module IdInfo (
IdInfo, -- Abstract
- vanillaIdInfo, mkIdInfo, seqIdInfo, megaSeqIdInfo,
+ vanillaIdInfo, constantIdInfo, mkIdInfo, seqIdInfo, megaSeqIdInfo,
-- Zapping
- zapFragileInfo, zapLamInfo, zapSpecPragInfo, copyIdInfo,
+ zapLamInfo, zapDemandInfo,
+ zapSpecPragInfo, shortableIdInfo, copyIdInfo,
-- Flavour
- IdFlavour(..), flavourInfo,
- setNoDiscardInfo,
+ IdFlavour(..), flavourInfo, makeConstantFlavour,
+ setNoDiscardInfo, setFlavourInfo,
ppFlavourInfo,
-- Arity
StrictnessInfo(..),
mkStrictnessInfo, noStrictnessInfo,
ppStrictnessInfo,isBottomingStrictness,
-
strictnessInfo, setStrictnessInfo,
+ -- Usage generalisation
+ TyGenInfo(..),
+ tyGenInfo, setTyGenInfo,
+ noTyGenInfo, isNoTyGenInfo, ppTyGenInfo, tyGenInfoString,
+
-- Worker
WorkerInfo(..), workerExists, wrapperArity, workerId,
workerInfo, setWorkerInfo, ppWorkerInfo,
isNeverInlinePrag, neverInlinePrag,
-- Occurrence info
- OccInfo(..), isFragileOccInfo,
+ OccInfo(..), isFragileOcc, isDeadOcc, isLoopBreaker,
InsideLam, OneBranch, insideLam, notInsideLam, oneBranch, notOneBranch,
occInfo, setOccInfo,
-- Specialisation
specInfo, setSpecInfo,
- -- Update
- UpdateInfo, UpdateSpec,
- mkUpdateInfo, updateInfo, updateInfoMaybe, ppUpdateInfo, setUpdateInfo,
-
-- CAF info
- CafInfo(..), cafInfo, setCafInfo, ppCafInfo,
+ CafInfo(..), cafInfo, setCafInfo, mayHaveCafRefs, ppCafInfo,
-- Constructed Product Result Info
CprInfo(..), cprInfo, setCprInfo, ppCprInfo, noCprInfo,
-- Lambda-bound variable info
- LBVarInfo(..), lbvarInfo, setLBVarInfo, noLBVarInfo
+ LBVarInfo(..), lbvarInfo, setLBVarInfo, noLBVarInfo, hasNoLBVarInfo
) where
#include "HsVersions.h"
import CoreSyn
+import Type ( Type, usOnce )
import PrimOp ( PrimOp )
import Var ( Id )
-import BasicTypes ( OccInfo(..), isFragileOccInfo, seqOccInfo,
+import BasicTypes ( OccInfo(..), isFragileOcc, isDeadOcc, seqOccInfo, isLoopBreaker,
InsideLam, insideLam, notInsideLam,
OneBranch, oneBranch, notOneBranch,
Arity
)
import DataCon ( DataCon )
import FieldLabel ( FieldLabel )
+import Type ( usOnce, usMany )
import Demand -- Lots of stuff
import Outputable
-import Maybe ( isJust )
+import Util ( seqList )
-infixl 1 `setUpdateInfo`,
- `setDemandInfo`,
+infixl 1 `setDemandInfo`,
+ `setTyGenInfo`,
`setStrictnessInfo`,
`setSpecInfo`,
`setArityInfo`,
`setUnfoldingInfo`,
`setCprInfo`,
`setWorkerInfo`,
+ `setLBVarInfo`,
`setCafInfo`,
`setOccInfo`
-- infixl so you can say (id `set` a `set` b)
arityInfo :: ArityInfo, -- Its arity
demandInfo :: Demand, -- Whether or not it is definitely demanded
specInfo :: CoreRules, -- Specialisations of this function which exist
+ tyGenInfo :: TyGenInfo, -- Restrictions on usage-generalisation of this Id
strictnessInfo :: StrictnessInfo, -- Strictness properties
workerInfo :: WorkerInfo, -- Pointer to Worker Function
unfoldingInfo :: Unfolding, -- Its unfolding
- updateInfo :: UpdateInfo, -- Which args should be updated
- cafInfo :: CafInfo,
+ cafInfo :: CafInfo, -- whether it refers (indirectly) to any CAFs
cprInfo :: CprInfo, -- Function always constructs a product result
lbvarInfo :: LBVarInfo, -- Info about a lambda-bound variable
inlinePragInfo :: InlinePragInfo, -- Inline pragma
seqArity (arityInfo info) `seq`
seqDemand (demandInfo info) `seq`
seqRules (specInfo info) `seq`
+ seqTyGenInfo (tyGenInfo info) `seq`
seqStrictnessInfo (strictnessInfo info) `seq`
seqWorker (workerInfo info) `seq`
Setters
\begin{code}
+setFlavourInfo info fl = fl `seq` info { flavourInfo = fl }
setWorkerInfo info wk = wk `seq` info { workerInfo = wk }
setSpecInfo info sp = PSEQ sp (info { specInfo = sp })
+setTyGenInfo info tg = tg `seq` info { tyGenInfo = tg }
setInlinePragInfo info pr = pr `seq` info { inlinePragInfo = pr }
setOccInfo info oc = oc `seq` info { occInfo = oc }
setStrictnessInfo info st = st `seq` info { strictnessInfo = st }
-- actually increases residency significantly.
= info { unfoldingInfo = uf }
-setUpdateInfo info ud = info { updateInfo = ud }
setDemandInfo info dd = info { demandInfo = dd }
setArityInfo info ar = info { arityInfo = ar }
setCafInfo info cf = info { cafInfo = cf }
setLBVarInfo info lb = info { lbvarInfo = lb }
setNoDiscardInfo info = case flavourInfo info of
- VanillaId -> info { flavourInfo = NoDiscardId }
+ VanillaId -> info { flavourInfo = ExportedId }
other -> info
zapSpecPragInfo info = case flavourInfo info of
SpecPragmaId -> info { flavourInfo = VanillaId }
\begin{code}
vanillaIdInfo :: IdInfo
-vanillaIdInfo = mkIdInfo VanillaId
-
-mkIdInfo :: IdFlavour -> IdInfo
-mkIdInfo flv = IdInfo {
- flavourInfo = flv,
- arityInfo = UnknownArity,
- demandInfo = wwLazy,
- specInfo = emptyCoreRules,
- workerInfo = NoWorker,
- strictnessInfo = NoStrictnessInfo,
- unfoldingInfo = noUnfolding,
- updateInfo = NoUpdateInfo,
- cafInfo = MayHaveCafRefs,
- cprInfo = NoCPRInfo,
- lbvarInfo = NoLBVarInfo,
- inlinePragInfo = NoInlinePragInfo,
- occInfo = NoOccInfo
+ -- Used for locally-defined Ids
+ -- We are going to calculate correct CAF information at the end
+vanillaIdInfo = mkIdInfo VanillaId NoCafRefs
+
+constantIdInfo :: IdInfo
+ -- Used for imported Ids
+ -- The default is that they *do* have CAFs; an interface-file pragma
+ -- may say "oh no it doesn't", but in the absence of such a pragma
+ -- we'd better assume it does
+constantIdInfo = mkIdInfo ConstantId MayHaveCafRefs
+
+mkIdInfo :: IdFlavour -> CafInfo -> IdInfo
+mkIdInfo flv caf
+ = IdInfo {
+ flavourInfo = flv,
+ cafInfo = caf,
+ arityInfo = UnknownArity,
+ demandInfo = wwLazy,
+ specInfo = emptyCoreRules,
+ tyGenInfo = noTyGenInfo,
+ workerInfo = NoWorker,
+ strictnessInfo = NoStrictnessInfo,
+ unfoldingInfo = noUnfolding,
+ cprInfo = NoCPRInfo,
+ lbvarInfo = NoLBVarInfo,
+ inlinePragInfo = NoInlinePragInfo,
+ occInfo = NoOccInfo
}
\end{code}
\begin{code}
data IdFlavour
- = VanillaId -- Most Ids are like this
+ = VanillaId -- Locally defined, not exported
+ | ExportedId -- Locally defined, exported
+ | SpecPragmaId -- Locally defined, RHS holds specialised call
+
+ | ConstantId -- Imported from elsewhere, or a default method Id.
+
+ | DictFunId -- We flag dictionary functions so that we can
+ -- conveniently extract the DictFuns from a set of
+ -- bindings when building a module's interface
+
| DataConId DataCon -- The Id for a data constructor *worker*
| DataConWrapId DataCon -- The Id for a data constructor *wrapper*
-- [the only reasons we need to know is so that
-- Id back to the data con]
| PrimOpId PrimOp -- The Id for a primitive operator
| RecordSelId FieldLabel -- The Id for a record selector
- | SpecPragmaId -- Don't discard these
- | NoDiscardId -- Don't discard these either
+
+
+makeConstantFlavour :: IdFlavour -> IdFlavour
+makeConstantFlavour flavour = new_flavour
+ where new_flavour = case flavour of
+ VanillaId -> ConstantId
+ ExportedId -> ConstantId
+ ConstantId -> ConstantId -- e.g. Default methods
+ DictFunId -> DictFunId
+ flavour -> pprTrace "makeConstantFlavour"
+ (ppFlavourInfo flavour)
+ flavour
+
ppFlavourInfo :: IdFlavour -> SDoc
ppFlavourInfo VanillaId = empty
+ppFlavourInfo ExportedId = ptext SLIT("[Exported]")
+ppFlavourInfo SpecPragmaId = ptext SLIT("[SpecPrag]")
+ppFlavourInfo ConstantId = ptext SLIT("[Constant]")
+ppFlavourInfo DictFunId = ptext SLIT("[DictFun]")
ppFlavourInfo (DataConId _) = ptext SLIT("[DataCon]")
ppFlavourInfo (DataConWrapId _) = ptext SLIT("[DataConWrapper]")
ppFlavourInfo (PrimOpId _) = ptext SLIT("[PrimOp]")
ppFlavourInfo (RecordSelId _) = ptext SLIT("[RecSel]")
-ppFlavourInfo SpecPragmaId = ptext SLIT("[SpecPrag]")
-ppFlavourInfo NoDiscardId = ptext SLIT("[NoDiscard]")
seqFlavour :: IdFlavour -> ()
seqFlavour f = f `seq` ()
-- function; it's already been compiled and we know its
-- arity for sure.
- | ArityAtLeast Arity -- Arity is this or greater. We attach this arity to
+ | ArityAtLeast Arity -- A partial application of this Id to up to n-1 value arguments
+ -- does essentially no work. That is not necessarily the
+ -- same as saying that it has n leading lambdas, because coerces
+ -- may get in the way.
+
-- functions in the module being compiled. Their arity
-- might increase later in the compilation process, if
-- an extra lambda floats up to the binding site.
+ deriving( Eq )
seqArity :: ArityInfo -> ()
seqArity a = arityLowerBound a `seq` ()
= NoInlinePragInfo
| IMustNotBeINLINEd Bool -- True <=> came from an INLINE prag, False <=> came from a NOINLINE prag
(Maybe Int) -- Phase number from pragma, if any
+ deriving( Eq )
-- The True, Nothing case doesn't need to be recorded
-- SEE COMMENTS WITH CoreUnfold.blackListed on the
-- exact significance of the IMustNotBeINLINEd pragma
isNeverInlinePrag :: InlinePragInfo -> Bool
-isNeverInlinePrag (IMustNotBeINLINEd True Nothing) = True
-isNeverInlinePrag other = False
+isNeverInlinePrag (IMustNotBeINLINEd _ Nothing) = True
+isNeverInlinePrag other = False
neverInlinePrag :: InlinePragInfo
-neverInlinePrag = IMustNotBeINLINEd True Nothing
+neverInlinePrag = IMustNotBeINLINEd True{-should be False? --SDM -} Nothing
instance Outputable InlinePragInfo where
-- This is now parsed in interface files
%************************************************************************
+%* *
+\subsection[TyGen-IdInfo]{Type generalisation info about an @Id@}
+%* *
+%************************************************************************
+
+Certain passes (notably usage inference) may change the type of an
+identifier, modifying all in-scope uses of that identifier
+appropriately to maintain type safety.
+
+However, some identifiers must not have their types changed in this
+way, because their types are conjured up in the front end of the
+compiler rather than being read from the interface file. Default
+methods, dictionary functions, record selectors, and others are in
+this category. (see comment at TcClassDcl.tcClassSig).
+
+To indicate this property, such identifiers are marked TyGenNever.
+
+Furthermore, if the usage inference generates a usage-specialised
+variant of a function, we must NOT re-infer a fully-generalised type
+at the next inference. This finer property is indicated by a
+TyGenUInfo on the identifier.
+
+\begin{code}
+data TyGenInfo
+ = NoTyGenInfo -- no restriction on type generalisation
+
+ | TyGenUInfo [Maybe Type] -- restrict generalisation of this Id to
+ -- preserve specified usage annotations
+
+ | TyGenNever -- never generalise the type of this Id
+
+ deriving ( Eq )
+\end{code}
+
+For TyGenUInfo, the list has one entry for each usage annotation on
+the type of the Id, in left-to-right pre-order (annotations come
+before the type they annotate). Nothing means no restriction; Just
+usOnce or Just usMany forces that annotation to that value. Other
+usage annotations are illegal.
+
+\begin{code}
+seqTyGenInfo :: TyGenInfo -> ()
+seqTyGenInfo NoTyGenInfo = ()
+seqTyGenInfo (TyGenUInfo us) = seqList us ()
+seqTyGenInfo TyGenNever = ()
+
+noTyGenInfo :: TyGenInfo
+noTyGenInfo = NoTyGenInfo
+
+isNoTyGenInfo :: TyGenInfo -> Bool
+isNoTyGenInfo NoTyGenInfo = True
+isNoTyGenInfo _ = False
+
+-- NB: There's probably no need to write this information out to the interface file.
+-- Why? Simply because imported identifiers never get their types re-inferred.
+-- But it's definitely nice to see in dumps, it for debugging purposes.
+
+ppTyGenInfo :: TyGenInfo -> SDoc
+ppTyGenInfo NoTyGenInfo = empty
+ppTyGenInfo (TyGenUInfo us) = ptext SLIT("__G") <+> text (tyGenInfoString us)
+ppTyGenInfo TyGenNever = ptext SLIT("__G N")
+
+tyGenInfoString us = map go us
+ where go Nothing = 'x' -- for legibility, choose
+ go (Just u) | u == usOnce = '1' -- chars with identity
+ | u == usMany = 'M' -- Z-encoding.
+ go other = pprPanic "IdInfo.tyGenInfoString: unexpected annotation" (ppr other)
+
+instance Outputable TyGenInfo where
+ ppr = ppTyGenInfo
+
+instance Show TyGenInfo where
+ showsPrec p c = showsPrecSDoc p (ppr c)
+\end{code}
+
+
+%************************************************************************
%* *
\subsection[worker-IdInfo]{Worker info about an @Id@}
%* *
data WorkerInfo = NoWorker
| HasWorker Id Arity
-- The Arity is the arity of the *wrapper* at the moment of the
- -- w/w split. It had better be the same as the arity of the wrapper
- -- at the moment it is spat into the interface file.
- -- This Arity just lets us make a (hopefully redundant) sanity check
+ -- w/w split. See comments in MkIface.ifaceId, with the 'Worker' code.
seqWorker :: WorkerInfo -> ()
seqWorker (HasWorker id _) = id `seq` ()
%************************************************************************
%* *
-\subsection[update-IdInfo]{Update-analysis info about an @Id@}
-%* *
-%************************************************************************
-
-\begin{code}
-data UpdateInfo
- = NoUpdateInfo
- | SomeUpdateInfo UpdateSpec
- deriving (Eq, Ord)
- -- we need Eq/Ord to cross-chk update infos in interfaces
-
--- the form in which we pass update-analysis info between modules:
-type UpdateSpec = [Int]
-\end{code}
-
-\begin{code}
-mkUpdateInfo = SomeUpdateInfo
-
-updateInfoMaybe NoUpdateInfo = Nothing
-updateInfoMaybe (SomeUpdateInfo []) = Nothing
-updateInfoMaybe (SomeUpdateInfo u) = Just u
-\end{code}
-
-Text instance so that the update annotations can be read in.
-
-\begin{code}
-ppUpdateInfo NoUpdateInfo = empty
-ppUpdateInfo (SomeUpdateInfo []) = empty
-ppUpdateInfo (SomeUpdateInfo spec) = (<>) (ptext SLIT("__UA ")) (hcat (map int spec))
- -- was "__U "; changed to avoid conflict with unfoldings. KSW 1999-07.
-\end{code}
-
-%************************************************************************
-%* *
\subsection[CAF-IdInfo]{CAF-related information}
%* *
%************************************************************************
-- | OneCafRef Id
+mayHaveCafRefs MayHaveCafRefs = True
+mayHaveCafRefs _ = False
+
seqCaf c = c `seq` ()
ppCafInfo NoCafRefs = ptext SLIT("__C")
data LBVarInfo
= NoLBVarInfo
- | IsOneShotLambda -- The lambda that binds this Id is applied
- -- at most once
+ | LBVarInfo Type -- The lambda that binds this Id has this usage
+ -- annotation (i.e., if ==usOnce, then the
+ -- lambda is applied at most once).
+ -- The annotation's kind must be `$'
-- HACK ALERT! placing this info here is a short-term hack,
-- but it minimises changes to the rest of the compiler.
-- Hack agreed by SLPJ/KSW 1999-04.
\end{code}
\begin{code}
+hasNoLBVarInfo NoLBVarInfo = True
+hasNoLBVarInfo other = False
+
noLBVarInfo = NoLBVarInfo
-- not safe to print or parse LBVarInfo because it is not really a
-- property of the definition, but a property of the context.
pprLBVarInfo NoLBVarInfo = empty
-pprLBVarInfo IsOneShotLambda = getPprStyle $ \ sty ->
- if ifaceStyle sty then empty
- else ptext SLIT("OneShot")
+pprLBVarInfo (LBVarInfo u) | u == usOnce
+ = getPprStyle $ \ sty ->
+ if ifaceStyle sty
+ then empty
+ else ptext SLIT("OneShot")
+ | otherwise
+ = empty
instance Outputable LBVarInfo where
ppr = pprLBVarInfo
%* *
%************************************************************************
-zapFragileInfo is used when cloning binders, mainly in the
-simplifier. We must forget about used-once information because that
-isn't necessarily correct in the transformed program.
-Also forget specialisations and unfoldings because they would need
-substitution to be correct. (They get pinned back on separately.)
-
-\begin{code}
-zapFragileInfo :: IdInfo -> Maybe IdInfo
-zapFragileInfo info@(IdInfo {occInfo = occ,
- workerInfo = wrkr,
- specInfo = rules,
- unfoldingInfo = unfolding})
- | not (isFragileOccInfo occ)
- -- We must forget about whether it was marked safe-to-inline,
- -- because that isn't necessarily true in the simplified expression.
- -- This is important because expressions may be re-simplified
- -- We don't zap deadness or loop-breaker-ness.
- -- The latter is important because it tells MkIface not to
- -- spit out an inlining for the thing. The former doesn't
- -- seem so important, but there's no harm.
-
- && isEmptyCoreRules rules
- -- Specialisations would need substituting. They get pinned
- -- back on separately.
-
- && not (workerExists wrkr)
-
- && not (hasUnfolding unfolding)
- -- This is very important; occasionally a let-bound binder is used
- -- as a binder in some lambda, in which case its unfolding is utterly
- -- bogus. Also the unfolding uses old binders so if we left it we'd
- -- have to substitute it. Much better simply to give the Id a new
- -- unfolding each time, which is what the simplifier does.
- = Nothing
-
- | otherwise
- = Just (info {occInfo = robust_occ_info,
- workerInfo = noWorkerInfo,
- specInfo = emptyCoreRules,
- unfoldingInfo = noUnfolding})
- where
- -- It's important to keep the loop-breaker info,
- -- because the substitution doesn't remember it.
- robust_occ_info = case occ of
- OneOcc _ _ -> NoOccInfo
- other -> occ
-\end{code}
-
@zapLamInfo@ is used for lambda binders that turn out to to be
part of an unsaturated lambda
other -> occ
\end{code}
+\begin{code}
+zapDemandInfo :: IdInfo -> Maybe IdInfo
+zapDemandInfo info@(IdInfo {demandInfo = demand})
+ | not (isStrict demand) = Nothing
+ | otherwise = Just (info {demandInfo = wwLazy})
+\end{code}
+
copyIdInfo is used when shorting out a top-level binding
f_local = BIG
where f is exported. We are going to swizzle it around to
f = BIG
f_local = f
-but we must be careful to combine their IdInfos right.
-The fact that things can go wrong here is a bad sign, but I can't see
-how to make it 'patently right', so copyIdInfo is derived (pretty much) by trial and error
-Here 'from' is f_local, 'to' is f, and the result is attached to f
+BUT (a) we must be careful about messing up rules
+ (b) we must ensure f's IdInfo ends up right
+
+(a) Messing up the rules
+~~~~~~~~~~~~~~~~~~~~
+The example that went bad on me was this one:
+
+ iterate :: (a -> a) -> a -> [a]
+ iterate = iterateList
+
+ iterateFB c f x = x `c` iterateFB c f (f x)
+ iterateList f x = x : iterateList f (f x)
+
+ {-# RULES
+ "iterate" forall f x. iterate f x = build (\c _n -> iterateFB c f x)
+ "iterateFB" iterateFB (:) = iterateList
+ #-}
+
+This got shorted out to:
+
+ iterateList :: (a -> a) -> a -> [a]
+ iterateList = iterate
+
+ iterateFB c f x = x `c` iterateFB c f (f x)
+ iterate f x = x : iterate f (f x)
+
+ {-# RULES
+ "iterate" forall f x. iterate f x = build (\c _n -> iterateFB c f x)
+ "iterateFB" iterateFB (:) = iterate
+ #-}
+
+And now we get an infinite loop in the rule system
+ iterate f x -> build (\cn -> iterateFB c f x
+ -> iterateFB (:) f x
+ -> iterate f x
+
+Tiresome solution: don't do shorting out if f has rewrite rules.
+Hence shortableIdInfo.
+
+(b) Keeping the IdInfo right
+~~~~~~~~~~~~~~~~~~~~~~~~
+We want to move strictness/worker info from f_local to f, but keep the rest.
+Hence copyIdInfo.
\begin{code}
-copyIdInfo :: IdInfo -- From
- -> IdInfo -- To
- -> IdInfo -- To, updated with stuff from From; except flavour unchanged
-copyIdInfo from to = from { flavourInfo = flavourInfo to,
- specInfo = specInfo to,
- inlinePragInfo = inlinePragInfo to
+shortableIdInfo :: IdInfo -> Bool
+shortableIdInfo info = isEmptyCoreRules (specInfo info)
+
+copyIdInfo :: IdInfo -- f_local
+ -> IdInfo -- f (the exported one)
+ -> IdInfo -- New info for f
+copyIdInfo f_local f = f { strictnessInfo = strictnessInfo f_local,
+ workerInfo = workerInfo f_local,
+ cprInfo = cprInfo f_local
}
- -- It's important to preserve the inline pragma on 'f'; e.g. consider
- -- {-# NOINLINE f #-}
- -- f = local
- --
- -- similarly, transformation rules may be attached to f
- -- and we want to preserve them.
- --
- -- On the other hand, we want the strictness info from f_local.
\end{code}
projects / ghc-hetmet.git / blobdiff