Gram matrix support for sparse input

cpp/bench/prims/distance/fused_l2_nn.cu

@@ -16,6 +16,7 @@
 
 #include <common/benchmark.hpp>
 #include <raft/distance/fused_l2_nn.cuh>
+#include <raft/linalg/norm.cuh>
 #include <raft/util/cudart_utils.hpp>
 #if defined RAFT_COMPILED
 #include <raft/distance/specializations.cuh>

cpp/include/raft/core/detail/nvtx.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021-2022, NVIDIA CORPORATION.
+ * Copyright (c) 2021-2023, NVIDIA CORPORATION.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.

cpp/include/raft/core/device_mdspan.hpp

@@ -259,6 +259,36 @@ auto make_device_matrix_view(ElementType* ptr, IndexType n_rows, IndexType n_col
   return device_matrix_view<ElementType, IndexType, LayoutPolicy>{ptr, extents};
 }
 
+/**
+ * @brief Create a 2-dim mdspan instance for device pointer with a strided layout
+ *        that is restricted to stride 1 in the trailing dimension. It's
+ *        expected that the given layout policy match the layout of the underlying
+ *        pointer.
+ * @tparam ElementType the data type of the matrix elements
+ * @tparam IndexType the index type of the extents
+ * @tparam LayoutPolicy policy for strides and layout ordering
+ * @param[in] ptr on device to wrap
+ * @param[in] n_rows number of rows in pointer
+ * @param[in] n_cols number of columns in pointer
+ * @param[in] stride leading dimension / stride of data
+ */
+template <typename ElementType, typename IndexType, typename LayoutPolicy = layout_c_contiguous>
+auto make_device_strided_matrix_view(ElementType* ptr,
+                                     IndexType n_rows,
+                                     IndexType n_cols,
+                                     IndexType stride)
+{
+  constexpr auto is_row_major = std::is_same_v<LayoutPolicy, layout_c_contiguous>;
+  IndexType stride0           = is_row_major ? (stride > 0 ? stride : n_cols) : 1;
+  IndexType stride1           = is_row_major ? 1 : (stride > 0 ? stride : n_rows);
+
+  assert(is_row_major ? stride0 >= n_cols : stride1 >= n_rows);
+  matrix_extent<IndexType> extents{n_rows, n_cols};
+
+  auto layout = make_strided_layout(extents, std::array<IndexType, 2>{stride0, stride1});
+  return device_matrix_view<ElementType, IndexType, layout_stride>{ptr, layout};
+}
+
 /**
  * @brief Create a 1-dim mdspan instance for device pointer.
  * @tparam ElementType the data type of the vector elements