The key here is "it looks like they are equivalent". In fact, I am not sure they are equivalent (in general, without taking into account the context), and even

The key here is "it looks like they are equivalent". In fact, I am not sure they are equivalent (in general, without taking into account the context), and even if they were, proving this would be S.F. for a compiler today (2020). Even coming up with such an optimisation without hardcoding it does not seem plausible.