[SPEC] v1::Split + onnx_importer adaptation (#3993)

* fused::v1::Split op skeleton & serialization

* Shape inference for Split and upgrade/downgrade passes

* Upgrade pass for the Split op

* Disable the failing onnx_importer Split op tests on interpreter

* Opset1 test correction for v1::Split

* Disable the failing Split op unit tests on PlaidML

* Fix of the upgrade pass for Split

* Remove one of the obsolete v0::Split constructors

src/ngraph/frontend/onnx_import/op/split.cpp

@@ -19,6 +19,7 @@
 
 #include "ngraph/op/constant.hpp"
 #include "ngraph/op/fused/split.hpp"
+#include "ngraph/op/variadic_split.hpp"
 #include "op/split.hpp"
 #include "utils/common.hpp"
 
@@ -37,21 +38,25 @@ namespace ngraph
                     const auto axis_node =
                         ngraph::op::Constant::create(element::i64, Shape{}, {axis});
 
-                    std::shared_ptr<ngraph::Node> fused_split;
+                    std::shared_ptr<ngraph::Node> split;
                     if (node.has_attribute("split"))
                     {
-                        const auto length_parts =
+                        const auto splits =
                             node.get_attribute_value<std::vector<std::size_t>>("split");
-                        fused_split =
-                            std::make_shared<ngraph::op::Split>(input, axis_node, length_parts);
+
+                        const auto split_lengths = ngraph::op::Constant::create(
+                            element::u64, Shape{splits.size()}, splits);
+
+                        split = std::make_shared<ngraph::op::v1::VariadicSplit>(
+                            input, axis_node, split_lengths);
                     }
                     else
                     {
                         const auto outputs_number = node.get_output_names().size();
-                        fused_split =
-                            std::make_shared<ngraph::op::Split>(input, axis_node, outputs_number);
+                        split = std::make_shared<ngraph::op::v1::Split>(
+                            input, axis_node, outputs_number);
                     }
-                    return common::get_outputs(fused_split);
+                    return common::get_outputs(split);
                 }
 
             } // namespace set_1

src/ngraph/node.cpp

@@ -317,6 +317,7 @@ const std::string& Node::description() const
         // type_name to const_char and virtual description() to virtual get_type_name()
         const_cast<Node*>(this)->m_node_type = get_type_name();
     }
+
     return m_node_type;
 }
 

src/ngraph/op/fused/split.cpp

@@ -23,9 +23,9 @@
 using namespace std;
 using namespace ngraph;
 
-constexpr NodeTypeInfo op::Split::type_info;
+constexpr NodeTypeInfo op::v0::Split::type_info;
 
-op::Split::Split(const Output<Node>& data, const Output<Node>& axis, const size_t num_split)
+op::v0::Split::Split(const Output<Node>& data, const Output<Node>& axis, const size_t num_split)
     : FusedOp({data, axis})
     , m_split_evenly{true}
     , m_num_split{num_split}
@@ -33,9 +33,9 @@ op::Split::Split(const Output<Node>& data, const Output<Node>& axis, const size_
     constructor_validate_and_infer_types();
 }
 
-op::Split::Split(const Output<Node>& data,
-                 const Output<Node>& axis,
-                 const std::vector<size_t>& splits)
+op::v0::Split::Split(const Output<Node>& data,
+                     const Output<Node>& axis,
+                     const std::vector<size_t>& splits)
     : FusedOp({data, axis})
     , m_split_evenly{false}
     , m_num_split{0}
@@ -45,7 +45,7 @@ op::Split::Split(const Output<Node>& data,
 }
 
 // TODO REMOVE THIS CONSTRUCTOR. INTRODUCED TO PROVIDE CI COMPATIBILITY
-op::Split::Split(const Output<Node>& data, int axis, const std::vector<size_t>& splits)
+op::v0::Split::Split(const Output<Node>& data, int axis, const std::vector<size_t>& splits)
     : FusedOp({data})
     , m_split_evenly{false}
     , m_axis{axis}
@@ -55,17 +55,7 @@ op::Split::Split(const Output<Node>& data, int axis, const std::vector<size_t>&
     constructor_validate_and_infer_types();
 }
 
-// TODO REMOVE THIS CONSTRUCTOR. INTRODUCED TO PROVIDE CI COMPATIBILITY
-op::Split::Split(const Output<Node>& data, int axis, size_t num_split)
-    : FusedOp({data})
-    , m_split_evenly{true}
-    , m_axis{axis}
-    , m_num_split{num_split}
-{
-    constructor_validate_and_infer_types();
-}
-
-void op::Split::pre_validate_and_infer_types()
+void op::v0::Split::pre_validate_and_infer_types()
 {
     // TODO REMOVE IF CHECK. INTRODUCED TO PROVIDE CI COMPATIBILITY
     if (get_input_size() == 2)
@@ -126,12 +116,12 @@ void op::Split::pre_validate_and_infer_types()
     set_input_is_relevant_to_shape(0);
 }
 
-NodeVector op::Split::decompose_op() const
+NodeVector op::v0::Split::decompose_op() const
 {
     return builder::split(input_value(0), m_splits, m_axis);
 }
 
-shared_ptr<Node> op::Split::copy_with_new_args(const NodeVector& new_args) const
+shared_ptr<Node> op::v0::Split::copy_with_new_args(const NodeVector& new_args) const
 {
     if (new_args.size() == 2)
     {
@@ -140,5 +130,96 @@ shared_ptr<Node> op::Split::copy_with_new_args(const NodeVector& new_args) const
     }
 
     // TODO REMOVE THIS RETURN AND IF ABOVE. INTRODUCED TO PROVIDE CI COMPATIBILITY
-    return make_shared<Split>(new_args.at(0), m_axis, m_splits);
+    return make_shared<op::v0::Split>(new_args.at(0), m_axis, m_splits);
+}
+
+constexpr NodeTypeInfo op::v1::Split::type_info;
+
+op::v1::Split::Split(const Output<Node>& data, const Output<Node>& axis, const size_t num_splits)
+    : FusedOp({data, axis})
+    , m_num_splits{num_splits}
+{
+    constructor_validate_and_infer_types();
+}
+
+void op::v1::Split::validate_and_infer_types()
+{
+    const auto data_ps = input_value(0).get_partial_shape();
+    const auto axis_ps = input_value(1).get_partial_shape();
+    const auto axis_et = input_value(1).get_element_type();
+
+    NODE_VALIDATION_CHECK(this,
+                          axis_ps.rank().is_static() && (size_t)axis_ps.rank() == 0,
+                          "The 'axis' input is expected to be a scalar. Got: ",
+                          axis_ps);
+
+    NODE_VALIDATION_CHECK(
+        this, axis_et.is_integral(), "The 'axis' input only accepts integral types");
+
+    if (input_value(1).get_node_shared_ptr()->is_constant())
+    {
+        auto axis = axis_value_from_input();
+
+        if (data_ps.is_static())
+        {
+            const auto data_shape = data_ps.to_shape();
+            axis = ngraph::normalize_axis(this, axis, data_shape.size());
+
+            const auto dimension_at_axis = data_shape.at(axis);
+
+            NODE_VALIDATION_CHECK(this,
+                                  dimension_at_axis % m_num_splits == 0,
+                                  "The input tensor's dimension pointed by the 'axis' parameter: ",
+                                  dimension_at_axis,
+                                  " has to be a multiple of the 'num_splits' attribute value: ",
+                                  m_num_splits);
+
+            Shape each_output_shape{data_shape};
+            each_output_shape.at(axis) = dimension_at_axis / m_num_splits;
+
+            for (size_t i = 0; i < m_num_splits; ++i)
+            {
+                set_output_type(i, input(0).get_element_type(), each_output_shape);
+            }
+        }
+    }
+    else
+    {
+        for (size_t i = 0; i < m_num_splits; ++i)
+        {
+            set_output_type(i, input(0).get_element_type(), PartialShape::dynamic());
+        }
+
+        set_input_is_relevant_to_shape(0);
+    }
+}
+
+shared_ptr<Node> op::v1::Split::copy_with_new_args(const NodeVector& new_args) const
+{
+    check_new_args_count(this, new_args);
+    return make_shared<v1::Split>(new_args.at(0), new_args.at(1), m_num_splits);
+}
+
+int64_t op::v1::Split::axis_value_from_input() const
+{
+    int64_t axis_value{0};
+
+    const auto axis_input = as_type_ptr<op::Constant>(input_value(1).get_node_shared_ptr());
+
+#if defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wswitch-enum"
+#endif
+    switch (static_cast<element::Type_t>(axis_input->get_element_type()))
+    {
+    case element::Type_t::i8: axis_value = axis_input->get_vector<int8_t>().at(0); break;
+    case element::Type_t::i32: axis_value = axis_input->get_vector<int32_t>().at(0); break;
+    case element::Type_t::i64: axis_value = axis_input->get_vector<int64_t>().at(0); break;
+    default: break;
+    }
+#if defined(__clang__)
+#pragma clang diagnostic pop
+#endif
+
+    return axis_value;
 }

src/ngraph/op/fused/split.hpp

@@ -61,9 +61,6 @@ namespace ngraph
                 // TODO REMOVE THIS CONSTRUCTOR. INTRODUCED TO PROVIDE CI COMPATIBILITY
                 Split(const Output<Node>& data, int axis, const std::vector<size_t>& splits);
 
-                // TODO REMOVE THIS CONSTRUCTOR. INTRODUCED TO PROVIDE CI COMPATIBILITY
-                Split(const Output<Node>& data, int axis, const size_t num_split);
-
                 void pre_validate_and_infer_types() override;
 
                 virtual NodeVector decompose_op() const override;
@@ -82,6 +79,40 @@ namespace ngraph
                 std::vector<size_t> m_splits;
             };
         }
+
+        namespace v1
+        {
+            /// \brief Splits the input tensor into a list of equal sized tensors
+            class NGRAPH_API Split : public ngraph::op::util::FusedOp
+            {
+            public:
+                static constexpr NodeTypeInfo type_info{"Split", 1};
+                const NodeTypeInfo& get_type_info() const override { return type_info; }
+                /// \brief Constructs a split operation.
+                Split() = default;
+                /// \brief Constructs a split operation.
+                /// \param data        The tensor to be split.
+                /// \param axis        The index of an axis in "data" along which to perform
+                ///                    the split.
+                /// \param num_splits  The number of pieces that the data tensor should be
+                ///                    split into.
+                Split(const Output<Node>& data, const Output<Node>& axis, const size_t num_splits);
+
+                void validate_and_infer_types() override;
+                virtual std::shared_ptr<Node>
+                    copy_with_new_args(const NodeVector& new_args) const override;
+
+                size_t get_num_splits() const { return m_num_splits; }
+                void set_num_splits(const size_t num_splits) { m_num_splits = num_splits; }
+                bool supports_decompose() const override { return false; }
+            protected:
+                size_t m_num_splits;
+
+            private:
+                int64_t axis_value_from_input() const;
+            };
+        }
+
         using v0::Split;
     }
 }

src/ngraph/op/op_version_tbl.hpp

@@ -227,6 +227,7 @@ NGRAPH_OP(Softmax, ngraph::op::v1, 1)
 NGRAPH_OP(SoftmaxCrossEntropy, ngraph::op::v0, 0)
 NGRAPH_OP(SoftmaxCrossEntropyBackprop, ngraph::op::v0, 0)
 NGRAPH_OP(SpaceToDepth, ngraph::op::v0, 0)
+NGRAPH_OP(Split, ngraph::op::v1, 1)
 NGRAPH_OP(Split, ngraph::op::v0, 0)
 NGRAPH_OP(Sqrt, ngraph::op, 0)
 NGRAPH_OP(SquaredDifference, ngraph::op::v0, 0)

src/ngraph/opsets/opset1_tbl.hpp

@@ -146,7 +146,7 @@ NGRAPH_OP(Sinh, ngraph::op::v0)
 NGRAPH_OP(Softmax, ngraph::op::v1)
 NGRAPH_OP(Sqrt, ngraph::op::v0)
 NGRAPH_OP(SpaceToDepth, ngraph::op::v0)
-NGRAPH_OP(Split, ngraph::op::v0)
+NGRAPH_OP(Split, ngraph::op::v1)
 NGRAPH_OP(SquaredDifference, ngraph::op::v0)
 NGRAPH_OP(Squeeze, ngraph::op::v0)
 NGRAPH_OP(StridedSlice, ngraph::op::v1)

src/ngraph/pass/opset0_downgrade.cpp

@@ -578,6 +578,17 @@ namespace
         return true;
     }
 
+    bool op_cast(shared_ptr<op::v1::Split> node)
+    {
+        const auto num_splits = node->get_num_splits();
+
+        auto replacement_node =
+            make_shared<op::v0::Split>(node->input_value(0), node->input_value(1), num_splits);
+
+        replace_node(node, replacement_node);
+        return true;
+    }
+
     bool op_cast(shared_ptr<op::v1::Subtract> node)
     {
         op_cast_binary_elementwise_node<op::v0::Subtract, op::v1::Subtract>(node);
@@ -643,6 +654,25 @@ namespace
         return true;
     }
 
+    bool op_cast(shared_ptr<op::v1::VariadicSplit> node)
+    {
+        const auto split_lengths = node->input_value(2).get_node_shared_ptr();
+
+        NGRAPH_CHECK(split_lengths->is_constant(),
+                     "Unable to convert VariadicSplit:v1 to Split:v0 "
+                     "if 'split_lengths' input is not constant. Node: ",
+                     *node);
+
+        const auto splits = as_type_ptr<op::Constant>(split_lengths)->get_vector<int64_t>();
+        const std::vector<size_t> splits_unsigned{splits.begin(), splits.end()};
+
+        auto replacement_node =
+            make_shared<op::v0::Split>(node->input_value(0), node->input_value(1), splits_unsigned);
+
+        replace_node(node, replacement_node);
+        return true;
+    }
+
     using DispatchMap = map<NodeTypeInfo, std::function<bool(shared_ptr<Node> node)>>;
 
     template <typename T>

src/ngraph/pass/opset1_upgrade.cpp

@@ -547,6 +547,35 @@ namespace
         return true;
     }
 
+    bool op_cast(shared_ptr<op::Split> node)
+    {
+        const auto& splits_vec = node->get_splits();
+        const auto first_elem = splits_vec.front();
+
+        const bool split_evenly =
+            std::all_of(splits_vec.begin(), splits_vec.end(), [first_elem](const size_t split) {
+                return split == first_elem;
+            });
+
+        std::shared_ptr<Node> replacement_node;
+        if (split_evenly)
+        {
+            replacement_node = make_shared<op::v1::Split>(
+                node->input_value(0), node->input_value(1), splits_vec.front());
+        }
+        else
+        {
+            const auto split_lengths =
+                ngraph::op::Constant::create(element::u64, Shape{splits_vec.size()}, splits_vec);
+
+            replacement_node = make_shared<op::v1::VariadicSplit>(
+                node->input_value(0), node->input_value(1), split_lengths);
+        }
+
+        replace_node(node, replacement_node);
+        return true;
+    }
+
     bool op_cast(shared_ptr<op::Subtract> node)
     {
         op_cast_binary_elementwise_node<op::v0::Subtract, op::v1::Subtract>(node);

src/ngraph/runtime/interpreter/unit_test.manifest

@@ -22,3 +22,8 @@ top_k_opset_11_const_k_smallest
 # Tile op case that the number of elements in "repeats" and shape of "data" are different
 tile_3d_small_data_rank
 tile_3d_few_repeats
+
+# Another fused op decomposition pass required after the downgrade pass
+model_split_equal_parts_default
+model_split_equal_parts_2d
+model_split_variable_parts_2d

src/ngraph/runtime/plaidml/unit_test.manifest

@@ -316,6 +316,11 @@ layer_norm_affine_stats
 layer_norm_bprop_affine_stats
 layer_norm_bprop_affine
 
+# Another fused op decomposition pass required after the downgrade pass
+model_split_equal_parts_default
+model_split_equal_parts_2d
+model_split_variable_parts_2d
+
 # shapes with zeros dimensions like (5, 0, 5) not supported in PlaidML backend
 dyn_replace_slice
 

src/ngraph/serializer.cpp

@@ -2747,6 +2747,12 @@ shared_ptr<Node> JSONDeserializer::deserialize_node(json node_js)
             node = make_shared<op::Split>(args[0], args[1], splits);
             break;
         }
+        case OP_TYPEID::Split_v1:
+        {
+            const auto num_splits = node_js.at("num_splits").get<size_t>();
+            node = make_shared<op::Split>(args[0], args[1], num_splits);
+            break;
+        }
         case OP_TYPEID::Sqrt:
         {
             node = make_shared<op::Sqrt>(args[0]);
@@ -4415,10 +4421,16 @@ json JSONSerializer::serialize_node(const Node& n)
     }
     case OP_TYPEID::Split:
     {
-        auto tmp = static_cast<const op::Split*>(&n);
+        const auto tmp = static_cast<const op::Split*>(&n);
         node["splits"] = tmp->get_splits();
         break;
     }
+    case OP_TYPEID::Split_v1:
+    {
+        const auto tmp = static_cast<const op::v1::Split*>(&n);
+        node["num_splits"] = tmp->get_num_splits();
+        break;
+    }
     case OP_TYPEID::Sqrt: { break;
     }
     case OP_TYPEID::SquaredDifference:

test/opset1.cpp

@@ -134,7 +134,7 @@ TEST(opset, check_opset1)
     CHECK_OPSET(op::v0::Sinh, opset1::Sinh)
     CHECK_OPSET(op::v1::Softmax, opset1::Softmax)
     CHECK_OPSET(op::v0::SpaceToDepth, opset1::SpaceToDepth)
-    CHECK_OPSET(op::v0::Split, opset1::Split)
+    CHECK_OPSET(op::v1::Split, opset1::Split)
     CHECK_OPSET(op::v0::Sqrt, opset1::Sqrt)
     CHECK_OPSET(op::v0::SquaredDifference, opset1::SquaredDifference)
     CHECK_OPSET(op::v0::Squeeze, opset1::Squeeze)