Cyphers/exec can create tensors (#3445)

* Add method to check if an Executable can create tensors

* Add a Backend check to see if Executable can create tensors

* Update per review comment

* style

* Possible fix so that backend does not keep holding on to the dummy ng_exec

src/ngraph/runtime/backend.cpp

@@ -151,3 +151,24 @@ bool runtime::Backend::set_config(const map<string, string>& config, string& err
     error = "set_config not supported";
     return false;
 }
+
+bool runtime::Backend::executable_can_create_tensors()
+{
+    auto A = make_shared<op::Parameter>(element::f32, Shape());
+    auto function = make_shared<Function>(NodeVector{A}, ParameterVector{A});
+    auto exec = compile(function);
+    bool exec_can_create_tensors = false;
+    try
+    {
+        auto t0 = exec->create_input_tensor(0);
+        auto t1 = exec->create_input_tensor(0, 1);
+        auto t2 = exec->create_output_tensor(0);
+        auto t3 = exec->create_output_tensor(0, 1);
+        exec_can_create_tensors = true;
+    }
+    catch (...)
+    {
+    }
+    remove_compiled_function(exec);
+    return exec_can_create_tensors;
+}

src/ngraph/runtime/backend.hpp

@@ -172,6 +172,8 @@ public:
     /// \param ptr pointer to the memory to determine if its in device memory or not
     virtual bool is_device_memory(void* ptr);
 
+    virtual bool executable_can_create_tensors();
+
 private:
     // mutex to modify s_backend_shared_library_search_directory thread safe
     static std::mutex m_mtx;

test/CMakeLists.txt

@@ -365,6 +365,7 @@ if (NGRAPH_CPU_ENABLE)
     # The INTERPRETER backend is required for convolution, and backwards unit tests
     target_link_libraries(unit-test PRIVATE cpu_backend interpreter_backend)
     target_link_libraries(unit-test PRIVATE libmkldnn)
+    target_compile_definitions(unit-test PRIVATE NGRAPH_CPU_ENABLE)
 endif()
 
 if (NGRAPH_TOOLS_ENABLE)

test/backend_api.cpp

@@ -91,3 +91,14 @@ TEST(backend_api, save_load)
     }
 }
 #endif
+
+#if defined(NGRAPH_INTERPRETER_ENABLE) && defined(NGRAPH_CPU_ENABLE)
+TEST(backend_api, executable_can_create_tensor)
+{
+    auto interpreter = runtime::Backend::create("INTERPRETER");
+    auto cpu = runtime::Backend::create("CPU");
+
+    EXPECT_TRUE(interpreter->executable_can_create_tensors());
+    EXPECT_FALSE(cpu->executable_can_create_tensors());
+}
+#endif