Make get_scalar_constant_value() recurse less.

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(v):
+def get_scalar_constant_value(orig_v):
     """return the constant scalar(0-D) value underlying variable `v`
 
     If v is the output of dimshuffles, fills, allocs, rebroadcasts, cast
@@ -544,7 +544,8 @@ def get_scalar_constant_value(v):
     :note: There may be another function similar to this one in the
         code, but I'm not sure where it is.
     """
-    if True:
+    v = orig_v
+    while True:
         if v is None:
             # None is not a scalar (and many uses of this function seem to depend
             # on passing it None)
@@ -567,7 +568,8 @@ def get_scalar_constant_value(v):
             if isinstance(v.owner.op, (Alloc, DimShuffle, Rebroadcast,
                                        compile.ops.OutputGuard,
                                        compile.DeepCopyOp)):
-                return get_scalar_constant_value(v.owner.inputs[0])
+                v = v.owner.inputs[0]
+                continue
             elif isinstance(v.owner.op, theano.compile.ops.Shape_i):
                 if isinstance(v.owner.inputs[0], Constant):
                     return v.owner.inputs[0].data.shape[v.owner.op.i]
@@ -580,7 +582,8 @@ def get_scalar_constant_value(v):
                 if isinstance(v.owner.op, scal.Second):
                     # We don't need both input to be constant for second
                     shape, val = v.owner.inputs
-                    return get_scalar_constant_value(val)
+                    v = val
+                    continue
                 if isinstance(v.owner.op, get_scalar_constant_value_elemwises):
                     const = [get_scalar_constant_value(i)
                              for i in v.owner.inputs]
@@ -591,7 +594,8 @@ def get_scalar_constant_value(v):
                 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
-                    return get_scalar_constant_value(val)
+                    v = val
+                    continue
                 elif isinstance(v.owner.op.scalar_op,
                                 get_scalar_constant_value_elemwises):
                     const = [get_scalar_constant_value(i) for i in v.owner.inputs]