X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FbasicTypes%2FIdInfo.lhs;h=a251c7e5aca25e22b9baacb4a83259cfa2740835;hb=33ce2a14d1220bd3b9f00e8d461b8f9ef31ee411;hp=f899847e18c7e2e7e421a6b80790e1a633059ddd;hpb=30b5ebe424ebae69b162ac3fc547eb14d898535f;p=ghc-hetmet.git diff --git a/ghc/compiler/basicTypes/IdInfo.lhs b/ghc/compiler/basicTypes/IdInfo.lhs index f899847..a251c7e 100644 --- a/ghc/compiler/basicTypes/IdInfo.lhs +++ b/ghc/compiler/basicTypes/IdInfo.lhs @@ -8,101 +8,264 @@ Haskell. [WDP 94/11]) \begin{code} module IdInfo ( - IdInfo, -- Abstract + GlobalIdDetails(..), notGlobalId, -- Not abstract - vanillaIdInfo, mkIdInfo, seqIdInfo, megaSeqIdInfo, + IdInfo, -- Abstract + vanillaIdInfo, noCafIdInfo, hasCafIdInfo, + seqIdInfo, megaSeqIdInfo, -- Zapping - zapFragileInfo, zapLamInfo, zapSpecPragInfo, copyIdInfo, - - -- Flavour - IdFlavour(..), flavourInfo, - setNoDiscardInfo, - ppFlavourInfo, + zapLamInfo, zapDemandInfo, + shortableIdInfo, copyIdInfo, -- Arity - ArityInfo(..), - exactArity, atLeastArity, unknownArity, hasArity, - arityInfo, setArityInfo, ppArityInfo, arityLowerBound, + ArityInfo, + unknownArity, + arityInfo, setArityInfo, ppArityInfo, - -- Strictness - StrictnessInfo(..), -- Non-abstract - mkStrictnessInfo, - noStrictnessInfo, strictnessInfo, - ppStrictnessInfo, setStrictnessInfo, - isBottomingStrictness, appIsBottom, + -- New demand and strictness info + newStrictnessInfo, setNewStrictnessInfo, + newDemandInfo, setNewDemandInfo, + + -- Strictness; imported from Demand + StrictnessInfo(..), + mkStrictnessInfo, noStrictnessInfo, + ppStrictnessInfo,isBottomingStrictness, + setAllStrictnessInfo, -- Worker - WorkerInfo, workerExists, + WorkerInfo(..), workerExists, wrapperArity, workerId, workerInfo, setWorkerInfo, ppWorkerInfo, -- Unfolding unfoldingInfo, setUnfoldingInfo, - -- DemandInfo +#ifdef OLD_STRICTNESS + -- Old DemandInfo and StrictnessInfo demandInfo, setDemandInfo, + strictnessInfo, setStrictnessInfo, + cprInfoFromNewStrictness, + oldStrictnessFromNew, newStrictnessFromOld, + oldDemand, newDemand, + + -- Constructed Product Result Info + CprInfo(..), cprInfo, setCprInfo, ppCprInfo, noCprInfo, +#endif -- Inline prags - InlinePragInfo(..), - inlinePragInfo, setInlinePragInfo, pprInlinePragInfo, + InlinePragInfo, + inlinePragInfo, setInlinePragInfo, -- Occurrence info - OccInfo(..), InsideLam, OneBranch, insideLam, notInsideLam, oneBranch, notOneBranch, - occInfo, setOccInfo, isFragileOccInfo, + OccInfo(..), isFragileOcc, isDeadOcc, isLoopBreaker, + InsideLam, OneBranch, insideLam, notInsideLam, oneBranch, notOneBranch, + occInfo, setOccInfo, -- Specialisation specInfo, setSpecInfo, - -- Update - UpdateInfo, UpdateSpec, - mkUpdateInfo, updateInfo, updateInfoMaybe, ppUpdateInfo, setUpdateInfo, + -- CG info + CgInfo(..), cgInfo, setCgInfo, pprCgInfo, + cgCafInfo, vanillaCgInfo, + CgInfoEnv, lookupCgInfo, -- CAF info - CafInfo(..), cafInfo, setCafInfo, ppCafInfo, - - -- Constructed Product Result Info - CprInfo(..), cprInfo, setCprInfo, ppCprInfo, noCprInfo, + CafInfo(..), ppCafInfo, setCafInfo, mayHaveCafRefs, -- Lambda-bound variable info - LBVarInfo(..), lbvarInfo, setLBVarInfo, noLBVarInfo + LBVarInfo(..), lbvarInfo, setLBVarInfo, noLBVarInfo, hasNoLBVarInfo ) 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, eqUsage ) +import PrimOp ( PrimOp ) +import NameEnv ( NameEnv, lookupNameEnv ) +import Name ( Name ) import Var ( Id ) -import VarSet ( IdOrTyVarSet ) +import BasicTypes ( OccInfo(..), isFragileOcc, isDeadOcc, seqOccInfo, isLoopBreaker, + InsideLam, insideLam, notInsideLam, + OneBranch, oneBranch, notOneBranch, + Arity, + Activation(..) + ) +import DataCon ( DataCon ) +import ForeignCall ( ForeignCall ) import FieldLabel ( FieldLabel ) -import Demand ( Demand, isStrict, isLazy, wwLazy, pprDemands, seqDemand, seqDemands ) +import Type ( usOnce, usMany ) +import Demand hiding( Demand, seqDemand ) +import qualified Demand +import NewDemand import Outputable -import Maybe ( isJust ) +import Util ( seqList, listLengthCmp ) +import Maybe ( isJust ) +import List ( replicate ) -infixl 1 `setUpdateInfo`, - `setDemandInfo`, - `setStrictnessInfo`, - `setSpecInfo`, +-- infixl so you can say (id `set` a `set` b) +infixl 1 `setSpecInfo`, `setArityInfo`, `setInlinePragInfo`, `setUnfoldingInfo`, - `setCprInfo`, `setWorkerInfo`, + `setLBVarInfo`, + `setOccInfo`, + `setCgInfo`, `setCafInfo`, - `setOccInfo` - -- infixl so you can say (id `set` a `set` b) + `setNewStrictnessInfo`, + `setAllStrictnessInfo`, + `setNewDemandInfo` +#ifdef OLD_STRICTNESS + , `setCprInfo` + , `setDemandInfo` + , `setStrictnessInfo` +#endif +\end{code} + +%************************************************************************ +%* * +\subsection{New strictness info} +%* * +%************************************************************************ + +To be removed later + +\begin{code} +-- setAllStrictnessInfo :: IdInfo -> Maybe StrictSig -> IdInfo +-- Set old and new strictness info +setAllStrictnessInfo info Nothing + = info { newStrictnessInfo = Nothing +#ifdef OLD_STRICTNESS + , strictnessInfo = NoStrictnessInfo + , cprInfo = NoCPRInfo +#endif + } + +setAllStrictnessInfo info (Just sig) + = info { newStrictnessInfo = Just sig +#ifdef OLD_STRICTNESS + , strictnessInfo = oldStrictnessFromNew sig + , cprInfo = cprInfoFromNewStrictness sig +#endif + } + +seqNewStrictnessInfo Nothing = () +seqNewStrictnessInfo (Just ty) = seqStrictSig ty + +#ifdef OLD_STRICTNESS +oldStrictnessFromNew :: StrictSig -> Demand.StrictnessInfo +oldStrictnessFromNew sig = mkStrictnessInfo (map oldDemand dmds, isBotRes res_info) + where + (dmds, res_info) = splitStrictSig sig + +cprInfoFromNewStrictness :: StrictSig -> CprInfo +cprInfoFromNewStrictness sig = case strictSigResInfo sig of + RetCPR -> ReturnsCPR + other -> NoCPRInfo + +newStrictnessFromOld :: Name -> Arity -> Demand.StrictnessInfo -> CprInfo -> StrictSig +newStrictnessFromOld name arity (Demand.StrictnessInfo ds res) cpr + | listLengthCmp ds arity /= GT -- length ds <= arity + -- Sometimes the old strictness analyser has more + -- demands than the arity justifies + = mk_strict_sig name arity $ + mkTopDmdType (map newDemand ds) (newRes res cpr) + +newStrictnessFromOld name arity other cpr + = -- Either no strictness info, or arity is too small + -- In either case we can't say anything useful + mk_strict_sig name arity $ + mkTopDmdType (replicate arity lazyDmd) (newRes False cpr) + +mk_strict_sig name arity dmd_ty + = WARN( arity /= dmdTypeDepth dmd_ty, ppr name <+> (ppr arity $$ ppr dmd_ty) ) + mkStrictSig dmd_ty + +newRes True _ = BotRes +newRes False ReturnsCPR = retCPR +newRes False NoCPRInfo = TopRes + +newDemand :: Demand.Demand -> NewDemand.Demand +newDemand (WwLazy True) = Abs +newDemand (WwLazy False) = lazyDmd +newDemand WwStrict = evalDmd +newDemand (WwUnpack unpk ds) = Eval (Prod (map newDemand ds)) +newDemand WwPrim = lazyDmd +newDemand WwEnum = evalDmd + +oldDemand :: NewDemand.Demand -> Demand.Demand +oldDemand Abs = WwLazy True +oldDemand Top = WwLazy False +oldDemand Bot = WwStrict +oldDemand (Box Bot) = WwStrict +oldDemand (Box Abs) = WwLazy False +oldDemand (Box (Eval _)) = WwStrict -- Pass box only +oldDemand (Defer d) = WwLazy False +oldDemand (Eval (Prod ds)) = WwUnpack True (map oldDemand ds) +oldDemand (Eval (Poly _)) = WwStrict +oldDemand (Call _) = WwStrict + +#endif /* OLD_STRICTNESS */ +\end{code} + + +\begin{code} +seqNewDemandInfo Nothing = () +seqNewDemandInfo (Just dmd) = seqDemand dmd \end{code} + +%************************************************************************ +%* * +\subsection{GlobalIdDetails +%* * +%************************************************************************ + +This type is here (rather than in Id.lhs) mainly because there's +an IdInfo.hi-boot, but no Id.hi-boot, and GlobalIdDetails is imported +(recursively) by Var.lhs. + +\begin{code} +data GlobalIdDetails + = VanillaGlobal -- Imported from elsewhere, a default method Id. + + | RecordSelId FieldLabel -- The Id for a record selector + | 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 + | FCallId ForeignCall -- The Id for a foreign call + + | NotGlobalId -- Used as a convenient extra return value from globalIdDetails + +notGlobalId = NotGlobalId + +instance Outputable GlobalIdDetails where + ppr NotGlobalId = ptext SLIT("[***NotGlobalId***]") + ppr VanillaGlobal = ptext SLIT("[GlobalId]") + ppr (DataConId _) = ptext SLIT("[DataCon]") + ppr (DataConWrapId _) = ptext SLIT("[DataConWrapper]") + ppr (PrimOpId _) = ptext SLIT("[PrimOp]") + ppr (FCallId _) = ptext SLIT("[ForeignCall]") + ppr (RecordSelId _) = ptext SLIT("[RecSel]") +\end{code} + + +%************************************************************************ +%* * +\subsection{The main IdInfo type} +%* * +%************************************************************************ + An @IdInfo@ gives {\em 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. - There is one exception: the 'flavour' is *not* optional. - You must not discard it. - It used to be in Var.lhs, but that seems unclean. - 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. @@ -115,19 +278,28 @@ case. KSW 1999-04). \begin{code} data IdInfo = IdInfo { - flavourInfo :: IdFlavour, -- NOT OPTIONAL - arityInfo :: ArityInfo, -- Its arity - demandInfo :: Demand, -- Whether or not it is definitely demanded + arityInfo :: !ArityInfo, -- Its arity specInfo :: CoreRules, -- Specialisations of this function which exist +#ifdef OLD_STRICTNESS + cprInfo :: CprInfo, -- Function always constructs a product result + demandInfo :: Demand.Demand, -- Whether or not it is definitely demanded strictnessInfo :: StrictnessInfo, -- Strictness properties +#endif 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 + cgInfo :: CgInfo, -- Code generator info (arity, CAF info) lbvarInfo :: LBVarInfo, -- Info about a lambda-bound variable inlinePragInfo :: InlinePragInfo, -- Inline pragma - occInfo :: OccInfo -- How it occurs + occInfo :: OccInfo, -- How it occurs + + newStrictnessInfo :: Maybe StrictSig, -- Reason for Maybe: the DmdAnal phase needs to + -- know whether whether this is the first visit, + -- so it can assign botSig. Other customers want + -- topSig. So Nothing is good. + + newDemandInfo :: Maybe Demand -- Similarly we want to know if there's no + -- known demand yet, for when we are looking for + -- CPR info } seqIdInfo :: IdInfo -> () @@ -135,19 +307,25 @@ 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` - --- seqUnfolding (unfoldingInfo info) `seq` + = seqRules (specInfo info) `seq` + seqWorker (workerInfo info) `seq` + -- Omitting this improves runtimes a little, presumably because -- some unfoldings are not calculated at all +-- seqUnfolding (unfoldingInfo info) `seq` + + seqNewDemandInfo (newDemandInfo info) `seq` + seqNewStrictnessInfo (newStrictnessInfo info) `seq` + +#ifdef OLD_STRICTNESS + Demand.seqDemand (demandInfo info) `seq` + seqStrictnessInfo (strictnessInfo info) `seq` + seqCpr (cprInfo info) `seq` +#endif - seqCaf (cafInfo info) `seq` - seqCpr (cprInfo info) `seq` +-- CgInfo is involved in a loop, so we have to be careful not to seq it +-- too early. +-- seqCg (cgInfo info) `seq` seqLBVar (lbvarInfo info) `seq` seqOccInfo (occInfo info) \end{code} @@ -156,91 +334,75 @@ Setters \begin{code} setWorkerInfo info wk = wk `seq` info { workerInfo = wk } -setSpecInfo info sp = PSEQ sp (info { specInfo = sp }) +setSpecInfo info sp = sp `seq` info { specInfo = sp } setInlinePragInfo info pr = pr `seq` info { inlinePragInfo = pr } setOccInfo info oc = oc `seq` info { occInfo = oc } +#ifdef OLD_STRICTNESS setStrictnessInfo info st = st `seq` info { strictnessInfo = st } +#endif -- Try to avoid spack leaks by seq'ing -setUnfoldingInfo info uf = info { unfoldingInfo = uf } +setUnfoldingInfo info uf + | isEvaldUnfolding uf + -- 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, newDemandInfo = Nothing } + + | 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 } +#ifdef OLD_STRICTNESS setDemandInfo info dd = info { demandInfo = dd } -setArityInfo info ar = info { arityInfo = ar } -setCafInfo info cf = info { cafInfo = cf } setCprInfo info cp = info { cprInfo = cp } -setLBVarInfo info lb = info { lbvarInfo = lb } +#endif + +setArityInfo info ar = info { arityInfo = ar } +setCgInfo info cg = info { cgInfo = cg } -setNoDiscardInfo info = case flavourInfo info of - VanillaId -> info { flavourInfo = NoDiscardId } - other -> info -zapSpecPragInfo info = case flavourInfo info of - SpecPragmaId -> info { flavourInfo = VanillaId } - other -> info +setLBVarInfo info lb = {-lb `seq`-} info { lbvarInfo = lb } +setNewDemandInfo info dd = dd `seq` info { newDemandInfo = dd } +setNewStrictnessInfo info dd = dd `seq` info { newStrictnessInfo = dd } \end{code} \begin{code} vanillaIdInfo :: IdInfo -vanillaIdInfo = mkIdInfo VanillaId - -mkIdInfo :: IdFlavour -> IdInfo -mkIdInfo flv = IdInfo { - flavourInfo = flv, - arityInfo = UnknownArity, - demandInfo = wwLazy, - specInfo = emptyCoreRules, - workerInfo = Nothing, - strictnessInfo = NoStrictnessInfo, - unfoldingInfo = noUnfolding, - updateInfo = NoUpdateInfo, - cafInfo = MayHaveCafRefs, - cprInfo = NoCPRInfo, - lbvarInfo = NoLBVarInfo, - inlinePragInfo = NoInlinePragInfo, - occInfo = NoOccInfo +vanillaIdInfo + = IdInfo { + cgInfo = noCgInfo, + arityInfo = unknownArity, +#ifdef OLD_STRICTNESS + cprInfo = NoCPRInfo, + demandInfo = wwLazy, + strictnessInfo = NoStrictnessInfo, +#endif + specInfo = emptyCoreRules, + workerInfo = NoWorker, + unfoldingInfo = noUnfolding, + lbvarInfo = NoLBVarInfo, + inlinePragInfo = AlwaysActive, + occInfo = NoOccInfo, + newDemandInfo = Nothing, + newStrictnessInfo = Nothing } -\end{code} - -%************************************************************************ -%* * -\subsection{Flavour} -%* * -%************************************************************************ - -\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 - -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]") - -seqFlavour :: IdFlavour -> () -seqFlavour f = f `seq` () +hasCafIdInfo = vanillaIdInfo `setCgInfo` CgInfo MayHaveCafRefs +noCafIdInfo = vanillaIdInfo `setCgInfo` CgInfo NoCafRefs + -- Used for built-in type Ids in MkId. + -- These must have a valid CgInfo set, so you can't + -- use vanillaIdInfo! \end{code} -The @SpecPragmaId@ exists only to make Ids that are -on the *LHS* of bindings created by SPECIALISE pragmas; -eg: s = f Int d -The SpecPragmaId is never itself mentioned; it -exists solely so that the specialiser will find -the call to f, and make specialised version of it. -The SpecPragmaId binding is discarded by the specialiser -when it gathers up overloaded calls. -Meanwhile, it is not discarded as dead code. - %************************************************************************ %* * @@ -253,37 +415,19 @@ of their arities; so it should not be asking... (but other things besides the code-generator need arity info!) \begin{code} -data ArityInfo - = UnknownArity -- No idea - - | ArityExactly Int -- Arity is exactly this. We use this when importing a - -- function; it's already been compiled and we know its - -- arity for sure. - - | ArityAtLeast Int -- Arity is this or greater. We attach this arity to - -- 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. - -seqArity :: ArityInfo -> () -seqArity a = arityLowerBound a `seq` () +type ArityInfo = 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. -exactArity = ArityExactly -atLeastArity = ArityAtLeast -unknownArity = UnknownArity + -- The arity might increase later in the compilation process, if + -- an extra lambda floats up to the binding site. -arityLowerBound :: ArityInfo -> Int -arityLowerBound UnknownArity = 0 -arityLowerBound (ArityAtLeast n) = n -arityLowerBound (ArityExactly n) = n +unknownArity = 0 :: Arity -hasArity :: ArityInfo -> Bool -hasArity UnknownArity = False -hasArity other = True - -ppArityInfo UnknownArity = empty -ppArityInfo (ArityExactly arity) = hsep [ptext SLIT("__A"), int arity] -ppArityInfo (ArityAtLeast arity) = hsep [ptext SLIT("__AL"), int arity] +ppArityInfo 0 = empty +ppArityInfo n = hsep [ptext SLIT("Arity"), int n] \end{code} %************************************************************************ @@ -293,136 +437,15 @@ ppArityInfo (ArityAtLeast arity) = hsep [ptext SLIT("__AL"), int arity] %************************************************************************ \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 - -- The True, Nothing case doesn't need to be recorded - -instance Outputable InlinePragInfo where - -- 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} - - -%************************************************************************ -%* * -\subsection{Occurrence information} -%* * -%************************************************************************ - -\begin{code} -data OccInfo - = NoOccInfo - - | IAmDead -- Marks unused variables. Sometimes useful for - -- lambda and case-bound variables. - - | OneOcc InsideLam - - OneBranch - - | IAmALoopBreaker -- Used by the occurrence analyser to mark loop-breakers - -- in a group of recursive definitions - -seqOccInfo :: OccInfo -> () -seqOccInfo (OneOcc in_lam once) = in_lam `seq` once `seq` () -seqOccInfo occ = () - -type InsideLam = Bool -- True <=> Occurs inside a non-linear lambda - -- Substituting a redex for this occurrence is - -- dangerous because it might duplicate work. -insideLam = True -notInsideLam = False - -type OneBranch = Bool -- True <=> Occurs in only one case branch - -- so no code-duplication issue to worry about -oneBranch = True -notOneBranch = False - -isFragileOccInfo :: OccInfo -> Bool -isFragileOccInfo (OneOcc _ _) = True -isFragileOccInfo other = False -\end{code} - -\begin{code} -instance Outputable OccInfo where - -- only used for debugging; never parsed. KSW 1999-07 - ppr NoOccInfo = empty - ppr IAmALoopBreaker = ptext SLIT("_Kx") - ppr IAmDead = ptext SLIT("_Kd") - ppr (OneOcc inside_lam one_branch) | inside_lam = ptext SLIT("_Kl") - | one_branch = ptext SLIT("_Ks") - | otherwise = ptext SLIT("_Ks*") - -instance Show OccInfo where - showsPrec p occ = showsPrecSDoc p (ppr occ) -\end{code} - -%************************************************************************ -%* * -\subsection[strictness-IdInfo]{Strictness 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). - -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. - -Note that the existence of a worker function is now denoted by the Id's -workerInfo field. - -\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 = () +type InlinePragInfo = Activation + -- 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 CoreSyn Inline Note \end{code} -\begin{code} -mkStrictnessInfo :: ([Demand], Bool) -> StrictnessInfo - -mkStrictnessInfo (xs, is_bot) - | all isLazy xs && not is_bot = NoStrictnessInfo -- Uninteresting - | otherwise = StrictnessInfo xs is_bot - -noStrictnessInfo = NoStrictnessInfo - -isBottomingStrictness (StrictnessInfo _ bot) = bot -isBottomingStrictness NoStrictnessInfo = False - --- appIsBottom returns true if an application to n args would diverge -appIsBottom (StrictnessInfo ds bot) n = bot && (n >= length ds) -appIsBottom NoStrictnessInfo n = False - -ppStrictnessInfo NoStrictnessInfo = empty -ppStrictnessInfo (StrictnessInfo wrapper_args bot) - = hsep [ptext SLIT("__S"), pprDemands wrapper_args bot] -\end{code} %************************************************************************ %* * @@ -432,80 +455,89 @@ ppStrictnessInfo (StrictnessInfo wrapper_args bot) If this Id has a worker then we store a reference to it. Worker functions are generated by the worker/wrapper pass. This uses -information from the strictness and CPR analyses. +information from strictness analysis. There might not be a worker, even for a strict function, because: (a) the function might be small enough to inline, so no need for w/w split (b) the strictness info might be "SSS" or something, so no w/w split. -\begin{code} +Sometimes the arity of a wrapper changes from the original arity from +which it was generated, so we always emit the "original" arity into +the interface file, as part of the worker info. -type WorkerInfo = Maybe Id +How can this happen? Sometimes we get + f = coerce t (\x y -> $wf x y) +at the moment of w/w split; but the eta reducer turns it into + f = coerce t $wf +which is perfectly fine except that the exposed arity so far as +the code generator is concerned (zero) differs from the arity +when we did the split (2). -{- UNUSED: -mkWorkerInfo :: Id -> WorkerInfo -mkWorkerInfo wk_id = Just wk_id --} +All this arises because we use 'arity' to mean "exactly how many +top level lambdas are there" in interface files; but during the +compilation of this module it means "how many things can I apply +this to". -seqWorker :: WorkerInfo -> () -seqWorker (Just id) = id `seq` () -seqWorker Nothing = () +\begin{code} + +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. -ppWorkerInfo Nothing = empty -ppWorkerInfo (Just wk_id) = ptext SLIT("__P") <+> ppr wk_id +seqWorker :: WorkerInfo -> () +seqWorker (HasWorker id a) = id `seq` a `seq` () +seqWorker NoWorker = () -noWorkerInfo = Nothing +ppWorkerInfo NoWorker = empty +ppWorkerInfo (HasWorker wk_id _) = ptext SLIT("__P") <+> ppr wk_id workerExists :: WorkerInfo -> Bool -workerExists = isJust +workerExists NoWorker = False +workerExists (HasWorker _ _) = True + +workerId :: WorkerInfo -> Id +workerId (HasWorker id _) = id + +wrapperArity :: WorkerInfo -> Arity +wrapperArity (HasWorker _ a) = a \end{code} %************************************************************************ %* * -\subsection[update-IdInfo]{Update-analysis info about an @Id@} +\subsection[CG-IdInfo]{Code generator-related information} %* * %************************************************************************ -\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} +CgInfo encapsulates calling-convention information produced by the code +generator. It is pasted into the IdInfo of each emitted Id by CoreTidy, +but only as a thunk --- the information is only actually produced further +downstream, by the code generator. \begin{code} -mkUpdateInfo = SomeUpdateInfo +#ifndef OLD_STRICTNESS +newtype CgInfo = CgInfo CafInfo -- We are back to only having CafRefs in CgInfo +noCgInfo = panic "NoCgInfo!" +#else +data CgInfo = CgInfo CafInfo + | NoCgInfo -- In debug mode we don't want a black hole here + -- See Id.idCgInfo + -- noCgInfo is used for local Ids, which shouldn't need any CgInfo +noCgInfo = NoCgInfo +#endif -updateInfoMaybe NoUpdateInfo = Nothing -updateInfoMaybe (SomeUpdateInfo []) = Nothing -updateInfoMaybe (SomeUpdateInfo u) = Just u -\end{code} +cgCafInfo (CgInfo caf_info) = caf_info -Text instance so that the update annotations can be read in. +setCafInfo info caf_info = info `setCgInfo` CgInfo caf_info -\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} +seqCg c = c `seq` () -- fields are strict anyhow -%************************************************************************ -%* * -\subsection[CAF-IdInfo]{CAF-related information} -%* * -%************************************************************************ +vanillaCgInfo = CgInfo MayHaveCafRefs -- Definitely safe -This information is used to build Static Reference Tables (see -simplStg/ComputeSRT.lhs). +-- CafInfo is used to build Static Reference Tables (see simplStg/SRT.lhs). -\begin{code} data CafInfo = MayHaveCafRefs -- either: -- (1) A function or static constructor @@ -515,16 +547,29 @@ data CafInfo | NoCafRefs -- A function or static constructor -- that refers to no CAFs. --- LATER: not sure how easy this is... --- | OneCafRef Id - +mayHaveCafRefs MayHaveCafRefs = True +mayHaveCafRefs _ = False seqCaf c = c `seq` () +pprCgInfo (CgInfo caf_info) = ppCafInfo caf_info + +ppArity 0 = empty +ppArity n = hsep [ptext SLIT("__A"), int n] + ppCafInfo NoCafRefs = ptext SLIT("__C") ppCafInfo MayHaveCafRefs = empty \end{code} +\begin{code} +type CgInfoEnv = NameEnv CgInfo + +lookupCgInfo :: NameEnv CgInfo -> Name -> CgInfo +lookupCgInfo env n = case lookupNameEnv env n of + Just info -> info + Nothing -> pprTrace "Urk! Not in CgInfo env" (ppr n) vanillaCgInfo +\end{code} + %************************************************************************ %* * @@ -551,49 +596,33 @@ function has the CPR property and which components of the result are also CPRs. \begin{code} +#ifdef OLD_STRICTNESS data CprInfo = NoCPRInfo + | 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 - | CPRInfo [CprInfo] - --- e.g. const 5 == CPRInfo [NoCPRInfo] --- == __M(-) --- \x -> (5, --- (x, --- 5, --- x) --- ) --- CPRInfo [CPRInfo [NoCPRInfo], --- CPRInfo [NoCprInfo, --- CPRInfo [NoCPRInfo], --- NoCPRInfo] --- ] --- __M((-)(-(-)-)-) -\end{code} + -- We used to keep nested info about sub-components, but + -- we never used it so I threw it away -\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 instance Show CprInfo where showsPrec p c = showsPrecSDoc p (ppr c) +#endif \end{code} @@ -616,8 +645,10 @@ work. 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. @@ -626,14 +657,18 @@ seqLBVar l = l `seq` () \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 `eqUsage` usOnce + = ptext SLIT("OneShot") + | otherwise + = empty instance Outputable LBVarInfo where ppr = pprLBVarInfo @@ -649,75 +684,35 @@ instance Show LBVarInfo where %* * %************************************************************************ -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 \begin{code} zapLamInfo :: IdInfo -> Maybe IdInfo -zapLamInfo info@(IdInfo {occInfo = occ, demandInfo = demand}) - | is_safe_occ && not (isStrict demand) +zapLamInfo info@(IdInfo {occInfo = occ, newDemandInfo = demand}) + | is_safe_occ occ && is_safe_dmd demand = Nothing | otherwise - = Just (info {occInfo = safe_occ, - demandInfo = wwLazy}) + = Just (info {occInfo = safe_occ, newDemandInfo = Nothing}) 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 + is_safe_occ (OneOcc in_lam once) = in_lam + is_safe_occ other = True safe_occ = case occ of OneOcc _ once -> OneOcc insideLam once other -> occ + + is_safe_dmd Nothing = True + is_safe_dmd (Just dmd) = not (isStrictDmd dmd) +\end{code} + +\begin{code} +zapDemandInfo :: IdInfo -> Maybe IdInfo +zapDemandInfo info@(IdInfo {newDemandInfo = dmd}) + | isJust dmd = Just (info {newDemandInfo = Nothing}) + | otherwise = Nothing \end{code} @@ -727,26 +722,63 @@ copyIdInfo is used when shorting out a top-level binding 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 { newStrictnessInfo = newStrictnessInfo f_local, +#ifdef OLD_STRICTNESS + strictnessInfo = strictnessInfo f_local, + cprInfo = cprInfo f_local, +#endif + workerInfo = workerInfo 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}