"Documentation by paper"

[Daniel Berlin]

>
> As I recall the extra PHI nodes were for correctness of a particular
> algorithm, not performance.

>  In other words, additional structure
> beyond SSA.
SSA includes phi nodes.  Having extraneous phi nodes is still an SSA 
form, it's just not a minimal one.
If you are referring to some algorithm that requires an extended SSA 
form, such as gated SSA, that would be a different case.

> I could be 100% mistaken, because it was many years ago,
> but your bizarre leap of logic here is still bizarre :/

I have never read an SSA optimization paper that *required* extra phi 
nodes for correctness.  I have read plenty that provide claims that 
extra phi nodes help performance of the algorithm  (all of which are 
based on some original claim by Cytron about pruned vs minimal vs 
semi-pruned).

An algorithm which required useless phi nodes for correctness (IE 
required semi-pruned and not working on minimal) would be 100% 
broken/unsound, and certainly, we would not use it.
--Dan
>
> -- Jamie