{- (c) The University of Glasgow 2006 (c) The GRASP/AQUA Project, Glasgow University, 1993-1998 \section[IdInfo]{@IdInfos@: Non-essential information about @Ids@} (And a pretty good illustration of quite a few things wrong with Haskell. [WDP 94/11]) -} module IdInfo ( -- * The IdDetails type IdDetails(..), pprIdDetails, coVarDetails, -- * The IdInfo type IdInfo, -- Abstract vanillaIdInfo, noCafIdInfo, seqIdInfo, megaSeqIdInfo, -- ** The OneShotInfo type OneShotInfo(..), oneShotInfo, noOneShotInfo, hasNoOneShotInfo, setOneShotInfo, -- ** Zapping various forms of Info zapLamInfo, zapFragileInfo, zapDemandInfo, zapUsageInfo, -- ** The ArityInfo type ArityInfo, unknownArity, arityInfo, setArityInfo, ppArityInfo, callArityInfo, setCallArityInfo, -- ** Demand and strictness Info strictnessInfo, setStrictnessInfo, demandInfo, setDemandInfo, pprStrictness, -- ** Unfolding Info unfoldingInfo, setUnfoldingInfo, setUnfoldingInfoLazily, -- ** The InlinePragInfo type InlinePragInfo, inlinePragInfo, setInlinePragInfo, -- ** The OccInfo type OccInfo(..), isDeadOcc, isStrongLoopBreaker, isWeakLoopBreaker, occInfo, setOccInfo, InsideLam, OneBranch, insideLam, notInsideLam, oneBranch, notOneBranch, -- ** The SpecInfo type SpecInfo(..), emptySpecInfo, isEmptySpecInfo, specInfoFreeVars, specInfoRules, seqSpecInfo, setSpecInfoHead, specInfo, setSpecInfo, -- ** The CAFInfo type CafInfo(..), ppCafInfo, mayHaveCafRefs, cafInfo, setCafInfo, -- ** Tick-box Info TickBoxOp(..), TickBoxId, ) where import CoreSyn import Class import {-# SOURCE #-} PrimOp (PrimOp) import Name import VarSet import BasicTypes import DataCon import TyCon import ForeignCall import Outputable import Module import FastString import Demand -- infixl so you can say (id `set` a `set` b) infixl 1 `setSpecInfo`, `setArityInfo`, `setInlinePragInfo`, `setUnfoldingInfo`, `setOneShotInfo`, `setOccInfo`, `setCafInfo`, `setStrictnessInfo`, `setDemandInfo` {- ************************************************************************ * * IdDetails * * ************************************************************************ -} -- | The 'IdDetails' of an 'Id' give stable, and necessary, -- information about the Id. data IdDetails = VanillaId -- | The 'Id' for a record selector | RecSelId { sel_tycon :: TyCon -- ^ For a data type family, this is the /instance/ 'TyCon' -- not the family 'TyCon' , sel_naughty :: Bool -- True <=> a "naughty" selector which can't actually exist, for example @x@ in: -- data T = forall a. MkT { x :: a } } -- See Note [Naughty record selectors] in TcTyClsDecls | DataConWorkId DataCon -- ^ The 'Id' is for a data constructor /worker/ | DataConWrapId DataCon -- ^ The 'Id' is for a data constructor /wrapper/ -- [the only reasons we need to know is so that -- a) to support isImplicitId -- b) when desugaring a RecordCon we can get -- from the Id back to the data con] | ClassOpId Class -- ^ The 'Id' is a superclass selector or class operation of a class | PrimOpId PrimOp -- ^ The 'Id' is for a primitive operator | FCallId ForeignCall -- ^ The 'Id' is for a foreign call | TickBoxOpId TickBoxOp -- ^ The 'Id' is for a HPC tick box (both traditional and binary) | DFunId Int Bool -- ^ A dictionary function. -- Int = the number of "silent" arguments to the dfun -- e.g. class D a => C a where ... -- instance C a => C [a] -- has is_silent = 1, because the dfun -- has type dfun :: (D a, C a) => C [a] -- See Note [Silent superclass arguments] in TcInstDcls -- -- Bool = True <=> the class has only one method, so may be -- implemented with a newtype, so it might be bad -- to be strict on this dictionary coVarDetails :: IdDetails coVarDetails = VanillaId instance Outputable IdDetails where ppr = pprIdDetails pprIdDetails :: IdDetails -> SDoc pprIdDetails VanillaId = empty pprIdDetails other = brackets (pp other) where pp VanillaId = panic "pprIdDetails" pp (DataConWorkId _) = ptext (sLit "DataCon") pp (DataConWrapId _) = ptext (sLit "DataConWrapper") pp (ClassOpId {}) = ptext (sLit "ClassOp") pp (PrimOpId _) = ptext (sLit "PrimOp") pp (FCallId _) = ptext (sLit "ForeignCall") pp (TickBoxOpId _) = ptext (sLit "TickBoxOp") pp (DFunId ns nt) = ptext (sLit "DFunId") <> ppWhen (ns /= 0) (brackets (int ns)) <> ppWhen nt (ptext (sLit "(nt)")) pp (RecSelId { sel_naughty = is_naughty }) = brackets $ ptext (sLit "RecSel") <> ppWhen is_naughty (ptext (sLit "(naughty)")) {- ************************************************************************ * * \subsection{The main IdInfo type} * * ************************************************************************ -} -- | An 'IdInfo' gives /optional/ information about an 'Id'. If -- present it never lies, but it may not be present, in which case there -- is always a conservative assumption which can be made. -- -- Two 'Id's may have different info even though they have the same -- 'Unique' (and are hence the same 'Id'); for example, one might lack -- the properties attached to the other. -- -- The 'IdInfo' gives information about the value, or definition, of the -- 'Id'. It does not contain information about the 'Id''s usage, -- except for 'demandInfo' and 'oneShotInfo'. data IdInfo = IdInfo { arityInfo :: !ArityInfo, -- ^ 'Id' arity specInfo :: SpecInfo, -- ^ Specialisations of the 'Id's function which exist -- See Note [Specialisations and RULES in IdInfo] unfoldingInfo :: Unfolding, -- ^ The 'Id's unfolding cafInfo :: CafInfo, -- ^ 'Id' CAF info oneShotInfo :: OneShotInfo, -- ^ Info about a lambda-bound variable, if the 'Id' is one inlinePragInfo :: InlinePragma, -- ^ Any inline pragma atached to the 'Id' occInfo :: OccInfo, -- ^ How the 'Id' occurs in the program strictnessInfo :: StrictSig, -- ^ A strictness signature demandInfo :: Demand, -- ^ ID demand information callArityInfo :: !ArityInfo -- ^ How this is called. -- n <=> all calls have at least n arguments } -- | Just evaluate the 'IdInfo' to WHNF seqIdInfo :: IdInfo -> () seqIdInfo (IdInfo {}) = () -- | Evaluate all the fields of the 'IdInfo' that are generally demanded by the -- compiler megaSeqIdInfo :: IdInfo -> () megaSeqIdInfo info = seqSpecInfo (specInfo info) `seq` -- Omitting this improves runtimes a little, presumably because -- some unfoldings are not calculated at all -- seqUnfolding (unfoldingInfo info) `seq` seqDemandInfo (demandInfo info) `seq` seqStrictnessInfo (strictnessInfo info) `seq` seqCaf (cafInfo info) `seq` seqOneShot (oneShotInfo info) `seq` seqOccInfo (occInfo info) seqOneShot :: OneShotInfo -> () seqOneShot l = l `seq` () seqStrictnessInfo :: StrictSig -> () seqStrictnessInfo ty = seqStrictSig ty seqDemandInfo :: Demand -> () seqDemandInfo dmd = seqDemand dmd -- Setters setSpecInfo :: IdInfo -> SpecInfo -> IdInfo setSpecInfo info sp = sp `seq` info { specInfo = sp } setInlinePragInfo :: IdInfo -> InlinePragma -> IdInfo setInlinePragInfo info pr = pr `seq` info { inlinePragInfo = pr } setOccInfo :: IdInfo -> OccInfo -> IdInfo setOccInfo info oc = oc `seq` info { occInfo = oc } -- Try to avoid spack leaks by seq'ing setUnfoldingInfoLazily :: IdInfo -> Unfolding -> IdInfo setUnfoldingInfoLazily info uf -- Lazy variant to avoid looking at the = -- unfolding of an imported Id unless necessary info { unfoldingInfo = uf } -- (In this case the demand-zapping is redundant.) setUnfoldingInfo :: IdInfo -> Unfolding -> IdInfo setUnfoldingInfo info uf = -- We don't seq the unfolding, as we generate intermediate -- unfoldings which are just thrown away, so evaluating them is a -- waste of time. -- seqUnfolding uf `seq` info { unfoldingInfo = uf } setArityInfo :: IdInfo -> ArityInfo -> IdInfo setArityInfo info ar = info { arityInfo = ar } setCallArityInfo :: IdInfo -> ArityInfo -> IdInfo setCallArityInfo info ar = info { callArityInfo = ar } setCafInfo :: IdInfo -> CafInfo -> IdInfo setCafInfo info caf = info { cafInfo = caf } setOneShotInfo :: IdInfo -> OneShotInfo -> IdInfo setOneShotInfo info lb = {-lb `seq`-} info { oneShotInfo = lb } setDemandInfo :: IdInfo -> Demand -> IdInfo setDemandInfo info dd = dd `seq` info { demandInfo = dd } setStrictnessInfo :: IdInfo -> StrictSig -> IdInfo setStrictnessInfo info dd = dd `seq` info { strictnessInfo = dd } -- | Basic 'IdInfo' that carries no useful information whatsoever vanillaIdInfo :: IdInfo vanillaIdInfo = IdInfo { cafInfo = vanillaCafInfo, arityInfo = unknownArity, specInfo = emptySpecInfo, unfoldingInfo = noUnfolding, oneShotInfo = NoOneShotInfo, inlinePragInfo = defaultInlinePragma, occInfo = NoOccInfo, demandInfo = topDmd, strictnessInfo = nopSig, callArityInfo = unknownArity } -- | More informative 'IdInfo' we can use when we know the 'Id' has no CAF references noCafIdInfo :: IdInfo noCafIdInfo = vanillaIdInfo `setCafInfo` NoCafRefs -- Used for built-in type Ids in MkId. {- ************************************************************************ * * \subsection[arity-IdInfo]{Arity info about an @Id@} * * ************************************************************************ For locally-defined Ids, the code generator maintains its own notion of their arities; so it should not be asking... (but other things besides the code-generator need arity info!) -} -- | An 'ArityInfo' of @n@ tells us that 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. -- -- The arity might increase later in the compilation process, if -- an extra lambda floats up to the binding site. type ArityInfo = Arity -- | It is always safe to assume that an 'Id' has an arity of 0 unknownArity :: Arity unknownArity = 0 :: Arity ppArityInfo :: Int -> SDoc ppArityInfo 0 = empty ppArityInfo n = hsep [ptext (sLit "Arity"), int n] {- ************************************************************************ * * \subsection{Inline-pragma information} * * ************************************************************************ -} -- | Tells when the inlining is active. -- When it is active the thing may be inlined, depending on how -- big it is. -- -- If there was an @INLINE@ pragma, then as a separate matter, the -- RHS will have been made to look small with a Core inline 'Note' -- -- The default 'InlinePragInfo' is 'AlwaysActive', so the info serves -- entirely as a way to inhibit inlining until we want it type InlinePragInfo = InlinePragma {- ************************************************************************ * * Strictness * * ************************************************************************ -} pprStrictness :: StrictSig -> SDoc pprStrictness sig = ppr sig {- ************************************************************************ * * SpecInfo * * ************************************************************************ Note [Specialisations and RULES in IdInfo] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Generally speaking, a GlobalIdshas an *empty* SpecInfo. All their RULES are contained in the globally-built rule-base. In principle, one could attach the to M.f the RULES for M.f that are defined in M. But we don't do that for instance declarations and so we just treat them all uniformly. The EXCEPTION is PrimOpIds, which do have rules in their IdInfo. That is jsut for convenience really. However, LocalIds may have non-empty SpecInfo. We treat them differently because: a) they might be nested, in which case a global table won't work b) the RULE might mention free variables, which we use to keep things alive In TidyPgm, when the LocalId becomes a GlobalId, its RULES are stripped off and put in the global list. -} -- | Records the specializations of this 'Id' that we know about -- in the form of rewrite 'CoreRule's that target them data SpecInfo = SpecInfo [CoreRule] VarSet -- Locally-defined free vars of *both* LHS and RHS -- of rules. I don't think it needs to include the -- ru_fn though. -- Note [Rule dependency info] in OccurAnal -- | Assume that no specilizations exist: always safe emptySpecInfo :: SpecInfo emptySpecInfo = SpecInfo [] emptyVarSet isEmptySpecInfo :: SpecInfo -> Bool isEmptySpecInfo (SpecInfo rs _) = null rs -- | Retrieve the locally-defined free variables of both the left and -- right hand sides of the specialization rules specInfoFreeVars :: SpecInfo -> VarSet specInfoFreeVars (SpecInfo _ fvs) = fvs specInfoRules :: SpecInfo -> [CoreRule] specInfoRules (SpecInfo rules _) = rules -- | Change the name of the function the rule is keyed on on all of the 'CoreRule's setSpecInfoHead :: Name -> SpecInfo -> SpecInfo setSpecInfoHead fn (SpecInfo rules fvs) = SpecInfo (map (setRuleIdName fn) rules) fvs seqSpecInfo :: SpecInfo -> () seqSpecInfo (SpecInfo rules fvs) = seqRules rules `seq` seqVarSet fvs {- ************************************************************************ * * \subsection[CG-IdInfo]{Code generator-related information} * * ************************************************************************ -} -- CafInfo is used to build Static Reference Tables (see simplStg/SRT.lhs). -- | Records whether an 'Id' makes Constant Applicative Form references data CafInfo = MayHaveCafRefs -- ^ Indicates that the 'Id' is for either: -- -- 1. A function or static constructor -- that refers to one or more CAFs, or -- -- 2. A real live CAF | NoCafRefs -- ^ A function or static constructor -- that refers to no CAFs. deriving (Eq, Ord) -- | Assumes that the 'Id' has CAF references: definitely safe vanillaCafInfo :: CafInfo vanillaCafInfo = MayHaveCafRefs mayHaveCafRefs :: CafInfo -> Bool mayHaveCafRefs MayHaveCafRefs = True mayHaveCafRefs _ = False seqCaf :: CafInfo -> () seqCaf c = c `seq` () instance Outputable CafInfo where ppr = ppCafInfo ppCafInfo :: CafInfo -> SDoc ppCafInfo NoCafRefs = ptext (sLit "NoCafRefs") ppCafInfo MayHaveCafRefs = empty {- ************************************************************************ * * \subsection{Bulk operations on IdInfo} * * ************************************************************************ -} -- | This is used to remove information on lambda binders that we have -- setup as part of a lambda group, assuming they will be applied all at once, -- but turn out to be part of an unsaturated lambda as in e.g: -- -- > (\x1. \x2. e) arg1 zapLamInfo :: IdInfo -> Maybe IdInfo zapLamInfo info@(IdInfo {occInfo = occ, demandInfo = demand}) | is_safe_occ occ && is_safe_dmd demand = Nothing | otherwise = Just (info {occInfo = safe_occ, demandInfo = topDmd}) 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 (OneOcc in_lam _ _) = in_lam is_safe_occ _other = True safe_occ = case occ of OneOcc _ once int_cxt -> OneOcc insideLam once int_cxt _other -> occ is_safe_dmd dmd = not (isStrictDmd dmd) -- | Remove all demand info on the 'IdInfo' zapDemandInfo :: IdInfo -> Maybe IdInfo zapDemandInfo info = Just (info {demandInfo = topDmd}) -- | Remove usage (but not strictness) info on the 'IdInfo' zapUsageInfo :: IdInfo -> Maybe IdInfo zapUsageInfo info = Just (info {demandInfo = zapUsageDemand (demandInfo info)}) zapFragileInfo :: IdInfo -> Maybe IdInfo -- ^ Zap info that depends on free variables zapFragileInfo info = Just (info `setSpecInfo` emptySpecInfo `setUnfoldingInfo` noUnfolding `setOccInfo` zapFragileOcc occ) where occ = occInfo info {- ************************************************************************ * * \subsection{TickBoxOp} * * ************************************************************************ -} type TickBoxId = Int -- | Tick box for Hpc-style coverage data TickBoxOp = TickBox Module {-# UNPACK #-} !TickBoxId instance Outputable TickBoxOp where ppr (TickBox mod n) = ptext (sLit "tick") <+> ppr (mod,n)