change hard_swish from plugin to layer (#29177)

* change hard_swish from plugin to layer

* add ut when threshold != scale

paddle/fluid/inference/tensorrt/convert/hard_swish_op.cc

@@ -65,13 +65,21 @@ class HardSwishOpConverter : public OpConverter {
     const float offset = op_desc.HasAttr("offset")
                              ? BOOST_GET_CONST(float, op_desc.GetAttr("offset"))
                              : 3.0f;
-
     nvinfer1::ILayer* layer = nullptr;
-
-    plugin::HardSwishPlugin* plugin =
-        new plugin::HardSwishPlugin(threshold, scale, offset);
-    layer = engine_->AddPlugin(&input, input_num, plugin);
-
+    if (threshold == scale) {
+      auto* hsig_layer = TRT_ENGINE_ADD_LAYER(
+          engine_, Activation, *input, nvinfer1::ActivationType::kHARD_SIGMOID);
+      hsig_layer->setAlpha(1.0 / scale);
+      hsig_layer->setBeta(offset / scale);
+      nvinfer1::IElementWiseLayer* eltwise_layer = TRT_ENGINE_ADD_LAYER(
+          engine_, ElementWise, *input, *(hsig_layer->getOutput(0)),
+          nvinfer1::ElementWiseOperation::kPROD);
+      layer = eltwise_layer;
+    } else {
+      plugin::HardSwishPlugin* plugin =
+          new plugin::HardSwishPlugin(threshold, scale, offset);
+      layer = engine_->AddPlugin(&input, input_num, plugin);
+    }
     auto output_name = op_desc.Output("Out")[0];
     RreplenishLayerAndOutput(layer, "hard_swish", {output_name}, test_mode);
   }

python/paddle/fluid/tests/unittests/ir/inference/test_trt_subgraph_pass.py

@@ -346,6 +346,12 @@ class TensorRTSubgraphPassHardSigmoidTest(TensorRTSubgraphPassActivationTest):
         return fluid.layers.hard_sigmoid(x)
 
 
+class TensorRTSubgraphPassHardSwishPluginTest(
+        TensorRTSubgraphPassActivationTest):
+    def append_act(self, x):
+        return fluid.layers.hard_swish(x, threshold=4.0, scale=8.0)
+
+
 class TensorRTSubgraphPassClipTest(TensorRTSubgraphPassActivationTest):
     def append_act(self, x):
         return fluid.layers.clip(x, 0, 1)