Re-enable some call to get_scalar_constant_value, but disable the tracking of elemwise.

theano/tensor/basic.py

@@ -532,7 +532,7 @@ get_scalar_constant_value_elemwises = (
     scal.LT, scal.GT, scal.LE, scal.GE,
     scal.Sub, scal.Add, scal.Mod, scal.Mul,
     scal.IntDiv, scal.TrueDiv)
-def get_scalar_constant_value(orig_v):
+def get_scalar_constant_value(orig_v, elemwise=True):
     """return the constant scalar(0-D) value underlying variable `v`
 
     If v is the output of dimshuffles, fills, allocs, rebroadcasts, cast
@@ -541,6 +541,9 @@ def get_scalar_constant_value(orig_v):
     If `v` is not some view of constant scalar data, then raise a
     NotScalarConstantError.
 
+    :param elemwise: If False, we won't try to go into elemwise.
+        So this call is faster.
+
     :note: There may be another function similar to this one in the
         code, but I'm not sure where it is.
     """
@@ -590,7 +593,7 @@ def get_scalar_constant_value(orig_v):
                     ret = [[None]]
                     v.owner.op.perform(v.owner, const, ret)
                     return ret[0][0]
-            elif isinstance(v.owner.op, Elemwise):
+            elif elemwise and isinstance(v.owner.op, Elemwise):
                 if isinstance(v.owner.op.scalar_op, scal.Second):
                     # We don't need both input to be constant for second
                     shape, val = v.owner.inputs
@@ -3079,7 +3082,7 @@ pprint.assign(pow, printing.OperatorPrinter('**', 1, 'right'))
 ##########################
 
 
-def extract_constant(x):
+def extract_constant(x, elemwise=True):
     '''
      This function is basically a call to tensor.get_scalar_constant_value. The
      main difference is the behaviour in case of failure. While
@@ -3089,7 +3092,7 @@ def extract_constant(x):
      ScalarVariable, we convert it to a tensor with tensor_from_scalar.
     '''
     try:
-        x = get_scalar_constant_value(x)
+        x = get_scalar_constant_value(x, elemwise=elemwise)
     except NotScalarConstantError:
         pass
     if (isinstance(x, scal.ScalarVariable) or

theano/tensor/opt.py

@@ -1580,10 +1580,8 @@ def local_upcast_elemwise_constant_inputs(node):
                     new_inputs.append(i)
                 else:
                     try:
-                        if not isinstance(i, Constant):
-                            raise NotScalarConstantError()
                         # works only for scalars
-                        cval_i = get_scalar_constant_value(i)
+                        cval_i = get_scalar_constant_value(i, elemwise=False)
                         if all(i.broadcastable):
                             new_inputs.append(T.shape_padleft(
                                 T.cast(cval_i, output_dtype),
@@ -2328,9 +2326,8 @@ def local_remove_switch_const_cond(node):
                if cond is constant and cond != 0: left
     """
     if (isinstance(node.op, T.Elemwise) and
-        isinstance(node.op.scalar_op, scalar.basic.Switch) and
-        isinstance(node.inputs[0], Constant)):
-        cond = T.extract_constant(node.inputs[0])
+        isinstance(node.op.scalar_op, scalar.basic.Switch)):
+        cond = T.extract_constant(node.inputs[0], elemwise=False)
         if type(cond) is numpy.ndarray and cond.ndim == 0:
             if cond == 0:
                 out = node.inputs[2]