non destructive ml opt (#1454)

src/ngraph/pass/memory_layout.cpp

@@ -49,9 +49,14 @@ bool pass::MemoryLayout::run_on_function(shared_ptr<ngraph::Function> function)
                 {
                     auto output = &node->get_outputs().at(oi_pair.output).get_tensor();
                     auto input = &node->get_inputs().at(oi_pair.input).get_tensor();
+                    auto input_node = node->get_inputs().at(oi_pair.input).get_output().get_node();
 
-                    if (node->liveness_free_list.count(input) != 0 &&
-                        node->liveness_new_list.count(output) != 0)
+                    //an input tensor can be reused if this is the last use or
+                    //an op isn't destructive (i.e. Reshape(DimShuffle))
+                    if ((node->liveness_free_list.count(input) != 0 &&
+                         node->liveness_new_list.count(output) != 0) ||
+                        (!oi_pair.destructive && !input_node->is_parameter() &&
+                         !input_node->is_constant()))
                     {
                         in_place_outputs.insert({output, input});
                         reused_inputs.insert(input);