add dense device_view type

Author: upsj

core/matrix/dense.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2017 - 2025 The Ginkgo authors
+// SPDX-FileCopyrightText: 2017 - 2026 The Ginkgo authors
 //
 // SPDX-License-Identifier: BSD-3-Clause
 
@@ -1956,6 +1956,22 @@ void Dense<ValueType>::get_imag(ptr_param<real_type> result) const
 }
 
 
+template <typename ValueType>
+auto Dense<ValueType>::get_device_view() -> device_view
+{
+    return device_view{this->get_size(), this->get_stride(),
+                       this->get_values()};
+};
+
+
+template <typename ValueType>
+auto Dense<ValueType>::get_const_device_view() const -> const_device_view
+{
+    return const_device_view{this->get_size(), this->get_stride(),
+                             this->get_const_values()};
+};
+
+
 template <typename ValueType>
 void Dense<ValueType>::add_scaled_identity_impl(const LinOp* a, const LinOp* b)
 {

core/test/matrix/CMakeLists.txt

@@ -7,6 +7,7 @@ ginkgo_create_test(coo_builder)
 ginkgo_create_test(csr)
 ginkgo_create_test(csr_builder)
 ginkgo_create_test(dense)
+ginkgo_create_test(device_views)
 ginkgo_create_test(diagonal)
 ginkgo_create_test(ell)
 ginkgo_create_test(fbcsr)

core/test/matrix/dense.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2017 - 2025 The Ginkgo authors
+// SPDX-FileCopyrightText: 2017 - 2026 The Ginkgo authors
 //
 // SPDX-License-Identifier: BSD-3-Clause
 
@@ -306,6 +306,26 @@ TYPED_TEST(Dense, CanBeReadFromMatrixAssemblyData)
 }
 
 
+TYPED_TEST(Dense, CanCreateDeviceView)
+{
+    auto view = this->mtx->get_device_view();
+
+    EXPECT_EQ(view.size, this->mtx->get_size());
+    EXPECT_EQ(view.stride, this->mtx->get_stride());
+    EXPECT_EQ(view.data, this->mtx->get_values());
+}
+
+
+TYPED_TEST(Dense, CanCreateConstDeviceView)
+{
+    auto view = this->mtx->get_const_device_view();
+
+    EXPECT_EQ(view.size, this->mtx->get_size());
+    EXPECT_EQ(view.stride, this->mtx->get_stride());
+    EXPECT_EQ(view.data, this->mtx->get_values());
+}
+
+
 TYPED_TEST(Dense, CanCreateSubmatrix)
 {
     using value_type = typename TestFixture::value_type;

core/test/matrix/device_views.cpp

@@ -0,0 +1,30 @@
+// SPDX-FileCopyrightText: 2026 The Ginkgo authors
+//
+// SPDX-License-Identifier: BSD-3-Clause
+
+#include <gtest/gtest.h>
+
+#include <ginkgo/core/matrix/device_views.hpp>
+
+#include "core/test/utils.hpp"
+
+
+template <typename T>
+class DenseView : public ::testing::Test {};
+
+TYPED_TEST_SUITE(DenseView, gko::test::ValueTypes, TypenameNameGenerator);
+
+
+TYPED_TEST(DenseView, AccessWorks)
+{
+    std::vector<TypeParam> values(10);
+    gko::matrix::device_view::dense<TypeParam> view{gko::dim<2>{1, 2}, 3,
+                                                    values.data()};
+
+    ASSERT_EQ(view.size, gko::dim<2>(1, 2));
+    ASSERT_EQ(view.stride, 3);
+    ASSERT_EQ(view.data, values.data());
+    ASSERT_EQ(&view(0, 0), &values[0]);
+    ASSERT_EQ(&view(1, 0), &values[3]);
+    ASSERT_EQ(&view(1, 1), &values[4]);
+}

include/ginkgo/core/matrix/dense.hpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2017 - 2025 The Ginkgo authors
+// SPDX-FileCopyrightText: 2017 - 2026 The Ginkgo authors
 //
 // SPDX-License-Identifier: BSD-3-Clause
 
@@ -16,6 +16,7 @@
 #include <ginkgo/core/base/range_accessors.hpp>
 #include <ginkgo/core/base/types.hpp>
 #include <ginkgo/core/base/utils.hpp>
+#include <ginkgo/core/matrix/device_views.hpp>
 #include <ginkgo/core/matrix/permutation.hpp>
 #include <ginkgo/core/matrix/scaled_permutation.hpp>
 
@@ -177,14 +178,16 @@ class Dense
 
     using value_type = ValueType;
     using index_type = int64;
-    using transposed_type = Dense<ValueType>;
-    using mat_data = matrix_data<ValueType, int64>;
-    using mat_data32 = matrix_data<ValueType, int32>;
-    using device_mat_data = device_matrix_data<ValueType, int64>;
-    using device_mat_data32 = device_matrix_data<ValueType, int32>;
+    using transposed_type = Dense<value_type>;
+    using mat_data = matrix_data<value_type, int64>;
+    using mat_data32 = matrix_data<value_type, int32>;
+    using device_mat_data = device_matrix_data<value_type, int64>;
+    using device_mat_data32 = device_matrix_data<value_type, int32>;
     using absolute_type = remove_complex<Dense>;
     using real_type = absolute_type;
     using complex_type = to_complex<Dense>;
+    using device_view = matrix::device_view::dense<value_type>;
+    using const_device_view = matrix::device_view::dense<const value_type>;
 
     using row_major_range = gko::range<gko::accessor::row_major<ValueType, 2>>;
 
@@ -889,6 +892,10 @@ class Dense
         return values_.get_size();
     }
 
+    device_view get_device_view();
+
+    const_device_view get_const_device_view() const;
+
     /**
      * Returns a single element of the matrix.
      *

include/ginkgo/core/matrix/device_views.hpp

@@ -0,0 +1,41 @@
+// SPDX-FileCopyrightText: 2026 The Ginkgo authors
+//
+// SPDX-License-Identifier: BSD-3-Clause
+
+#ifndef GKO_PUBLIC_CORE_MATRIX_DEVICE_DENSE_HPP_
+#define GKO_PUBLIC_CORE_MATRIX_DEVICE_DENSE_HPP_
+
+#include <ginkgo/core/base/dim.hpp>
+
+
+namespace gko {
+namespace matrix {
+namespace device_view {
+
+
+/**
+ * non-owning view of a matrix::Dense to be used inside device kernels.
+ * This type is used to provide a simple and stable ABI for passing data between
+ * libraries.
+ *
+ * @tparam ValueType  the value type used to store matrix entries.
+ */
+template <typename ValueType>
+struct dense {
+    dim<2> size;
+    size_type stride;
+    ValueType* data;
+
+    ValueType& operator()(size_type row, size_type col) const
+    {
+        return data[row * stride + col];
+    }
+};
+
+
+}  // namespace device_view
+}  // namespace matrix
+}  // namespace gko
+
+
+#endif  // GKO_PUBLIC_CORE_MATRIX_DEVICE_DENSE_HPP_