Grid/Grid/tensors/Tensor_SIMT.h

/*************************************************************************************

    Grid physics library, www.github.com/paboyle/Grid 

    Source file: ./lib/tensors/Tensor_SIMT.h

    Copyright (C) 2015

Author: Peter Boyle <paboyle@ph.ed.ac.uk>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

    See the full license in the file "LICENSE" in the top level distribution directory
*************************************************************************************/
/*  END LEGAL */
#pragma once 

#include <string.h>

NAMESPACE_BEGIN(Grid);

////////////////////////////////////////////////
// Inside a GPU thread
////////////////////////////////////////////////
template<class vobj>
accelerator_inline void exchangeSIMT(vobj &mp0,vobj &mp1,const vobj &vp0,const vobj &vp1,Integer type)
{
    typedef decltype(coalescedRead(mp0)) sobj;
    unsigned int Nsimd = vobj::Nsimd();
    unsigned int mask = Nsimd >> (type + 1);
    int lane = acceleratorSIMTlane(Nsimd);
    int j0 = lane &(~mask); // inner coor zero
    int j1 = lane |(mask) ; // inner coor one
    const vobj *vpa = &vp0;
    const vobj *vpb = &vp1;
    const vobj *vp = (lane&mask) ? (vpb) : (vpa);
    auto sa = coalescedRead(vp[0],j0);
    auto sb = coalescedRead(vp[0],j1);
    coalescedWrite(mp0,sa);
    coalescedWrite(mp1,sb);
}


#ifndef GRID_SIMT
//////////////////////////////////////////
// Trivial mapping of vectors on host
//////////////////////////////////////////
template<class vobj> accelerator_inline
vobj coalescedRead(const vobj & __restrict__ vec,int lane=0)
{
  return vec;
}
template<class vobj> accelerator_inline
vobj coalescedReadPermute(const vobj & __restrict__ vec,int ptype,int doperm,int lane=0)
{
  if ( doperm ) {
    vobj ret;
    permute(ret,vec, ptype);
    return ret;
  } else { 
    return vec;
  }
}
template<class vobj> accelerator_inline
void coalescedWrite(vobj & __restrict__ vec,const vobj & __restrict__ extracted,int lane=0)
{
  vec = extracted;
}
template<class vobj> accelerator_inline
void coalescedWriteNonTemporal(vobj & __restrict__ vec,const vobj & __restrict__ extracted,int lane=0)
{
  vstream(vec, extracted);
}
#else


//#ifndef GRID_SYCL
#if 1
// Use the scalar as our own complex on GPU ... thrust::complex or std::complex
template<class vsimd,IfSimd<vsimd> = 0> accelerator_inline
typename vsimd::scalar_type
coalescedRead(const vsimd & __restrict__ vec,int lane=acceleratorSIMTlane(vsimd::Nsimd()))
{
  typedef typename vsimd::scalar_type S;
  S * __restrict__ p=(S *)&vec;
  return p[lane];
}
template<int ptype,class vsimd,IfSimd<vsimd> = 0> accelerator_inline
typename vsimd::scalar_type
coalescedReadPermute(const vsimd & __restrict__ vec,int doperm,int lane=acceleratorSIMTlane(vsimd::Nsimd()))
{
  typedef typename vsimd::scalar_type S;

  S * __restrict__ p=(S *)&vec;
  int mask = vsimd::Nsimd() >> (ptype + 1);
  int plane= doperm ? lane ^ mask : lane;
  return p[plane];
}
template<class vsimd,IfSimd<vsimd> = 0> accelerator_inline
void coalescedWrite(vsimd & __restrict__ vec,
		    const typename vsimd::scalar_type & __restrict__ extracted,
		    int lane=acceleratorSIMTlane(vsimd::Nsimd()))
{
  typedef typename vsimd::scalar_type S;
  S * __restrict__ p=(S *)&vec;
  p[lane]=extracted;
}
#else
// For SyCL have option to use GpuComplex from inside the vector type in SIMT loops
// Faster for some reason
template<class vsimd,IfSimd<vsimd> = 0> accelerator_inline
typename vsimd::vector_type::datum
coalescedRead(const vsimd & __restrict__ vec,int lane=acceleratorSIMTlane(vsimd::Nsimd()))
{
  typedef typename vsimd::vector_type::datum S;
  S * __restrict__ p=(S *)&vec;
  return p[lane];
}
template<int ptype,class vsimd,IfSimd<vsimd> = 0> accelerator_inline
typename vsimd::vector_type::datum
coalescedReadPermute(const vsimd & __restrict__ vec,int doperm,int lane=acceleratorSIMTlane(vsimd::Nsimd()))
{
  typedef typename vsimd::vector_type::datum S;

  S * __restrict__ p=(S *)&vec;
  int mask = vsimd::Nsimd() >> (ptype + 1);
  int plane= doperm ? lane ^ mask : lane;
  return p[plane];
}
template<class vsimd,IfSimd<vsimd> = 0> accelerator_inline
void coalescedWrite(vsimd & __restrict__ vec,
		    const typename vsimd::vector_type::datum & __restrict__ extracted,
		    int lane=acceleratorSIMTlane(vsimd::Nsimd()))
{
  typedef typename vsimd::vector_type::datum S;
  S * __restrict__ p=(S *)&vec;
  p[lane]=extracted;
}
#endif

//////////////////////////////////////////
// Extract and insert slices on the GPU
//////////////////////////////////////////
template<class vobj> accelerator_inline
typename vobj::scalar_object coalescedRead(const vobj & __restrict__ vec,int lane=acceleratorSIMTlane(vobj::Nsimd()))
{
  return extractLane(lane,vec);
}
template<class vobj> accelerator_inline
typename vobj::scalar_object coalescedReadPermute(const vobj & __restrict__ vec,int ptype,int doperm,int lane=acceleratorSIMTlane(vobj::Nsimd()))
{
  int mask = vobj::Nsimd() >> (ptype + 1);		
  int plane= doperm ? lane ^ mask : lane;
  return extractLane(plane,vec);
}
template<class vobj> accelerator_inline
void coalescedWrite(vobj & __restrict__ vec,const typename vobj::scalar_object & __restrict__ extracted,int lane=acceleratorSIMTlane(vobj::Nsimd()))
{
  insertLane(lane,vec,extracted);
}
template<class vobj> accelerator_inline
void coalescedWriteNonTemporal(vobj & __restrict__ vec,const vobj & __restrict__ extracted,int lane=0)
{
  insertLane(lane,vec,extracted);
}
#endif


NAMESPACE_END(Grid);