Generalize AddNoOutputFromInplace to AddFeatureOptimizer

theano/compile/mode.py

@@ -161,22 +161,16 @@ class AddDestroyHandler(gof.Optimizer):
         fgraph.attach_feature(gof.DestroyHandler())
 
 
-class AddNoOutputFromInplace(gof.Optimizer):
+class AddFeatureOptimizer(gof.Optimizer):
     """
-    This optimizer adds to the fgraph a feature that will prevent outputs
-    of a fgraph to be created by performing inplace operations on intermediary
-    variables. This is useful when the outputs of the fgraph are preallocated
-    to prevent useless copying of the data. Currently, scan preallocates its
-    outputs
-
+    This optimizer adds a provided feature to the function graph.
     """
 
-    def __init__(self, first_output_idx=0, last_output_idx=None):
-        self.feature = gof.NoOutputFromInplace(first_output_idx,
-                                               last_output_idx)
+    def __init__(self, feature):
+        self.feature = feature
 
     def add_requirements(self, fgraph):
-        super(AddNoOutputFromInplace, self).add_requirements(fgraph)
+        super(AddFeatureOptimizer, self).add_requirements(fgraph)
         fgraph.attach_feature(self.feature)
 
 
@@ -234,9 +228,6 @@ optdb.register('specialize_device', gof.EquilibriumDB(),
 optdb.register('merge2', gof.MergeOptimizer(),
                49, 'fast_run', 'merge')
 
-optdb.register('add_no_output_from_inplace', AddNoOutputFromInplace(),
-               49.4)
-
 optdb.register('add_destroy_handler', AddDestroyHandler(),
                49.5, 'fast_run', 'inplace')
 

theano/scan_module/scan_op.py

@@ -68,10 +68,11 @@ from six.moves import xrange
 import theano
 from theano.compat import exc_message
 from theano.compile import function, In, Param, Out
-from theano.compile.mode import AddNoOutputFromInplace
+from theano.compile.mode import AddFeatureOptimizer
 from theano import compile, config, gradient, gof, tensor
 from theano.gof import PureOp, Apply
 from theano.gof.graph import io_connection_pattern
+from theano.gof.toolbox import NoOutputFromInplace
 from theano.compat import OrderedDict, izip
 from theano.tensor import TensorType
 from theano.tensor.opt import Shape_i
@@ -802,16 +803,18 @@ class Scan(PureOp):
             self.mitmots_preallocated = [i in preallocated_mitmot_outs
                                          for i in range(self.n_mit_mot_outs)]
 
-            # Add an optimization to the compilation mode to prevent mitsot,
-            # sitsot and nitsot outputs from being computed inplace (to allow
-            # their preallocation). This optimization is added such that it
-            # will run just before the inplace optimizations
+            # Add an optimization to the compilation mode to attach a feature
+            # to the function graph just before the inplace optimizations are
+            # applied. This feature will prevent mitsot, sitsot and nitsot
+            # outputs from being computed inplace (to allow their
+            # preallocation).
             mitsot_start = self.n_mit_mot_outs - len(preallocated_mitmot_outs)
             nitsot_end = (mitsot_start + self.n_mit_sot + self.n_sit_sot +
                           self.n_nit_sot)
-            no_inplace_opt = AddNoOutputFromInplace(mitsot_start, nitsot_end)
-            compilation_mode = self.mode_instance.register((no_inplace_opt,
-                                                            49.9))
+
+            feature = NoOutputFromInplace(mitsot_start, nitsot_end)
+            opt = AddFeatureOptimizer(feature)
+            compilation_mode = self.mode_instance.register((opt, 49.9))
 
         else:
             # Output preallocation is not activated. Mark every mitmot output