mirror of
https://github.com/paboyle/Grid.git
synced 2024-11-14 01:35:36 +00:00
c0ead94791
any particular success in increasing the performance.
346 lines
10 KiB
C++
346 lines
10 KiB
C++
#include "Grid.h"
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namespace Grid {
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void CartesianStencil::LebesgueOrder(void)
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{
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_LebesgueReorder.resize(0);
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// Align up dimensions to power of two.
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const StencilInteger one=1;
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StencilInteger ND = _grid->_ndimension;
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std::vector<StencilInteger> dims(ND);
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std::vector<StencilInteger> adims(ND);
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std::vector<std::vector<StencilInteger> > bitlist(ND);
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for(StencilInteger mu=0;mu<ND;mu++){
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dims[mu] = _grid->_rdimensions[mu];
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assert ( dims[mu] != 0 );
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adims[mu] = alignup(dims[mu]);
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}
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// List which bits of padded volume coordinate contribute; this strategy
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// i) avoids recursion
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// ii) has loop lengths at most the width of a 32 bit word.
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int sitebit=0;
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int split=24;
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for(int mu=0;mu<ND;mu++){ // mu 0 takes bit 0; mu 1 takes bit 1 etc...
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for(int bit=0;bit<split;bit++){
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StencilInteger mask = one<<bit;
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if ( mask&(adims[mu]-1) ){
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bitlist[mu].push_back(sitebit);
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sitebit++;
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}
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}
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}
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for(int bit=split;bit<32;bit++){
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StencilInteger mask = one<<bit;
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for(int mu=0;mu<ND;mu++){ // mu 0 takes bit 0; mu 1 takes bit 1 etc...
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if ( mask&(adims[mu]-1) ){
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bitlist[mu].push_back(sitebit);
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sitebit++;
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}
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}
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}
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// Work out padded and unpadded volumes
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StencilInteger avol = 1;
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for(int mu=0;mu<ND;mu++) avol = avol * adims[mu];
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StencilInteger vol = 1;
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for(int mu=0;mu<ND;mu++) vol = vol * dims[mu];
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// Loop over padded volume, following Lebesgue curve
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// We interleave the bits from sequential "mu".
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std::vector<StencilInteger> ax(ND);
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for(StencilInteger asite=0;asite<avol;asite++){
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// Start with zero and collect bits
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for(int mu=0;mu<ND;mu++) ax[mu] = 0;
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int contained = 1;
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for(int mu=0;mu<ND;mu++){
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// Build the coordinate on the aligned volume
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for(int bit=0;bit<bitlist[mu].size();bit++){
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int sbit=bitlist[mu][bit];
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if(asite&(one<<sbit)){
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ax[mu]|=one<<bit;
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}
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}
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// Is it contained in original box
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if ( ax[mu]>dims[mu]-1 ) contained = 0;
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}
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if ( contained ) {
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int site = ax[0]
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+ dims[0]*ax[1]
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+dims[0]*dims[1]*ax[2]
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+dims[0]*dims[1]*dims[2]*ax[3];
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_LebesgueReorder.push_back(site);
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}
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}
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assert( _LebesgueReorder.size() == vol );
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}
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CartesianStencil::CartesianStencil(GridBase *grid,
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int npoints,
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int checkerboard,
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const std::vector<int> &directions,
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const std::vector<int> &distances)
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: _offsets(npoints),
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_is_local(npoints),
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_comm_buf_size(npoints),
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_permute_type(npoints),
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_permute(npoints)
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{
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_npoints = npoints;
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_grid = grid;
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_directions = directions;
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_distances = distances;
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_unified_buffer_size=0;
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_request_count =0;
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LebesgueOrder();
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int osites = _grid->oSites();
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for(int i=0;i<npoints;i++){
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int point = i;
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_offsets[i].resize( osites);
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_is_local[i].resize(osites);
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_permute[i].resize( osites);
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int dimension = directions[i];
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int displacement = distances[i];
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int shift = displacement;
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int fd = _grid->_fdimensions[dimension];
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int rd = _grid->_rdimensions[dimension];
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_permute_type[point]=_grid->PermuteType(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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// Underlying approach. For each local site build
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// up a table containing the npoint "neighbours" and whether they
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// live in lattice or a comms buffer.
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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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Local(point,dimension,shift,0x3);
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} else {
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Local(point,dimension,shift,0x1);// if checkerboard is unfavourable take two passes
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Local(point,dimension,shift,0x2);// both with block stride loop iteration
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}
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} else { // All permute extract done in comms phase prior to Stencil application
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// So tables are the same whether comm_dim or 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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Comms(point,dimension,shift,0x3);
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} else {
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Comms(point,dimension,shift,0x1);// if checkerboard is unfavourable take two passes
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Comms(point,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 CartesianStencil::Local (int point, 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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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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CopyPlane(point,dimension,x,sx,cbmask,permute_slice);
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}
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}
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void CartesianStencil::Comms (int point,int dimension,int shift,int cbmask)
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{
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GridBase *grid=_grid;
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int fd = _grid->_fdimensions[dimension];
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int ld = _grid->_ldimensions[dimension];
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int rd = _grid->_rdimensions[dimension];
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int pd = _grid->_processors[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); // Why?
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assert(comm_dim==1);
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shift = (shift + fd) %fd;
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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]*_grid->_slice_block[dimension];
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_comm_buf_size[point] = buffer_size; // Size of _one_ plane. Multiple planes may be gathered and
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// send to one or more remote nodes.
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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)%fd) >= rd );
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// int comm_proc = ((x+sshift)/ld)%pd;
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// int offnode = (comm_proc!=0);
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int sx = (x+sshift)%rd;
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if (!offnode) {
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int permute_slice=0;
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CopyPlane(point,dimension,x,sx,cbmask,permute_slice);
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} else {
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int words = buffer_size;
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if (cbmask != 0x3) words=words>>1;
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// GatherPlaneSimple (point,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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int unified_buffer_offset = _unified_buffer_size;
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_unified_buffer_size += words;
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ScatterPlane(point,dimension,x,cbmask,unified_buffer_offset); // permute/extract/merge is done in comms phase
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}
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}
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}
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// Routine builds up integer table for each site in _offsets, _is_local, _permute
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void CartesianStencil::CopyPlane(int point, int dimension,int lplane,int rplane,int cbmask,int permute)
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{
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int rd = _grid->_rdimensions[dimension];
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if ( !_grid->CheckerBoarded(dimension) ) {
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int o = 0; // relative offset to base within plane
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int ro = rplane*_grid->_ostride[dimension]; // base offset for start of plane
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int lo = lplane*_grid->_ostride[dimension]; // offset in buffer
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// Simple block stride gather of SIMD objects
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for(int n=0;n<_grid->_slice_nblock[dimension];n++){
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for(int b=0;b<_grid->_slice_block[dimension];b++){
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_offsets [point][lo+o+b]=ro+o+b;
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_is_local[point][lo+o+b]=1;
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_permute [point][lo+o+b]=permute;
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}
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o +=_grid->_slice_stride[dimension];
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}
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} else {
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int ro = rplane*_grid->_ostride[dimension]; // base offset for start of plane
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int lo = lplane*_grid->_ostride[dimension]; // base offset for start of plane
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int o = 0; // relative offset to base within plane
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for(int n=0;n<_grid->_slice_nblock[dimension];n++){
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for(int b=0;b<_grid->_slice_block[dimension];b++){
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int ocb=1<<_grid->CheckerBoardFromOindex(o+b);
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if ( ocb&cbmask ) {
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_offsets [point][lo+o+b]=ro+o+b;
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_is_local[point][lo+o+b]=1;
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_permute [point][lo+o+b]=permute;
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}
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}
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o +=_grid->_slice_stride[dimension];
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}
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}
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}
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// Routine builds up integer table for each site in _offsets, _is_local, _permute
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void CartesianStencil::ScatterPlane (int point,int dimension,int plane,int cbmask,int offset)
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{
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int rd = _grid->_rdimensions[dimension];
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if ( !_grid->CheckerBoarded(dimension) ) {
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int so = plane*_grid->_ostride[dimension]; // base offset for start of plane
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int o = 0; // relative offset to base within plane
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int bo = 0; // offset in buffer
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// Simple block stride gather of SIMD objects
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for(int n=0;n<_grid->_slice_nblock[dimension];n++){
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for(int b=0;b<_grid->_slice_block[dimension];b++){
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_offsets [point][so+o+b]=offset+(bo++);
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_is_local[point][so+o+b]=0;
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_permute [point][so+o+b]=0;
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}
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o +=_grid->_slice_stride[dimension];
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}
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} else {
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int so = plane*_grid->_ostride[dimension]; // base offset for start of plane
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int o = 0; // relative offset to base within plane
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int bo = 0; // offset in buffer
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for(int n=0;n<_grid->_slice_nblock[dimension];n++){
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for(int b=0;b<_grid->_slice_block[dimension];b++){
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int ocb=1<<_grid->CheckerBoardFromOindex(o+b);// Could easily be a table lookup
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if ( ocb & cbmask ) {
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_offsets [point][so+o+b]=offset+(bo++);
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_is_local[point][so+o+b]=0;
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_permute [point][so+o+b]=0;
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}
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}
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o +=_grid->_slice_stride[dimension];
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}
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}
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}
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}
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