reshape inplace without copy data if possible. (#1206)

src/ngraph/op/reshape.cpp

@@ -67,6 +67,11 @@ op::Reshape::Reshape(const shared_ptr<Node>& arg,
             "dimensions for reshape");
     }
 
+    if (!std::is_sorted(m_input_order.begin(), m_input_order.end()))
+    {
+        m_is_transpose = true;
+    }
+
     set_value_type_checked(input.get_element_type(), m_output_shape);
 }
 

src/ngraph/op/reshape.hpp

@@ -78,12 +78,14 @@ namespace ngraph
             const AxisVector& get_input_order() const { return m_input_order; }
             /// \return The shape of the output tensor.
             const Shape& get_output_shape() const { return m_output_shape; }
+            bool get_is_transpose() const { return m_is_transpose; }
         protected:
             virtual void generate_adjoints(autodiff::Adjoints& adjoints,
                                            const NodeVector& deltas) override;
 
             const AxisVector m_input_order;
             const Shape m_output_shape;
+            bool m_is_transpose{false};
         };
     }
 }

src/ngraph/runtime/cpu/cpu_emitter.cpp

@@ -1652,6 +1652,15 @@ namespace ngraph
             void CPU_Emitter::EMITTER_DECL(ngraph::op::Reshape)
             {
                 auto reshape = static_cast<const ngraph::op::Reshape*>(node);
+                auto annotation = reshape->get_op_annotations();
+                if (annotation && annotation->get_in_place_oi_pairs().size() > 0 &&
+                    out[0].get_name() == args[0].get_name())
+                {
+                    writer.block_begin();
+                    writer << "// Stride change only, skipping.\n";
+                    writer.block_end();
+                    return;
+                }
                 writer.block_begin();
 #if USE_EIGEN_CORE_INLINE == 1
                 auto arg_shape = args[0].get_shape();

src/ngraph/runtime/cpu/pass/cpu_assignment.cpp

@@ -563,6 +563,30 @@ namespace ngraph
                     auto axis_order = reshape->get_input_order();
                     bool flag = true;
 
+                    auto op_annotations =
+                        std::make_shared<ngraph::runtime::cpu::CPUOpAnnotations>();
+
+                    auto users = reshape->get_users();
+                    auto arg = reshape->get_argument(0);
+                    // we need to copy input data if reshape modifies the data or inputs are
+                    // not in the memory pool, or has output users.
+                    bool need_copy =
+                        reshape->get_is_transpose() || arg->is_parameter() || arg->is_constant();
+                    for (auto n = users.begin(); !need_copy && n != users.end(); ++n)
+                    {
+                        if ((*n)->is_output())
+                        {
+                            need_copy = true;
+                        }
+                    }
+                    if (!need_copy)
+                    {
+                        // map output to the input memory
+                        std::map<size_t, size_t> oi_pairs = {{0, 0}};
+                        op_annotations->set_in_place_oi_pairs(oi_pairs);
+                        reshape->set_op_annotations(op_annotations);
+                    }
+
                     // Use Eigen for 3D
                     if (node->get_input_element_type(0) == element::f32 &&
                         arg0_shape.size() < TENSOR_MAX_DIMS && arg0_shape.size() > 3 &&
@@ -579,8 +603,6 @@ namespace ngraph
 
                         if (flag)
                         {
-                            auto op_annotations =
-                                std::make_shared<ngraph::runtime::cpu::CPUOpAnnotations>();
                             op_annotations->set_mkldnn_op(true);
                             reshape->set_op_annotations(op_annotations);
                         }