Tpetra_Details_getGraphDiagOffsets_def.hpp

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// @HEADER
// *****************************************************************************
//          Tpetra: Templated Linear Algebra Services Package
//
// Copyright 2008 NTESS and the Tpetra contributors.
// SPDX-License-Identifier: BSD-3-Clause
// *****************************************************************************
// @HEADER

#ifndef TPETRA_DETAILS_GETGRAPHDIAGOFFSETS_DEF_HPP
#define TPETRA_DETAILS_GETGRAPHDIAGOFFSETS_DEF_HPP


#include "Tpetra_Details_OrdinalTraits.hpp"
#include "Tpetra_Map.hpp"
#include "KokkosSparse_findRelOffset.hpp"

namespace Tpetra {
namespace Details {
namespace Impl {

template <class LO,
          class GO,
          class Node,
          class DiagOffsetType>
GetGraphDiagOffsets<LO, GO, Node, DiagOffsetType>::
    GetGraphDiagOffsets(const diag_offsets_type& diagOffsets,
                        const local_map_type& lclRowMap,
                        const local_map_type& lclColMap,
                        const row_offsets_type& ptr,
                        const lcl_col_inds_type& ind,
                        const bool isSorted)
  : diagOffsets_(diagOffsets)
  , lclRowMap_(lclRowMap)
  , lclColMap_(lclColMap)
  , ptr_(ptr)
  , ind_(ind)
  , isSorted_(isSorted) {
  typedef typename device_type::execution_space execution_space;
  typedef Kokkos::RangePolicy<execution_space, LO> policy_type;

  const LO lclNumRows = lclRowMap.getLocalNumElements();
  policy_type range(0, lclNumRows);
  Kokkos::parallel_for(range, *this);
}

template <class LO,
          class GO,
          class Node,
          class DiagOffsetType>
KOKKOS_FUNCTION void
GetGraphDiagOffsets<LO, GO, Node, DiagOffsetType>::
operator()(const LO& lclRowInd) const {
  const size_t STINV =
      Tpetra::Details::OrdinalTraits<diag_offset_type>::invalid();
  const GO gblRowInd = lclRowMap_.getGlobalElement(lclRowInd);
  const GO gblColInd = gblRowInd;
  const LO lclColInd = lclColMap_.getLocalElement(gblColInd);

  if (lclColInd == Tpetra::Details::OrdinalTraits<LO>::invalid()) {
    diagOffsets_[lclRowInd] = STINV;
  } else {
    // Could be empty, but that's OK.
    const LO numEnt = ptr_[lclRowInd + 1] - ptr_[lclRowInd];
    // std::pair doesn't have its methods marked as device
    // functions, so we have to use Kokkos::pair.
    auto lclColInds =
        Kokkos::subview(ind_, Kokkos::make_pair(ptr_[lclRowInd],
                                                ptr_[lclRowInd + 1]));
    using ::KokkosSparse::findRelOffset;
    const LO diagOffset =
        findRelOffset<LO, lcl_col_inds_type>(lclColInds, numEnt,
                                             lclColInd, 0, isSorted_);
    diagOffsets_[lclRowInd] = (diagOffset == numEnt) ? STINV : static_cast<diag_offset_type>(diagOffset);
  }
}

}  // namespace Impl
}  // namespace Details
}  // namespace Tpetra

// Explicit template instantiation macro for
// Tpetra::Details::Impl::GetGraphDiagOffsets.  NOT FOR USERS!!!  Must
// be used inside the Tpetra namespace.
#define TPETRA_DETAILS_IMPL_GETGRAPHDIAGOFFSETS_INSTANT(LO, GO, NODE) \
  template class Details::Impl::GetGraphDiagOffsets<LO, GO, NODE::device_type>;

#endif  // TPETRA_DETAILS_GETGRAPHDIAGOFFSETS_DEF_HPP