Add inplace filtering for GpuArrayType so that shared value replacement

theano/gpuarray/type.py

@@ -197,6 +197,11 @@ class GpuArrayType(Type):
                                              self.broadcastable)
 
     def filter(self, data, strict=False, allow_downcast=None):
+        return self.filter_inplace(data, None, strict=strict,
+                                   allow_downcast=allow_downcast)
+
+    def filter_inplace(self, data, old_data, strict=False,
+                       allow_downcast=None):
         if (isinstance(data, gpuarray.GpuArray) and
                 data.typecode == self.typecode):
             # This is just to make this condition not enter the
@@ -218,9 +223,13 @@ class GpuArrayType(Type):
               (allow_downcast is None and
                type(data) == float and
                self.dtype == config.floatX)):
-            data = gpuarray.array(data, dtype=self.typecode, copy=False,
-                                  ndmin=len(self.broadcastable),
-                                  context=self.context)
+            if not isinstance(data, gpuarray.GpuArray):
+                data = numpy.array(data, dtype=self.dtype, copy=False,
+                                   ndmin=len(self.broadcastable))
+            else:
+                data = gpuarray.array(data, dtype=self.typecode, copy=False,
+                                      ndmin=len(self.broadcastable),
+                                      context=self.context)
         else:
             if not hasattr(data, 'dtype'):
                 converted_data = theano._asarray(data, self.dtype)
@@ -230,12 +239,10 @@ class GpuArrayType(Type):
                                         converted_data,
                                         force_same_dtype=False):
                     data = converted_data
-                    data = gpuarray.array(data, context=self.context)
 
             up_dtype = scalar.upcast(self.dtype, data.dtype)
             if up_dtype == self.dtype:
-                data = gpuarray.array(data, dtype=self.dtype, copy=False,
-                                      context=self.context)
+                data = numpy.array(data, dtype=self.dtype, copy=False)
             else:
                 raise TypeError("%s cannot store a value of dtype %s "
                                 "without risking loss of precision." %
@@ -250,6 +257,12 @@ class GpuArrayType(Type):
             if b and shp[i] != 1:
                 raise TypeError("Non-unit value on shape on a broadcastable"
                                 " dimension.", shp, self.broadcastable)
+        if not isinstance(data, gpuarray.GpuArray):
+            if old_data and old_data.shape == data.shape:
+                old_data.write(data)
+                data = old_data
+            else:
+                data = pygpu.array(data, context=self.context)
         return data
 
     def filter_variable(self, other, allow_convert=True):