fix one_to_many op Canonicalization (PaddlePaddle#15)

* fix one_to_many op Canonicalization

* rename func

Author: gglin001

paddle/fluid/framework/ipu/popart_canonicalization_utils.cc

@@ -38,5 +38,29 @@ SymbolHandler GetHandler(const std::string &kind) {
   return {};
 }
 
+void MoveNodeInputs(ir::Node *node, ir::Node *new_node) {
+  new_node->inputs = node->inputs;
+  for (auto *node_in : node->inputs) {
+    for (size_t i = 0; i < node_in->outputs.size(); ++i) {
+      if (node_in->outputs[i] == node) {
+        node_in->outputs[i] = new_node;
+        break;
+      }
+    }
+  }
+}
+
+void MoveNodeOutputs(ir::Node *node, ir::Node *new_node) {
+  new_node->outputs = node->outputs;
+  for (auto *node_out : node->outputs) {
+    for (size_t i = 0; i < node_out->inputs.size(); ++i) {
+      if (node_out->inputs[i] == node) {
+        node_out->inputs[i] = new_node;
+        break;
+      }
+    }
+  }
+}
+
 }  // namespace framework
 }  // namespace paddle

paddle/fluid/framework/ipu/popart_canonicalization_utils.h

@@ -36,5 +36,8 @@ bool RegisterHandler(const std::string &, const SymbolHandler &);
 
 SymbolHandler GetHandler(const std::string &);
 
+void MoveNodeInputs(ir::Node *node, ir::Node *new_node);
+void MoveNodeOutputs(ir::Node *node, ir::Node *new_node);
+
 }  // namespace framework
 }  // namespace paddle

paddle/fluid/framework/ir/ipu/popart_canonicalization_pass.cc

@@ -43,27 +43,12 @@ void PopartCanonicalizationPass::ApplyImpl(ir::Graph* graph) const {
     SymbolHandler handler = GetHandler(op_type);
     if (handler) {
       new_node = handler(graph, node);
-      new_node->inputs = node->inputs;
-      new_node->outputs = node->outputs;
-      // restore node releations
-      for (auto* node_in : node->inputs) {
-        for (size_t i = 0; i < node_in->outputs.size(); ++i) {
-          if (node_in->outputs[i] == node) {
-            node_in->outputs[i] = new_node;
-            break;
-          }
-        }
+      if (new_node->inputs.empty()) {
+        MoveNodeInputs(node, new_node);
       }
-      for (auto* node_out : node->outputs) {
-        for (size_t i = 0; i < node_out->inputs.size(); ++i) {
-          if (node_out->inputs[i] == node) {
-            node_out->inputs[i] = new_node;
-            break;
-          }
-        }
+      if (new_node->outputs.empty()) {
+        MoveNodeOutputs(node, new_node);
       }
-    }
-    if (new_node) {
       graph->RemoveNode(node);
     }
   }