591 lines
22 KiB
Plaintext
591 lines
22 KiB
Plaintext
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//---------------------------------------------------------------------------//
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// Copyright (c) 2016 Jakub Szuppe <j.szuppe@gmail.com>
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//
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// Distributed under the Boost Software License, Version 1.0
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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//
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// See http://boostorg.github.com/compute for more information.
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//---------------------------------------------------------------------------//
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#ifndef BOOST_COMPUTE_ALGORITHM_DETAIL_MERGE_SORT_ON_GPU_HPP_
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#define BOOST_COMPUTE_ALGORITHM_DETAIL_MERGE_SORT_ON_GPU_HPP_
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#include <algorithm>
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#include <boost/compute/kernel.hpp>
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#include <boost/compute/program.hpp>
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#include <boost/compute/command_queue.hpp>
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#include <boost/compute/container/vector.hpp>
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#include <boost/compute/memory/local_buffer.hpp>
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#include <boost/compute/detail/meta_kernel.hpp>
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#include <boost/compute/detail/iterator_range_size.hpp>
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namespace boost {
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namespace compute {
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namespace detail {
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template<class KeyType, class ValueType>
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inline size_t pick_bitonic_block_sort_block_size(size_t proposed_wg,
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size_t lmem_size,
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bool sort_by_key)
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{
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size_t n = proposed_wg;
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size_t lmem_required = n * sizeof(KeyType);
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if(sort_by_key) {
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lmem_required += n * sizeof(ValueType);
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}
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// try to force at least 4 work-groups of >64 elements
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// for better occupancy
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while(lmem_size < (lmem_required * 4) && (n > 64)) {
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n /= 2;
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lmem_required = n * sizeof(KeyType);
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}
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while(lmem_size < lmem_required && (n != 1)) {
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n /= 2;
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if(n < 1) n = 1;
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lmem_required = n * sizeof(KeyType);
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}
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if(n < 2) { return 1; }
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else if(n < 4) { return 2; }
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else if(n < 8) { return 4; }
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else if(n < 16) { return 8; }
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else if(n < 32) { return 16; }
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else if(n < 64) { return 32; }
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else if(n < 128) { return 64; }
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else if(n < 256) { return 128; }
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else { return 256; }
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}
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/// Performs bitonic block sort according to \p compare.
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///
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/// Since bitonic sort can be only performed when input size is equal to 2^n,
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/// in this case input size is block size (\p work_group_size), we would have
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/// to require \p count be a exact multiple of block size. That would not be
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/// great.
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/// Instead, bitonic sort kernel is merged with odd-even merge sort so if the
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/// last block is not equal to 2^n (where n is some natural number) the odd-even
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/// sort is performed for that block. That way bitonic_block_sort() works for
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/// input of any size. Block size (\p work_group_size) still have to be equal
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/// to 2^n.
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///
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/// This is NOT stable.
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///
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/// \param keys_first first key element in the range to sort
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/// \param values_first first value element in the range to sort
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/// \param compare comparison function for keys
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/// \param count number of elements in the range; count > 0
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/// \param work_group_size size of the work group, also the block size; must be
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/// equal to n^2 where n is natural number
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/// \param queue command queue to perform the operation
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template<class KeyIterator, class ValueIterator, class Compare>
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inline size_t bitonic_block_sort(KeyIterator keys_first,
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ValueIterator values_first,
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Compare compare,
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const size_t count,
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const bool sort_by_key,
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command_queue &queue)
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{
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typedef typename std::iterator_traits<KeyIterator>::value_type key_type;
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meta_kernel k("bitonic_block_sort");
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size_t count_arg = k.add_arg<const uint_>("count");
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size_t local_keys_arg = k.add_arg<key_type *>(memory_object::local_memory, "lkeys");
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size_t local_vals_arg = 0;
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if(sort_by_key) {
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local_vals_arg = k.add_arg<uchar_ *>(memory_object::local_memory, "lidx");
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}
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k <<
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// Work item global and local ids
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k.decl<const uint_>("gid") << " = get_global_id(0);\n" <<
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k.decl<const uint_>("lid") << " = get_local_id(0);\n";
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// declare my_key and my_value
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k <<
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k.decl<key_type>("my_key") << ";\n";
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// Instead of copying values (my_value) in local memory with keys
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// we save local index (uchar) and copy my_value at the end at
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// final index. This saves local memory.
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if(sort_by_key)
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{
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k <<
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k.decl<uchar_>("my_index") << " = (uchar)(lid);\n";
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}
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// load key
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k <<
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"if(gid < count) {\n" <<
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k.var<key_type>("my_key") << " = " <<
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keys_first[k.var<const uint_>("gid")] << ";\n" <<
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"}\n";
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// load key and index to local memory
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k <<
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"lkeys[lid] = my_key;\n";
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if(sort_by_key)
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{
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k <<
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"lidx[lid] = my_index;\n";
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}
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k <<
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k.decl<const uint_>("offset") << " = get_group_id(0) * get_local_size(0);\n" <<
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k.decl<const uint_>("n") << " = min((uint)(get_local_size(0)),(count - offset));\n";
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// When work group size is a power of 2 bitonic sorter can be used;
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// otherwise, slower odd-even sort is used.
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k <<
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// check if n is power of 2
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"if(((n != 0) && ((n & (~n + 1)) == n))) {\n";
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// bitonic sort, not stable
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k <<
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// wait for keys and vals to be stored in local memory
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"barrier(CLK_LOCAL_MEM_FENCE);\n" <<
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"#pragma unroll\n" <<
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"for(" <<
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k.decl<uint_>("length") << " = 1; " <<
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"length < n; " <<
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"length <<= 1" <<
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") {\n" <<
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// direction of sort: false -> asc, true -> desc
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k.decl<bool>("direction") << "= ((lid & (length<<1)) != 0);\n" <<
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"for(" <<
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k.decl<uint_>("k") << " = length; " <<
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"k > 0; " <<
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"k >>= 1" <<
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") {\n" <<
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// sibling to compare with my key
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k.decl<uint_>("sibling_idx") << " = lid ^ k;\n" <<
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k.decl<key_type>("sibling_key") << " = lkeys[sibling_idx];\n" <<
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k.decl<bool>("compare") << " = " <<
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compare(k.var<key_type>("sibling_key"),
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k.var<key_type>("my_key")) << ";\n" <<
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k.decl<bool>("swap") <<
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" = compare ^ (sibling_idx < lid) ^ direction;\n" <<
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"my_key = swap ? sibling_key : my_key;\n";
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if(sort_by_key)
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{
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k <<
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"my_index = swap ? lidx[sibling_idx] : my_index;\n";
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}
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k <<
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"barrier(CLK_LOCAL_MEM_FENCE);\n" <<
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"lkeys[lid] = my_key;\n";
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if(sort_by_key)
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{
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k <<
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"lidx[lid] = my_index;\n";
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}
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k <<
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"barrier(CLK_LOCAL_MEM_FENCE);\n" <<
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"}\n" <<
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"}\n";
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// end of bitonic sort
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// odd-even sort, not stable
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k <<
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"}\n" <<
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"else { \n";
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k <<
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k.decl<bool>("lid_is_even") << " = (lid%2) == 0;\n" <<
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k.decl<uint_>("oddsibling_idx") << " = " <<
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"(lid_is_even) ? max(lid,(uint)(1)) - 1 : min(lid+1,n-1);\n" <<
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k.decl<uint_>("evensibling_idx") << " = " <<
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"(lid_is_even) ? min(lid+1,n-1) : max(lid,(uint)(1)) - 1;\n" <<
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// wait for keys and vals to be stored in local memory
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"barrier(CLK_LOCAL_MEM_FENCE);\n" <<
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"#pragma unroll\n" <<
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"for(" <<
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k.decl<uint_>("i") << " = 0; " <<
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"i < n; " <<
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"i++" <<
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") {\n" <<
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k.decl<uint_>("sibling_idx") <<
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" = i%2 == 0 ? evensibling_idx : oddsibling_idx;\n" <<
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k.decl<key_type>("sibling_key") << " = lkeys[sibling_idx];\n" <<
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k.decl<bool>("compare") << " = " <<
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compare(k.var<key_type>("sibling_key"),
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k.var<key_type>("my_key")) << ";\n" <<
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k.decl<bool>("swap") <<
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" = compare ^ (sibling_idx < lid);\n" <<
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"my_key = swap ? sibling_key : my_key;\n";
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if(sort_by_key)
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{
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k <<
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"my_index = swap ? lidx[sibling_idx] : my_index;\n";
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}
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k <<
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"barrier(CLK_LOCAL_MEM_FENCE);\n" <<
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"lkeys[lid] = my_key;\n";
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if(sort_by_key)
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{
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k <<
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"lidx[lid] = my_index;\n";
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}
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k <<
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"barrier(CLK_LOCAL_MEM_FENCE);\n"
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"}\n" << // for
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"}\n"; // else
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// end of odd-even sort
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// save key and value
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k <<
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"if(gid < count) {\n" <<
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keys_first[k.var<const uint_>("gid")] << " = " <<
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k.var<key_type>("my_key") << ";\n";
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if(sort_by_key)
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{
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k << values_first[k.var<const uint_>("gid")] << " = " <<
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values_first[k.var<const uint_>("offset + my_index")] << ";\n";
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}
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k <<
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// end if
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"}\n";
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const context &context = queue.get_context();
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const device &device = queue.get_device();
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::boost::compute::kernel kernel = k.compile(context);
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const size_t work_group_size =
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pick_bitonic_block_sort_block_size<key_type, uchar_>(
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kernel.get_work_group_info<size_t>(
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device, CL_KERNEL_WORK_GROUP_SIZE
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),
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device.get_info<size_t>(CL_DEVICE_LOCAL_MEM_SIZE),
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sort_by_key
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);
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const size_t global_size =
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work_group_size * static_cast<size_t>(
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std::ceil(float(count) / work_group_size)
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);
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kernel.set_arg(count_arg, static_cast<uint_>(count));
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kernel.set_arg(local_keys_arg, local_buffer<key_type>(work_group_size));
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if(sort_by_key) {
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kernel.set_arg(local_vals_arg, local_buffer<uchar_>(work_group_size));
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}
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queue.enqueue_1d_range_kernel(kernel, 0, global_size, work_group_size);
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// return size of the block
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return work_group_size;
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}
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template<class KeyIterator, class ValueIterator, class Compare>
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inline size_t block_sort(KeyIterator keys_first,
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ValueIterator values_first,
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Compare compare,
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const size_t count,
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const bool sort_by_key,
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const bool stable,
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command_queue &queue)
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{
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if(stable) {
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// TODO: Implement stable block sort (stable odd-even merge sort)
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return size_t(1);
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}
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return bitonic_block_sort(
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keys_first, values_first,
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compare, count,
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sort_by_key, queue
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);
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}
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/// space: O(n + m); n - number of keys, m - number of values
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template<class KeyIterator, class ValueIterator, class Compare>
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inline void merge_blocks_on_gpu(KeyIterator keys_first,
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ValueIterator values_first,
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KeyIterator out_keys_first,
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ValueIterator out_values_first,
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Compare compare,
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const size_t count,
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const size_t block_size,
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const bool sort_by_key,
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command_queue &queue)
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{
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typedef typename std::iterator_traits<KeyIterator>::value_type key_type;
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typedef typename std::iterator_traits<ValueIterator>::value_type value_type;
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meta_kernel k("merge_blocks");
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size_t count_arg = k.add_arg<const uint_>("count");
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size_t block_size_arg = k.add_arg<const uint_>("block_size");
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k <<
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// get global id
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k.decl<const uint_>("gid") << " = get_global_id(0);\n" <<
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"if(gid >= count) {\n" <<
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"return;\n" <<
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"}\n" <<
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k.decl<const key_type>("my_key") << " = " <<
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keys_first[k.var<const uint_>("gid")] << ";\n";
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if(sort_by_key) {
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k <<
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k.decl<const value_type>("my_value") << " = " <<
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values_first[k.var<const uint_>("gid")] << ";\n";
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}
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k <<
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// get my block idx
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k.decl<const uint_>("my_block_idx") << " = gid / block_size;\n" <<
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k.decl<const bool>("my_block_idx_is_odd") << " = " <<
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"my_block_idx & 0x1;\n" <<
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k.decl<const uint_>("other_block_idx") << " = " <<
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// if(my_block_idx is odd) {} else {}
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"my_block_idx_is_odd ? my_block_idx - 1 : my_block_idx + 1;\n" <<
|
||
|
|
|
||
|
|
// get ranges of my block and the other block
|
||
|
|
// [my_block_start; my_block_end)
|
||
|
|
// [other_block_start; other_block_end)
|
||
|
|
k.decl<const uint_>("my_block_start") << " = " <<
|
||
|
|
"min(my_block_idx * block_size, count);\n" << // including
|
||
|
|
k.decl<const uint_>("my_block_end") << " = " <<
|
||
|
|
"min((my_block_idx + 1) * block_size, count);\n" << // excluding
|
||
|
|
|
||
|
|
k.decl<const uint_>("other_block_start") << " = " <<
|
||
|
|
"min(other_block_idx * block_size, count);\n" << // including
|
||
|
|
k.decl<const uint_>("other_block_end") << " = " <<
|
||
|
|
"min((other_block_idx + 1) * block_size, count);\n" << // excluding
|
||
|
|
|
||
|
|
// other block is empty, nothing to merge here
|
||
|
|
"if(other_block_start == count){\n" <<
|
||
|
|
out_keys_first[k.var<uint_>("gid")] << " = my_key;\n";
|
||
|
|
if(sort_by_key) {
|
||
|
|
k <<
|
||
|
|
out_values_first[k.var<uint_>("gid")] << " = my_value;\n";
|
||
|
|
}
|
||
|
|
|
||
|
|
k <<
|
||
|
|
"return;\n" <<
|
||
|
|
"}\n" <<
|
||
|
|
|
||
|
|
// lower bound
|
||
|
|
// left_idx - lower bound
|
||
|
|
k.decl<uint_>("left_idx") << " = other_block_start;\n" <<
|
||
|
|
k.decl<uint_>("right_idx") << " = other_block_end;\n" <<
|
||
|
|
"while(left_idx < right_idx) {\n" <<
|
||
|
|
k.decl<uint_>("mid_idx") << " = (left_idx + right_idx) / 2;\n" <<
|
||
|
|
k.decl<key_type>("mid_key") << " = " <<
|
||
|
|
keys_first[k.var<const uint_>("mid_idx")] << ";\n" <<
|
||
|
|
k.decl<bool>("smaller") << " = " <<
|
||
|
|
compare(k.var<key_type>("mid_key"),
|
||
|
|
k.var<key_type>("my_key")) << ";\n" <<
|
||
|
|
"left_idx = smaller ? mid_idx + 1 : left_idx;\n" <<
|
||
|
|
"right_idx = smaller ? right_idx : mid_idx;\n" <<
|
||
|
|
"}\n" <<
|
||
|
|
// left_idx is found position in other block
|
||
|
|
|
||
|
|
// if my_block is odd we need to get the upper bound
|
||
|
|
"right_idx = other_block_end;\n" <<
|
||
|
|
"if(my_block_idx_is_odd && left_idx != right_idx) {\n" <<
|
||
|
|
k.decl<key_type>("upper_key") << " = " <<
|
||
|
|
keys_first[k.var<const uint_>("left_idx")] << ";\n" <<
|
||
|
|
"while(" <<
|
||
|
|
"!(" << compare(k.var<key_type>("upper_key"),
|
||
|
|
k.var<key_type>("my_key")) <<
|
||
|
|
") && " <<
|
||
|
|
"!(" << compare(k.var<key_type>("my_key"),
|
||
|
|
k.var<key_type>("upper_key")) <<
|
||
|
|
") && " <<
|
||
|
|
"left_idx < right_idx" <<
|
||
|
|
")" <<
|
||
|
|
"{\n" <<
|
||
|
|
k.decl<uint_>("mid_idx") << " = (left_idx + right_idx) / 2;\n" <<
|
||
|
|
k.decl<key_type>("mid_key") << " = " <<
|
||
|
|
keys_first[k.var<const uint_>("mid_idx")] << ";\n" <<
|
||
|
|
k.decl<bool>("equal") << " = " <<
|
||
|
|
"!(" << compare(k.var<key_type>("mid_key"),
|
||
|
|
k.var<key_type>("my_key")) <<
|
||
|
|
") && " <<
|
||
|
|
"!(" << compare(k.var<key_type>("my_key"),
|
||
|
|
k.var<key_type>("mid_key")) <<
|
||
|
|
");\n" <<
|
||
|
|
"left_idx = equal ? mid_idx + 1 : left_idx + 1;\n" <<
|
||
|
|
"right_idx = equal ? right_idx : mid_idx;\n" <<
|
||
|
|
"upper_key = equal ? upper_key : " <<
|
||
|
|
keys_first[k.var<const uint_>("left_idx")] << ";\n" <<
|
||
|
|
"}\n" <<
|
||
|
|
"}\n" <<
|
||
|
|
|
||
|
|
k.decl<uint_>("offset") << " = 0;\n" <<
|
||
|
|
"offset += gid - my_block_start;\n" <<
|
||
|
|
"offset += left_idx - other_block_start;\n" <<
|
||
|
|
"offset += min(my_block_start, other_block_start);\n" <<
|
||
|
|
out_keys_first[k.var<uint_>("offset")] << " = my_key;\n";
|
||
|
|
if(sort_by_key) {
|
||
|
|
k <<
|
||
|
|
out_values_first[k.var<uint_>("offset")] << " = my_value;\n";
|
||
|
|
}
|
||
|
|
|
||
|
|
const context &context = queue.get_context();
|
||
|
|
::boost::compute::kernel kernel = k.compile(context);
|
||
|
|
|
||
|
|
const size_t work_group_size = (std::min)(
|
||
|
|
size_t(256),
|
||
|
|
kernel.get_work_group_info<size_t>(
|
||
|
|
queue.get_device(), CL_KERNEL_WORK_GROUP_SIZE
|
||
|
|
)
|
||
|
|
);
|
||
|
|
const size_t global_size =
|
||
|
|
work_group_size * static_cast<size_t>(
|
||
|
|
std::ceil(float(count) / work_group_size)
|
||
|
|
);
|
||
|
|
|
||
|
|
kernel.set_arg(count_arg, static_cast<uint_>(count));
|
||
|
|
kernel.set_arg(block_size_arg, static_cast<uint_>(block_size));
|
||
|
|
queue.enqueue_1d_range_kernel(kernel, 0, global_size, work_group_size);
|
||
|
|
}
|
||
|
|
|
||
|
|
template<class KeyIterator, class ValueIterator, class Compare>
|
||
|
|
inline void merge_sort_by_key_on_gpu(KeyIterator keys_first,
|
||
|
|
KeyIterator keys_last,
|
||
|
|
ValueIterator values_first,
|
||
|
|
Compare compare,
|
||
|
|
bool stable,
|
||
|
|
command_queue &queue)
|
||
|
|
{
|
||
|
|
typedef typename std::iterator_traits<KeyIterator>::value_type key_type;
|
||
|
|
typedef typename std::iterator_traits<ValueIterator>::value_type value_type;
|
||
|
|
|
||
|
|
size_t count = iterator_range_size(keys_first, keys_last);
|
||
|
|
if(count < 2){
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
size_t block_size =
|
||
|
|
block_sort(
|
||
|
|
keys_first, values_first,
|
||
|
|
compare, count,
|
||
|
|
true /* sort_by_key */, stable /* stable */,
|
||
|
|
queue
|
||
|
|
);
|
||
|
|
|
||
|
|
// for small input size only block sort is performed
|
||
|
|
if(count <= block_size) {
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
const context &context = queue.get_context();
|
||
|
|
|
||
|
|
bool result_in_temporary_buffer = false;
|
||
|
|
::boost::compute::vector<key_type> temp_keys(count, context);
|
||
|
|
::boost::compute::vector<value_type> temp_values(count, context);
|
||
|
|
|
||
|
|
for(; block_size < count; block_size *= 2) {
|
||
|
|
result_in_temporary_buffer = !result_in_temporary_buffer;
|
||
|
|
if(result_in_temporary_buffer) {
|
||
|
|
merge_blocks_on_gpu(keys_first, values_first,
|
||
|
|
temp_keys.begin(), temp_values.begin(),
|
||
|
|
compare, count, block_size,
|
||
|
|
true /* sort_by_key */, queue);
|
||
|
|
} else {
|
||
|
|
merge_blocks_on_gpu(temp_keys.begin(), temp_values.begin(),
|
||
|
|
keys_first, values_first,
|
||
|
|
compare, count, block_size,
|
||
|
|
true /* sort_by_key */, queue);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if(result_in_temporary_buffer) {
|
||
|
|
copy_async(temp_keys.begin(), temp_keys.end(), keys_first, queue);
|
||
|
|
copy_async(temp_values.begin(), temp_values.end(), values_first, queue);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
template<class Iterator, class Compare>
|
||
|
|
inline void merge_sort_on_gpu(Iterator first,
|
||
|
|
Iterator last,
|
||
|
|
Compare compare,
|
||
|
|
bool stable,
|
||
|
|
command_queue &queue)
|
||
|
|
{
|
||
|
|
typedef typename std::iterator_traits<Iterator>::value_type key_type;
|
||
|
|
|
||
|
|
size_t count = iterator_range_size(first, last);
|
||
|
|
if(count < 2){
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
Iterator dummy;
|
||
|
|
size_t block_size =
|
||
|
|
block_sort(
|
||
|
|
first, dummy,
|
||
|
|
compare, count,
|
||
|
|
false /* sort_by_key */, stable /* stable */,
|
||
|
|
queue
|
||
|
|
);
|
||
|
|
|
||
|
|
// for small input size only block sort is performed
|
||
|
|
if(count <= block_size) {
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
const context &context = queue.get_context();
|
||
|
|
|
||
|
|
bool result_in_temporary_buffer = false;
|
||
|
|
::boost::compute::vector<key_type> temp_keys(count, context);
|
||
|
|
|
||
|
|
for(; block_size < count; block_size *= 2) {
|
||
|
|
result_in_temporary_buffer = !result_in_temporary_buffer;
|
||
|
|
if(result_in_temporary_buffer) {
|
||
|
|
merge_blocks_on_gpu(first, dummy, temp_keys.begin(), dummy,
|
||
|
|
compare, count, block_size,
|
||
|
|
false /* sort_by_key */, queue);
|
||
|
|
} else {
|
||
|
|
merge_blocks_on_gpu(temp_keys.begin(), dummy, first, dummy,
|
||
|
|
compare, count, block_size,
|
||
|
|
false /* sort_by_key */, queue);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if(result_in_temporary_buffer) {
|
||
|
|
copy_async(temp_keys.begin(), temp_keys.end(), first, queue);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
template<class KeyIterator, class ValueIterator, class Compare>
|
||
|
|
inline void merge_sort_by_key_on_gpu(KeyIterator keys_first,
|
||
|
|
KeyIterator keys_last,
|
||
|
|
ValueIterator values_first,
|
||
|
|
Compare compare,
|
||
|
|
command_queue &queue)
|
||
|
|
{
|
||
|
|
merge_sort_by_key_on_gpu(
|
||
|
|
keys_first, keys_last, values_first,
|
||
|
|
compare, false /* not stable */, queue
|
||
|
|
);
|
||
|
|
}
|
||
|
|
|
||
|
|
template<class Iterator, class Compare>
|
||
|
|
inline void merge_sort_on_gpu(Iterator first,
|
||
|
|
Iterator last,
|
||
|
|
Compare compare,
|
||
|
|
command_queue &queue)
|
||
|
|
{
|
||
|
|
merge_sort_on_gpu(
|
||
|
|
first, last, compare, false /* not stable */, queue
|
||
|
|
);
|
||
|
|
}
|
||
|
|
|
||
|
|
} // end detail namespace
|
||
|
|
} // end compute namespace
|
||
|
|
} // end boost namespace
|
||
|
|
|
||
|
|
#endif /* BOOST_COMPUTE_ALGORITHM_DETAIL_MERGE_SORT_ON_GPU_HPP_ */
|