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   * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
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  /*! \internal \file
   * \brief
   * Implements common routines for PME tests.
   *
   * \author Aleksei Iupinov <a.yupinov@gmail.com>
   * \author Mark Abraham <mark.j.abraham@gmail.com>
   * \ingroup module_ewald
   */
  #include "gmxpre.h"
  
  #include "pmetestcommon.h"
  
  #include <cstring>
  
  #include <algorithm>
  
  #include "gromacs/domdec/domdec.h"
  #include "gromacs/ewald/pme_gather.h"
  #include "gromacs/ewald/pme_gpu_calculate_splines.h"
  #include "gromacs/ewald/pme_gpu_constants.h"
  #include "gromacs/ewald/pme_gpu_internal.h"
  #include "gromacs/ewald/pme_gpu_staging.h"
  #include "gromacs/ewald/pme_grid.h"
  #include "gromacs/ewald/pme_internal.h"
  #include "gromacs/ewald/pme_redistribute.h"
  #include "gromacs/ewald/pme_solve.h"
  #include "gromacs/ewald/pme_spread.h"
  #include "gromacs/fft/parallel_3dfft.h"
  #include "gromacs/gpu_utils/gpu_utils.h"
  #include "gromacs/hardware/device_management.h"
  #include "gromacs/math/invertmatrix.h"
  #include "gromacs/mdtypes/commrec.h"
  #include "gromacs/pbcutil/pbc.h"
  #include "gromacs/topology/topology.h"
  #include "gromacs/utility/exceptions.h"
  #include "gromacs/utility/gmxassert.h"
  #include "gromacs/utility/logger.h"
  #include "gromacs/utility/stringutil.h"
  #include "gromacs/ewald/pme_coordinate_receiver_gpu.h"
  
  #include "testutils/test_hardware_environment.h"
  #include "testutils/testasserts.h"
  #include "testutils/testinit.h"
  
  class DeviceContext;
  
  namespace gmx
  {
  namespace test
  {
  
  //! A couple of valid inputs for boxes.
  const std::map<std::string, Matrix3x3> c_inputBoxes = {
      { "rect", { { 8.0F, 0.0F, 0.0F, 0.0F, 3.4F, 0.0F, 0.0F, 0.0F, 2.0F } } },
      { "tric", { { 7.0F, 0.0F, 0.0F, 0.0F, 4.1F, 0.0F, 3.5F, 2.0F, 12.2F } } },
  };
  
  //! Valid PME orders for testing
  std::vector<int> c_inputPmeOrders{ 3, 4, 5 };
  
  MessageStringCollector getSkipMessagesIfNecessary(const gmx_hw_info_t& hwinfo,
                                                    const t_inputrec&    inputRec,
                                                    const CodePath       codePath)
  {
      // Note that we can't call GTEST_SKIP() from within this method,
      // because it only returns from the current function. So we
      // collect all the reasons why the test cannot run, return them
      // and skip in a higher stack frame.
  
      MessageStringCollector messages;
      messages.startContext("Test is being skipped because:");
  
      if (codePath == CodePath::CPU)
      {
          // Everything is implemented, no reason to skip
          return messages;
      }
  
      std::string errorMessage;
      messages.appendIf(!pme_gpu_supports_build(&errorMessage), errorMessage);
      messages.appendIf(!pme_gpu_supports_hardware(hwinfo, &errorMessage), errorMessage);
      messages.appendIf(!pme_gpu_supports_input(inputRec, &errorMessage), errorMessage);
      return messages;
  }
  
  uint64_t getSplineModuliDoublePrecisionUlps(int splineOrder)
  {
      /* Arbitrary ulp tolerance for sine/cosine implementation. It's
       * hard to know what to pick without testing lots of
       * implementations. */
      const uint64_t sineUlps = 10;
      return 4 * (splineOrder - 2) + 2 * sineUlps * splineOrder;
  }
  
  //! PME initialization
  PmeSafePointer pmeInitWrapper(const t_inputrec*    inputRec,
                                const CodePath       mode,
                                const DeviceContext* deviceContext,
                                const DeviceStream*  deviceStream,
                                const PmeGpuProgram* pmeGpuProgram,
                                const Matrix3x3&     box,
                                const real           ewaldCoeff_q,
                                const real           ewaldCoeff_lj)
  {
      const MDLogger dummyLogger;
      const matrix   dummyBox      = { { 0 } };
      const auto     runMode       = (mode == CodePath::CPU) ? PmeRunMode::CPU : PmeRunMode::Mixed;
      t_commrec      dummyCommrec  = { 0 };
      NumPmeDomains  numPmeDomains = { 1, 1 };
      // TODO: Need to use proper value when GPU PME decomposition code path is tested
      const real     haloExtentForAtomDisplacement = 1.0;
      gmx_pme_t*     pmeDataRaw                    = gmx_pme_init(&dummyCommrec,
                                           numPmeDomains,
                                           inputRec,
                                           dummyBox,
                                           haloExtentForAtomDisplacement,
                                           false,
                                           false,
                                           true,
                                           ewaldCoeff_q,
                                           ewaldCoeff_lj,
                                           1,
                                           runMode,
                                           nullptr,
                                           deviceContext,
                                           deviceStream,
                                           pmeGpuProgram,
                                           dummyLogger);
      PmeSafePointer pme(pmeDataRaw); // taking ownership
  
      // TODO get rid of this with proper matrix type
      matrix boxTemp;
      for (int i = 0; i < DIM; i++)
      {
          for (int j = 0; j < DIM; j++)
          {
              boxTemp[i][j] = box[i * DIM + j];
          }
      }
      const char* boxError = check_box(PbcType::Unset, boxTemp);
      GMX_RELEASE_ASSERT(boxError == nullptr, boxError);
  
      switch (mode)
      {
          case CodePath::CPU: invertBoxMatrix(boxTemp, pme->recipbox); break;
  
          case CodePath::GPU:
              pme_gpu_set_testing(pme->gpu, true);
              pme_gpu_update_input_box(pme->gpu, boxTemp);
              break;
  
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
  
      return pme;
  }
  
  PmeSafePointer pmeInitEmpty(const t_inputrec* inputRec)
  {
      const Matrix3x3 defaultBox = { { 1.0F, 0.0F, 0.0F, 0.0F, 1.0F, 0.0F, 0.0F, 0.0F, 1.0F } };
      return pmeInitWrapper(inputRec, CodePath::CPU, nullptr, nullptr, nullptr, defaultBox, 0.0F, 0.0F);
  }
  
  //! Make a GPU state-propagator manager
  std::unique_ptr<StatePropagatorDataGpu> makeStatePropagatorDataGpu(const gmx_pme_t&     pme,
                                                                     const DeviceContext* deviceContext,
                                                                     const DeviceStream* deviceStream)
  {
      // TODO: Pin the host buffer and use async memory copies
      // TODO: Special constructor for PME-only rank / PME-tests is used here. There should be a mechanism to
      //       restrict one from using other constructor here.
      return std::make_unique<StatePropagatorDataGpu>(
              deviceStream, *deviceContext, GpuApiCallBehavior::Sync, pme_gpu_get_block_size(&pme), nullptr);
  }
  
  //! PME initialization with atom data
  void pmeInitAtoms(gmx_pme_t*               pme,
                    StatePropagatorDataGpu*  stateGpu,
                    const CodePath           mode,
                    const CoordinatesVector& coordinates,
                    const ChargesVector&     charges)
  {
      const index atomCount = coordinates.size();
      GMX_RELEASE_ASSERT(atomCount == gmx::ssize(charges), "Mismatch in atom data");
      PmeAtomComm* atc = nullptr;
  
      switch (mode)
      {
          case CodePath::CPU:
              atc              = &(pme->atc[0]);
              atc->x           = coordinates;
              atc->coefficient = charges;
              gmx_pme_reinit_atoms(pme, atomCount, charges, {});
              /* With decomposition there would be more boilerplate atc code here, e.g. do_redist_pos_coeffs */
              break;
  
          case CodePath::GPU:
              // TODO: Avoid use of atc in the GPU code path
              atc = &(pme->atc[0]);
              // We need to set atc->n for passing the size in the tests
              atc->setNumAtoms(atomCount);
              gmx_pme_reinit_atoms(pme, atomCount, charges, {});
  
              stateGpu->reinit(atomCount, atomCount);
              stateGpu->copyCoordinatesToGpu(arrayRefFromArray(coordinates.data(), coordinates.size()),
                                             gmx::AtomLocality::Local);
              pme_gpu_set_kernelparam_coordinates(pme->gpu, stateGpu->getCoordinates());
  
              break;
  
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
  }
  
  //! Getting local PME real grid pointer for test I/O
  static real* pmeGetRealGridInternal(const gmx_pme_t* pme)
  {
      const size_t gridIndex = 0;
      return pme->fftgrid[gridIndex];
  }
  
  //! Getting local PME real grid dimensions
  static void pmeGetRealGridSizesInternal(const gmx_pme_t* pme,
                                          CodePath         mode,
                                          IVec& gridSize,       //NOLINT(google-runtime-references)
                                          IVec& paddedGridSize) //NOLINT(google-runtime-references)
  {
      const size_t gridIndex = 0;
      IVec         gridOffsetUnused;
      switch (mode)
      {
          case CodePath::CPU:
              gmx_parallel_3dfft_real_limits(
                      pme->pfft_setup[gridIndex], gridSize, gridOffsetUnused, paddedGridSize);
              break;
  
          case CodePath::GPU:
              pme_gpu_get_real_grid_sizes(pme->gpu, &gridSize, &paddedGridSize);
              break;
  
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
  }
  
  //! Getting local PME complex grid pointer for test I/O
  static t_complex* pmeGetComplexGridInternal(const gmx_pme_t* pme)
  {
      const size_t gridIndex = 0;
      return pme->cfftgrid[gridIndex];
  }
  
  //! Getting local PME complex grid dimensions
  static void pmeGetComplexGridSizesInternal(const gmx_pme_t* pme,
                                             IVec& gridSize,       //NOLINT(google-runtime-references)
                                             IVec& paddedGridSize) //NOLINT(google-runtime-references)
  {
      const size_t gridIndex = 0;
      IVec         gridOffsetUnused, complexOrderUnused;
      gmx_parallel_3dfft_complex_limits(
              pme->pfft_setup[gridIndex], complexOrderUnused, gridSize, gridOffsetUnused, paddedGridSize); // TODO: what about YZX ordering?
  }
  
  //! Getting the PME grid memory buffer and its sizes - template definition
  template<typename ValueType>
  static void pmeGetGridAndSizesInternal(const gmx_pme_t* /*unused*/,
                                         CodePath /*unused*/,
                                         ValueType*& /*unused*/, //NOLINT(google-runtime-references)
                                         IVec& /*unused*/,       //NOLINT(google-runtime-references)
                                         IVec& /*unused*/)       //NOLINT(google-runtime-references)
  {
      GMX_THROW(InternalError("Deleted function call"));
      // explicitly deleting general template does not compile in clang, see https://llvm.org/bugs/show_bug.cgi?id=17537
  }
  
  //! Getting the PME real grid memory buffer and its sizes
  template<>
  void pmeGetGridAndSizesInternal<real>(const gmx_pme_t* pme, CodePath mode, real*& grid, IVec& gridSize, IVec& paddedGridSize)
  {
      grid = pmeGetRealGridInternal(pme);
      pmeGetRealGridSizesInternal(pme, mode, gridSize, paddedGridSize);
  }
  
  //! Getting the PME complex grid memory buffer and its sizes
  template<>
  void pmeGetGridAndSizesInternal<t_complex>(const gmx_pme_t* pme,
                                             CodePath /*unused*/,
                                             t_complex*& grid,
                                             IVec&       gridSize,
                                             IVec&       paddedGridSize)
  {
      grid = pmeGetComplexGridInternal(pme);
      pmeGetComplexGridSizesInternal(pme, gridSize, paddedGridSize);
  }
  
  //! PME spline calculation and charge spreading
  void pmePerformSplineAndSpread(gmx_pme_t* pme,
                                 CodePath   mode, // TODO const qualifiers elsewhere
                                 bool       computeSplines,
                                 bool       spreadCharges)
  {
      GMX_RELEASE_ASSERT(pme != nullptr, "PME data is not initialized");
      PmeAtomComm* atc                          = &(pme->atc[0]);
      const size_t gridIndex                    = 0;
      const bool   computeSplinesForZeroCharges = true;
      real**       fftgrid                      = spreadCharges ? pme->fftgrid : nullptr;
      real*        pmegrid                      = pme->pmegrid[gridIndex].grid.grid;
  
      switch (mode)
      {
          case CodePath::CPU:
              spread_on_grid(pme,
                             atc,
                             &pme->pmegrid[gridIndex],
                             computeSplines,
                             spreadCharges,
                             fftgrid != nullptr ? fftgrid[gridIndex] : nullptr,
                             computeSplinesForZeroCharges,
                             gridIndex);
              if (spreadCharges && !pme->bUseThreads)
              {
                  wrap_periodic_pmegrid(pme, pmegrid);
                  copy_pmegrid_to_fftgrid(
                          pme, pmegrid, fftgrid != nullptr ? fftgrid[gridIndex] : nullptr, gridIndex);
              }
              break;
  
  /* The compiler will complain about passing fftgrid (converting double ** to float **) if using
   * double precision. GPUs are not used with double precision anyhow. */
  #if !GMX_DOUBLE
          case CodePath::GPU:
          {
              const real lambdaQ = 1.0;
              // no synchronization needed as x is transferred in the PME stream
              GpuEventSynchronizer* xReadyOnDevice = nullptr;
  
              bool                           useGpuDirectComm         = false;
              gmx::PmeCoordinateReceiverGpu* pmeCoordinateReceiverGpu = nullptr;
  
              pme_gpu_spread(pme->gpu,
                             xReadyOnDevice,
                             fftgrid,
                             pme->pfft_setup,
                             computeSplines,
                             spreadCharges,
                             lambdaQ,
                             useGpuDirectComm,
                             pmeCoordinateReceiverGpu);
          }
          break;
  #endif
  
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
  }
  
  //! Getting the internal spline data buffer pointer
  static real* pmeGetSplineDataInternal(const gmx_pme_t* pme, PmeSplineDataType type, int dimIndex)
  {
      GMX_ASSERT((0 <= dimIndex) && (dimIndex < DIM), "Invalid dimension index");
      const PmeAtomComm* atc          = &(pme->atc[0]);
      const size_t       threadIndex  = 0;
      real*              splineBuffer = nullptr;
      switch (type)
      {
          case PmeSplineDataType::Values:
              splineBuffer = atc->spline[threadIndex].theta.coefficients[dimIndex];
              break;
  
          case PmeSplineDataType::Derivatives:
              splineBuffer = atc->spline[threadIndex].dtheta.coefficients[dimIndex];
              break;
  
          default: GMX_THROW(InternalError("Unknown spline data type"));
      }
      return splineBuffer;
  }
  
  //! PME solving
  void pmePerformSolve(const gmx_pme_t*  pme,
                       CodePath          mode,
                       PmeSolveAlgorithm method,
                       real              cellVolume,
                       GridOrdering      gridOrdering,
                       bool              computeEnergyAndVirial)
  {
      t_complex*   h_grid              = pmeGetComplexGridInternal(pme);
      const bool   useLorentzBerthelot = false;
      const size_t threadIndex         = 0;
      const size_t gridIndex           = 0;
      switch (mode)
      {
          case CodePath::CPU:
              if (gridOrdering != GridOrdering::YZX)
              {
                  GMX_THROW(InternalError("Test not implemented for this mode"));
              }
              switch (method)
              {
                  case PmeSolveAlgorithm::Coulomb:
                      solve_pme_yzx(pme, h_grid, cellVolume, computeEnergyAndVirial, pme->nthread, threadIndex);
                      break;
  
                  case PmeSolveAlgorithm::LennardJones:
                      solve_pme_lj_yzx(pme,
                                       &h_grid,
                                       useLorentzBerthelot,
                                       cellVolume,
                                       computeEnergyAndVirial,
                                       pme->nthread,
                                       threadIndex);
                      break;
  
                  default: GMX_THROW(InternalError("Test not implemented for this mode"));
              }
              break;
  
          case CodePath::GPU:
              switch (method)
              {
                  case PmeSolveAlgorithm::Coulomb:
                      pme_gpu_solve(pme->gpu, gridIndex, h_grid, gridOrdering, computeEnergyAndVirial);
                      break;
  
                  default: GMX_THROW(InternalError("Test not implemented for this mode"));
              }
              break;
  
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
  }
  
  //! PME force gathering
  void pmePerformGather(gmx_pme_t* pme, CodePath mode, ForcesVector& forces)
  {
      PmeAtomComm* atc       = &(pme->atc[0]);
      const index  atomCount = atc->numAtoms();
      GMX_RELEASE_ASSERT(forces.ssize() == atomCount, "Invalid force buffer size");
      const real   scale       = 1.0;
      const size_t threadIndex = 0;
      const size_t gridIndex   = 0;
      real*        pmegrid     = pme->pmegrid[gridIndex].grid.grid;
      real**       fftgrid     = pme->fftgrid;
  
      switch (mode)
      {
          case CodePath::CPU:
              atc->f = forces;
              if (atc->nthread == 1)
              {
                  // something which is normally done in serial spline computation (make_thread_local_ind())
                  atc->spline[threadIndex].n = atomCount;
              }
              copy_fftgrid_to_pmegrid(pme, fftgrid[gridIndex], pmegrid, gridIndex, pme->nthread, threadIndex);
              unwrap_periodic_pmegrid(pme, pmegrid);
              gather_f_bsplines(pme, pmegrid, true, atc, &atc->spline[threadIndex], scale);
              break;
  
  /* The compiler will complain about passing fftgrid (converting double ** to float **) if using
   * double precision. GPUs are not used with double precision anyhow. */
  #if !GMX_DOUBLE
          case CodePath::GPU:
          {
              // Variable initialization needs a non-switch scope
              const bool computeEnergyAndVirial = false;
              const real lambdaQ                = 1.0;
              PmeOutput  output = pme_gpu_getOutput(*pme, computeEnergyAndVirial, lambdaQ);
              GMX_ASSERT(forces.size() == output.forces_.size(),
                         "Size of force buffers did not match");
              pme_gpu_gather(pme->gpu, fftgrid, pme->pfft_setup, lambdaQ);
              std::copy(std::begin(output.forces_), std::end(output.forces_), std::begin(forces));
          }
          break;
  #endif
  
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
  }
  
  //! PME test finalization before fetching the outputs
  void pmeFinalizeTest(const gmx_pme_t* pme, CodePath mode)
  {
      switch (mode)
      {
          case CodePath::CPU: break;
  
          case CodePath::GPU: pme_gpu_synchronize(pme->gpu); break;
  
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
  }
  
  //! A binary enum for spline data layout transformation
  enum class PmeLayoutTransform
  {
      GpuToHost,
      HostToGpu
  };
  
  /*! \brief Gets a unique index to an element in a spline parameter buffer.
   *
   * These theta/dtheta buffers are laid out for GPU spread/gather
   * kernels. The index is wrt the execution block, in range(0,
   * atomsPerBlock * order * DIM).
   *
   * This is a wrapper, only used in unit tests.
   * \param[in] order            PME order
   * \param[in] splineIndex      Spline contribution index (from 0 to \p order - 1)
   * \param[in] dimIndex         Dimension index (from 0 to 2)
   * \param[in] atomIndex        Atom index wrt the block.
   * \param[in] atomsPerWarp     Number of atoms processed by a warp.
   *
   * \returns Index into theta or dtheta array using GPU layout.
   */
  static int getSplineParamFullIndex(int order, int splineIndex, int dimIndex, int atomIndex, int atomsPerWarp)
  {
      if (order != c_pmeGpuOrder)
      {
          throw order;
      }
      constexpr int fixedOrder = c_pmeGpuOrder;
      GMX_UNUSED_VALUE(fixedOrder);
  
      const int atomWarpIndex = atomIndex % atomsPerWarp;
      const int warpIndex     = atomIndex / atomsPerWarp;
      int       indexBase, result;
      switch (atomsPerWarp)
      {
          case 1:
              indexBase = getSplineParamIndexBase<fixedOrder, 1>(warpIndex, atomWarpIndex);
              result    = getSplineParamIndex<fixedOrder, 1>(indexBase, dimIndex, splineIndex);
              break;
  
          case 2:
              indexBase = getSplineParamIndexBase<fixedOrder, 2>(warpIndex, atomWarpIndex);
              result    = getSplineParamIndex<fixedOrder, 2>(indexBase, dimIndex, splineIndex);
              break;
  
          case 4:
              indexBase = getSplineParamIndexBase<fixedOrder, 4>(warpIndex, atomWarpIndex);
              result    = getSplineParamIndex<fixedOrder, 4>(indexBase, dimIndex, splineIndex);
              break;
  
          case 8:
              indexBase = getSplineParamIndexBase<fixedOrder, 8>(warpIndex, atomWarpIndex);
              result    = getSplineParamIndex<fixedOrder, 8>(indexBase, dimIndex, splineIndex);
              break;
  
          default:
              GMX_THROW(NotImplementedError(
                      formatString("Test function call not unrolled for atomsPerWarp = %d in "
                                   "getSplineParamFullIndex",
                                   atomsPerWarp)));
      }
      return result;
  }
  
  /*!\brief Return the number of atoms per warp */
  static int pme_gpu_get_atoms_per_warp(const PmeGpu* pmeGpu)
  {
      const int order = pmeGpu->common->pme_order;
      const int threadsPerAtom =
              (pmeGpu->settings.threadsPerAtom == ThreadsPerAtom::Order ? order : order * order);
      return pmeGpu->programHandle_->warpSize() / threadsPerAtom;
  }
  
  /*! \brief Rearranges the atom spline data between the GPU and host layouts.
   * Only used for test purposes so far, likely to be horribly slow.
   *
   * \param[in]  pmeGpu     The PME GPU structure.
   * \param[out] atc        The PME CPU atom data structure (with a single-threaded layout).
   * \param[in]  type       The spline data type (values or derivatives).
   * \param[in]  dimIndex   Dimension index.
   * \param[in]  transform  Layout transform type
   */
  static void pme_gpu_transform_spline_atom_data(const PmeGpu*      pmeGpu,
                                                 const PmeAtomComm* atc,
                                                 PmeSplineDataType  type,
                                                 int                dimIndex,
                                                 PmeLayoutTransform transform)
  {
      // The GPU atom spline data is laid out in a different way currently than the CPU one.
      // This function converts the data from GPU to CPU layout (in the host memory).
      // It is only intended for testing purposes so far.
      // Ideally we should use similar layouts on CPU and GPU if we care about mixed modes and their
      // performance (e.g. spreading on GPU, gathering on CPU).
      GMX_RELEASE_ASSERT(atc->nthread == 1, "Only the serial PME data layout is supported");
      const uintmax_t threadIndex  = 0;
      const auto      atomCount    = atc->numAtoms();
      const auto      atomsPerWarp = pme_gpu_get_atoms_per_warp(pmeGpu);
      const auto      pmeOrder     = pmeGpu->common->pme_order;
      GMX_ASSERT(pmeOrder == c_pmeGpuOrder, "Only PME order 4 is implemented");
  
      real*  cpuSplineBuffer;
      float* h_splineBuffer;
      switch (type)
      {
          case PmeSplineDataType::Values:
              cpuSplineBuffer = atc->spline[threadIndex].theta.coefficients[dimIndex];
              h_splineBuffer  = pmeGpu->staging.h_theta;
              break;
  
          case PmeSplineDataType::Derivatives:
              cpuSplineBuffer = atc->spline[threadIndex].dtheta.coefficients[dimIndex];
              h_splineBuffer  = pmeGpu->staging.h_dtheta;
              break;
  
          default: GMX_THROW(InternalError("Unknown spline data type"));
      }
  
      for (auto atomIndex = 0; atomIndex < atomCount; atomIndex++)
      {
          for (auto orderIndex = 0; orderIndex < pmeOrder; orderIndex++)
          {
              const auto gpuValueIndex =
                      getSplineParamFullIndex(pmeOrder, orderIndex, dimIndex, atomIndex, atomsPerWarp);
              const auto cpuValueIndex = atomIndex * pmeOrder + orderIndex;
              GMX_ASSERT(cpuValueIndex < atomCount * pmeOrder,
                         "Atom spline data index out of bounds (while transforming GPU data layout "
                         "for host)");
              switch (transform)
              {
                  case PmeLayoutTransform::GpuToHost:
                      cpuSplineBuffer[cpuValueIndex] = h_splineBuffer[gpuValueIndex];
                      break;
  
                  case PmeLayoutTransform::HostToGpu:
                      h_splineBuffer[gpuValueIndex] = cpuSplineBuffer[cpuValueIndex];
                      break;
  
                  default: GMX_THROW(InternalError("Unknown layout transform"));
              }
          }
      }
  }
  
  //! Setting atom spline values/derivatives to be used in spread/gather
  void pmeSetSplineData(const gmx_pme_t*             pme,
                        CodePath                     mode,
                        const SplineParamsDimVector& splineValues,
                        PmeSplineDataType            type,
                        int                          dimIndex)
  {
      const PmeAtomComm* atc       = &(pme->atc[0]);
      const index        atomCount = atc->numAtoms();
      const index        pmeOrder  = pme->pme_order;
      const index        dimSize   = pmeOrder * atomCount;
      GMX_RELEASE_ASSERT(dimSize == splineValues.ssize(), "Mismatch in spline data");
      real* splineBuffer = pmeGetSplineDataInternal(pme, type, dimIndex);
  
      switch (mode)
      {
          case CodePath::CPU:
              std::copy(splineValues.begin(), splineValues.end(), splineBuffer);
              break;
  
          case CodePath::GPU:
              std::copy(splineValues.begin(), splineValues.end(), splineBuffer);
              pme_gpu_transform_spline_atom_data(pme->gpu, atc, type, dimIndex, PmeLayoutTransform::HostToGpu);
              break;
  
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
  }
  
  //! Setting gridline indices to be used in spread/gather
  void pmeSetGridLineIndices(gmx_pme_t* pme, CodePath mode, const GridLineIndicesVector& gridLineIndices)
  {
      PmeAtomComm* atc       = &(pme->atc[0]);
      const index  atomCount = atc->numAtoms();
      GMX_RELEASE_ASSERT(atomCount == ssize(gridLineIndices), "Mismatch in gridline indices size");
  
      IVec paddedGridSizeUnused, gridSize(0, 0, 0);
      pmeGetRealGridSizesInternal(pme, mode, gridSize, paddedGridSizeUnused);
  
      for (const auto& index : gridLineIndices)
      {
          for (int i = 0; i < DIM; i++)
          {
              GMX_RELEASE_ASSERT((0 <= index[i]) && (index[i] < gridSize[i]),
                                 "Invalid gridline index");
          }
      }
  
      switch (mode)
      {
          case CodePath::GPU:
              memcpy(pme_gpu_staging(pme->gpu).h_gridlineIndices,
                     gridLineIndices.data(),
                     atomCount * sizeof(gridLineIndices[0]));
              break;
  
          case CodePath::CPU:
              atc->idx.resize(gridLineIndices.size());
              std::copy(gridLineIndices.begin(), gridLineIndices.end(), atc->idx.begin());
              break;
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
  }
  
  //! Getting plain index into the complex 3d grid
  inline size_t pmeGetGridPlainIndexInternal(const IVec& index, const IVec& paddedGridSize, GridOrdering gridOrdering)
  {
      size_t result;
      switch (gridOrdering)
      {
          case GridOrdering::YZX:
              result = (index[YY] * paddedGridSize[ZZ] + index[ZZ]) * paddedGridSize[XX] + index[XX];
              break;
  
          case GridOrdering::XYZ:
              result = (index[XX] * paddedGridSize[YY] + index[YY]) * paddedGridSize[ZZ] + index[ZZ];
              break;
  
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
      return result;
  }
  
  //! Setting real or complex grid
  template<typename ValueType>
  static void pmeSetGridInternal(const gmx_pme_t*                        pme,
                                 CodePath                                mode,
                                 GridOrdering                            gridOrdering,
                                 const SparseGridValuesInput<ValueType>& gridValues)
  {
      IVec       gridSize(0, 0, 0), paddedGridSize(0, 0, 0);
      ValueType* grid;
      pmeGetGridAndSizesInternal<ValueType>(pme, mode, grid, gridSize, paddedGridSize);
  
      switch (mode)
      {
          case CodePath::GPU: // intentional absence of break, the grid will be copied from the host buffer in testing mode
          case CodePath::CPU:
              std::memset(grid, 0, paddedGridSize[XX] * paddedGridSize[YY] * paddedGridSize[ZZ] * sizeof(ValueType));
              for (const auto& gridValue : gridValues)
              {
                  for (int i = 0; i < DIM; i++)
                  {
                      GMX_RELEASE_ASSERT((0 <= gridValue.first[i]) && (gridValue.first[i] < gridSize[i]),
                                         "Invalid grid value index");
                  }
                  const size_t gridValueIndex =
                          pmeGetGridPlainIndexInternal(gridValue.first, paddedGridSize, gridOrdering);
                  grid[gridValueIndex] = gridValue.second;
              }
              break;
  
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
  }
  
  //! Setting real grid to be used in gather
  void pmeSetRealGrid(const gmx_pme_t* pme, CodePath mode, const SparseRealGridValuesInput& gridValues)
  {
      pmeSetGridInternal<real>(pme, mode, GridOrdering::XYZ, gridValues);
  }
  
  //! Setting complex grid to be used in solve
  void pmeSetComplexGrid(const gmx_pme_t*                    pme,
                         CodePath                            mode,
                         GridOrdering                        gridOrdering,
                         const SparseComplexGridValuesInput& gridValues)
  {
      pmeSetGridInternal<t_complex>(pme, mode, gridOrdering, gridValues);
  }
  
  //! Getting the single dimension's spline values or derivatives
  SplineParamsDimVector pmeGetSplineData(const gmx_pme_t* pme, CodePath mode, PmeSplineDataType type, int dimIndex)
  {
      GMX_RELEASE_ASSERT(pme != nullptr, "PME data is not initialized");
      const PmeAtomComm* atc       = &(pme->atc[0]);
      const size_t       atomCount = atc->numAtoms();
      const size_t       pmeOrder  = pme->pme_order;
      const size_t       dimSize   = pmeOrder * atomCount;
  
      real*                 sourceBuffer = pmeGetSplineDataInternal(pme, type, dimIndex);
      SplineParamsDimVector result;
      switch (mode)
      {
          case CodePath::GPU:
              pme_gpu_transform_spline_atom_data(pme->gpu, atc, type, dimIndex, PmeLayoutTransform::GpuToHost);
              result = arrayRefFromArray(sourceBuffer, dimSize);
              break;
  
          case CodePath::CPU: result = arrayRefFromArray(sourceBuffer, dimSize); break;
  
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
      return result;
  }
  
  //! Getting the gridline indices
  GridLineIndicesVector pmeGetGridlineIndices(const gmx_pme_t* pme, CodePath mode)
  {
      GMX_RELEASE_ASSERT(pme != nullptr, "PME data is not initialized");
      const PmeAtomComm* atc       = &(pme->atc[0]);
      const size_t       atomCount = atc->numAtoms();
  
      GridLineIndicesVector gridLineIndices;
      switch (mode)
      {
          case CodePath::GPU:
          {
              auto* gridlineIndicesAsIVec =
                      reinterpret_cast<IVec*>(pme_gpu_staging(pme->gpu).h_gridlineIndices);
              ArrayRef<IVec> gridlineIndicesArrayRef = arrayRefFromArray(gridlineIndicesAsIVec, atomCount);
              gridLineIndices = { gridlineIndicesArrayRef.begin(), gridlineIndicesArrayRef.end() };
          }
          break;
  
          case CodePath::CPU: gridLineIndices = { atc->idx.begin(), atc->idx.end() }; break;
  
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
      return gridLineIndices;
  }
  
  //! Getting real or complex grid - only non zero values
  template<typename ValueType>
  static SparseGridValuesOutput<ValueType> pmeGetGridInternal(const gmx_pme_t* pme,
                                                              CodePath         mode,
                                                              GridOrdering     gridOrdering)
  {
      IVec       gridSize(0, 0, 0), paddedGridSize(0, 0, 0);
      ValueType* grid;
      pmeGetGridAndSizesInternal<ValueType>(pme, mode, grid, gridSize, paddedGridSize);
      SparseGridValuesOutput<ValueType> gridValues;
      switch (mode)
      {
          case CodePath::GPU: // intentional absence of break
          case CodePath::CPU:
              gridValues.clear();
              for (int ix = 0; ix < gridSize[XX]; ix++)
              {
                  for (int iy = 0; iy < gridSize[YY]; iy++)
                  {
                      for (int iz = 0; iz < gridSize[ZZ]; iz++)
                      {
                          IVec         temp(ix, iy, iz);
                          const size_t gridValueIndex =
                                  pmeGetGridPlainIndexInternal(temp, paddedGridSize, gridOrdering);
                          const ValueType value = grid[gridValueIndex];
                          if (value != ValueType{})
                          {
                              auto key        = formatString("Cell %d %d %d", ix, iy, iz);
                              gridValues[key] = value;
                          }
                      }
                  }
              }
              break;
  
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
      return gridValues;
  }
  
  //! Getting the real grid (spreading output of pmePerformSplineAndSpread())
  SparseRealGridValuesOutput pmeGetRealGrid(const gmx_pme_t* pme, CodePath mode)
  {
      return pmeGetGridInternal<real>(pme, mode, GridOrdering::XYZ);
  }
  
  //! Getting the complex grid output of pmePerformSolve()
  SparseComplexGridValuesOutput pmeGetComplexGrid(const gmx_pme_t* pme, CodePath mode, GridOrdering gridOrdering)
  {
      return pmeGetGridInternal<t_complex>(pme, mode, gridOrdering);
  }
  
  //! Getting the reciprocal energy and virial
  PmeOutput pmeGetReciprocalEnergyAndVirial(const gmx_pme_t* pme, CodePath mode, PmeSolveAlgorithm method)
  {
      PmeOutput  output;
      const real lambdaQ = 1.0;
      switch (mode)
      {
          case CodePath::CPU:
              switch (method)
              {
                  case PmeSolveAlgorithm::Coulomb:
                      get_pme_ener_vir_q(pme->solve_work, pme->nthread, &output);
                      break;
  
                  case PmeSolveAlgorithm::LennardJones:
                      get_pme_ener_vir_lj(pme->solve_work, pme->nthread, &output);
                      break;
  
                  default: GMX_THROW(InternalError("Test not implemented for this mode"));
              }
              break;
          case CodePath::GPU:
              switch (method)
              {
                  case PmeSolveAlgorithm::Coulomb:
                      pme_gpu_getEnergyAndVirial(*pme, lambdaQ, &output);
                      break;
  
                  default: GMX_THROW(InternalError("Test not implemented for this mode"));
              }
              break;
  
          default: GMX_THROW(InternalError("Test not implemented for this mode"));
      }
      return output;
  }
  
  std::string makeRefDataFileName()
  {
      // By default, the reference data filename is set via a call to
      // gmx::TestFileManager::getTestSpecificFileName() that queries
      // GoogleTest and gets a string that includes the return value for
      // nameOfTest(). The logic here must match that of the call to
      // ::testing::RegisterTest, so that it works as intended. In
      // particular, the name must include a "WorksOn" substring that
      // precedes the name of the hardware context, so that this can be
      // removed.
      //
      // Get the info about the test
      const ::testing::TestInfo* testInfo = ::testing::UnitTest::GetInstance()->current_test_info();
  
      // Get the test name and prepare to remove the part describing the
      // hardware context.
      std::string testName(testInfo->name());
      auto        worksOnPos = testName.find("WorksOn");
      GMX_RELEASE_ASSERT(worksOnPos != testName.size(),
                         "Test name must include the 'WorksOn' fragment");
  
      // Build the complete refdata filename like
      // getTestSpecificFilename() would do it for a non-dynamical
      // parameterized test.
      std::string refDataFileName = formatString("%s_%sWorksWith_%s.xml",
                                                 testInfo->test_suite_name(),
                                                 testName.substr(0, worksOnPos).c_str(),
                                                 testInfo->value_param());
      // Use the check that the name isn't too long
      checkTestNameLength(refDataFileName);
      return refDataFileName;
  }
  
  std::string makeHardwareContextName(const int hardwareContextIndex)
  {
      std::optional<int> gpuId = getPmeTestHardwareContexts()[hardwareContextIndex].gpuId();
      std::string        description;
      if (gpuId.has_value())
      {
          description = "GPU" + std::to_string(gpuId.value());
      }
      else
      {
          description = "CPU";
      }
      return description;
  }
  
  PmeTestHardwareContext::PmeTestHardwareContext() : codePath_(CodePath::CPU) {}
  
  PmeTestHardwareContext::PmeTestHardwareContext(TestDevice* testDevice) :
      codePath_(CodePath::GPU), testDevice_(testDevice)
  {
      setActiveDevice(testDevice_->deviceInfo());
      pmeGpuProgram_ = buildPmeGpuProgram(testDevice_->deviceContext());
  }
  
  //! Returns a human-readable context description line
  std::string PmeTestHardwareContext::description() const
  {
      switch (codePath_)
      {
          case CodePath::CPU: return "CPU";
          case CodePath::GPU: return "GPU (" + testDevice_->description() + ")";
          default: return "Unknown code path.";
      }
  }
  
  std::optional<int> PmeTestHardwareContext::gpuId() const
  {
      switch (codePath_)
      {
          case CodePath::CPU: return std::nullopt;
          case CodePath::GPU: return testDevice_->id();
          default: return std::nullopt;
      }
  }
  
  void PmeTestHardwareContext::activate() const
  {
      if (codePath_ == CodePath::GPU)
      {
          setActiveDevice(testDevice_->deviceInfo());
      }
  }
  
  ArrayRef<const PmeTestHardwareContext> getPmeTestHardwareContexts()
  {
      // The test hardware contexts used in PME tests
      static std::vector<PmeTestHardwareContext> s_pmeTestHardwareContexts;
  
      // Lazily make s_pmeTestHardwareContexts to avoid static
      // initialization fiasco.
      if (s_pmeTestHardwareContexts.empty())
      {
          // Add CPU
          s_pmeTestHardwareContexts.emplace_back(PmeTestHardwareContext());
          // Add GPU devices
          const auto& testDeviceList = getTestHardwareEnvironment()->getTestDeviceList();
          for (const auto& testDevice : testDeviceList)
          {
              s_pmeTestHardwareContexts.emplace_back(PmeTestHardwareContext(testDevice.get()));
          }
      }
      return s_pmeTestHardwareContexts;
  }
  
  void registerTestsDynamically()
  {
      auto       contexts = getPmeTestHardwareContexts();
      Range<int> contextIndexRange(0, contexts.size());
      registerDynamicalPmeSplineSpreadTests(contextIndexRange);
      registerDynamicalPmeSolveTests(contextIndexRange);
      registerDynamicalPmeGatherTests(contextIndexRange);
  }
  
  } // namespace test
  } // namespace gmx
  