ExpressionOpCounter: account for NaNs

Author: kaushikcfd

loopy/statistics.py

@@ -921,6 +921,7 @@ def map_constant(self, expr):
 
     map_tagged_variable = map_constant
     map_variable = map_constant
+    map_nan = map_constant
 
     def map_call(self, expr):
         from loopy.symbolic import ResolvedFunction