[cfe-dev] Removing "TransferFuncs" from the analyzer

[Jordy Rose]

> The main role of the summaries is to memoize the computation of the transfer function logic. Those should stay around primarily to make the checker faster. You are correct, however, that they are currently used for generating the diagnostics

Oops, right, I meant why the summaries have to be attached to ExplodedNodes -- the only time they're used once attached is for bug reports, and only in those three cases (-dealloc, MakeCollectable in non-GC, and retain/release in GC). Which, actually, is something we could change right now, by only attaching summaries if they have interesting ArgEffects. The actual RetainSummaryManager can still live on RetainReleaseChecker when everything blows over.

For AnnotatedGRState, I think if we're going to add new infrastructure this isn't a bad way to go. I would think Annotations would be a lot like a GRState's GDM, a wrapper around some kind of tag-keyed map (though it doesn't have to be immutable until it goes into an AnnotatedGRState.

How do annotations interact with ExplodedNodes being FoldingSetNodes? Are annotations merged, or do they make two different nodes unique? (If they make the nodes unique, does that mean all annotation data—which I'm currently thinking of like a GRState's GDM—has to be profileable?)

Lastly, I'm a little wary of using AnnotatedGRState to carry around a state+annotations, rather than just adding an Annotations parameter to getNode, but I guess it makes things easier for existing code. We'll probably have to look at all the callers of getNode either way if we make this change.

I guess the big question is whether or not this is actually necessary: will checkers need a way to associate information with certain nodes /besides/ RetainReleaseChecker? Probably yes, but there should probably be a guideline to avoid over-using annotations, putting off most of the work until you know there's a diagnostic.

Or not. Maybe we decide annotations are cheap, and that checkers should go ahead and use them for better diagnostics.

Jordy