Flush denormals to zero in nbench (#1857)

src/tools/nbench/benchmark.cpp

@@ -29,6 +29,15 @@ using namespace ngraph;
 
 static default_random_engine s_random_engine;
 
+void set_denormals_flush_to_zero()
+{
+#if defined(__x86_64__) || defined(__amd64__)
+    // Avoids perf impact from denormals while benchmarking with random data
+    _MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_ON);
+    _MM_SET_DENORMALS_ZERO_MODE(_MM_DENORMALS_ZERO_ON);
+#endif
+}
+
 template <typename T>
 void init_int_tv(shared_ptr<runtime::Tensor> tv, T min, T max)
 {
@@ -176,6 +185,8 @@ vector<runtime::PerformanceCounter> run_benchmark(shared_ptr<Function> f,
         arg_data.push_back(tensor_data);
         args_cacheable.push_back(param->get_cacheable());
     }
+    set_denormals_flush_to_zero();
+
     vector<shared_ptr<runtime::HostTensor>> result_data;
     vector<shared_ptr<runtime::Tensor>> results;
     for (shared_ptr<Node> out : f->get_results())