Add Matrix::subPipeline(Const)

include/dlaf/matrix/matrix.h

@@ -129,6 +129,15 @@ class Matrix : public Matrix<const T, D> {
     return readwrite(this->distribution().localTileIndex(index));
   }
 
+private:
+  using typename Matrix<const T, D>::SubPipelineTag;
+  Matrix(Matrix& mat, const SubPipelineTag);
+
+public:
+  Matrix subPipeline() {
+    return Matrix(*this, SubPipelineTag{});
+  }
+
 protected:
   using Matrix<const T, D>::tileLinearIndex;
 
@@ -186,10 +195,18 @@ class Matrix<const T, D> : public internal::MatrixBase {
   /// involving any of the locally available tiles are completed.
   void waitLocalTiles() noexcept;
 
+  Matrix subPipelineConst() {
+    return Matrix(*this, SubPipelineTag{});
+  }
+
 protected:
   Matrix(Distribution distribution) : internal::MatrixBase{std::move(distribution)} {}
 
+  struct SubPipelineTag {};
+  Matrix(Matrix& mat, const SubPipelineTag);
+
   void setUpTiles(const memory::MemoryView<ElementType, D>& mem, const LayoutInfo& layout) noexcept;
+  void setUpSubPipelines(Matrix<const T, D>&) noexcept;
 
   std::vector<internal::TilePipeline<T, D>> tile_managers_;
 };

include/dlaf/matrix/matrix.tpp

@@ -56,5 +56,8 @@ Matrix<T, D>::Matrix(Distribution distribution, const LayoutInfo& layout, Elemen
 template <class T, Device D>
 Matrix<T, D>::Matrix(const LayoutInfo& layout, ElementType* ptr) : Matrix<const T, D>(layout, ptr) {}
 
+template <class T, Device D>
+Matrix<T, D>::Matrix(Matrix<T, D>& mat, const SubPipelineTag tag) : Matrix<const T, D>(mat, tag) {}
+
 }
 }

include/dlaf/matrix/matrix_const.tpp

@@ -72,5 +72,29 @@ void Matrix<const T, D>::setUpTiles(const memory::MemoryView<ElementType, D>& me
   }
 }
 
+template <class T, Device D>
+Matrix<const T, D>::Matrix(Matrix<const T, D>& mat, const SubPipelineTag)
+    : MatrixBase(mat.distribution()) {
+  setUpSubPipelines(mat);
+}
+
+template <class T, Device D>
+void Matrix<const T, D>::setUpSubPipelines(Matrix<const T, D>& mat) noexcept {
+  namespace ex = pika::execution::experimental;
+
+  // TODO: Optimize read-after-read. This is currently forced to access the base
+  // matrix in readwrite mode so that we can move the tile into the
+  // sub-pipeline. This is semantically not required and should eventually be
+  // optimized.
+  tile_managers_.reserve(mat.tile_managers_.size());
+  for (auto& tm : mat.tile_managers_) {
+    tile_managers_.emplace_back(Tile<T, D>());
+    auto s = ex::when_all(tile_managers_.back().readwrite_with_wrapper(), tm.readwrite()) |
+             ex::then([](internal::TileAsyncRwMutexReadWriteWrapper<T, D> empty_tile_wrapper,
+                         Tile<T, D> tile) { empty_tile_wrapper.get() = std::move(tile); });
+    ex::start_detached(std::move(s));
+  }
+}
+
 }
 }