optimize blas call

paddle/fluid/operators/math/selected_rows_functor.cc

@@ -232,18 +232,18 @@ template <typename DeviceContext, typename T>
 typename std::enable_if<
     std::is_floating_point<T>::value &&
     std::is_same<DeviceContext, platform::CPUDeviceContext>::value>::type
-elementwise_add(const DeviceContext& ctx, size_t data_len, const T* in,
-                T* out) {
-  auto blas = math::GetBlas<DeviceContext, T>(ctx);
-  blas.AXPY(data_len, 1., in, out);
+elementwise_add(const DeviceContext& ctx, BlasT<DeviceContext, T>* blas,
+                size_t data_len, const T* in, T* out) {
+  //  auto blas = math::GetBlas<DeviceContext, T>(ctx);
+  blas->AXPY(data_len, 1., in, out);
 }
 
 template <typename DeviceContext, typename T>
 typename std::enable_if<
     !std::is_floating_point<T>::value &&
     std::is_same<DeviceContext, platform::CPUDeviceContext>::value>::type
-elementwise_add(const DeviceContext& ctx, size_t data_len, const T* in,
-                T* out) {
+elementwise_add(const DeviceContext& ctx, BlasT<DeviceContext, T>* blas,
+                size_t data_len, const T* in, T* out) {
   for (int64_t i = 0; i < data_len; i++) {
     out[i] += in[i];
   }
@@ -305,10 +305,11 @@ struct MergeAdd<platform::CPUDeviceContext, T> {
       auto* input_data = input->value().data<T>();
       auto& input_rows = input->rows();
 
+      auto blas = math::GetBlas<platform::CPUDeviceContext, T>(context);
       for (size_t i = 0; i < input_rows.size(); i++) {
         size_t out_i = rows_to_id[input_rows[i]];
         elementwise_add<platform::CPUDeviceContext, T>(
-            context, static_cast<size_t>(input_width),
+            context, &blas, static_cast<size_t>(input_width),
             &input_data[i * input_width], &out_data[out_i * input_width]);
       }
     }