Reuse the output of mul when there is only one input in FCOp.

paddle/operators/fc_op.cc

@@ -66,22 +66,25 @@ class FCOp : public NetOp {
     }
 
     // sum_out = X[0] * W[0] + ... + X[n-1] * W[n-1]
+    auto sum_out = mul_out[0];
     if (n > 1) {
-      AppendOp(framework::OpRegistry::CreateOp(
-          "sum", {{"X", {mul_out}}}, {{"Out", {Output("SumOut")}}}, {}));
+      sum_out = Output("SumOut");
+      AppendOp(framework::OpRegistry::CreateOp("sum", {{"X", {mul_out}}},
+                                               {{"Out", {sum_out}}}, {}));
     } else {
-      AppendOp(framework::OpRegistry::CreateOp(
-          "identity", {{"X", {mul_out[0]}}}, {{"Y", {Output("SumOut")}}}, {}));
+      if (Output("SumOut") != framework::kEmptyVarName) {
+        this->Rename(Output("SumOut"), framework::kEmptyVarName);
+      }
     }
 
     // add_out = sum_out + b
     auto b = Input("B");
-    std::string add_out = "SumOut";
+    auto add_out = sum_out;
     if (b != framework::kEmptyVarName) {
-      add_out = "AddOut";
+      add_out = Output("AddOut");
       AppendOp(framework::OpRegistry::CreateOp(
-          "rowwise_add", {{"X", {Output("SumOut")}}, {"b", {Input("B")}}},
-          {{"Out", {Output(add_out)}}}, {}));
+          "rowwise_add", {{"X", {sum_out}}, {"b", {Input("B")}}},
+          {{"Out", {add_out}}}, {}));
     } else {
       if (Output("AddOut") != framework::kEmptyVarName) {
         this->Rename(Output("AddOut"), framework::kEmptyVarName);
@@ -89,8 +92,8 @@ class FCOp : public NetOp {
     }
 
     auto activation = Attr<std::string>("activation");
-    AppendOp(framework::OpRegistry::CreateOp(
-        activation, {{"X", {Output(add_out)}}}, {{"Y", {Output("Out")}}}, {}));
+    AppendOp(framework::OpRegistry::CreateOp(activation, {{"X", {add_out}}},
+                                             {{"Y", {Output("Out")}}}, {}));
     CompleteAddOp(false);
   }
 };

python/paddle/v2/framework/tests/op_test.py

@@ -193,7 +193,9 @@ class OpTest(unittest.TestCase):
                             actual, expect, atol=1e-05),
                         "output name: " + out_name + " has diff")
             else:
-                actual = np.array(self.scope.find_var(out_name).get_tensor())
+                var = self.scope.find_var(out_name)
+                if var is not None:
+                    actual = np.array(var.get_tensor())
                     expect = self.outputs[out_name]
                     self.assertTrue(
                         np.allclose(

python/paddle/v2/framework/tests/test_fc_op.py

@@ -7,27 +7,19 @@ class TestFCOp1(OpTest):
     def setUp(self):
         x0 = np.random.random((16, 32)).astype("float32")
         w0 = np.random.random((32, 10)).astype("float32")
-        b = np.random.random(10).astype("float32")
 
         mul_out0 = np.dot(x0, w0)
-        sum_out = mul_out0
-        add_out = sum_out + b
-        identity_out = add_out
+        identity_out = mul_out0
 
         self.op_type = "fc"
-        self.inputs = {"X": [("X0", x0)], "W": [("W0", w0)], "B": b}
-        self.outputs = {
-            "MulOut": [("MulOut0", mul_out0)],
-            "SumOut": sum_out,
-            "AddOut": add_out,
-            "Out": identity_out
-        }
+        self.inputs = {"X": [("X0", x0)], "W": [("W0", w0)]}
+        self.outputs = {"MulOut": [("MulOut0", mul_out0)], "Out": identity_out}
 
     def test_check_output(self):
         self.check_output()
 
     def test_check_grad(self):
-        self.check_grad(["X0", "W0", "B"], "Out", max_relative_error=0.01)
+        self.check_grad(["X0", "W0"], "Out", max_relative_error=0.01)
 
 
 class TestFCOp2(OpTest):