perf(imperative): add apply_on_physical_tensor for Elemwise

GitOrigin-RevId: 27087d90e431d0fbdb0439827f8bf6088781f6a5

imperative/src/impl/ops/elemwise.cpp

@@ -65,10 +65,30 @@ std::tuple<SmallVector<LogicalTensorDesc>, bool> infer_output_attrs_fallible(
     return {{{TensorLayout(out_shape, out_dt, inputs[0].layout.format), out_cn}}, true};
 }
 
+SmallVector<TensorPtr> apply_on_physical_tensor(
+        const OpDef& def,
+        const SmallVector<TensorPtr>& inputs) {
+    auto&& op_def = def.cast_final_safe<Elemwise>();
+    auto trait = megdnn::Elemwise::ModeTrait::from_mode(op_def.mode);
+    mgb_assert(inputs.size() == trait.arity,
+               "%s expects %u inputs; got %zu actually", trait.name,
+               trait.arity, inputs.size());
+
+    DeviceTensorND out;
+    SmallVector<DeviceTensorND> dt_inputs(inputs.size());
+    for (unsigned i = 0; i < inputs.size(); ++i){
+        dt_inputs[i] = inputs[i]->dev_tensor();
+    }
+    auto&& dnn_opr = opr::intl::create_megdnn_opr<megdnn::Elemwise>(inputs[0]->comp_node());
+    opr::Elemwise::perform(op_def.mode, out, dt_inputs, dnn_opr);
+    return {Tensor::make(out)};
+}
+
 OP_TRAIT_REG(Elemwise, Elemwise, opr::Elemwise)
     .make_from_op_node(make_from_op_node)
     .apply_on_var_node(apply_on_var_node)
     .infer_output_attrs_fallible(infer_output_attrs_fallible)
+    .apply_on_physical_tensor(apply_on_physical_tensor)
     .fallback();
 } // anonymous namespace