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8f5281563e
assignment. LatticeCoordinate helper to get global (reduced) coordinate. Some more work of similar type perhaps needed, but the bulk of the required structure for masked array assignment is now in place.
363 lines
10 KiB
C++
363 lines
10 KiB
C++
//////////////////////////////////////////////////////////////////////////////////////////
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// Must not lose sight that goal is to be able to construct really efficient
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// gather to a point stencil code. CSHIFT is not the best way, so probably need
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// additional stencil support.
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//
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// Stencil based code could pre-exchange haloes and use a table lookup for neighbours
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//
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// Lattice <foo> could also allocate haloes which get used for stencil code.
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//
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// Grid could create a neighbour index table for a given stencil.
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//
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// Could also implement CovariantCshift, to fuse the loops and enhance performance.
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//
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//
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// General stencil computation:
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//
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// Generic services
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// 0) Prebuild neighbour tables
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// 1) Compute sizes of all haloes/comms buffers; allocate them.
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//
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// 2) Gather all faces, and communicate.
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// 3) Loop over result sites, giving nbr index/offnode info for each
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//
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// Could take a
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// SpinProjectFaces
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// start comms
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// complete comms
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// Reconstruct Umu
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//
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// Approach.
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//
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//////////////////////////////////////////////////////////////////////////////////////////
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namespace Grid {
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class Stencil {
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public:
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Stencil(GridBase *grid,
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int npoints,
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int checkerboard,
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std::vector<int> directions,
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std::vector<int> distances);
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void Stencil_local (int dimension,int shift,int cbmask);
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void Stencil_comms (int dimension,int shift,int cbmask);
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void Stencil_comms_simd(int dimension,int shift,int cbmask);
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// Will need to implement actions for
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//
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Copy_plane;
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Copy_plane_permute;
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Gather_plane;
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// The offsets to all neibours in stencil in each direction
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int _checkerboard;
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int _npoints; // Move to template param?
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GridBase * _grid;
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// Store these as SIMD Integer needed
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//
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// std::vector< iVector<Integer, Npoint> > _offsets;
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// std::vector< iVector<Integer, Npoint> > _local;
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// std::vector< iVector<Integer, Npoint> > _comm_buf_size;
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// std::vector< iVector<Integer, Npoint> > _permute;
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std::vector<std::vector<int> > _offsets;
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std::vector<std::vector<int> > _local;
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std::vector<int> _comm_buf_size;
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std::vector<int> _permute;
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};
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Stencil::Stencil(GridBase *grid,
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int npoints,
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int checkerboard,
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std::vector<int> directions,
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std::vector<int> distances){
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_npoints = npoints;
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_grid = grid;
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for(int i=0;i<npoints;i++){
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int dimension = directions[i];
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int displacement = distances[i];
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int fd = _grid->_fdimensions[dimension];
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int rd = _grid->_rdimensions[dimension];
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_checkerboard = checkerboard;
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// the permute type
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int simd_layout = _grid->_simd_layout[dimension];
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int comm_dim = _grid->_processors[dimension] >1 ;
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int splice_dim = _grid->_simd_layout[dimension]>1 && (comm_dim);
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int sshift[2];
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if ( !comm_dim ) {
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sshift[0] = _grid->CheckerBoardShift(_checkerboard,dimension,shift,0);
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sshift[1] = _grid->CheckerBoardShift(_checkerboard,dimension,shift,1);
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if ( sshift[0] == sshift[1] ) {
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Stencil_local(dimension,shift,0x3);
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} else {
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Stencil_local(dimension,shift,0x1);// if checkerboard is unfavourable take two passes
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Stencil_local(dimension,shift,0x2);// both with block stride loop iteration
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}
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} else if ( splice_dim ) {
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sshift[0] = _grid->CheckerBoardShift(_checkerboard,dimension,shift,0);
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sshift[1] = _grid->CheckerBoardShift(_checkerboard,dimension,shift,1);
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if ( sshift[0] == sshift[1] ) {
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Stencil_comms_simd(dimension,shift,0x3);
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} else {
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Stencil_comms_simd(dimension,shift,0x1);// if checkerboard is unfavourable take two passes
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Stencil_comms_simd(dimension,shift,0x2);// both with block stride loop iteration
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}
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} else {
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// Cshift_comms(ret,rhs,dimension,shift);
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sshift[0] = _grid->CheckerBoardShift(_checkerboard,dimension,shift,0);
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sshift[1] = _grid->CheckerBoardShift(_checkerboard,dimension,shift,1);
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if ( sshift[0] == sshift[1] ) {
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Stencil_comms(dimension,shift,0x3);
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} else {
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Stencil_comms(dimension,shift,0x1);// if checkerboard is unfavourable take two passes
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Stencil_comms(dimension,shift,0x2);// both with block stride loop iteration
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}
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}
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}
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}
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void Stencil::Stencil_local (int dimension,int shift,int cbmask)
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{
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int fd = _grid->_fdimensions[dimension];
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int rd = _grid->_rdimensions[dimension];
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int ld = _grid->_ldimensions[dimension];
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int gd = _grid->_gdimensions[dimension];
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// Map to always positive shift modulo global full dimension.
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shift = (shift+fd)%fd;
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// the permute type
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int permute_dim =_grid->PermuteDim(dimension);
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int permute_type=_grid->PermuteType(dimension);
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for(int x=0;x<rd;x++){
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int o = 0;
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int bo = x * _grid->_ostride[dimension];
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int cb= (cbmask==0x2)? 1 : 0;
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int sshift = _grid->CheckerBoardShift(_checkerboard,dimension,shift,cb);
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int sx = (x+sshift)%rd;
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int permute_slice=0;
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if(permute_dim){
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int wrap = sshift/rd;
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int num = sshift%rd;
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if ( x< rd-num ) permute_slice=wrap;
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else permute_slice = 1-wrap;
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}
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if ( permute_slice ) Copy_plane_permute(dimension,x,sx,cbmask,permute_type);
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else Copy_plane (dimension,x,sx,cbmask);
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}
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}
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void Stencil::Stencil_comms (int dimension,int shift,int cbmask)
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{
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typedef typename vobj::vector_type vector_type;
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typedef typename vobj::scalar_type scalar_type;
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GridBase *grid=_grid;
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int fd = _grid->_fdimensions[dimension];
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int rd = _grid->_rdimensions[dimension];
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int simd_layout = _grid->_simd_layout[dimension];
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int comm_dim = _grid->_processors[dimension] >1 ;
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assert(simd_layout==1);
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assert(comm_dim==1);
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assert(shift>=0);
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assert(shift<fd);
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int buffer_size = _grid->_slice_nblock[dimension]*rhs._grid->_slice_block[dimension];
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// FIXME: Do something with buffer_size??
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int cb= (cbmask==0x2)? 1 : 0;
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int sshift= _grid->CheckerBoardShift(_checkerboard,dimension,shift,cb);
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for(int x=0;x<rd;x++){
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int offnode = ( x+sshift >= rd );
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int sx = (x+sshift)%rd;
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int comm_proc = (x+sshift)/rd;
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if (!offnode) {
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Copy_plane(dimension,x,sx,cbmask);
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} else {
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int words = send_buf.size();
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if (cbmask != 0x3) words=words>>1;
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int bytes = words * sizeof(vobj);
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Gather_plane_simple (dimension,sx,cbmask);
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int rank = grid->_processor;
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int recv_from_rank;
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int xmit_to_rank;
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grid->ShiftedRanks(dimension,comm_proc,xmit_to_rank,recv_from_rank);
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/*
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grid->SendToRecvFrom((void *)&send_buf[0],
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xmit_to_rank,
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(void *)&recv_buf[0],
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recv_from_rank,
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bytes);
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*/
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Scatter_plane_simple (dimension,x,cbmask);
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}
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}
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}
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void Stencil::Stencil_comms_simd(int dimension,int shift,int cbmask)
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{
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GridBase *grid=_grid;
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const int Nsimd = _grid->Nsimd();
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typedef typename vobj::vector_type vector_type;
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typedef typename vobj::scalar_type scalar_type;
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int fd = _grid->_fdimensions[dimension];
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int rd = _grid->_rdimensions[dimension];
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int ld = _grid->_ldimensions[dimension];
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int simd_layout = _grid->_simd_layout[dimension];
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int comm_dim = _grid->_processors[dimension] >1 ;
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assert(comm_dim==1);
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assert(simd_layout==2);
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assert(shift>=0);
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assert(shift<fd);
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int permute_type=_grid->PermuteType(dimension);
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///////////////////////////////////////////////
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// Simd direction uses an extract/merge pair
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///////////////////////////////////////////////
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int buffer_size = _grid->_slice_nblock[dimension]*grid->_slice_block[dimension];
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// FIXME do something with buffer size
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std::vector<scalar_type *> pointers(Nsimd); //
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std::vector<scalar_type *> rpointers(Nsimd); // received pointers
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///////////////////////////////////////////
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// Work out what to send where
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///////////////////////////////////////////
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int cb = (cbmask==0x2)? 1 : 0;
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int sshift= _grid->CheckerBoardShift(_checkerboard,dimension,shift,cb);
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std::vector<int> comm_offnode(simd_layout);
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std::vector<int> comm_proc (simd_layout); //relative processor coord in dim=dimension
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std::vector<int> icoor(grid->Nd());
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for(int x=0;x<rd;x++){
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int comm_any = 0;
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for(int s=0;s<simd_layout;s++) {
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int shifted_x = x+s*rd+sshift;
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comm_offnode[s] = shifted_x >= ld;
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comm_any = comm_any | comm_offnode[s];
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comm_proc[s] = shifted_x/ld;
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}
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int o = 0;
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int bo = x*grid->_ostride[dimension];
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int sx = (x+sshift)%rd;
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if ( comm_any ) {
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for(int i=0;i<Nsimd;i++){
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pointers[i] = (scalar_type *)&send_buf_extract[i][0];
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}
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Gather_plane_extract(rhs,pointers,dimension,sx,cbmask);
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for(int i=0;i<Nsimd;i++){
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int s;
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grid->iCoorFromIindex(icoor,i);
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s = icoor[dimension];
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if(comm_offnode[s]){
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int rank = grid->_processor;
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int recv_from_rank;
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int xmit_to_rank;
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grid->ShiftedRanks(dimension,comm_proc[s],xmit_to_rank,recv_from_rank);
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/*
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grid->SendToRecvFrom((void *)&send_buf_extract[i][0],
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xmit_to_rank,
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(void *)&recv_buf_extract[i][0],
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recv_from_rank,
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bytes);
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*/
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rpointers[i] = (scalar_type *)&recv_buf_extract[i][0];
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} else {
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rpointers[i] = (scalar_type *)&send_buf_extract[i][0];
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}
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}
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// Permute by swizzling pointers in merge
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int permute_slice=0;
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int lshift=sshift%ld;
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int wrap =lshift/rd;
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int num =lshift%rd;
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if ( x< rd-num ) permute_slice=wrap;
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else permute_slice = 1-wrap;
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int toggle_bit = (Nsimd>>(permute_type+1));
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int PermuteMap;
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for(int i=0;i<Nsimd;i++){
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if ( permute_slice ) {
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PermuteMap=i^toggle_bit;
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pointers[i] = rpointers[PermuteMap];
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} else {
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pointers[i] = rpointers[i];
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}
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}
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Scatter_plane_merge(pointers,dimension,x,cbmask);
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} else {
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int permute_slice=0;
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int wrap = sshift/rd;
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int num = sshift%rd;
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if ( x< rd-num ) permute_slice=wrap;
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else permute_slice = 1-wrap;
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if ( permute_slice ) Copy_plane_permute(ret,rhs,dimension,x,sx,cbmask,permute_type);
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else Copy_plane(ret,rhs,dimension,x,sx,cbmask);
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}
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}
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}
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};
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