recursive local_dimshuffle_lift

theano/tensor/opt.py

@@ -440,6 +440,17 @@ def local_0_dot_x(node):
 ######################
 
 
+def apply_local_dimshuffle_lift(var):
+    # return var
+    # lift recursively
+    if not var.owner:
+        return var
+    new = local_dimshuffle_lift.transform(var.owner)
+    if new:
+        return new[0]
+    return var
+
+
 @gof.local_optimizer([DimShuffle])
 def local_dimshuffle_lift(node):
     """
@@ -449,6 +460,7 @@ def local_dimshuffle_lift(node):
 
     DimShuffle(Elemwise(x, y)) => Elemwise(DimShuffle(x), DimShuffle(y))
     DimShuffle(DimShuffle(x)) => DimShuffle(x)
+    DimShuffle{0,1,...}(x) => x (when the dimshuffle do nothing)
 
     After this transform, clusters of Elemwise operations are
     void of DimShuffle operations.
@@ -461,23 +473,27 @@ def local_dimshuffle_lift(node):
     inode = input.owner
     if inode and isinstance(inode.op, Elemwise) and (len(input.clients) == 1):
         # Don't use make_node to have tag.test_value set.
-        ret = inode.op(*[op.__class__(inp.type.broadcastable,
+        new_inputs = []
+        for inp in inode.inputs:
+            new_inp = op.__class__(inp.type.broadcastable,
                                    op.new_order,
-                                      op.inplace)(inp) for inp in
-                         inode.inputs], **dict(return_list=True))
+                                   op.inplace)(inp)
+            new_inputs.append(apply_local_dimshuffle_lift(new_inp))
+        ret = inode.op(*new_inputs, **dict(return_list=True))
         return ret
     if inode and isinstance(inode.op, DimShuffle):
         new_order = [x == 'x' and 'x' or inode.op.new_order[x] for x in
                      op.new_order]
         inplace = op.inplace and inode.op.inplace
         iinput = inode.inputs[0]
+        # remove useless dimshuffle
         if new_order == range(len(new_order)) and (len(new_order) ==
                                                    iinput.type.ndim):
             return [iinput]
         else:
             ret = op.__class__(iinput.type.broadcastable, new_order,
-                               inplace)(iinput, **dict(return_list=True))
-            return ret
+                               inplace)(iinput)
+            return [apply_local_dimshuffle_lift(ret)]
 
 
 @register_canonicalize