Now, during the simplification of short-circuits the so called
`de-optimization` is also applied to the corresponding `RegionCFGTree`.
This allows us to avoid loss of information during the iterative
refinement phase, which basically divides for ever the existencies of
two nodes that have been cloned starting from a single original one.
First concept of short-circuit simplification.
The `isEqual` operator between ASTNodes is very limited (it does only
check if two nodes originate from the same `BasicBlock` in the original
IR.
Andrea Gussoni