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      1 // This file is part of Eigen, a lightweight C++ template library
      2 // for linear algebra.
      3 //
      4 // Copyright (C) 2008-2009 Gael Guennebaud <gael.guennebaud (at) inria.fr>
      5 //
      6 // This Source Code Form is subject to the terms of the Mozilla
      7 // Public License v. 2.0. If a copy of the MPL was not distributed
      8 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
      9 
     10 #ifndef EIGEN_GENERAL_MATRIX_VECTOR_H
     11 #define EIGEN_GENERAL_MATRIX_VECTOR_H
     12 
     13 namespace Eigen {
     14 
     15 namespace internal {
     16 
     17 /* Optimized col-major matrix * vector product:
     18  * This algorithm processes 4 columns at onces that allows to both reduce
     19  * the number of load/stores of the result by a factor 4 and to reduce
     20  * the instruction dependency. Moreover, we know that all bands have the
     21  * same alignment pattern.
     22  *
     23  * Mixing type logic: C += alpha * A * B
     24  *  |  A  |  B  |alpha| comments
     25  *  |real |cplx |cplx | no vectorization
     26  *  |real |cplx |real | alpha is converted to a cplx when calling the run function, no vectorization
     27  *  |cplx |real |cplx | invalid, the caller has to do tmp: = A * B; C += alpha*tmp
     28  *  |cplx |real |real | optimal case, vectorization possible via real-cplx mul
     29  */
     30 template<typename Index, typename LhsScalar, bool ConjugateLhs, typename RhsScalar, bool ConjugateRhs, int Version>
     31 struct general_matrix_vector_product<Index,LhsScalar,ColMajor,ConjugateLhs,RhsScalar,ConjugateRhs,Version>
     32 {
     33 typedef typename scalar_product_traits<LhsScalar, RhsScalar>::ReturnType ResScalar;
     34 
     35 enum {
     36   Vectorizable = packet_traits<LhsScalar>::Vectorizable && packet_traits<RhsScalar>::Vectorizable
     37               && int(packet_traits<LhsScalar>::size)==int(packet_traits<RhsScalar>::size),
     38   LhsPacketSize = Vectorizable ? packet_traits<LhsScalar>::size : 1,
     39   RhsPacketSize = Vectorizable ? packet_traits<RhsScalar>::size : 1,
     40   ResPacketSize = Vectorizable ? packet_traits<ResScalar>::size : 1
     41 };
     42 
     43 typedef typename packet_traits<LhsScalar>::type  _LhsPacket;
     44 typedef typename packet_traits<RhsScalar>::type  _RhsPacket;
     45 typedef typename packet_traits<ResScalar>::type  _ResPacket;
     46 
     47 typedef typename conditional<Vectorizable,_LhsPacket,LhsScalar>::type LhsPacket;
     48 typedef typename conditional<Vectorizable,_RhsPacket,RhsScalar>::type RhsPacket;
     49 typedef typename conditional<Vectorizable,_ResPacket,ResScalar>::type ResPacket;
     50 
     51 EIGEN_DONT_INLINE static void run(
     52   Index rows, Index cols,
     53   const LhsScalar* lhs, Index lhsStride,
     54   const RhsScalar* rhs, Index rhsIncr,
     55   ResScalar* res, Index resIncr, RhsScalar alpha);
     56 };
     57 
     58 template<typename Index, typename LhsScalar, bool ConjugateLhs, typename RhsScalar, bool ConjugateRhs, int Version>
     59 EIGEN_DONT_INLINE void general_matrix_vector_product<Index,LhsScalar,ColMajor,ConjugateLhs,RhsScalar,ConjugateRhs,Version>::run(
     60   Index rows, Index cols,
     61   const LhsScalar* lhs, Index lhsStride,
     62   const RhsScalar* rhs, Index rhsIncr,
     63   ResScalar* res, Index resIncr, RhsScalar alpha)
     64 {
     65   EIGEN_UNUSED_VARIABLE(resIncr)
     66   eigen_internal_assert(resIncr==1);
     67   #ifdef _EIGEN_ACCUMULATE_PACKETS
     68   #error _EIGEN_ACCUMULATE_PACKETS has already been defined
     69   #endif
     70   #define _EIGEN_ACCUMULATE_PACKETS(A0,A13,A2) \
     71     pstore(&res[j], \
     72       padd(pload<ResPacket>(&res[j]), \
     73         padd( \
     74           padd(pcj.pmul(EIGEN_CAT(ploa , A0)<LhsPacket>(&lhs0[j]),    ptmp0), \
     75                   pcj.pmul(EIGEN_CAT(ploa , A13)<LhsPacket>(&lhs1[j]),   ptmp1)), \
     76           padd(pcj.pmul(EIGEN_CAT(ploa , A2)<LhsPacket>(&lhs2[j]),    ptmp2), \
     77                   pcj.pmul(EIGEN_CAT(ploa , A13)<LhsPacket>(&lhs3[j]),   ptmp3)) )))
     78 
     79   conj_helper<LhsScalar,RhsScalar,ConjugateLhs,ConjugateRhs> cj;
     80   conj_helper<LhsPacket,RhsPacket,ConjugateLhs,ConjugateRhs> pcj;
     81   if(ConjugateRhs)
     82     alpha = numext::conj(alpha);
     83 
     84   enum { AllAligned = 0, EvenAligned, FirstAligned, NoneAligned };
     85   const Index columnsAtOnce = 4;
     86   const Index peels = 2;
     87   const Index LhsPacketAlignedMask = LhsPacketSize-1;
     88   const Index ResPacketAlignedMask = ResPacketSize-1;
     89 //  const Index PeelAlignedMask = ResPacketSize*peels-1;
     90   const Index size = rows;
     91 
     92   // How many coeffs of the result do we have to skip to be aligned.
     93   // Here we assume data are at least aligned on the base scalar type.
     94   Index alignedStart = internal::first_aligned(res,size);
     95   Index alignedSize = ResPacketSize>1 ? alignedStart + ((size-alignedStart) & ~ResPacketAlignedMask) : 0;
     96   const Index peeledSize = alignedSize - RhsPacketSize*peels - RhsPacketSize + 1;
     97 
     98   const Index alignmentStep = LhsPacketSize>1 ? (LhsPacketSize - lhsStride % LhsPacketSize) & LhsPacketAlignedMask : 0;
     99   Index alignmentPattern = alignmentStep==0 ? AllAligned
    100                        : alignmentStep==(LhsPacketSize/2) ? EvenAligned
    101                        : FirstAligned;
    102 
    103   // we cannot assume the first element is aligned because of sub-matrices
    104   const Index lhsAlignmentOffset = internal::first_aligned(lhs,size);
    105 
    106   // find how many columns do we have to skip to be aligned with the result (if possible)
    107   Index skipColumns = 0;
    108   // if the data cannot be aligned (TODO add some compile time tests when possible, e.g. for floats)
    109   if( (size_t(lhs)%sizeof(LhsScalar)) || (size_t(res)%sizeof(ResScalar)) )
    110   {
    111     alignedSize = 0;
    112     alignedStart = 0;
    113   }
    114   else if (LhsPacketSize>1)
    115   {
    116     eigen_internal_assert(size_t(lhs+lhsAlignmentOffset)%sizeof(LhsPacket)==0 || size<LhsPacketSize);
    117 
    118     while (skipColumns<LhsPacketSize &&
    119           alignedStart != ((lhsAlignmentOffset + alignmentStep*skipColumns)%LhsPacketSize))
    120       ++skipColumns;
    121     if (skipColumns==LhsPacketSize)
    122     {
    123       // nothing can be aligned, no need to skip any column
    124       alignmentPattern = NoneAligned;
    125       skipColumns = 0;
    126     }
    127     else
    128     {
    129       skipColumns = (std::min)(skipColumns,cols);
    130       // note that the skiped columns are processed later.
    131     }
    132 
    133     eigen_internal_assert(  (alignmentPattern==NoneAligned)
    134                       || (skipColumns + columnsAtOnce >= cols)
    135                       || LhsPacketSize > size
    136                       || (size_t(lhs+alignedStart+lhsStride*skipColumns)%sizeof(LhsPacket))==0);
    137   }
    138   else if(Vectorizable)
    139   {
    140     alignedStart = 0;
    141     alignedSize = size;
    142     alignmentPattern = AllAligned;
    143   }
    144 
    145   Index offset1 = (FirstAligned && alignmentStep==1?3:1);
    146   Index offset3 = (FirstAligned && alignmentStep==1?1:3);
    147 
    148   Index columnBound = ((cols-skipColumns)/columnsAtOnce)*columnsAtOnce + skipColumns;
    149   for (Index i=skipColumns; i<columnBound; i+=columnsAtOnce)
    150   {
    151     RhsPacket ptmp0 = pset1<RhsPacket>(alpha*rhs[i*rhsIncr]),
    152               ptmp1 = pset1<RhsPacket>(alpha*rhs[(i+offset1)*rhsIncr]),
    153               ptmp2 = pset1<RhsPacket>(alpha*rhs[(i+2)*rhsIncr]),
    154               ptmp3 = pset1<RhsPacket>(alpha*rhs[(i+offset3)*rhsIncr]);
    155 
    156     // this helps a lot generating better binary code
    157     const LhsScalar *lhs0 = lhs + i*lhsStride,     *lhs1 = lhs + (i+offset1)*lhsStride,
    158                     *lhs2 = lhs + (i+2)*lhsStride, *lhs3 = lhs + (i+offset3)*lhsStride;
    159 
    160     if (Vectorizable)
    161     {
    162       /* explicit vectorization */
    163       // process initial unaligned coeffs
    164       for (Index j=0; j<alignedStart; ++j)
    165       {
    166         res[j] = cj.pmadd(lhs0[j], pfirst(ptmp0), res[j]);
    167         res[j] = cj.pmadd(lhs1[j], pfirst(ptmp1), res[j]);
    168         res[j] = cj.pmadd(lhs2[j], pfirst(ptmp2), res[j]);
    169         res[j] = cj.pmadd(lhs3[j], pfirst(ptmp3), res[j]);
    170       }
    171 
    172       if (alignedSize>alignedStart)
    173       {
    174         switch(alignmentPattern)
    175         {
    176           case AllAligned:
    177             for (Index j = alignedStart; j<alignedSize; j+=ResPacketSize)
    178               _EIGEN_ACCUMULATE_PACKETS(d,d,d);
    179             break;
    180           case EvenAligned:
    181             for (Index j = alignedStart; j<alignedSize; j+=ResPacketSize)
    182               _EIGEN_ACCUMULATE_PACKETS(d,du,d);
    183             break;
    184           case FirstAligned:
    185           {
    186             Index j = alignedStart;
    187             if(peels>1)
    188             {
    189               LhsPacket A00, A01, A02, A03, A10, A11, A12, A13;
    190               ResPacket T0, T1;
    191 
    192               A01 = pload<LhsPacket>(&lhs1[alignedStart-1]);
    193               A02 = pload<LhsPacket>(&lhs2[alignedStart-2]);
    194               A03 = pload<LhsPacket>(&lhs3[alignedStart-3]);
    195 
    196               for (; j<peeledSize; j+=peels*ResPacketSize)
    197               {
    198                 A11 = pload<LhsPacket>(&lhs1[j-1+LhsPacketSize]);  palign<1>(A01,A11);
    199                 A12 = pload<LhsPacket>(&lhs2[j-2+LhsPacketSize]);  palign<2>(A02,A12);
    200                 A13 = pload<LhsPacket>(&lhs3[j-3+LhsPacketSize]);  palign<3>(A03,A13);
    201 
    202                 A00 = pload<LhsPacket>(&lhs0[j]);
    203                 A10 = pload<LhsPacket>(&lhs0[j+LhsPacketSize]);
    204                 T0  = pcj.pmadd(A00, ptmp0, pload<ResPacket>(&res[j]));
    205                 T1  = pcj.pmadd(A10, ptmp0, pload<ResPacket>(&res[j+ResPacketSize]));
    206 
    207                 T0  = pcj.pmadd(A01, ptmp1, T0);
    208                 A01 = pload<LhsPacket>(&lhs1[j-1+2*LhsPacketSize]);  palign<1>(A11,A01);
    209                 T0  = pcj.pmadd(A02, ptmp2, T0);
    210                 A02 = pload<LhsPacket>(&lhs2[j-2+2*LhsPacketSize]);  palign<2>(A12,A02);
    211                 T0  = pcj.pmadd(A03, ptmp3, T0);
    212                 pstore(&res[j],T0);
    213                 A03 = pload<LhsPacket>(&lhs3[j-3+2*LhsPacketSize]);  palign<3>(A13,A03);
    214                 T1  = pcj.pmadd(A11, ptmp1, T1);
    215                 T1  = pcj.pmadd(A12, ptmp2, T1);
    216                 T1  = pcj.pmadd(A13, ptmp3, T1);
    217                 pstore(&res[j+ResPacketSize],T1);
    218               }
    219             }
    220             for (; j<alignedSize; j+=ResPacketSize)
    221               _EIGEN_ACCUMULATE_PACKETS(d,du,du);
    222             break;
    223           }
    224           default:
    225             for (Index j = alignedStart; j<alignedSize; j+=ResPacketSize)
    226               _EIGEN_ACCUMULATE_PACKETS(du,du,du);
    227             break;
    228         }
    229       }
    230     } // end explicit vectorization
    231 
    232     /* process remaining coeffs (or all if there is no explicit vectorization) */
    233     for (Index j=alignedSize; j<size; ++j)
    234     {
    235       res[j] = cj.pmadd(lhs0[j], pfirst(ptmp0), res[j]);
    236       res[j] = cj.pmadd(lhs1[j], pfirst(ptmp1), res[j]);
    237       res[j] = cj.pmadd(lhs2[j], pfirst(ptmp2), res[j]);
    238       res[j] = cj.pmadd(lhs3[j], pfirst(ptmp3), res[j]);
    239     }
    240   }
    241 
    242   // process remaining first and last columns (at most columnsAtOnce-1)
    243   Index end = cols;
    244   Index start = columnBound;
    245   do
    246   {
    247     for (Index k=start; k<end; ++k)
    248     {
    249       RhsPacket ptmp0 = pset1<RhsPacket>(alpha*rhs[k*rhsIncr]);
    250       const LhsScalar* lhs0 = lhs + k*lhsStride;
    251 
    252       if (Vectorizable)
    253       {
    254         /* explicit vectorization */
    255         // process first unaligned result's coeffs
    256         for (Index j=0; j<alignedStart; ++j)
    257           res[j] += cj.pmul(lhs0[j], pfirst(ptmp0));
    258         // process aligned result's coeffs
    259         if ((size_t(lhs0+alignedStart)%sizeof(LhsPacket))==0)
    260           for (Index i = alignedStart;i<alignedSize;i+=ResPacketSize)
    261             pstore(&res[i], pcj.pmadd(pload<LhsPacket>(&lhs0[i]), ptmp0, pload<ResPacket>(&res[i])));
    262         else
    263           for (Index i = alignedStart;i<alignedSize;i+=ResPacketSize)
    264             pstore(&res[i], pcj.pmadd(ploadu<LhsPacket>(&lhs0[i]), ptmp0, pload<ResPacket>(&res[i])));
    265       }
    266 
    267       // process remaining scalars (or all if no explicit vectorization)
    268       for (Index i=alignedSize; i<size; ++i)
    269         res[i] += cj.pmul(lhs0[i], pfirst(ptmp0));
    270     }
    271     if (skipColumns)
    272     {
    273       start = 0;
    274       end = skipColumns;
    275       skipColumns = 0;
    276     }
    277     else
    278       break;
    279   } while(Vectorizable);
    280   #undef _EIGEN_ACCUMULATE_PACKETS
    281 }
    282 
    283 /* Optimized row-major matrix * vector product:
    284  * This algorithm processes 4 rows at onces that allows to both reduce
    285  * the number of load/stores of the result by a factor 4 and to reduce
    286  * the instruction dependency. Moreover, we know that all bands have the
    287  * same alignment pattern.
    288  *
    289  * Mixing type logic:
    290  *  - alpha is always a complex (or converted to a complex)
    291  *  - no vectorization
    292  */
    293 template<typename Index, typename LhsScalar, bool ConjugateLhs, typename RhsScalar, bool ConjugateRhs, int Version>
    294 struct general_matrix_vector_product<Index,LhsScalar,RowMajor,ConjugateLhs,RhsScalar,ConjugateRhs,Version>
    295 {
    296 typedef typename scalar_product_traits<LhsScalar, RhsScalar>::ReturnType ResScalar;
    297 
    298 enum {
    299   Vectorizable = packet_traits<LhsScalar>::Vectorizable && packet_traits<RhsScalar>::Vectorizable
    300               && int(packet_traits<LhsScalar>::size)==int(packet_traits<RhsScalar>::size),
    301   LhsPacketSize = Vectorizable ? packet_traits<LhsScalar>::size : 1,
    302   RhsPacketSize = Vectorizable ? packet_traits<RhsScalar>::size : 1,
    303   ResPacketSize = Vectorizable ? packet_traits<ResScalar>::size : 1
    304 };
    305 
    306 typedef typename packet_traits<LhsScalar>::type  _LhsPacket;
    307 typedef typename packet_traits<RhsScalar>::type  _RhsPacket;
    308 typedef typename packet_traits<ResScalar>::type  _ResPacket;
    309 
    310 typedef typename conditional<Vectorizable,_LhsPacket,LhsScalar>::type LhsPacket;
    311 typedef typename conditional<Vectorizable,_RhsPacket,RhsScalar>::type RhsPacket;
    312 typedef typename conditional<Vectorizable,_ResPacket,ResScalar>::type ResPacket;
    313 
    314 EIGEN_DONT_INLINE static void run(
    315   Index rows, Index cols,
    316   const LhsScalar* lhs, Index lhsStride,
    317   const RhsScalar* rhs, Index rhsIncr,
    318   ResScalar* res, Index resIncr,
    319   ResScalar alpha);
    320 };
    321 
    322 template<typename Index, typename LhsScalar, bool ConjugateLhs, typename RhsScalar, bool ConjugateRhs, int Version>
    323 EIGEN_DONT_INLINE void general_matrix_vector_product<Index,LhsScalar,RowMajor,ConjugateLhs,RhsScalar,ConjugateRhs,Version>::run(
    324   Index rows, Index cols,
    325   const LhsScalar* lhs, Index lhsStride,
    326   const RhsScalar* rhs, Index rhsIncr,
    327   ResScalar* res, Index resIncr,
    328   ResScalar alpha)
    329 {
    330   EIGEN_UNUSED_VARIABLE(rhsIncr);
    331   eigen_internal_assert(rhsIncr==1);
    332   #ifdef _EIGEN_ACCUMULATE_PACKETS
    333   #error _EIGEN_ACCUMULATE_PACKETS has already been defined
    334   #endif
    335 
    336   #define _EIGEN_ACCUMULATE_PACKETS(A0,A13,A2) {\
    337     RhsPacket b = pload<RhsPacket>(&rhs[j]); \
    338     ptmp0 = pcj.pmadd(EIGEN_CAT(ploa,A0) <LhsPacket>(&lhs0[j]), b, ptmp0); \
    339     ptmp1 = pcj.pmadd(EIGEN_CAT(ploa,A13)<LhsPacket>(&lhs1[j]), b, ptmp1); \
    340     ptmp2 = pcj.pmadd(EIGEN_CAT(ploa,A2) <LhsPacket>(&lhs2[j]), b, ptmp2); \
    341     ptmp3 = pcj.pmadd(EIGEN_CAT(ploa,A13)<LhsPacket>(&lhs3[j]), b, ptmp3); }
    342 
    343   conj_helper<LhsScalar,RhsScalar,ConjugateLhs,ConjugateRhs> cj;
    344   conj_helper<LhsPacket,RhsPacket,ConjugateLhs,ConjugateRhs> pcj;
    345 
    346   enum { AllAligned=0, EvenAligned=1, FirstAligned=2, NoneAligned=3 };
    347   const Index rowsAtOnce = 4;
    348   const Index peels = 2;
    349   const Index RhsPacketAlignedMask = RhsPacketSize-1;
    350   const Index LhsPacketAlignedMask = LhsPacketSize-1;
    351 //   const Index PeelAlignedMask = RhsPacketSize*peels-1;
    352   const Index depth = cols;
    353 
    354   // How many coeffs of the result do we have to skip to be aligned.
    355   // Here we assume data are at least aligned on the base scalar type
    356   // if that's not the case then vectorization is discarded, see below.
    357   Index alignedStart = internal::first_aligned(rhs, depth);
    358   Index alignedSize = RhsPacketSize>1 ? alignedStart + ((depth-alignedStart) & ~RhsPacketAlignedMask) : 0;
    359   const Index peeledSize = alignedSize - RhsPacketSize*peels - RhsPacketSize + 1;
    360 
    361   const Index alignmentStep = LhsPacketSize>1 ? (LhsPacketSize - lhsStride % LhsPacketSize) & LhsPacketAlignedMask : 0;
    362   Index alignmentPattern = alignmentStep==0 ? AllAligned
    363                          : alignmentStep==(LhsPacketSize/2) ? EvenAligned
    364                          : FirstAligned;
    365 
    366   // we cannot assume the first element is aligned because of sub-matrices
    367   const Index lhsAlignmentOffset = internal::first_aligned(lhs,depth);
    368 
    369   // find how many rows do we have to skip to be aligned with rhs (if possible)
    370   Index skipRows = 0;
    371   // if the data cannot be aligned (TODO add some compile time tests when possible, e.g. for floats)
    372   if( (sizeof(LhsScalar)!=sizeof(RhsScalar)) || (size_t(lhs)%sizeof(LhsScalar)) || (size_t(rhs)%sizeof(RhsScalar)) )
    373   {
    374     alignedSize = 0;
    375     alignedStart = 0;
    376   }
    377   else if (LhsPacketSize>1)
    378   {
    379     eigen_internal_assert(size_t(lhs+lhsAlignmentOffset)%sizeof(LhsPacket)==0  || depth<LhsPacketSize);
    380 
    381     while (skipRows<LhsPacketSize &&
    382            alignedStart != ((lhsAlignmentOffset + alignmentStep*skipRows)%LhsPacketSize))
    383       ++skipRows;
    384     if (skipRows==LhsPacketSize)
    385     {
    386       // nothing can be aligned, no need to skip any column
    387       alignmentPattern = NoneAligned;
    388       skipRows = 0;
    389     }
    390     else
    391     {
    392       skipRows = (std::min)(skipRows,Index(rows));
    393       // note that the skiped columns are processed later.
    394     }
    395     eigen_internal_assert(  alignmentPattern==NoneAligned
    396                       || LhsPacketSize==1
    397                       || (skipRows + rowsAtOnce >= rows)
    398                       || LhsPacketSize > depth
    399                       || (size_t(lhs+alignedStart+lhsStride*skipRows)%sizeof(LhsPacket))==0);
    400   }
    401   else if(Vectorizable)
    402   {
    403     alignedStart = 0;
    404     alignedSize = depth;
    405     alignmentPattern = AllAligned;
    406   }
    407 
    408   Index offset1 = (FirstAligned && alignmentStep==1?3:1);
    409   Index offset3 = (FirstAligned && alignmentStep==1?1:3);
    410 
    411   Index rowBound = ((rows-skipRows)/rowsAtOnce)*rowsAtOnce + skipRows;
    412   for (Index i=skipRows; i<rowBound; i+=rowsAtOnce)
    413   {
    414     EIGEN_ALIGN16 ResScalar tmp0 = ResScalar(0);
    415     ResScalar tmp1 = ResScalar(0), tmp2 = ResScalar(0), tmp3 = ResScalar(0);
    416 
    417     // this helps the compiler generating good binary code
    418     const LhsScalar *lhs0 = lhs + i*lhsStride,     *lhs1 = lhs + (i+offset1)*lhsStride,
    419                     *lhs2 = lhs + (i+2)*lhsStride, *lhs3 = lhs + (i+offset3)*lhsStride;
    420 
    421     if (Vectorizable)
    422     {
    423       /* explicit vectorization */
    424       ResPacket ptmp0 = pset1<ResPacket>(ResScalar(0)), ptmp1 = pset1<ResPacket>(ResScalar(0)),
    425                 ptmp2 = pset1<ResPacket>(ResScalar(0)), ptmp3 = pset1<ResPacket>(ResScalar(0));
    426 
    427       // process initial unaligned coeffs
    428       // FIXME this loop get vectorized by the compiler !
    429       for (Index j=0; j<alignedStart; ++j)
    430       {
    431         RhsScalar b = rhs[j];
    432         tmp0 += cj.pmul(lhs0[j],b); tmp1 += cj.pmul(lhs1[j],b);
    433         tmp2 += cj.pmul(lhs2[j],b); tmp3 += cj.pmul(lhs3[j],b);
    434       }
    435 
    436       if (alignedSize>alignedStart)
    437       {
    438         switch(alignmentPattern)
    439         {
    440           case AllAligned:
    441             for (Index j = alignedStart; j<alignedSize; j+=RhsPacketSize)
    442               _EIGEN_ACCUMULATE_PACKETS(d,d,d);
    443             break;
    444           case EvenAligned:
    445             for (Index j = alignedStart; j<alignedSize; j+=RhsPacketSize)
    446               _EIGEN_ACCUMULATE_PACKETS(d,du,d);
    447             break;
    448           case FirstAligned:
    449           {
    450             Index j = alignedStart;
    451             if (peels>1)
    452             {
    453               /* Here we proccess 4 rows with with two peeled iterations to hide
    454                * the overhead of unaligned loads. Moreover unaligned loads are handled
    455                * using special shift/move operations between the two aligned packets
    456                * overlaping the desired unaligned packet. This is *much* more efficient
    457                * than basic unaligned loads.
    458                */
    459               LhsPacket A01, A02, A03, A11, A12, A13;
    460               A01 = pload<LhsPacket>(&lhs1[alignedStart-1]);
    461               A02 = pload<LhsPacket>(&lhs2[alignedStart-2]);
    462               A03 = pload<LhsPacket>(&lhs3[alignedStart-3]);
    463 
    464               for (; j<peeledSize; j+=peels*RhsPacketSize)
    465               {
    466                 RhsPacket b = pload<RhsPacket>(&rhs[j]);
    467                 A11 = pload<LhsPacket>(&lhs1[j-1+LhsPacketSize]);  palign<1>(A01,A11);
    468                 A12 = pload<LhsPacket>(&lhs2[j-2+LhsPacketSize]);  palign<2>(A02,A12);
    469                 A13 = pload<LhsPacket>(&lhs3[j-3+LhsPacketSize]);  palign<3>(A03,A13);
    470 
    471                 ptmp0 = pcj.pmadd(pload<LhsPacket>(&lhs0[j]), b, ptmp0);
    472                 ptmp1 = pcj.pmadd(A01, b, ptmp1);
    473                 A01 = pload<LhsPacket>(&lhs1[j-1+2*LhsPacketSize]);  palign<1>(A11,A01);
    474                 ptmp2 = pcj.pmadd(A02, b, ptmp2);
    475                 A02 = pload<LhsPacket>(&lhs2[j-2+2*LhsPacketSize]);  palign<2>(A12,A02);
    476                 ptmp3 = pcj.pmadd(A03, b, ptmp3);
    477                 A03 = pload<LhsPacket>(&lhs3[j-3+2*LhsPacketSize]);  palign<3>(A13,A03);
    478 
    479                 b = pload<RhsPacket>(&rhs[j+RhsPacketSize]);
    480                 ptmp0 = pcj.pmadd(pload<LhsPacket>(&lhs0[j+LhsPacketSize]), b, ptmp0);
    481                 ptmp1 = pcj.pmadd(A11, b, ptmp1);
    482                 ptmp2 = pcj.pmadd(A12, b, ptmp2);
    483                 ptmp3 = pcj.pmadd(A13, b, ptmp3);
    484               }
    485             }
    486             for (; j<alignedSize; j+=RhsPacketSize)
    487               _EIGEN_ACCUMULATE_PACKETS(d,du,du);
    488             break;
    489           }
    490           default:
    491             for (Index j = alignedStart; j<alignedSize; j+=RhsPacketSize)
    492               _EIGEN_ACCUMULATE_PACKETS(du,du,du);
    493             break;
    494         }
    495         tmp0 += predux(ptmp0);
    496         tmp1 += predux(ptmp1);
    497         tmp2 += predux(ptmp2);
    498         tmp3 += predux(ptmp3);
    499       }
    500     } // end explicit vectorization
    501 
    502     // process remaining coeffs (or all if no explicit vectorization)
    503     // FIXME this loop get vectorized by the compiler !
    504     for (Index j=alignedSize; j<depth; ++j)
    505     {
    506       RhsScalar b = rhs[j];
    507       tmp0 += cj.pmul(lhs0[j],b); tmp1 += cj.pmul(lhs1[j],b);
    508       tmp2 += cj.pmul(lhs2[j],b); tmp3 += cj.pmul(lhs3[j],b);
    509     }
    510     res[i*resIncr]            += alpha*tmp0;
    511     res[(i+offset1)*resIncr]  += alpha*tmp1;
    512     res[(i+2)*resIncr]        += alpha*tmp2;
    513     res[(i+offset3)*resIncr]  += alpha*tmp3;
    514   }
    515 
    516   // process remaining first and last rows (at most columnsAtOnce-1)
    517   Index end = rows;
    518   Index start = rowBound;
    519   do
    520   {
    521     for (Index i=start; i<end; ++i)
    522     {
    523       EIGEN_ALIGN16 ResScalar tmp0 = ResScalar(0);
    524       ResPacket ptmp0 = pset1<ResPacket>(tmp0);
    525       const LhsScalar* lhs0 = lhs + i*lhsStride;
    526       // process first unaligned result's coeffs
    527       // FIXME this loop get vectorized by the compiler !
    528       for (Index j=0; j<alignedStart; ++j)
    529         tmp0 += cj.pmul(lhs0[j], rhs[j]);
    530 
    531       if (alignedSize>alignedStart)
    532       {
    533         // process aligned rhs coeffs
    534         if ((size_t(lhs0+alignedStart)%sizeof(LhsPacket))==0)
    535           for (Index j = alignedStart;j<alignedSize;j+=RhsPacketSize)
    536             ptmp0 = pcj.pmadd(pload<LhsPacket>(&lhs0[j]), pload<RhsPacket>(&rhs[j]), ptmp0);
    537         else
    538           for (Index j = alignedStart;j<alignedSize;j+=RhsPacketSize)
    539             ptmp0 = pcj.pmadd(ploadu<LhsPacket>(&lhs0[j]), pload<RhsPacket>(&rhs[j]), ptmp0);
    540         tmp0 += predux(ptmp0);
    541       }
    542 
    543       // process remaining scalars
    544       // FIXME this loop get vectorized by the compiler !
    545       for (Index j=alignedSize; j<depth; ++j)
    546         tmp0 += cj.pmul(lhs0[j], rhs[j]);
    547       res[i*resIncr] += alpha*tmp0;
    548     }
    549     if (skipRows)
    550     {
    551       start = 0;
    552       end = skipRows;
    553       skipRows = 0;
    554     }
    555     else
    556       break;
    557   } while(Vectorizable);
    558 
    559   #undef _EIGEN_ACCUMULATE_PACKETS
    560 }
    561 
    562 } // end namespace internal
    563 
    564 } // end namespace Eigen
    565 
    566 #endif // EIGEN_GENERAL_MATRIX_VECTOR_H
    567