Let Layout determine padding

src/lbm/list/List.h

@@ -61,7 +61,8 @@ struct LayoutAoS
 {
    constexpr LayoutAoS() = delete;
 
-   constexpr uint_t alignment() { return uint_t(1); } 
+   constexpr static uint_t alignment() { return uint_t(1); } 
+   constexpr static uint_t numFluidCellsToAllocate( const uint_t numFluidCellsRequired ) { return numFluidCellsRequired; }
 
    constexpr static Index_T getPDFIdx( const uint_t idx, const uint_t f, const uint_t /*N*/ ) { return numeric_cast<Index_T>( idx * Stencil::Size + f ); }
    constexpr static Index_T getPullIdxIdx( const uint_t idx, const stencil::Direction d, const uint_t /*N*/ )
@@ -82,11 +83,19 @@ struct LayoutAoS
 template< typename Stencil, typename Index_T = walberla::uint32_t, uint_t ALIGNMENT = 64 >
 struct LayoutSoA
 {
-   static_assert( ( ( ALIGNMENT & ( ALIGNMENT - uint_t( 1 ) ) ) == 0 ) && ( ALIGNMENT >= uint_t(1) ), "The alignment for the list layout has to a power of two!" );
+   static_assert( ( ( ALIGNMENT & ( ALIGNMENT - uint_t( 1 ) ) ) == 0 ) && ( ALIGNMENT >= uint_t(1) ), "The alignment for the SoA list layout has to a power of two!" );
 
    constexpr LayoutSoA() = delete;
 
    constexpr static uint_t alignment() { return ALIGNMENT; }
+   constexpr static uint_t numFluidCellsToAllocate( const uint_t numFluidCellsRequired )
+   { 
+      uint_t alignedStepSize = std::max( uint_t(1), alignment() / sizeof( real_t ) );
+      if( ( numFluidCellsRequired % alignedStepSize ) == 0 )
+         return numFluidCellsRequired;
+      else
+         return ( numFluidCellsRequired / alignedStepSize + uint_t(1) ) * alignedStepSize;
+   }
 
    constexpr static Index_T getPDFIdx( const uint_t idx, const uint_t f, const uint_t N ) { return numeric_cast<Index_T>( f * N + idx ); }
    constexpr static Index_T getPullIdxIdx( const uint_t idx, const stencil::Direction d, const uint_t N )
@@ -145,10 +154,10 @@ public:
       return it->second;
    }
 
-   const Cell & getCell( const uint_t idx ) const
+   const Cell & getCell( const uint_t cellIdx ) const
    {
-      WALBERLA_ASSERT_LESS( idx, idxToCell_.size() );
-      return idxToCell_[ idx ];
+      WALBERLA_ASSERT_LESS( cellIdx, idxToCell_.size() );
+      return idxToCell_[ cellIdx ];
    }
 
    const std::vector<Cell> & getFluidCells() const { return idxToCell_; }
@@ -262,20 +271,16 @@ void List<LatticeModel_T, Layout_T, Index_T>::init( const std::vector<Cell> & fl
    {
       uint_t idx = 0;
       cellToIdx_.reserve( fluidCells.size() );
-      for( auto it = fluidCells.begin(); it != fluidCells.end(); ++it, ++idx )
+      for( const Cell & cell : fluidCells )
       {
-         cellToIdx_.push_back( std::make_pair( *it, idx ) );
+         cellToIdx_.push_back( std::make_pair( cell, idx++ ) );
       }
       std::sort( cellToIdx_.begin(), cellToIdx_.end(), CellToIdxOrdering() );
    }
 
    // Allocate Fluid PDFs
    
-   uint_t alignedStepSize = std::max( uint_t(1), Layout_T::alignment() / sizeof( real_t ) );
-   if( ( fluidCells.size() % alignedStepSize ) == 0 )
-      numFluidCellsPadded_  = fluidCells.size();
-   else
-      numFluidCellsPadded_  = ( fluidCells.size() / alignedStepSize + uint_t(1) ) * alignedStepSize; // add padding to pdfs in order to ensure alignment for the first value of every pdf-direction
+   numFluidCellsPadded_  = Layout::numFluidCellsToAllocate( fluidCells.size() );
 
    WALBERLA_CHECK_LESS( Stencil::Size * numFluidCellsPadded_, numeric_cast<size_t>( std::numeric_limits<Index_T>::max() ),
                         "The number of PDFs you want to initialize the PDFs list with is beyond the capacity of Index_T (a.k.a. "