+++ /dev/null
-%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
-%
-%************************************************************************
-%* *
-\section[BinderInfo]{Information attached to binders by SubstAnal}
-%* *
-%************************************************************************
-
-\begin{code}
-module BinderInfo (
- BinderInfo,
-
- addBinderInfo, orBinderInfo,
-
- deadOccurrence, funOccurrence, noBinderInfo,
-
- markMany, markInsideLam, markInsideSCC,
- getBinderInfoArity,
- setBinderInfoArityToZero,
-
- binderInfoToOccInfo
- ) where
-
-#include "HsVersions.h"
-
-import IdInfo ( OccInfo(..), InsideLam, insideLam, notInsideLam )
-import Outputable
-\end{code}
-
-The @BinderInfo@ describes how a variable is used in a given scope.
-
-NOTE: With SCCs we have to be careful what we unfold! We don't want to
-change the attribution of execution costs. If we decide to unfold
-within an SCC we can tag the definition as @DontKeepBinder@.
-Definitions tagged as @KeepBinder@ are discarded when we enter the
-scope of an SCC.
-
-\begin{code}
-data BinderInfo
- = DeadCode -- Dead code; discard the binding.
-
- | ManyOcc -- Everything else besides DeadCode and OneOccs
-
- !Int -- number of arguments on stack when called; this is a minimum guarantee
-
-
- | SingleOcc -- Just one occurrence (or one each in
- -- mutually-exclusive case alts).
-
- !InsideLam
-
- !InsideSCC
-
- !Int -- Number of mutually-exclusive case alternatives
- -- in which it occurs
-
- -- Note that we only worry about the case-alt counts
- -- if the SingleOcc is substitutable -- that's the only
- -- time we *use* the info; we could be more clever for
- -- other cases if we really had to. (WDP/PS)
-
- !Int -- number of arguments on stack when called; minimum guarantee
-
--- In general, we are feel free to substitute unless
--- (a) is in an argument position (ArgOcc)
--- (b) is inside a lambda [or type lambda?] (DupDanger)
--- (c) is inside an SCC expression (InsideSCC)
--- (d) is in the RHS of a binding for a variable with an INLINE pragma
--- (because the RHS will be inlined regardless of its size)
--- [again, DupDanger]
-
-data InsideSCC
- = InsideSCC -- Inside an SCC; so be careful when substituting.
- | NotInsideSCC -- It's ok.
-
-noBinderInfo = ManyOcc 0 -- A non-committal value
-\end{code}
-
-\begin{code}
-binderInfoToOccInfo :: BinderInfo -> OccInfo
-binderInfoToOccInfo DeadCode = IAmDead
-binderInfoToOccInfo (SingleOcc in_lam NotInsideSCC n_alts _) = OneOcc in_lam (n_alts==1)
-binderInfoToOccInfo other = NoOccInfo
-\end{code}
-
-
-
-Construction
-~~~~~~~~~~~~~
-\begin{code}
-deadOccurrence :: BinderInfo
-deadOccurrence = DeadCode
-
-funOccurrence :: Int -> BinderInfo
-funOccurrence = SingleOcc notInsideLam NotInsideSCC 1
-
-markMany, markInsideLam, markInsideSCC :: BinderInfo -> BinderInfo
-
-markMany (SingleOcc _ _ _ ar) = ManyOcc ar
-markMany (ManyOcc ar) = ManyOcc ar
-markMany DeadCode = panic "markMany"
-
-markInsideLam (SingleOcc _ in_scc n_alts ar) = SingleOcc insideLam in_scc n_alts ar
-markInsideLam other = other
-
-markInsideSCC (SingleOcc dup_danger _ n_alts ar) = SingleOcc dup_danger InsideSCC n_alts ar
-markInsideSCC other = other
-
-addBinderInfo, orBinderInfo :: BinderInfo -> BinderInfo -> BinderInfo
-
-addBinderInfo DeadCode info2 = info2
-addBinderInfo info1 DeadCode = info1
-addBinderInfo info1 info2
- = ManyOcc (min (getBinderInfoArity info1) (getBinderInfoArity info2))
-
--- (orBinderInfo orig new) is used
--- when combining occurrence info from branches of a case
-
-orBinderInfo DeadCode info2 = info2
-orBinderInfo info1 DeadCode = info1
-orBinderInfo (SingleOcc dup1 scc1 n_alts1 ar_1)
- (SingleOcc dup2 scc2 n_alts2 ar_2)
- = let
- scc = or_sccs scc1 scc2
- dup = or_dups dup1 dup2
- alts = n_alts1 + n_alts2
- ar = min ar_1 ar_2
- in
- SingleOcc dup scc alts ar
-
-orBinderInfo info1 info2
- = ManyOcc (min (getBinderInfoArity info1) (getBinderInfoArity info2))
-
-or_dups in_lam1 in_lam2 = in_lam1 || in_lam2
-
-or_sccs InsideSCC _ = InsideSCC
-or_sccs _ InsideSCC = InsideSCC
-or_sccs _ _ = NotInsideSCC
-
-setBinderInfoArityToZero :: BinderInfo -> BinderInfo
-setBinderInfoArityToZero DeadCode = DeadCode
-setBinderInfoArityToZero (ManyOcc _) = ManyOcc 0
-setBinderInfoArityToZero (SingleOcc dd sc i _) = SingleOcc dd sc i 0
-\end{code}
-
-\begin{code}
-getBinderInfoArity (DeadCode) = 0
-getBinderInfoArity (ManyOcc i) = i
-getBinderInfoArity (SingleOcc _ _ _ i) = i
-\end{code}
-
-\begin{code}
-instance Outputable BinderInfo where
- ppr DeadCode = ptext SLIT("Dead")
- ppr (ManyOcc ar) = hcat [ ptext SLIT("Many-"), int ar ]
- ppr (SingleOcc dup_danger in_scc n_alts ar)
- = hcat [ ptext SLIT("One-"), ppr dup_danger,
- char '-', pp_scc in_scc, char '-', int n_alts,
- char '-', int ar ]
- where
- pp_scc InsideSCC = ptext SLIT("*SCC*")
- pp_scc NotInsideSCC = ptext SLIT("noscc")
-\end{code}
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