%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
%************************************************************************
%* *
\begin{code}
module BinderInfo (
- BinderInfo(..),
- FunOrArg, DuplicationDanger, InsideSCC, -- NB: all abstract (yay!)
+ BinderInfo,
- addBinderInfo, orBinderInfo, andBinderInfo,
+ addBinderInfo, orBinderInfo,
- deadOccurrence, argOccurrence, funOccurrence, dangerousArgOcc, noBinderInfo,
+ deadOccurrence, funOccurrence, noBinderInfo,
- markMany, markDangerousToDup, markInsideSCC,
+ markMany, markInsideLam, markInsideSCC,
getBinderInfoArity,
setBinderInfoArityToZero,
- okToInline, isOneOcc, isOneFunOcc, isOneSafeFunOcc, isDeadOcc,
-
- isFun, isDupDanger -- for Simon Marlow deforestation
+ binderInfoToOccInfo
) where
#include "HsVersions.h"
-import Util ( panic )
+import IdInfo ( OccInfo(..), InsideLam, OneBranch, insideLam, notInsideLam, oneBranch )
import GlaExts ( Int(..), (+#) )
import Outputable
-
\end{code}
The @BinderInfo@ describes how a variable is used in a given scope.
| ManyOcc -- Everything else besides DeadCode and OneOccs
- Int -- number of arguments on stack when called; this is a minimum guarantee
+ !Int -- number of arguments on stack when called; this is a minimum guarantee
- | OneOcc -- Just one occurrence (or one each in
+ | SingleOcc -- Just one occurrence (or one each in
-- mutually-exclusive case alts).
- FunOrArg -- How it occurs
-
- DuplicationDanger
+ !InsideLam
- InsideSCC
+ !InsideSCC
- Int -- Number of mutually-exclusive case alternatives
+ !Int -- Number of mutually-exclusive case alternatives
-- in which it occurs
-- Note that we only worry about the case-alt counts
- -- if the OneOcc is substitutable -- that's the only
+ -- 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
+ !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)
-- (because the RHS will be inlined regardless of its size)
-- [again, DupDanger]
-data FunOrArg
- = FunOcc -- An occurrence in a function position
- | ArgOcc -- Other arg occurrence
-
- -- When combining branches of a case, only report FunOcc if
- -- both branches are FunOccs
-
-data DuplicationDanger
- = DupDanger -- Inside a non-linear lambda (that is, a lambda which
- -- is sure to be instantiated only once), or inside
- -- the rhs of an INLINE-pragma'd thing. Either way,
- -- substituting a redex for this occurrence is
- -- dangerous because it might duplicate work.
-
- | NoDupDanger -- It's ok; substitution won't duplicate work.
-
data InsideSCC
= InsideSCC -- Inside an SCC; so be careful when substituting.
| NotInsideSCC -- It's ok.
noBinderInfo = ManyOcc 0 -- A non-committal value
-\end{code}
-
-
+\end{code}
\begin{code}
-isOneOcc :: BinderInfo -> Bool
-isOneOcc (OneOcc _ _ _ _ _) = True
-isOneOcc other_bind = False
-
-isOneFunOcc :: BinderInfo -> Bool
-isOneFunOcc (OneOcc FunOcc _ _ _ _) = True
-isOneFunOcc other_bind = False
-
-isOneSafeFunOcc :: Bool -> BinderInfo -> Bool
-isOneSafeFunOcc ok_to_dup (OneOcc FunOcc NoDupDanger NotInsideSCC n_alts _)
- = ok_to_dup || n_alts <= 1
-isOneSafeFunOcc ok_to_dup other_bind = False
-
-isDeadOcc :: BinderInfo -> Bool
-isDeadOcc DeadCode = True
-isDeadOcc other = False
-
-isFun :: FunOrArg -> Bool
-isFun FunOcc = True
-isFun _ = False
-
-isDupDanger :: DuplicationDanger -> Bool
-isDupDanger DupDanger = True
-isDupDanger _ = False
+binderInfoToOccInfo :: BinderInfo -> OccInfo
+binderInfoToOccInfo DeadCode = IAmDead
+binderInfoToOccInfo (SingleOcc in_lam NotInsideSCC n_alts _) = OneOcc in_lam (n_alts==1)
+binderInfoToOccInfo other = NoOccInfo
\end{code}
-\begin{code}
-okToInline :: Bool -- The thing is WHNF or bottom;
- -> Bool -- It's small enough to duplicate the code
- -> BinderInfo
- -> Bool -- True <=> inline it
-
--- A non-WHNF can be inlined if it doesn't occur inside a lambda,
--- and occurs exactly once or
--- occurs once in each branch of a case and is small
-okToInline False small_enough (OneOcc _ NoDupDanger _ n_alts _)
- = n_alts <= 1 || small_enough
-
--- If the thing isn't a redex, there's no danger of duplicating work,
--- so we can inline if it occurs once, or is small
-okToInline True small_enough occ_info
- = one_occ || small_enough
- where
- one_occ = case occ_info of
- OneOcc _ _ _ n_alts _ -> n_alts <= 1
- other -> False
-
-okToInline whnf_or_bot small_enough any_occ = False
-\end{code}
-
Construction
~~~~~~~~~~~~~
deadOccurrence :: BinderInfo
deadOccurrence = DeadCode
-argOccurrence, funOccurrence :: Int -> BinderInfo
-
-funOccurrence = OneOcc FunOcc NoDupDanger NotInsideSCC 1
-argOccurrence = OneOcc ArgOcc NoDupDanger NotInsideSCC 1
-
-markMany, markDangerousToDup, markInsideSCC :: BinderInfo -> BinderInfo
+funOccurrence :: Int -> BinderInfo
+funOccurrence = SingleOcc notInsideLam NotInsideSCC 1
-markMany (OneOcc _ _ _ _ ar) = ManyOcc ar
-markMany (ManyOcc ar) = ManyOcc ar
-markMany DeadCode = panic "markMany"
+markMany, markInsideLam, markInsideSCC :: BinderInfo -> BinderInfo
-markDangerousToDup (OneOcc posn _ in_scc n_alts ar)
- = OneOcc posn DupDanger in_scc n_alts ar
-markDangerousToDup other = other
+markMany (SingleOcc _ _ _ ar) = ManyOcc ar
+markMany (ManyOcc ar) = ManyOcc ar
+markMany DeadCode = panic "markMany"
-dangerousArgOcc = OneOcc ArgOcc DupDanger NotInsideSCC 1 0
+markInsideLam (SingleOcc _ in_scc n_alts ar) = SingleOcc insideLam in_scc n_alts ar
+markInsideLam other = other
-markInsideSCC (OneOcc posn dup_danger _ n_alts ar)
- = OneOcc posn dup_danger InsideSCC n_alts ar
-markInsideSCC 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, orBinderInfo :: BinderInfo -> BinderInfo -> BinderInfo
addBinderInfo DeadCode info2 = info2
addBinderInfo info1 DeadCode = info1
addBinderInfo info1 info2
- = case (min (getBinderInfoArity info1) (getBinderInfoArity info2)) of
- (I# i#) -> ManyOcc (I# i#)
- -- ManyOcc min (getBinderInfoArity info1) (getBinderInfoArity info2))
+ = ManyOcc (min (getBinderInfoArity info1) (getBinderInfoArity info2))
--- (orBinderInfo orig new) is used when combining occurrence
--- info from branches of a case
+-- (orBinderInfo orig new) is used
+-- when combining occurrence info from branches of a case
orBinderInfo DeadCode info2 = info2
orBinderInfo info1 DeadCode = info1
-orBinderInfo (OneOcc posn1 dup1 scc1 n_alts1 ar_1)
- (OneOcc posn2 dup2 scc2 n_alts2 ar_2)
+orBinderInfo (SingleOcc dup1 scc1 n_alts1 ar_1)
+ (SingleOcc dup2 scc2 n_alts2 ar_2)
= let
- -- Seriously maligned in order to make it stricter,
- -- let's hope it is worth it..
- posn = combine_posns posn1 posn2
- scc = combine_sccs scc1 scc2
- dup = combine_dups dup1 dup2
+ 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
- -- No CSE, please!
- cont1 = case scc of { InsideSCC -> cont2; _ -> cont2 }
- cont2 = case dup of { DupDanger -> cont3; _ -> cont3 }
- cont3 = case alts of { (I# 0#) -> cont4; _ -> cont4 }
- cont4 = case ar of { (I# 0#) -> cont5; _ -> cont5 }
- cont5 = OneOcc posn dup scc alts ar
- in
- case posn of { FunOcc -> cont1; _ -> cont1 }
orBinderInfo info1 info2
- = case (min (getBinderInfoArity info1) (getBinderInfoArity info2)) of
- (I# i#) -> ManyOcc (I# i#)
-
--- (andBinderInfo orig new) is used in two situations:
--- First, when a variable whose occurrence info
--- is currently "orig" is bound to a variable whose occurrence info is "new"
--- eg (\new -> e) orig
--- What we want to do is to *worsen* orig's info to take account of new's
---
--- second, when completing a let-binding
--- let new = ...orig...
--- we compute the way orig occurs in (...orig...), and then use orBinderInfo
--- to worsen this info by the way new occurs in the let body; then we use
--- that to worsen orig's currently recorded occurrence info.
-
-andBinderInfo DeadCode info2 = DeadCode
-andBinderInfo info1 DeadCode = DeadCode
-andBinderInfo (OneOcc posn1 dup1 scc1 (I# n_alts1#) (I# ar_1#))
- (OneOcc posn2 dup2 scc2 (I# n_alts2#) ar_2)
- = let
- -- Perversly maligned in order to make it stricter.
- posn = combine_posns posn1 posn2
- scc = combine_sccs scc1 scc2
- dup = combine_dups dup1 dup2
- alts = I# (n_alts1# +# n_alts2#)
-
- -- No CSE, please!
- cont1 = case scc of { InsideSCC -> cont2; _ -> cont2 }
- cont2 = case dup of { DupDanger -> cont3; _ -> cont3 }
- cont3 = case alts of { (I# 0#) -> cont4; _ -> cont4 }
- cont4 = OneOcc posn dup scc alts (I# ar_1#)
- in
- case posn of {FunOcc -> cont1; _ -> cont1}
-
-andBinderInfo info1 info2 =
- case getBinderInfoArity info1 of
- (I# i#) -> ManyOcc (I# i#)
- --ManyOcc (getBinderInfoArity info1)
+ = ManyOcc (min (getBinderInfoArity info1) (getBinderInfoArity info2))
+or_dups in_lam1 in_lam2 = in_lam1 || in_lam2
-combine_posns FunOcc FunOcc = FunOcc -- see comment at FunOrArg defn
-combine_posns _ _ = ArgOcc
-
-combine_dups DupDanger _ = DupDanger -- Too paranoid?? ToDo
-combine_dups _ DupDanger = DupDanger
-combine_dups _ _ = NoDupDanger
-
-combine_sccs InsideSCC _ = InsideSCC -- Too paranoid?? ToDo
-combine_sccs _ InsideSCC = InsideSCC
-combine_sccs _ _ = NotInsideSCC
+or_sccs InsideSCC _ = InsideSCC
+or_sccs _ InsideSCC = InsideSCC
+or_sccs _ _ = NotInsideSCC
setBinderInfoArityToZero :: BinderInfo -> BinderInfo
setBinderInfoArityToZero DeadCode = DeadCode
setBinderInfoArityToZero (ManyOcc _) = ManyOcc 0
-setBinderInfoArityToZero (OneOcc fa dd sc i _) = OneOcc fa dd sc i 0
+setBinderInfoArityToZero (SingleOcc dd sc i _) = SingleOcc dd sc i 0
\end{code}
\begin{code}
getBinderInfoArity (DeadCode) = 0
getBinderInfoArity (ManyOcc i) = i
-getBinderInfoArity (OneOcc _ _ _ _ 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 (OneOcc posn dup_danger in_scc n_alts ar)
- = hcat [ ptext SLIT("One-"), pp_posn posn, char '-', pp_danger dup_danger,
+ 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_posn FunOcc = ptext SLIT("fun")
- pp_posn ArgOcc = ptext SLIT("arg")
-
- pp_danger DupDanger = ptext SLIT("*dup*")
- pp_danger NoDupDanger = ptext SLIT("nodup")
-
pp_scc InsideSCC = ptext SLIT("*SCC*")
pp_scc NotInsideSCC = ptext SLIT("noscc")
\end{code}
-
projects / ghc-hetmet.git / blobdiff