add cudnn conv forward alternative

theano/gpuarray/dnn.py

@@ -2993,6 +2993,50 @@ def local_abstractconv_cudnn_alternative(node):
     return [rval]
 
 
+@local_optimizer([AbstractConv3d, AbstractConv3d_gradWeights, AbstractConv3d_gradInputs])
+def local_abstractconv3d_cudnn_alternative(node):
+    if(not isinstance(node.op, (AbstractConv3d,
+                                AbstractConv3d_gradWeights,
+                                AbstractConv3d_gradInputs))):
+        return
+
+    if version(raises=False) < 6000 and node.op.filter_dilation != (1, 1, 1):
+        return None
+    inp1 = node.inputs[0]
+    inp2 = node.inputs[1]
+
+    if not dnn_available(inp1.type.context_name):
+        return
+
+    op = node.op
+    border_mode = node.op.border_mode
+    subsample = node.op.subsample
+    filter_dilation = node.op.filter_dilation
+
+    if node.op.filter_flip:
+        conv_mode = 'conv'
+    else:
+        conv_mode = 'cross'
+
+    if isinstance(op, AbstractConv3d):
+        if border_mode == 'half' or subsample != (1, 1, 1):
+            return None
+        if border_mode == 'full':
+            direction_hint = 'bprop inputs'
+        elif border_mode == 'valid' and filter_dilation == (1, 1, 1):
+            direction_hint = 'bprop weights'
+        else:
+            return None
+
+        rval = dnn_conv3d(inp1, inp2,
+                          border_mode=border_mode,
+                          subsample=subsample,
+                          dilation=filter_dilation,
+                          direction_hint=direction_hint,
+                          conv_mode=conv_mode)
+    return rval
+
+
 @local_optimizer([AbstractConv2d_gradWeights, AbstractConv3d_gradWeights])
 def local_abstractconv_gw_cudnn(node):
     ctx = infer_context_name(*node.inputs)

theano/gpuarray/opt.py

@@ -2649,7 +2649,8 @@ register_opt('fast_compile')(abstractconv_groupopt)
 from .dnn import (local_abstractconv_cudnn,
                   local_abstractconv_gw_cudnn,
                   local_abstractconv_gi_cudnn,     # noqa: 402
-                  local_abstractconv_cudnn_alternative)
+                  local_abstractconv_cudnn_alternative,
+                  local_abstractconv3d_cudnn_alternative)
 
 abstractconv_groupopt.register('local_abstractconv_dnn',
                                local_abstractconv_cudnn, 20,
@@ -2706,6 +2707,7 @@ conv_metaopt.register([local_abstractconv3d2d])
 conv_metaopt.register([local_abstractconv3d_alt])
 conv_metaopt.register([local_abstractconv3d_gemm_gradweights_alt])
 conv_metaopt.register([local_abstractconv3d_gradinputs_gemm_alt])
+conv_metaopt.register([local_abstractconv3d_cudnn_alternative])
 abstractconv_groupopt.register('conv_metaopt', conv_metaopt, 'conv_meta', position=0)
 
 # Register cuDNN batch normalization implementation