Fix grad

theano/gpuarray/dnn.py

@@ -2249,11 +2249,12 @@ class GpuDnnRNNOp(DnnBase):
             dy = as_gpuarray_variable(dhy[-1],
                                       context_name=dhy.type.context_name)
         if isinstance(dhy.type, DisconnectedType):
-            dhy = as_gpuarray_variable(hy.zeros_like(),
-                                       context_name=hy.type.context_name)
+            dhy = None
         if dcy and isinstance(dcy.type, DisconnectedType):
             dcy = None
-        dinputs = GpuDnnRNNGradInputs()(
+        dinputs = GpuDnnRNNGradInputs(rnn_mode=self.rnn_mode,
+                                      grad_h=(dhy is not None),
+                                      grad_c=(dcy is not None))(
             desc, x, y, dy, dhy, dcy, w, hx, cx, reserve, return_list=True)
         reserve2, dx, dhx = dinputs[:3]
         dw = GpuDnnRNNGradWeights()(
@@ -2270,28 +2271,55 @@ class GpuDnnRNNOp(DnnBase):
 
 
 class GpuDnnRNNGradInputs(DnnBase):
-    __props__ = ()
+    __props__ = ('rnn_mode', 'grad_c', 'grad_h')
     _cop_num_inputs = 10
     _cop_num_outputs = 4
 
-    def __init__(self):
+    def __init__(self, rnn_mode, grad_h, grad_c):
         DnnBase.__init__(self, ['dnn_rnn_gi.c'], 'dnn_rnn_gi')
+        self.rnn_mode = rnn_mode
+        self.grad_h = grad_h
+        self.grad_c = grad_c
+        if self.grad_c:
+            assert self.rnn_mode == 'lstm'
 
     def dnn_context(self, node):
         return node.outputs[1].type.context_name
 
     def make_node(self, desc, x, y, dy, dhy, dcy, w, hx, cx, reserve):
         # We trust the callers here
-
         xshp = as_scalar(x.shape[2]).astype('uint64')
-        inputs = [desc, xshp, y, dy, dhy, w, hx, reserve]
+        inputs = [desc, xshp, y, dy, w, hx, reserve]
         outputs = [reserve.type(), x.type(), hx.type()]
-        if dcy is not None:
-            inputs.append(dcy)
+        if self.rnn_mode == 'lstm':
             inputs.append(cx)
             outputs.append(cx.type())
+        if self.grad_h:
+            inputs.append(dhy)
+        if self.grad_c:
+            inputs.append(dcy)
+
         return Apply(self, inputs, outputs)
 
+    # We have special requirements so this is hooking into COp
+    def format_c_function_args(self, inp, out):
+        rinp = inp[:7]
+        others = inp[7:]
+        if self.rnn_mode == 'lstm':
+            rinp.append(others.pop(0))
+        else:
+            rinp.append('NULL')
+        if self.grad_h:
+            rinp.append(others.pop(0))
+        else:
+            rinp.append('NULL')
+        if self.grad_c:
+            rinp.append(others.pop(0))
+        else:
+            rinp.append('NULL')
+        assert len(others) == 0
+        return COp.format_c_function_args(self, rinp, out)
+
 
 class GpuDnnRNNGradWeights(DnnBase):
     __props__ = ()

theano/gpuarray/dnn_rnn_gi.c

@@ -2,11 +2,12 @@
 
 int dnn_rnn_gi(cudnnRNNDescriptor_t desc, npy_uint64 xshp,
                PyGpuArrayObject *y, PyGpuArrayObject *dy,
-               PyGpuArrayObject *dhy, PyGpuArrayObject *w,
-               PyGpuArrayObject *hx, gpudata *reserve, PyGpuArrayObject *dcy,
-               PyGpuArrayObject *cx, gpudata **oreserve,
-               PyGpuArrayObject **dx, PyGpuArrayObject **dhx,
-               PyGpuArrayObject **dcx, cudnnHandle_t _handle) {
+               PyGpuArrayObject *w, PyGpuArrayObject *hx,
+               gpudata *reserve, PyGpuArrayObject *cx,
+               PyGpuArrayObject *dhy, PyGpuArrayObject *dcy,
+               gpudata **oreserve, PyGpuArrayObject **dx,
+               PyGpuArrayObject **dhx, PyGpuArrayObject **dcx,
+               cudnnHandle_t _handle) {
   PyGpuContextObject *c = y->context;
   cudnnTensorDescriptor_t ydesc = NULL;
   cudnnTensorDescriptor_t dhydesc = NULL;
@@ -72,8 +73,9 @@ int dnn_rnn_gi(cudnnRNNDescriptor_t desc, npy_uint64 xshp,
     goto fail;
   }
 
-  if (c_make_tensorNd(dhy, &dhydesc) != 0)
-    goto fail;
+  if (dhy != NULL)
+    if (c_make_tensorNd(dhy, &dhydesc) != 0)
+      goto fail;
 
   if (dcy != NULL)
     if (c_make_tensorNd(dcy, &dcydesc) != 0)