feature/dynamic recurrent op forward and backward

doc/design/block.md

@@ -189,7 +189,7 @@ OpDesc {
   inputs = {0} // the index of x in vars of BlockDesc above
   outputs = {5, 3} // indices of act and hidden_out in vars of BlockDesc above
   attrs {
-    "memories" : {1} // the index of h
+    "states" : {1} // the index of h
     "step_net" : <above step net>
   }
 };

paddle/framework/backward.cc

@@ -21,6 +21,7 @@
 
 #include "paddle/framework/block_desc.h"
 #include "paddle/framework/op_registry.h"
+#include "paddle/operators/dynamic_recurrent_op.h"
 #include "paddle/operators/net_op.h"
 #include "paddle/operators/recurrent_op.h"
 
@@ -220,8 +221,7 @@ static std::unique_ptr<OperatorBase> BackwardRecursive(
     // process recurrent gradient op as a special operator.
     if (forwardOp.Type() == "recurrent") {
       // NOTE clean up cycle call somewhere (RNN's stepnet constains itself),
-      // or
-      // this will result in infinite loop.
+      // or this will result in infinite loop.
       const auto& rnnop =
           *static_cast<const operators::RecurrentOp*>(&forwardOp);
       auto rnn_grad_op =
@@ -231,6 +231,18 @@ static std::unique_ptr<OperatorBase> BackwardRecursive(
       // create stepnet's gradient op
       rnn_grad_op->set_stepnet(
           BackwardRecursive(stepnet_op, no_grad_names, grad_to_var, uniq_id));
+    } else if (forwardOp.Type() == "dynamic_recurrent") {
+      // NOTE clean up cycle call somewhere (RNN's stepnet constains itself),
+      // or this will result in infinite loop.
+      const auto& rnnop =
+          *static_cast<const operators::DynamicRecurrentOp*>(&forwardOp);
+      auto rnn_grad_op =
+          static_cast<operators::DynamicRecurrentGradientOp*>(grad_op.get());
+      const auto& stepnet_op =
+          *static_cast<const OperatorBase*>(&rnnop.rnn.GetStepUnit());
+      // create stepnet's gradient op
+      rnn_grad_op->rnn.SetStepUnit(
+          BackwardRecursive(stepnet_op, no_grad_names, grad_to_var, uniq_id));
     }
 
     if (net->ops_.empty()) {  // Current no aux op is added to network