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ArborX_DetailsBruteForceImpl.hpp
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ArborX_DetailsBruteForceImpl.hpp
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/****************************************************************************
* Copyright (c) 2017-2022 by the ArborX authors *
* All rights reserved. *
* *
* This file is part of the ArborX library. ArborX is *
* distributed under a BSD 3-clause license. For the licensing terms see *
* the LICENSE file in the top-level directory. *
* *
* SPDX-License-Identifier: BSD-3-Clause *
****************************************************************************/
#ifndef ARBORX_DETAILS_BRUTE_FORCE_IMPL_HPP
#define ARBORX_DETAILS_BRUTE_FORCE_IMPL_HPP
#include <ArborX_DetailsAlgorithms.hpp> // expand
#include <ArborX_Exception.hpp>
#include <Kokkos_Core.hpp>
namespace ArborX
{
namespace Details
{
struct BruteForceImpl
{
template <class ExecutionSpace, class Values, class IndexableGetter,
class Nodes, class Bounds>
static void initializeBoundingVolumesAndReduceBoundsOfTheScene(
ExecutionSpace const &space, Values const &values,
IndexableGetter const &indexable_getter, Nodes const &nodes,
Bounds &bounds)
{
Kokkos::parallel_reduce(
"ArborX::BruteForce::BruteForce::"
"initialize_values_and_reduce_bounds",
Kokkos::RangePolicy<ExecutionSpace>(space, 0, values.size()),
KOKKOS_LAMBDA(int i, Bounds &update) {
nodes(i) = values(i);
using Details::expand;
Bounds bounding_volume{};
expand(bounding_volume, indexable_getter(nodes(i)));
update += bounding_volume;
},
Kokkos::Sum<Bounds>{bounds});
}
template <class ExecutionSpace, class Predicates, class Values,
class Indexables, class Callback>
static void query(ExecutionSpace const &space, Predicates const &predicates,
Values const &values, Indexables const &indexables,
Callback const &callback)
{
using TeamPolicy = Kokkos::TeamPolicy<ExecutionSpace>;
using PredicateType = typename Predicates::value_type;
using IndexableType = std::decay_t<decltype(indexables(0))>;
int const n_indexables = values.size();
int const n_predicates = predicates.size();
int max_scratch_size = TeamPolicy::scratch_size_max(0);
// half of the scratch memory used by predicates and half for indexables
int const predicates_per_team =
max_scratch_size / 2 / sizeof(PredicateType);
int const indexables_per_team =
max_scratch_size / 2 / sizeof(IndexableType);
ARBORX_ASSERT(predicates_per_team > 0);
ARBORX_ASSERT(indexables_per_team > 0);
int const n_indexable_tiles =
std::ceil((float)n_indexables / indexables_per_team);
int const n_predicate_tiles =
std::ceil((float)n_predicates / predicates_per_team);
int const n_teams = n_indexable_tiles * n_predicate_tiles;
using ScratchPredicateType =
Kokkos::View<PredicateType *,
typename ExecutionSpace::scratch_memory_space,
Kokkos::MemoryTraits<Kokkos::Unmanaged>>;
using ScratchIndexableType =
Kokkos::View<IndexableType *,
typename ExecutionSpace::scratch_memory_space,
Kokkos::MemoryTraits<Kokkos::Unmanaged>>;
int scratch_size = ScratchPredicateType::shmem_size(predicates_per_team) +
ScratchIndexableType::shmem_size(indexables_per_team);
Kokkos::parallel_for(
"ArborX::BruteForce::query::spatial::"
"check_all_predicates_against_all_indexables",
TeamPolicy(space, n_teams, Kokkos::AUTO, 1)
.set_scratch_size(0, Kokkos::PerTeam(scratch_size)),
KOKKOS_LAMBDA(typename TeamPolicy::member_type const &teamMember) {
// select the tiles of predicates/indexables checked by each team
int predicate_start = predicates_per_team *
(teamMember.league_rank() / n_indexable_tiles);
int indexable_start = indexables_per_team *
(teamMember.league_rank() % n_indexable_tiles);
int predicates_in_this_team = KokkosExt::min(
predicates_per_team, n_predicates - predicate_start);
int indexables_in_this_team = KokkosExt::min(
indexables_per_team, n_indexables - indexable_start);
ScratchPredicateType scratch_predicates(teamMember.team_scratch(0),
predicates_per_team);
ScratchIndexableType scratch_indexables(teamMember.team_scratch(0),
indexables_per_team);
// fill the scratch space with the predicates / indexables in the tile
Kokkos::parallel_for(
Kokkos::TeamVectorRange(teamMember, predicates_in_this_team),
[&](const int q) {
scratch_predicates(q) = predicates(predicate_start + q);
});
Kokkos::parallel_for(
Kokkos::TeamVectorRange(teamMember, indexables_in_this_team),
[&](const int j) {
scratch_indexables(j) = indexables(indexable_start + j);
});
teamMember.team_barrier();
// start threads for every predicate / indexable combination
Kokkos::parallel_for(
Kokkos::TeamThreadRange(teamMember, indexables_in_this_team),
[&](int j) {
Kokkos::parallel_for(
Kokkos::ThreadVectorRange(teamMember,
predicates_in_this_team),
[&](const int q) {
auto const &predicate = scratch_predicates(q);
auto const &indexable = scratch_indexables(j);
if (predicate(indexable))
{
callback(predicate, values(indexable_start + j));
}
});
});
});
}
};
} // namespace Details
} // namespace ArborX
#endif