LAST_TILE>
__device__ __forceinline__ void InitializeSelections(
OffsetT /*tile_offset*/,
OffsetT num_tile_items,
OutputT (&items)[ITEMS_PER_THREAD],
OffsetT (&selection_flags)[ITEMS_PER_THREAD],
Int2Type<USE_SELECT_OP> /*select_method*/)
{
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ++ITEM)
{
// Out-of-bounds items are selection_flags
selection_flags[ITEM] = 1;
if (!IS_LAST_TILE || (OffsetT(threadIdx.x * ITEMS_PER_THREAD) + ITEM < num_tile_items))
selection_flags[ITEM] = select_op(items[ITEM]);
}
}
/**
* Initialize selections (specialized for valid flags)
*/
template <bool IS_FIRST_TILE, bool IS_LAST_TILE>
__device__ __forceinline__ void InitializeSelections(
OffsetT tile_offset,
OffsetT num_tile_items,
OutputT (&/*items*/)[ITEMS_PER_THREAD],
OffsetT (&selection_flags)[ITEMS_PER_THREAD],
Int2Type<USE_SELECT_FLAGS> /*select_method*/)
{
CTA_SYNC();
FlagT flags[ITEMS_PER_THREAD];
if (IS_LAST_TILE)
{
// Out-of-bounds items are selection_flags
BlockLoadFlags(temp_storage.load_flags).Load(d_flags_in + tile_offset, flags, num_tile_items, 1);
}
else
{
BlockLoadFlags(temp_storage.load_flags).Load(d_flags_in + tile_offset, flags);
}
// Convert flag type to selection_flags type
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ++ITEM)
{
selection_flags[ITEM] = flags[ITEM];
}
}
/**
* Initialize selections (specialized for discontinuity detection)
*/
template <bool IS_FIRST_TILE, bool IS_LAST_TILE>
__device__ __forceinline__ void InitializeSelections(
OffsetT tile_offset,
OffsetT num_tile_items,
OutputT (&items)[ITEMS_PER_THREAD],
OffsetT (&selection_flags)[ITEMS_PER_THREAD],
Int2Type<USE_DISCONTINUITY> /*select_method*/)
{
if (IS_FIRST_TILE)
{
CTA_SYNC();
// Set head selection_flags. First tile sets the first flag for the first item
BlockDiscontinuityT(temp_storage.discontinuity).FlagHeads(selection_flags, items, inequality_op);
}
else
{
OutputT tile_predecessor;
if (threadIdx.x == 0)
tile_predecessor = d_in[tile_offset - 1];
CTA_SYNC();
BlockDiscontinuityT(temp_storage.discontinuity).FlagHeads(selection_flags, items, inequality_op, tile_predecessor);
}
// Set selection flags for out-of-bounds items
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ++ITEM)
{
// Set selection_flags for out-of-bounds items
if ((IS_LAST_TILE) && (OffsetT(threadIdx.x * ITEMS_PER_THREAD) + ITEM >= num_tile_items))
selection_flags[ITEM] = 1;
}
}
//---------------------------------------------------------------------
// Scatter utility methods
//---------------------------------------------------------------------
/**
* Scatter flagged items to output offsets (specialized for direct scattering)
*/
template <bool IS_LAST_TILE, bool IS_FIRST_TILE>
__device__ __forceinline__ void ScatterDirect(
OutputT (&items)[ITEMS_PER_THREAD],
OffsetT (&selection_flags)[ITEMS_PER_THREAD],
OffsetT (&selection_indices)[ITEMS_PER_THREAD],
OffsetT num_selections)
{
// Scatter flagged items
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ++ITEM)
{
if (selection_flags[ITEM])
{
if ((!IS_LAST_TILE) || selection_indices[ITEM] < num_selections)
{
d_selected_out[selection_indices[ITEM]] = items[ITEM];
}
}
}
}
/**
* Scatter flagged items to output offsets (specialized for two-phase scattering)
*/
template <bool IS_LAST_TILE, bool IS_FIRST_TILE>
__device__ __forceinline__ void ScatterTwoPhase(
OutputT (&items)[ITEMS_PER_THREAD],
OffsetT (&selection_flags)[ITEMS_PER_THREAD],
OffsetT (&selection_indices)[ITEMS_PER_THREAD],
int /*num_tile_items*/, ///< Number of valid items in this tile
int num_tile_selections, ///< Number of selections in this tile
OffsetT num_selections_prefix, ///< Total number of selections prior to this tile
OffsetT /*num_rejected_prefix*/, ///< Total number of rejections prior to this tile
Int2Type<false> /*is_keep_rejects*/) ///< Marker type indicating whether to keep rejected items in the second partition
{
CTA_SYNC();
// Compact and scatter items
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ++ITEM)
{
int local_scatter_offset = selection_indices[ITEM] - num_selections_prefix;
if (selection_flags[ITEM])
{
temp_storage.raw_exchange.Alias()[local_scatter_offset] = items[ITEM];
}
}
CTA_SYNC();
for (int item = threadIdx.x; item < num_tile_selections; item += BLOCK_THREADS)
{
d_selected_out[num_selections_prefix + item] = temp_storage.raw_exchange.Alias()[item];
}
}
/**
* Scatter flagged items to output offsets (specialized for two-phase scattering)
*/
template <bool IS_LAST_TILE, bool IS_FIRST_TILE>
__device__ __forceinline__ void ScatterTwoPhase(
OutputT (&items)[ITEMS_PER_THREAD],
OffsetT (&selection_flags)[ITEMS_PER_THREAD],
OffsetT (&selection_indices)[ITEMS_PER_THREAD],
int num_tile_items, ///< Number of valid items in this tile
int num_tile_selections, ///< Number of selections in this tile
OffsetT num_selections_prefix, ///< Total number of selections prior to this tile
OffsetT num_rejected_prefix, ///< Total number of rejections prior to this tile
Int2Type<true> /*is_keep_rejects*/) ///< Marker type indicating whether to keep rejected items in the second partition
{
CTA_SYNC();
int tile_num_rejections = num_tile_items - num_tile_selections;
// Scatter items to shared memory (rejections first)
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ++ITEM)
{
int item_idx = (threadIdx.x * ITEMS_PER_THREAD) + ITEM;
int local_selection_idx = selection_indices[ITEM] - num_selections_prefix;
int local_rejection_idx = item_idx - local_selection_idx;
int local_scatter_offset = (selection_flags[ITEM]) ?
tile_num_rejections + local_selection_idx :
local_rejection_idx;
temp_storage.raw_exchange.Alias()[local_scatter_offset] = items[ITEM];
}
CTA_SYNC();
// Gather items from shared memory and scatter to global
#pragma unroll
for (int ITEM = 0; ITEM < ITEMS_PER_THREAD; ++ITEM)
{
int item_idx = (ITEM * BLOCK_THREADS) + threadIdx.x;
int rejection_idx = item_idx;
int selection_idx = item_idx - tile_num_rejections;
OffsetT scatter_offset = (item_idx < tile_num_rejections) ?
num_items - num_rejected_prefix - rejection_idx - 1 :
num_selections_prefix + selection_idx;
OutputT item = temp_storage.raw_exchange.Alias()[item_idx];
if (!IS_LAST_TILE || (item_idx < num_tile_items))
{
d_selected_out[scatter_offset] = item;
}
}
}
/**
* Scatter flagged items
*/
template <bool IS_LAST_TILE, bool IS_FIRST_TILE>
__device__ __forceinline__ void Scatter(
OutputT (&items)[ITEMS_PER_THREAD],
OffsetT (&selection_flags)[ITEMS_PER_THREAD],
OffsetT (&selection_indices)[ITEMS_PER_THREAD],
int num_tile_items, ///< Number of valid items in this tile
int num_tile_selections, ///< Number of selections in this tile
OffsetT num_selections_prefix, ///< Total number of selections prior to this tile
OffsetT num_rejected_prefix, ///< Total number of rejections prior to this tile
OffsetT num_selections) ///< Total number of selections including this tile
{
// Do a two-phase scatter if (a) keeping both partitions or (b) two-phase is enabled and the average number of selection_flags items per thread is greater than one
if (KEEP_REJECTS || (TWO_PHASE_SCATTER && (num_tile_selections > BLOCK_THREADS)))
{
ScatterTwoPhase<IS_LAST_TILE, IS_FIRST_TILE>(
items,
selection_flags,
selection_indices,
num_tile_items,
num_tile_selections,
num_selections_prefix,
num_rejected_prefix,
Int2Type<KEEP_REJECTS>());
}
else
{
ScatterDirect<IS_LAST_TILE, IS_FIRST_TILE>(
items,
selection_flags,
selection_indices,
num_selections);
}
}
//---------------------------------------------------------------------
// Cooperatively scan a device-wide sequence of tiles with other CTAs
//---------------------------------------------------------------------
/**
* Process first tile of input (dynamic chained scan). Returns the running count of selections (including this tile)
*/
template <bool IS_LAST_TILE>
__device__ __forceinline__ OffsetT ConsumeFirstTile(
int num_tile_items, ///< Number of input items comprising this tile
OffsetT tile_offset, ///< Tile offset
ScanTileStateT& tile_state) ///< Global tile state descriptor
{
OutputT items[ITEMS_PER_THREAD];
OffsetT selection_flags[ITEMS_PER_THREAD];
OffsetT selection_indices[ITEMS_PER_THREAD];
// Load items
if (IS_LAST_TILE)
BlockLoadT(temp_storage.load_items).Load(d_in + tile_offset, items, num_tile_items);
else
BlockLoadT(temp_storage.load_items).Load(d_in + tile_offset, items);
// Initialize selection_flags
InitializeSelections<true, IS_LAST_TILE>(
tile_offset,
num_tile_items,
items,
selection_flags,
Int2Type<SELECT_METHOD>());
CTA_SYNC();
// Exclusive scan of selection_flags
OffsetT num_tile_selections;
BlockScanT(temp_storage.scan).ExclusiveSum(selection_flags, selection_indices, num_tile_selections);
if (threadIdx.x == 0)
{
// Update tile status if this is not the last tile
if (!IS_LAST_TILE)
tile_state.SetInclusive(0, num_tile_selections);
}
// Discount any out-of-bounds selections
if (IS_LAST_TILE)
num_tile_selections -= (TILE_ITEMS - num_tile_items);
// Scatter flagged items
Scatter<IS_LAST_TILE, true>(
items,
selection_flags,
selection_indices,
num_tile_items,
num_tile_selections,
0,
0,
num_tile_selections);
return num_tile_selections;
}
/**
* Process subsequent tile of input (dynamic chained scan). Returns the running count of selections (including this tile)
*/
template <bool IS_LAST_TILE>
__device__ __forceinline__ OffsetT ConsumeSubsequentTile(
int num_tile_items, ///< Number of input items comprising this tile
int tile_idx, ///< Tile index
OffsetT tile_offset, ///< Tile offset
ScanTileStateT& tile_state) ///< Global tile state descriptor
{
OutputT items[ITEMS_PER_THREAD];
OffsetT selection_flags[ITEMS_PER_THREAD];
OffsetT selection_indices[ITEMS_PER_THREAD];
// Load items
if (IS_LAST_TILE)
BlockLoadT(temp_storage.load_items).Load(d_in + tile_offset, items, num_tile_items);
else
BlockLoadT(temp_storage.load_items).Load(d_in + tile_offset, items);
// Initialize selection_flags
InitializeSelections<false, IS_LAST_TILE>(
tile_offset,
num_tile_items,
items,
selection_flags,
Int2Type<SELECT_METHOD>());
CTA_SYNC();
// Exclusive scan of values and selection_flags
TilePrefixCallbackOpT prefix_op(tile_state, temp_storage.prefix, cub::Sum(), tile_idx);
BlockScanT(temp_storage.scan).ExclusiveSum(selection_flags, selection_indices, prefix_op);
OffsetT num_tile_selections = prefix_op.GetBlockAggregate();
OffsetT num_selections = prefix_op.GetInclusivePrefix();
OffsetT num_selections_prefix = prefix_op.GetExclusivePrefix();
OffsetT num_rejected_prefix = (tile_idx * TILE_ITEMS) - num_selections_prefix;
// Discount any out-of-bounds selections
if (IS_LAST_TILE)
{
int num_discount = TILE_ITEMS - num_tile_items;
num_selections -= num_discount;
num_tile_selections -= num_discount;
}
// Scatter flagged items
Scatter<IS_LAST_TILE, false>(
items,
selection_flags,
selection_indices,
num_tile_items,
num_tile_selections,
num_selections_prefix,
num_rejected_prefix,
num_selections);
return num_selections;
}
/**
* Process a tile of input
*/
template <bool IS_LAST_TILE>
__device__ __forceinline__ OffsetT ConsumeTile(
int num_tile_items, ///< Number of input items comprising this tile
int tile_idx, ///< Tile index
OffsetT tile_offset, ///< Tile offset
ScanTileStateT& tile_state) ///< Global tile state descriptor
{
OffsetT num_selections;
if (tile_idx == 0)
{
num_selections = ConsumeFirstTile<IS_LAST_TILE>(num_tile_items, tile_offset, tile_state);
}
else
{
num_selections = ConsumeSubsequentTile<IS_LAST_TILE>(num_tile_items, tile_idx, tile_offset, tile_state);
}
return num_selections;
}
/**
* Scan tiles of items as part of a dynamic chained scan
*/
template <typename NumSelectedIteratorT> ///< Output iterator type for recording number of items selection_flags
__device__ __forceinline__ void ConsumeRange(
int num_tiles, ///< Total number of input tiles
ScanTileStateT& tile_state, ///< Global tile state descriptor
NumSelectedIteratorT d_num_selected_out) ///< Output total number selection_flags
{
// 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
if (tile_idx < num_tiles - 1)
{
// Not the last tile (full)
ConsumeTile<false>(TILE_ITEMS, tile_idx, tile_offset, tile_state);
}
else
{
// The last tile (possibly partially-full)
OffsetT num_remaining = num_items - tile_offset;
OffsetT num_selections = ConsumeTile<true>(num_remaining, tile_idx, tile_offset, tile_state);
if (threadIdx.x == 0)
{
// Output the total number of items selection_flags
*d_num_selected_out = num_selections;
}
}
}
};
} // CUB namespace
CUB_NS_POSTFIX // Optional outer namespace(s)
|