I'm currently trying to get the interface file bulk imposed by TTypeable down. The branch will currently produce two top-level bindings for each TyCon. For instance, given the type,
data Proxy (a :: k) = Proxy
the branch will produce (ignoring the promoted datacon for a moment),
$tcProxy :: TyCon
$tcProxy
= GHC.Types.TyCon
fpr1 fpr2 -- fingerprints
$trModule
(GHC.Types.TrNameS "Proxy"#)
1
krep_aebr
krep_aebr :: KindRep
krep_aebr [InlPrag=NOINLINE CONLIKE]
= GHC.Types.KindRepFun
(GHC.Types.KindRepVar 0)
(GHC.Types.KindRepTYPE GHC.Types.LiftedRep)
Note that the KindRep has been marked as NOINLINE; I do this
intentionally as these things can grow quite large (consider, for
instance, the kind of a promoted tuple constructor). This is especially
true as the simplifier tends to float out the constituents of the
KindRep. After the first simplifier phase we end up with,
krep_sebQ :: GHC.Types.KindRep
[LclId,
Unf=Unf{Src=<vanilla>, TopLvl=True, Value=False, ConLike=False,
WorkFree=False, Expandable=False, Guidance=IF_ARGS [] 30 0}]
krep_sebQ = GHC.Types.$WKindRepVar (GHC.Types.I# 0#)
krep_sebR :: GHC.Types.KindRep
[LclId,
Unf=Unf{Src=<vanilla>, TopLvl=True, Value=False, ConLike=False,
WorkFree=False, Expandable=False, Guidance=IF_ARGS [] 20 0}]
krep_sebR = GHC.Types.$WKindRepTYPE GHC.Types.LiftedRep
krep_aebr [InlPrag=NOINLINE CONLIKE] :: GHC.Types.KindRep
[LclId,
Unf=Unf{Src=<vanilla>, TopLvl=True, Value=True, ConLike=True,
WorkFree=True, Expandable=True, Guidance=IF_ARGS [] 10 30}]
krep_aebr = GHC.Types.KindRepFun krep_sebQ krep_sebR
This means that GHC will now include each of the bindings floated out
from krep_aebr in the interface file, despite the NOINLINE pragma, as
they are all depended upon by the exported $tcProxy through their
unfoldings. This is Quite Bad.
I have observed that the floated bindings are not included in the
interface file with -O0. Moreover, the core2core output clearly shows
the unfoldings being added after the first simplifier phase. I haven't
yet determined where in the simplifier these unfoldings are being
introduced, but if anyone has ideas I'd love to hear them.
Cheers,
- Ben
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