[MXNET-750] fix nested call on CachedOp.

src/imperative/cached_op.cc

@@ -821,12 +821,11 @@ OpStatePtr CachedOp::DynamicForward(
 
   const auto& dispatch_modes = g.GetAttr<DispatchModeVector>("dispatch_mode");
 
-  if (recording && !inlining_) Imperative::Get()->set_is_recording(false);
-
+  // If we are already recording, we don't need RunGraph to record all
+  // computation again.
   RunGraph(false, idx, arrays, 0, idx.num_nodes(), std::move(array_reqs),
-           std::move(ref_count), &states, dispatch_modes);
-
-  Imperative::Get()->set_is_recording(recording);
+           std::move(ref_count), &states, dispatch_modes,
+           !recording || inlining_);
 
   return op_state;
 }
@@ -947,7 +946,8 @@ void CachedOp::DynamicBackward(
   const auto& dispatch_modes = g.GetAttr<DispatchModeVector>("dispatch_mode");
 
   RunGraph(retain_graph, idx, arrays, num_forward_nodes, idx.num_nodes(),
-           std::move(array_reqs), std::move(ref_count), &states, dispatch_modes);
+           std::move(array_reqs), std::move(ref_count), &states, dispatch_modes,
+           Imperative::Get()->is_recording());
 
   if (retain_graph) {
     buff.resize(num_forward_entries);

src/imperative/imperative.cc

@@ -495,7 +495,8 @@ std::vector<NDArray*> Imperative::Backward(
   int prev_bulk_size = Engine::Get()->set_bulk_size(backward_bulk_size_);
 
   RunGraph(retain_graph, idx, arrays, num_forward_nodes, idx.num_nodes(),
-           std::move(array_reqs), std::move(ref_count), &states, dispatch_modes);
+           std::move(array_reqs), std::move(ref_count), &states, dispatch_modes,
+           is_recording());
 
   Engine::Get()->set_bulk_size(prev_bulk_size);
   set_is_recording(prev_recording);

src/imperative/imperative_utils.cc

@@ -30,7 +30,8 @@ void RunGraph(
     std::vector<OpReqType>&& array_reqs,
     std::vector<uint32_t>&& ref_count,
     std::vector<OpStatePtr> *p_states,
-    const DispatchModeVector &dispatch_modes) {
+    const DispatchModeVector &dispatch_modes,
+    bool recording) {
   using namespace nnvm;
   using namespace imperative;
   static auto& createop = nnvm::Op::GetAttr<FCreateOpState>("FCreateOpState");
@@ -40,7 +41,6 @@ void RunGraph(
   const auto imp = Imperative::Get();
 
   std::vector<OpStatePtr>& states = *p_states;
-  bool recording = imp->is_recording();
 
   std::vector<NDArray*> ndinputs, ndoutputs;
   ShapeVector arg_shapes;

src/imperative/imperative_utils.h

@@ -994,7 +994,8 @@ void RunGraph(const bool retain_graph,
               std::vector<OpReqType>&& array_reqs,
               std::vector<uint32_t>&& ref_count,
               std::vector<OpStatePtr> *p_states,
-              const DispatchModeVector &dispatch_modes);
+              const DispatchModeVector &dispatch_modes,
+              bool recording);
 
 }  // namespace imperative
 }  // namespace mxnet

tests/python/unittest/test_contrib_control_flow.py

@@ -1159,6 +1159,7 @@ def check_contrib_rnn(cell_type, num_states):
 
     configs = [
             {},
+            {'inline_limit': 0},
             {'static_alloc': True},
             {'static_alloc': True, 'static_shape': True} ]
     for config in configs: