CPR signatures for DataCon application bindings are redundant
If you look at interface files for e.g.
ghc-prim:GHC.Types, you'll see that there are quite a few top-level bindings o type
KindRep, introduced for
Typeable support. Attaching CPR signatures to each of them is quite wasteful.
In general, DataCon application bindings
- Never get WW'd, so their CPR signature should be irrelevant after analysis (in fact the signature might even be harmful for that reason)
- Would need to be inlined to see their CPR
- Recording (Nested!) CPR on them blows up interface file sizes
But we can't just stop giving DataCon application bindings the CPR property, for example
fac 0 = 1 fac n = n * fac (n-1)
fac certainly has the CPR property and should be WW'd! But FloatOut will transform the first clause to
lvl = 1 fac 0 = lvl
If lvl doesn't have the CPR property, fac won't either.
So instead we should keep on looking through expandable unfoldings for these arity 0 bindings.