Cleanup of cudnn pooling zero-batch code.

theano/sandbox/cuda/dnn.py

@@ -1709,19 +1709,10 @@ if (CudaNdarray_prep_output(&%(out)s, %(nd)s+2, %(out)s_dims) != 0)
 }
 
 // if input batch is empty, we return the empty output without calling cuDNN
-// (which will fail on zero batch size)
-if (CudaNdarray_DIMS(%(input)s)[0] == 0) {
-  cudaError_t err2 = cudaMemset((%(out)s)->devdata, 0,
-                                CudaNdarray_SIZE(%(out)s) * sizeof(real));
-  if (err2 != cudaSuccess) {
-    PyErr_Format(PyExc_RuntimeError,
-                 "GpuDnnConv could not fill the output with zeros: %%s",
-                 cudaGetErrorString(err2));
-    %(fail)s
-  }
-
-  // Ideally, "return success" here, but we don't have a %%(done)s
-} else {
+// (which will fail on zero batch size).
+// Ideally, "return success" here, but we don't have a %%(done)s, so just skip the call.
+if (CudaNdarray_DIMS(%(input)s)[0] > 0) {
+// Don't indent for keeping history
 
 if (c_set_tensorNd(%(input)s, %(input_desc)s) != 0)
   %(fail)s
@@ -1748,7 +1739,7 @@ if (err != CUDNN_STATUS_SUCCESS) {
   %(fail)s
 }
 
-}
+} // Closes the batchdim > 0 check.
 """ % dict(out=out, fail=sub['fail'],
            name=name, input=inputs[0],
            ws=ws, pad=pad, str=stride,
@@ -1963,19 +1954,10 @@ if (CudaNdarray_prep_output(&%(output_grad)s,
 }
 
 // if input batch is empty, we return the empty output without calling cuDNN
-// (which will fail on zero batch size)
-if (CudaNdarray_DIMS(%(input)s)[0] == 0) {
-  cudaError_t err2 = cudaMemset((%(output)s)->devdata, 0,
-                                CudaNdarray_SIZE(%(output)s) * sizeof(real));
-  if (err2 != cudaSuccess) {
-    PyErr_Format(PyExc_RuntimeError,
-                 "GpuDnnConv could not fill the output with zeros: %%s",
-                 cudaGetErrorString(err2));
-    %(fail)s
-  }
-
-  // Ideally, "return success" here, but we don't have a %%(done)s, so do else.
-} else {
+// (which will fail on zero batch size).
+// Ideally, "return success" here, but we don't have a %%(done)s, so just skip the call.
+if (CudaNdarray_DIMS(%(input)s)[0] > 0) {
+// Don't indent for keeping history
 
 if (c_set_tensorNd(%(input)s, %(input_desc)s) != 0)
   %(fail)s
@@ -2031,7 +2013,7 @@ if (err%(name)s != CUDNN_STATUS_SUCCESS) {
  %(fail)s
 }
 
-}
+} // Closes the batchdim > 0 check.
 """ % dict(output_grad=out_grad,
            fail=sub['fail'], name=name,
            input=inp, input_grad=inp_grad, output=out,