add logging to fc residual fuse pass (#46760)

* add logging to fc residual fuse pass

* expand logging message to fc residual fuse pass

* Add test for fc residual not fusing with activation

paddle/fluid/framework/ir/mkldnn/fc_elementwise_add_mkldnn_fuse_pass.cc

@@ -77,6 +77,7 @@ GraphWithStats FCResidualConnectionMKLDNNFusePass::FuseFC(
 
   auto handler = [&](const GraphPatternDetector::subgraph_t& subgraph,
                      Graph* g) {
+    VLOG(4) << "Fuse fc + elementwise_add as residual";
     GET_IR_NODE_FROM_SUBGRAPH(fc_op, fc, fc_pattern);
     GET_IR_NODE_FROM_SUBGRAPH(fc_input, input, fc_pattern);
     GET_IR_NODE_FROM_SUBGRAPH(fc_weights, weights, fc_pattern);
@@ -89,9 +90,28 @@ GraphWithStats FCResidualConnectionMKLDNNFusePass::FuseFC(
     GET_IR_NODE_FROM_SUBGRAPH(
         elementwise_out, elementwise_out, elementwise_pattern);
 
-    if (FindFuseOption(*fc_op, *elementwise_op) != FUSE_MKLDNN) return;
-    if (!IsReachable(g, residual_data, fc_output)) return;
-    if (HasFusedActivation(fc_op)) return;
+    if (FindFuseOption(*fc_op, *elementwise_op) != FUSE_MKLDNN) {
+      VLOG(4) << "Skipping fusion for " << fc_op->Name() << "(" << fc_op->id()
+              << ") with " << elementwise_op->Name() << "("
+              << elementwise_op->id()
+              << ") because not both ops have use_mkldnn";
+      return;
+    }
+    if (!IsReachable(g, residual_data, fc_output)) {
+      VLOG(4) << "Skipping fusion for " << fc_op->Name() << "(" << fc_op->id()
+              << ") with " << elementwise_op->Name() << "("
+              << elementwise_op->id() << ") because residual input "
+              << residual_data->Name() << "(" << residual_data->id()
+              << ") is not "
+                 "reachable";
+      return;
+    }
+    if (HasFusedActivation(fc_op)) {
+      VLOG(4) << "Skipping fusion for " << fc_op->Name() << "(" << fc_op->id()
+              << ") with " << elementwise_op->Name() << "("
+              << elementwise_op->id() << ") because fc has activation fused";
+      return;
+    }
 
     if (!IsCompat(subgraph, g)) {
       LOG(WARNING)

paddle/fluid/framework/ir/mkldnn/fc_elementwise_add_mkldnn_fuse_pass_tester.cc

@@ -139,6 +139,28 @@ TEST(FCElementwiseAddMKLDNNFusePass, NoFusion_NotResidualConnection) {
   EXPECT_TRUE(test::AssertOpsCount(graph, {{"fc", 2}, {"elementwise_add", 1}}));
 }
 
+TEST(FCElementwiseAddMKLDNNFusePass, NoFusion_HasActivationFused) {
+  auto prog =
+      test::BuildProgramDesc({"a", "b", "c", "d", "e"}, {"bias", "weights"});
+
+  test::CreateOp(&prog, "sigmoid", {{"X", "a"}}, {{"Out", "b"}});
+  OpDesc* fc =
+      Create_Op_FC(&prog,
+                   {{"Input", "b"}, {"Bias", "bias"}, {"W", "weights"}},
+                   {{"Out", "c"}});
+  std::string activation{"relu"};
+  fc->SetAttr("activation_type", activation);
+
+  Create_Op_elementwise_add(&prog, {{"X", "c"}, {"Y", "a"}}, {{"Out", "d"}});
+  test::CreateOp(&prog, "relu", {{"X", "d"}}, {{"Out", "e"}});
+
+  Graph graph(prog);
+
+  EXPECT_TRUE(test::RunPassAndAssert(
+      &graph, "fc_elementwise_add_mkldnn_fuse_pass", "a", "e", 0, 0));
+  EXPECT_TRUE(test::AssertOpsCount(graph, {{"fc", 1}, {"elementwise_add", 1}}));
+}
+
 TEST(FCElementwiseAddMKLDNNFusePass, FC_Residual_VITOCR) {
   auto prog = test::BuildProgramDesc(
       {"a", "b", "c", "d", "e", "f", "g", "h", "i"},