module IdInfo (
IdInfo, -- Abstract
- vanillaIdInfo, mkIdInfo, seqIdInfo, megaSeqIdInfo,
+ vanillaIdInfo, constantIdInfo, mkIdInfo, seqIdInfo, megaSeqIdInfo,
+
+ -- Zapping
+ zapFragileInfo, zapLamInfo, zapSpecPragInfo, shortableIdInfo, copyIdInfo,
-- Flavour
IdFlavour(..), flavourInfo,
- setNoDiscardInfo, zapSpecPragInfo, copyIdInfo,
+ setNoDiscardInfo, setFlavourInfo,
ppFlavourInfo,
-- Arity
exactArity, atLeastArity, unknownArity, hasArity,
arityInfo, setArityInfo, ppArityInfo, arityLowerBound,
- -- Strictness
- StrictnessInfo(..), -- Non-abstract
- mkStrictnessInfo,
- noStrictnessInfo, strictnessInfo,
- ppStrictnessInfo, setStrictnessInfo,
- isBottomingStrictness, appIsBottom,
+ -- Strictness; imported from Demand
+ StrictnessInfo(..),
+ mkStrictnessInfo, noStrictnessInfo,
+ ppStrictnessInfo,isBottomingStrictness,
+ strictnessInfo, setStrictnessInfo,
+
+ -- Usage generalisation
+ TyGenInfo(..),
+ tyGenInfo, setTyGenInfo,
+ noTyGenInfo, isNoTyGenInfo, ppTyGenInfo, tyGenInfoString,
-- Worker
- WorkerInfo, workerExists,
+ WorkerInfo(..), workerExists, wrapperArity, workerId,
workerInfo, setWorkerInfo, ppWorkerInfo,
-- Unfolding
demandInfo, setDemandInfo,
-- Inline prags
- InlinePragInfo(..), OccInfo(..),
- inlinePragInfo, setInlinePragInfo, notInsideLambda,
+ InlinePragInfo(..),
+ inlinePragInfo, setInlinePragInfo, pprInlinePragInfo,
+ isNeverInlinePrag, neverInlinePrag,
+
+ -- Occurrence info
+ 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,
-- Constructed Product Result Info
CprInfo(..), cprInfo, setCprInfo, ppCprInfo, noCprInfo,
- -- Zapping
- zapLamIdInfo, zapFragileIdInfo, zapIdInfoForStg,
-
-- Lambda-bound variable info
LBVarInfo(..), lbvarInfo, setLBVarInfo, noLBVarInfo
) where
#include "HsVersions.h"
-import {-# SOURCE #-} CoreUnfold ( Unfolding, noUnfolding, hasUnfolding, seqUnfolding )
-import {-# SOURCE #-} CoreSyn ( CoreExpr, CoreRules, emptyCoreRules, isEmptyCoreRules, seqRules )
-import {-# SOURCE #-} Const ( Con )
-
+import CoreSyn
+import Type ( Type, usOnce )
+import PrimOp ( PrimOp )
import Var ( Id )
+import BasicTypes ( OccInfo(..), isFragileOcc, isDeadOcc, seqOccInfo, isLoopBreaker,
+ InsideLam, insideLam, notInsideLam,
+ OneBranch, oneBranch, notOneBranch,
+ Arity
+ )
+import DataCon ( DataCon )
import FieldLabel ( FieldLabel )
-import Demand ( Demand, isStrict, isLazy, wwLazy, pprDemands, seqDemand, seqDemands )
-import Type ( UsageAnn )
+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`,
- `setCafInfo`
+ `setLBVarInfo`,
+ `setCafInfo`,
+ `setOccInfo`
-- infixl so you can say (id `set` a `set` b)
\end{code}
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,
cprInfo :: CprInfo, -- Function always constructs a product result
lbvarInfo :: LBVarInfo, -- Info about a lambda-bound variable
- inlinePragInfo :: InlinePragInfo -- Inline pragmas
+ inlinePragInfo :: InlinePragInfo, -- Inline pragma
+ occInfo :: OccInfo -- How it occurs
}
seqIdInfo :: IdInfo -> ()
megaSeqIdInfo :: IdInfo -> ()
megaSeqIdInfo info
- = seqFlavour (flavourInfo info) `seq`
- seqArity (arityInfo info) `seq`
- seqDemand (demandInfo info) `seq`
- seqRules (specInfo info) `seq`
- seqStrictness (strictnessInfo info) `seq`
- seqWorker (workerInfo info) `seq`
+ = seqFlavour (flavourInfo info) `seq`
+ seqArity (arityInfo info) `seq`
+ seqDemand (demandInfo info) `seq`
+ seqRules (specInfo info) `seq`
+ seqTyGenInfo (tyGenInfo info) `seq`
+ seqStrictnessInfo (strictnessInfo info) `seq`
+ seqWorker (workerInfo info) `seq`
-- seqUnfolding (unfoldingInfo info) `seq`
-- Omitting this improves runtimes a little, presumably because
seqCaf (cafInfo info) `seq`
seqCpr (cprInfo info) `seq`
seqLBVar (lbvarInfo info) `seq`
- seqInlinePrag (inlinePragInfo info)
+ seqOccInfo (occInfo info)
\end{code}
Setters
\begin{code}
+setFlavourInfo info fl = fl `seq` info { flavourInfo = fl }
setWorkerInfo info wk = wk `seq` info { workerInfo = wk }
-setSpecInfo info sp = sp `seq` info { specInfo = sp }
+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 }
-- Try to avoid spack leaks by seq'ing
-setUnfoldingInfo info uf = info { unfoldingInfo = uf }
+setUnfoldingInfo info uf
+ | isEvaldUnfolding uf && isStrict (demandInfo info)
+ -- If the unfolding is a value, the demand info may
+ -- go pear-shaped, so we nuke it. Example:
+ -- let x = (a,b) in
+ -- case x of (p,q) -> h p q x
+ -- Here x is certainly demanded. But after we've nuked
+ -- the case, we'll get just
+ -- let x = (a,b) in h a b x
+ -- and now x is not demanded (I'm assuming h is lazy)
+ -- This really happens. The solution here is a bit ad hoc...
+ = info { unfoldingInfo = uf, demandInfo = wwLazy }
+
+ | otherwise
-- We do *not* seq on the unfolding info, For some reason, doing so
-- 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 }
other -> info
-
-copyIdInfo :: IdInfo -- From
- -> IdInfo -- To
- -> IdInfo -- To updated with stuff from From; except flavour unchanged
--- copyIdInfo is used when shorting out a top-level binding
--- f_local = BIG
--- f = f_local
--- 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.
-
-copyIdInfo from to = from { flavourInfo = flavourInfo to,
- specInfo = specInfo to
- }
- -- It's important to propagate the inline pragmas from bndr
- -- to exportd_id. Ditto strictness etc. This "bites" when we use an INLNE pragma:
- -- {-# INLINE f #-}
- -- f x = (x,x)
- --
- -- This becomes (where the "*" means INLINE prag)
- --
- -- M.f = /\a -> let mf* = \x -> (x,x) in mf
- --
- -- Now the mf floats out and we end up with the trivial binding
- --
- -- mf* = /\a -> \x -> (x,x)
- -- M.f = mf
- --
- -- Now, when we short out the M.f = mf binding we must preserve the inline
- -- pragma on the mf binding.
- --
- -- On the other hand, transformation rules may be attached to the
- -- 'to' Id, and we want to preserve them.
\end{code}
vanillaIdInfo :: IdInfo
vanillaIdInfo = mkIdInfo VanillaId
+constantIdInfo :: IdInfo
+constantIdInfo = mkIdInfo ConstantId
+
mkIdInfo :: IdFlavour -> IdInfo
mkIdInfo flv = IdInfo {
flavourInfo = flv,
arityInfo = UnknownArity,
demandInfo = wwLazy,
specInfo = emptyCoreRules,
- workerInfo = Nothing,
+ tyGenInfo = noTyGenInfo,
+ workerInfo = NoWorker,
strictnessInfo = NoStrictnessInfo,
unfoldingInfo = noUnfolding,
- updateInfo = NoUpdateInfo,
cafInfo = MayHaveCafRefs,
cprInfo = NoCPRInfo,
lbvarInfo = NoLBVarInfo,
- inlinePragInfo = NoInlinePragInfo
+ inlinePragInfo = NoInlinePragInfo,
+ occInfo = NoOccInfo
}
\end{code}
\begin{code}
data IdFlavour
- = VanillaId -- Most Ids are like this
- | ConstantId Con -- The Id for a constant (data constructor or primop)
- | RecordSelId FieldLabel -- The Id for a record selector
- | SpecPragmaId -- Don't discard these
- | NoDiscardId -- Don't discard these either
+ = VanillaId -- Locally defined, not exported
+ | ExportedId -- Locally defined, exported
+ | SpecPragmaId -- Locally defined, RHS holds specialised call
+
+ | ConstantId -- Imported from elsewhere, or a dictionary function,
+ -- default method Id.
+
+ | 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
+ -- a) we can suppress printing a definition in the interface file
+ -- b) when typechecking a pattern we can get from the
+ -- Id back to the data con]
+ | PrimOpId PrimOp -- The Id for a primitive operator
+ | RecordSelId FieldLabel -- The Id for a record selector
+
ppFlavourInfo :: IdFlavour -> SDoc
-ppFlavourInfo VanillaId = empty
-ppFlavourInfo (ConstantId _) = ptext SLIT("[Constr]")
-ppFlavourInfo (RecordSelId _) = ptext SLIT("[RecSel]")
-ppFlavourInfo SpecPragmaId = ptext SLIT("[SpecPrag]")
-ppFlavourInfo NoDiscardId = ptext SLIT("[NoDiscard]")
+ppFlavourInfo VanillaId = empty
+ppFlavourInfo ExportedId = ptext SLIT("[Exported]")
+ppFlavourInfo SpecPragmaId = ptext SLIT("[SpecPrag]")
+ppFlavourInfo ConstantId = ptext SLIT("[Constant]")
+ppFlavourInfo (DataConId _) = ptext SLIT("[DataCon]")
+ppFlavourInfo (DataConWrapId _) = ptext SLIT("[DataConWrapper]")
+ppFlavourInfo (PrimOpId _) = ptext SLIT("[PrimOp]")
+ppFlavourInfo (RecordSelId _) = ptext SLIT("[RecSel]")
seqFlavour :: IdFlavour -> ()
seqFlavour f = f `seq` ()
\begin{code}
data ArityInfo
= UnknownArity -- No idea
- | ArityExactly Int -- Arity is exactly this
- | ArityAtLeast Int -- Arity is this or greater
+
+ | ArityExactly Arity -- Arity is exactly this. We use this when importing a
+ -- function; it's already been compiled and we know its
+ -- arity for sure.
+
+ | 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` ()
atLeastArity = ArityAtLeast
unknownArity = UnknownArity
-arityLowerBound :: ArityInfo -> Int
+arityLowerBound :: ArityInfo -> Arity
arityLowerBound UnknownArity = 0
arityLowerBound (ArityAtLeast n) = n
arityLowerBound (ArityExactly n) = n
\begin{code}
data InlinePragInfo
= 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
- | IMustNotBeINLINEd -- User NOINLINE pragma
-
- | IAmALoopBreaker -- Used by the occurrence analyser to mark loop-breakers
- -- in a group of recursive definitions
-
- | ICanSafelyBeINLINEd -- Used by the occurrence analyser to mark things
- -- that manifesly occur once, not inside SCCs,
- -- not in constructor arguments
+ -- SEE COMMENTS WITH CoreUnfold.blackListed on the
+ -- exact significance of the IMustNotBeINLINEd pragma
- OccInfo -- Says whether the occurrence is inside a lambda
- -- If so, must only substitute WHNFs
+isNeverInlinePrag :: InlinePragInfo -> Bool
+isNeverInlinePrag (IMustNotBeINLINEd _ Nothing) = True
+isNeverInlinePrag other = False
- Bool -- False <=> occurs in more than one case branch
- -- If so, there's a code-duplication issue
-
- | IAmDead -- Marks unused variables. Sometimes useful for
- -- lambda and case-bound variables.
-
- | IMustBeINLINEd -- Absolutely must inline; used for PrimOps and
- -- constructors only.
-
-seqInlinePrag :: InlinePragInfo -> ()
-seqInlinePrag (ICanSafelyBeINLINEd occ alts)
- = occ `seq` alts `seq` ()
-seqInlinePrag other
- = ()
+neverInlinePrag :: InlinePragInfo
+neverInlinePrag = IMustNotBeINLINEd True{-should be False? --SDM -} Nothing
instance Outputable InlinePragInfo where
- -- only used for debugging; never parsed. KSW 1999-07
- ppr NoInlinePragInfo = empty
- ppr IMustBeINLINEd = ptext SLIT("__UU")
- ppr IMustNotBeINLINEd = ptext SLIT("__Unot")
- ppr IAmALoopBreaker = ptext SLIT("__Ux")
- ppr IAmDead = ptext SLIT("__Ud")
- ppr (ICanSafelyBeINLINEd InsideLam _) = ptext SLIT("__Ul")
- ppr (ICanSafelyBeINLINEd _ _) = ptext SLIT("__Us")
-
+ -- This is now parsed in interface files
+ ppr NoInlinePragInfo = empty
+ ppr other_prag = ptext SLIT("__U") <> pprInlinePragInfo other_prag
+
+pprInlinePragInfo NoInlinePragInfo = empty
+pprInlinePragInfo (IMustNotBeINLINEd True Nothing) = empty
+pprInlinePragInfo (IMustNotBeINLINEd True (Just n)) = brackets (int n)
+pprInlinePragInfo (IMustNotBeINLINEd False Nothing) = brackets (char '!')
+pprInlinePragInfo (IMustNotBeINLINEd False (Just n)) = brackets (char '!' <> int n)
+
instance Show InlinePragInfo where
showsPrec p prag = showsPrecSDoc p (ppr prag)
\end{code}
-\begin{code}
-data OccInfo
- = NotInsideLam
-
- | InsideLam -- Inside a non-linear lambda (that is, a lambda which
- -- is sure to be instantiated only once).
- -- Substituting a redex for this occurrence is
- -- dangerous because it might duplicate work.
-
-instance Outputable OccInfo where
- ppr NotInsideLam = empty
- ppr InsideLam = text "l"
-
-
-notInsideLambda :: OccInfo -> Bool
-notInsideLambda NotInsideLam = True
-notInsideLambda InsideLam = False
-\end{code}
%************************************************************************
-%* *
-\subsection[strictness-IdInfo]{Strictness info about an @Id@}
-%* *
+%* *
+\subsection[TyGen-IdInfo]{Type generalisation info about an @Id@}
+%* *
%************************************************************************
-We specify the strictness of a function by giving information about
-each of the ``wrapper's'' arguments (see the description about
-worker/wrapper-style transformations in the PJ/Launchbury paper on
-unboxed types).
+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.
-The list of @Demands@ specifies: (a)~the strictness properties of a
-function's arguments; and (b)~the type signature of that worker (if it
-exists); i.e. its calling convention.
+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).
-Note that the existence of a worker function is now denoted by the Id's
-workerInfo field.
+To indicate this property, such identifiers are marked TyGenNever.
-\begin{code}
-data StrictnessInfo
- = NoStrictnessInfo
-
- | StrictnessInfo [Demand]
- Bool -- True <=> the function diverges regardless of its arguments
- -- Useful for "error" and other disguised variants thereof.
- -- BUT NB: f = \x y. error "urk"
- -- will have info SI [SS] True
- -- but still (f) and (f 2) are not bot; only (f 3 2) is bot
-
-seqStrictness :: StrictnessInfo -> ()
-seqStrictness (StrictnessInfo ds b) = b `seq` seqDemands ds
-seqStrictness other = ()
-\end{code}
+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}
-mkStrictnessInfo :: ([Demand], Bool) -> StrictnessInfo
+data TyGenInfo
+ = NoTyGenInfo -- no restriction on type generalisation
-mkStrictnessInfo (xs, is_bot)
- | all isLazy xs && not is_bot = NoStrictnessInfo -- Uninteresting
- | otherwise = StrictnessInfo xs is_bot
+ | TyGenUInfo [Maybe Type] -- restrict generalisation of this Id to
+ -- preserve specified usage annotations
-noStrictnessInfo = NoStrictnessInfo
+ | TyGenNever -- never generalise the type of this Id
-isBottomingStrictness (StrictnessInfo _ bot) = bot
-isBottomingStrictness NoStrictnessInfo = False
+ deriving ( Eq )
+\end{code}
--- appIsBottom returns true if an application to n args would diverge
-appIsBottom (StrictnessInfo ds bot) n = bot && (n >= length ds)
-appIsBottom NoStrictnessInfo n = False
+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.
-ppStrictnessInfo NoStrictnessInfo = empty
-ppStrictnessInfo (StrictnessInfo wrapper_args bot)
- = hsep [ptext SLIT("__S"), pprDemands wrapper_args bot]
+\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@}
\begin{code}
-type WorkerInfo = Maybe Id
-
-{- UNUSED:
-mkWorkerInfo :: Id -> WorkerInfo
-mkWorkerInfo wk_id = Just wk_id
--}
+data WorkerInfo = NoWorker
+ | HasWorker Id Arity
+ -- The Arity is the arity of the *wrapper* at the moment of the
+ -- w/w split. See comments in MkIface.ifaceId, with the 'Worker' code.
seqWorker :: WorkerInfo -> ()
-seqWorker (Just id) = id `seq` ()
-seqWorker Nothing = ()
+seqWorker (HasWorker id _) = id `seq` ()
+seqWorker NoWorker = ()
-ppWorkerInfo Nothing = empty
-ppWorkerInfo (Just wk_id) = ptext SLIT("__P") <+> ppr wk_id
+ppWorkerInfo NoWorker = empty
+ppWorkerInfo (HasWorker wk_id _) = ptext SLIT("__P") <+> ppr wk_id
-noWorkerInfo = Nothing
+noWorkerInfo = NoWorker
-workerExists :: Maybe Id -> Bool
-workerExists = isJust
-\end{code}
+workerExists :: WorkerInfo -> Bool
+workerExists NoWorker = False
+workerExists (HasWorker _ _) = True
+workerId :: WorkerInfo -> Id
+workerId (HasWorker id _) = id
-%************************************************************************
-%* *
-\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]
+wrapperArity :: WorkerInfo -> Arity
+wrapperArity (HasWorker _ a) = a
\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}
-%* *
-%************************************************************************
-
-zapFragileIdInfo 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}
-zapFragileIdInfo :: IdInfo -> Maybe IdInfo
-zapFragileIdInfo info@(IdInfo {inlinePragInfo = inline_prag,
- workerInfo = wrkr,
- specInfo = rules,
- unfoldingInfo = unfolding})
- | not is_fragile_inline_prag
- -- 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
-
- && 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 {inlinePragInfo = safe_inline_prag,
- workerInfo = noWorkerInfo,
- specInfo = emptyCoreRules,
- unfoldingInfo = noUnfolding})
-
- where
- is_fragile_inline_prag = case inline_prag of
- ICanSafelyBeINLINEd _ _ -> True
-
--- We used to say the dead-ness was fragile, but I don't
--- see why it is. Furthermore, deadness is a pain to lose;
--- see Simplify.mkDupableCont (Select ...)
--- IAmDead -> True
-
- other -> False
-
- -- Be careful not to destroy real 'pragma' info
- safe_inline_prag | is_fragile_inline_prag = NoInlinePragInfo
- | otherwise = inline_prag
-\end{code}
-
-
-@zapLamIdInfo@ is used for lambda binders that turn out to to be
-part of an unsaturated lambda
-
-\begin{code}
-zapLamIdInfo :: IdInfo -> Maybe IdInfo
-zapLamIdInfo info@(IdInfo {inlinePragInfo = inline_prag, demandInfo = demand})
- | is_safe_inline_prag && not (isStrict demand)
- = Nothing
- | otherwise
- = Just (info {inlinePragInfo = safe_inline_prag,
- demandInfo = wwLazy})
- where
- -- The "unsafe" prags are the ones that say I'm not in a lambda
- -- because that might not be true for an unsaturated lambda
- is_safe_inline_prag = case inline_prag of
- ICanSafelyBeINLINEd NotInsideLam nalts -> False
- other -> True
-
- safe_inline_prag = case inline_prag of
- ICanSafelyBeINLINEd _ nalts
- -> ICanSafelyBeINLINEd InsideLam nalts
- other -> inline_prag
-\end{code}
-
-\begin{code}
-zapIdInfoForStg :: IdInfo -> IdInfo
- -- Return only the info needed for STG stuff
- -- Namely, nothing, I think
-zapIdInfoForStg info = vanillaIdInfo
-\end{code}
-
-
-%************************************************************************
-%* *
\subsection[cpr-IdInfo]{Constructed Product Result info about an @Id@}
%* *
%************************************************************************
\begin{code}
data CprInfo
= NoCPRInfo
-
- | CPRInfo [CprInfo]
-
--- e.g. const 5 == CPRInfo [NoCPRInfo]
--- == __M(-)
--- \x -> (5,
--- (x,
--- 5,
--- x)
--- )
--- CPRInfo [CPRInfo [NoCPRInfo],
--- CPRInfo [NoCprInfo,
--- CPRInfo [NoCPRInfo],
--- NoCPRInfo]
--- ]
--- __M((-)(-(-)-)-)
+ | ReturnsCPR -- Yes, this function returns a constructed product
+ -- Implicitly, this means "after the function has been applied
+ -- to all its arguments", so the worker/wrapper builder in
+ -- WwLib.mkWWcpr checks that that it is indeed saturated before
+ -- making use of the CPR info
+
+ -- We used to keep nested info about sub-components, but
+ -- we never used it so I threw it away
\end{code}
\begin{code}
seqCpr :: CprInfo -> ()
-seqCpr (CPRInfo cs) = seqCprs cs
-seqCpr NoCPRInfo = ()
-
-seqCprs [] = ()
-seqCprs (c:cs) = seqCpr c `seq` seqCprs cs
-
+seqCpr ReturnsCPR = ()
+seqCpr NoCPRInfo = ()
noCprInfo = NoCPRInfo
-ppCprInfo NoCPRInfo = empty
-ppCprInfo c@(CPRInfo _)
- = hsep [ptext SLIT("__M"), ppCprInfo' c]
- where
- ppCprInfo' NoCPRInfo = char '-'
- ppCprInfo' (CPRInfo args) = parens (hcat (map ppCprInfo' args))
+ppCprInfo NoCPRInfo = empty
+ppCprInfo ReturnsCPR = ptext SLIT("__M")
instance Outputable CprInfo where
ppr = ppCprInfo
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.
-- 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
instance Show LBVarInfo where
showsPrec p c = showsPrecSDoc p (ppr c)
\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{Bulk operations on IdInfo}
+%* *
+%************************************************************************
+
+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 (isFragileOcc 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
+
+\begin{code}
+zapLamInfo :: IdInfo -> Maybe IdInfo
+zapLamInfo info@(IdInfo {occInfo = occ, demandInfo = demand})
+ | is_safe_occ && not (isStrict demand)
+ = Nothing
+ | otherwise
+ = Just (info {occInfo = safe_occ,
+ demandInfo = wwLazy})
+ where
+ -- The "unsafe" occ info is the ones that say I'm not in a lambda
+ -- because that might not be true for an unsaturated lambda
+ is_safe_occ = case occ of
+ OneOcc in_lam once -> in_lam
+ other -> True
+
+ safe_occ = case occ of
+ OneOcc _ once -> OneOcc insideLam once
+ other -> occ
+\end{code}
+
+
+copyIdInfo is used when shorting out a top-level binding
+ f_local = BIG
+ f = f_local
+where f is exported. We are going to swizzle it around to
+ f = BIG
+ f_local = 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}
+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
+ }
+\end{code}
projects / ghc-hetmet.git / blobdiff