X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FbasicTypes%2FIdInfo.lhs;h=d2be7f9a923b2c31988edff6d7c3fe9edc6982f6;hb=e4fd736410f1f62c7a176e35a78751112390cd63;hp=0a9ef0e9dde9a4df986856ba9bfefb7569f8999e;hpb=bfaf6cc0f7e0e51dc6ac70ca62edde3fb4c69631;p=ghc-hetmet.git diff --git a/ghc/compiler/basicTypes/IdInfo.lhs b/ghc/compiler/basicTypes/IdInfo.lhs index 0a9ef0e..d2be7f9 100644 --- a/ghc/compiler/basicTypes/IdInfo.lhs +++ b/ghc/compiler/basicTypes/IdInfo.lhs @@ -1,5 +1,5 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1993-1996 +% (c) The GRASP/AQUA Project, Glasgow University, 1993-1998 % \section[IdInfo]{@IdInfos@: Non-essential information about @Ids@} @@ -7,81 +7,218 @@ Haskell. [WDP 94/11]) \begin{code} -#include "HsVersions.h" - module IdInfo ( - IdInfo, -- Abstract - - noIdInfo, - ppIdInfo, - applySubstToIdInfo, apply_to_IdInfo, -- not for general use, please + GlobalIdDetails(..), notGlobalId, -- Not abstract - ArityInfo(..), - exactArity, atLeastArity, unknownArity, - arityInfo, addArityInfo, ppArityInfo, - - DemandInfo, - noDemandInfo, mkDemandInfo, demandInfo, ppDemandInfo, addDemandInfo, willBeDemanded, - - StrictnessInfo(..), -- Non-abstract - Demand(..), NewOrData, -- Non-abstract - - getWorkerId_maybe, - workerExists, - mkStrictnessInfo, mkBottomStrictnessInfo, noStrictnessInfo, bottomIsGuaranteed, - strictnessInfo, ppStrictnessInfo, addStrictnessInfo, + IdInfo, -- Abstract + vanillaIdInfo, noCafNoTyGenIdInfo, + seqIdInfo, megaSeqIdInfo, + + -- Zapping + zapLamInfo, zapDemandInfo, + shortableIdInfo, copyIdInfo, + + -- Arity + ArityInfo, + exactArity, unknownArity, hasArity, + arityInfo, setArityInfo, ppArityInfo, arityLowerBound, + + -- New demand and strictness info + newStrictnessInfo, setNewStrictnessInfo, mkNewStrictnessInfo, + newDemandInfo, setNewDemandInfo, newDemand, oldDemand, + + -- Strictness; imported from Demand + StrictnessInfo(..), + mkStrictnessInfo, noStrictnessInfo, + ppStrictnessInfo,isBottomingStrictness, + strictnessInfo, setStrictnessInfo, + + -- Usage generalisation + TyGenInfo(..), + tyGenInfo, setTyGenInfo, + noTyGenInfo, isNoTyGenInfo, ppTyGenInfo, tyGenInfoString, + + -- Worker + WorkerInfo(..), workerExists, wrapperArity, workerId, + workerInfo, setWorkerInfo, ppWorkerInfo, + + -- Unfolding + unfoldingInfo, setUnfoldingInfo, + + -- DemandInfo + demandInfo, setDemandInfo, + + -- Inline prags + InlinePragInfo(..), + inlinePragInfo, setInlinePragInfo, pprInlinePragInfo, + isNeverInlinePrag, neverInlinePrag, + + -- Occurrence info + OccInfo(..), isFragileOcc, isDeadOcc, isLoopBreaker, + InsideLam, OneBranch, insideLam, notInsideLam, oneBranch, notOneBranch, + occInfo, setOccInfo, + + -- Specialisation + specInfo, setSpecInfo, + + -- CG info + CgInfo(..), cgInfo, setCgInfo, cgMayHaveCafRefs, pprCgInfo, + cgArity, cgCafInfo, vanillaCgInfo, + CgInfoEnv, lookupCgInfo, + setCgArity, + + -- CAF info + CafInfo(..), ppCafInfo, setCafInfo, mayHaveCafRefs, + + -- Constructed Product Result Info + CprInfo(..), cprInfo, setCprInfo, ppCprInfo, noCprInfo, + + -- Lambda-bound variable info + LBVarInfo(..), lbvarInfo, setLBVarInfo, noLBVarInfo, hasNoLBVarInfo + ) where - unfoldInfo, addUnfoldInfo, +#include "HsVersions.h" - specInfo, addSpecInfo, - UpdateInfo, SYN_IE(UpdateSpec), - mkUpdateInfo, updateInfo, updateInfoMaybe, ppUpdateInfo, addUpdateInfo, +import CoreSyn +import Type ( Type, usOnce, eqUsage ) +import PrimOp ( PrimOp ) +import NameEnv ( NameEnv, lookupNameEnv ) +import Name ( Name ) +import Var ( Id ) +import BasicTypes ( OccInfo(..), isFragileOcc, isDeadOcc, seqOccInfo, isLoopBreaker, + InsideLam, insideLam, notInsideLam, + OneBranch, oneBranch, notOneBranch, + Arity + ) +import DataCon ( DataCon ) +import ForeignCall ( ForeignCall ) +import FieldLabel ( FieldLabel ) +import Type ( usOnce, usMany ) +import Demand hiding( Demand ) +import qualified Demand +import NewDemand ( Demand(..), Keepity(..), DmdResult(..), + lazyDmd, topDmd, dmdTypeDepth, isStrictDmd, + StrictSig, mkStrictSig, mkTopDmdType + ) +import Outputable +import Util ( seqList ) +import List ( replicate ) + +infixl 1 `setDemandInfo`, + `setTyGenInfo`, + `setStrictnessInfo`, + `setSpecInfo`, + `setArityInfo`, + `setInlinePragInfo`, + `setUnfoldingInfo`, + `setCprInfo`, + `setWorkerInfo`, + `setLBVarInfo`, + `setOccInfo`, + `setCgInfo`, + `setCafInfo`, + `setCgArity`, + `setNewStrictnessInfo`, + `setNewDemandInfo` + -- infixl so you can say (id `set` a `set` b) +\end{code} - DeforestInfo(..), - deforestInfo, ppDeforestInfo, addDeforestInfo, +%************************************************************************ +%* * +\subsection{New strictness info} +%* * +%************************************************************************ - ArgUsageInfo, ArgUsage(..), SYN_IE(ArgUsageType), - mkArgUsageInfo, argUsageInfo, addArgUsageInfo, getArgUsage, +To be removed later - FBTypeInfo, FBType(..), FBConsum(..), FBProd(..), - fbTypeInfo, ppFBTypeInfo, addFBTypeInfo, mkFBTypeInfo, getFBType - ) where +\begin{code} +mkNewStrictnessInfo :: Id -> Arity -> Demand.StrictnessInfo -> CprInfo -> StrictSig +mkNewStrictnessInfo id arity (Demand.StrictnessInfo ds res) cpr + | length ds <= arity + -- Sometimes the old strictness analyser has more + -- demands than the arity justifies + = mk_strict_sig id arity $ + mkTopDmdType (map newDemand ds) (newRes res cpr) + +mkNewStrictnessInfo id arity other cpr + = -- Either no strictness info, or arity is too small + -- In either case we can't say anything useful + mk_strict_sig id arity $ + mkTopDmdType (replicate arity lazyDmd) (newRes False cpr) + +mk_strict_sig id arity dmd_ty + = WARN( arity /= dmdTypeDepth dmd_ty, ppr id <+> (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) = Lazy +newDemand WwStrict = Eval +newDemand (WwUnpack unpk ds) = Seq Drop (map newDemand ds) +newDemand WwPrim = Lazy +newDemand WwEnum = Eval + +oldDemand :: NewDemand.Demand -> Demand.Demand +oldDemand Abs = WwLazy True +oldDemand Lazy = WwLazy False +oldDemand Bot = WwStrict +oldDemand Err = WwStrict +oldDemand Eval = WwStrict +oldDemand (Seq _ ds) = WwUnpack True (map oldDemand ds) +oldDemand (Call _) = WwStrict +\end{code} -IMP_Ubiq() -IMPORT_1_3(Char(toLower)) -#if defined(__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ <= 201 -IMPORT_DELOOPER(IdLoop) -- IdInfo is a dependency-loop ranch, and - -- we break those loops by using IdLoop and - -- *not* importing much of anything else, - -- except from the very general "utils". -#else -import {-# SOURCE #-} SpecEnv -import {-# SOURCE #-} Id -import {-# SOURCE #-} CoreUnfold -import {-# SOURCE #-} StdIdInfo -#endif +%************************************************************************ +%* * +\subsection{GlobalIdDetails +%* * +%************************************************************************ -import Type ( eqSimpleTy, splitFunTyExpandingDicts ) -import BasicTypes ( NewOrData ) -import CmdLineOpts ( opt_OmitInterfacePragmas ) +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. -import Demand -import Maybes ( firstJust ) -import Outputable ( ifaceStyle, PprStyle(..), Outputable(..){-instances-} ) -import Pretty -import PprType () -import Unique ( pprUnique ) -import Util ( mapAccumL, panic, assertPanic, pprPanic ) +\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} -#ifdef REALLY_HASKELL_1_3 -ord = fromEnum :: Char -> Int -#endif -applySubstToTy = panic "IdInfo.applySubstToTy" -showTypeCategory = panic "IdInfo.showTypeCategory" -\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 @@ -93,476 +230,616 @@ the properties attached to the other. The @IdInfo@ gives information about the value, or definition, of the @Id@. It does {\em not} contain information about the @Id@'s usage -(except for @DemandInfo@? ToDo). +(except for @DemandInfo@? ToDo). (@lbvarInfo@ is also a marginal +case. KSW 1999-04). \begin{code} data IdInfo - = IdInfo - ArityInfo -- Its arity - - DemandInfo -- Whether or not it is definitely - -- demanded - - SpecEnv - -- Specialisations of this function which exist - - (StrictnessInfo Id) - -- Strictness properties, notably - -- how to conjure up "worker" functions - - Unfolding - -- Its unfolding; for locally-defined - -- things, this can *only* be NoUnfolding - - UpdateInfo -- Which args should be updated - - DeforestInfo -- Whether its definition should be - -- unfolded during deforestation - - ArgUsageInfo -- how this Id uses its arguments - - FBTypeInfo -- the Foldr/Build W/W property of this function. + = IdInfo { + arityInfo :: ArityInfo, -- Its arity + demandInfo :: Demand.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 + cgInfo :: CgInfo, -- Code generator info (arity, CAF info) + cprInfo :: CprInfo, -- Function always constructs a product result + lbvarInfo :: LBVarInfo, -- Info about a lambda-bound variable + inlinePragInfo :: InlinePragInfo, -- Inline pragma + occInfo :: OccInfo, -- How it occurs + + newStrictnessInfo :: Maybe StrictSig, + newDemandInfo :: Demand + } + +seqIdInfo :: IdInfo -> () +seqIdInfo (IdInfo {}) = () + +megaSeqIdInfo :: IdInfo -> () +megaSeqIdInfo info + = 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 +-- some unfoldings are not calculated at all + +-- CgInfo is involved in a loop, so we have to be careful not to seq it +-- too early. +-- seqCg (cgInfo info) `seq` + seqCpr (cprInfo info) `seq` + seqLBVar (lbvarInfo info) `seq` + seqOccInfo (occInfo info) \end{code} -\begin{code} -noIdInfo = IdInfo UnknownArity UnknownDemand nullSpecEnv NoStrictnessInfo noUnfolding - NoUpdateInfo Don'tDeforest NoArgUsageInfo NoFBTypeInfo -\end{code} +Setters -Simply turgid. But BE CAREFUL: don't @apply_to_Id@ if that @Id@ -will in turn @apply_to_IdInfo@ of the self-same @IdInfo@. (A very -nasty loop, friends...) \begin{code} -apply_to_IdInfo ty_fn idinfo@(IdInfo arity demand spec strictness unfold - update deforest arg_usage fb_ww) - | isNullSpecEnv spec - = idinfo +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 } + -- Try to avoid spack leaks by seq'ing + +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 = Lazy } + | otherwise - = panic "IdInfo:apply_to_IdInfo" -{- LATER: - let - new_spec = apply_spec spec - - -- NOT a good idea: - -- apply_strict strictness `thenLft` \ new_strict -> - -- apply_wrap wrap `thenLft` \ new_wrap -> - in - IdInfo arity demand new_spec strictness unfold - update deforest arg_usage fb_ww - where - apply_spec (SpecEnv is) - = SpecEnv (map do_one is) - where - do_one (SpecInfo ty_maybes ds spec_id) - = --apply_to_Id ty_fn spec_id `thenLft` \ new_spec_id -> - SpecInfo (map apply_to_maybe ty_maybes) ds spec_id - where - apply_to_maybe Nothing = Nothing - apply_to_maybe (Just ty) = Just (ty_fn ty) --} - -{- NOT a good idea; - apply_strict info@NoStrictnessInfo = returnLft info - apply_strict BottomGuaranteed = ??? - apply_strict (StrictnessInfo wrap_arg_info id_maybe) - = (case id_maybe of - Nothing -> returnLft Nothing - Just xx -> applySubstToId subst xx `thenLft` \ new_xx -> - returnLft (Just new_xx) - ) `thenLft` \ new_id_maybe -> - returnLft (StrictnessInfo wrap_arg_info new_id_maybe) --} + -- We do *not* seq on the unfolding info, For some reason, doing so + -- actually increases residency significantly. + = info { unfoldingInfo = uf } + +setDemandInfo info dd = info { demandInfo = dd } +setArityInfo info ar = info { arityInfo = Just ar } +setCgInfo info cg = info { cgInfo = cg } +setCprInfo info cp = info { cprInfo = cp } +setLBVarInfo info lb = info { lbvarInfo = lb } + +setNewDemandInfo info dd = info { newDemandInfo = dd } +setNewStrictnessInfo info dd = info { newStrictnessInfo = dd } \end{code} -Variant of the same thing for the typechecker. -\begin{code} -applySubstToIdInfo s0 (IdInfo arity demand spec strictness unfold - update deforest arg_usage fb_ww) - = panic "IdInfo:applySubstToIdInfo" -{- LATER: - case (apply_spec s0 spec) of { (s1, new_spec) -> - (s1, IdInfo arity demand new_spec strictness unfold update deforest arg_usage fb_ww) } - where - apply_spec s0 (SpecEnv is) - = case (mapAccumL do_one s0 is) of { (s1, new_is) -> - (s1, SpecEnv new_is) } - where - do_one s0 (SpecInfo ty_maybes ds spec_id) - = case (mapAccumL apply_to_maybe s0 ty_maybes) of { (s1, new_maybes) -> - (s1, SpecInfo new_maybes ds spec_id) } - where - apply_to_maybe s0 Nothing = (s0, Nothing) - apply_to_maybe s0 (Just ty) - = case (applySubstToTy s0 ty) of { (s1, new_ty) -> - (s1, Just new_ty) } --} -\end{code} \begin{code} -ppIdInfo :: PprStyle - -> Bool -- True <=> print specialisations, please - -> IdInfo - -> Doc - -ppIdInfo sty specs_please - (IdInfo arity demand specenv strictness unfold update deforest arg_usage fbtype) - = hsep [ - -- order is important!: - ppArityInfo sty arity, - ppUpdateInfo sty update, - ppDeforestInfo sty deforest, - - ppStrictnessInfo sty strictness, - - if specs_please - then empty -- ToDo -- sty (not (isDataCon for_this_id)) - -- better_id_fn inline_env (mEnvToList specenv) - else empty, - - -- DemandInfo needn't be printed since it has no effect on interfaces - ppDemandInfo sty demand, - ppFBTypeInfo sty fbtype - ] +vanillaIdInfo :: IdInfo +vanillaIdInfo + = IdInfo { + cgInfo = noCgInfo, + arityInfo = unknownArity, + demandInfo = wwLazy, + specInfo = emptyCoreRules, + tyGenInfo = noTyGenInfo, + workerInfo = NoWorker, + strictnessInfo = NoStrictnessInfo, + unfoldingInfo = noUnfolding, + cprInfo = NoCPRInfo, + lbvarInfo = NoLBVarInfo, + inlinePragInfo = NoInlinePragInfo, + occInfo = NoOccInfo, + newDemandInfo = topDmd, + newStrictnessInfo = Nothing + } + +noCafNoTyGenIdInfo = vanillaIdInfo `setTyGenInfo` TyGenNever + `setCgInfo` (CgInfo 0 NoCafRefs) + -- Used for built-in type Ids in MkId. + -- Many built-in things have fixed types, so we shouldn't + -- run around generalising them \end{code} + %************************************************************************ %* * \subsection[arity-IdInfo]{Arity info about an @Id@} %* * %************************************************************************ -\begin{code} -data ArityInfo - = UnknownArity -- No idea - | ArityExactly Int -- Arity is exactly this - | ArityAtLeast Int -- Arity is this or greater -\end{code} +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!) \begin{code} -exactArity = ArityExactly -atLeastArity = ArityAtLeast -unknownArity = UnknownArity +type ArityInfo = Maybe 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. + + -- The 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` () -arityInfo (IdInfo arity _ _ _ _ _ _ _ _) = arity +exactArity = Just +unknownArity = Nothing -addArityInfo (IdInfo _ a c d e f g h i) arity = IdInfo arity a c d e f g h i +arityLowerBound :: ArityInfo -> Arity +arityLowerBound Nothing = 0 +arityLowerBound (Just n) = n -ppArityInfo sty UnknownArity = empty -ppArityInfo sty (ArityExactly arity) = hsep [ptext SLIT("_A_"), int arity] -ppArityInfo sty (ArityAtLeast arity) = hsep [ptext SLIT("_A>_"), int arity] +hasArity :: ArityInfo -> Bool +hasArity Nothing = False +hasArity other = True + +ppArityInfo Nothing = empty +ppArityInfo (Just arity) = hsep [ptext SLIT("Arity"), int arity] \end{code} %************************************************************************ %* * -\subsection[demand-IdInfo]{Demand info about an @Id@} +\subsection{Inline-pragma information} %* * %************************************************************************ -Whether a value is certain to be demanded or not. (This is the -information that is computed by the ``front-end'' of the strictness -analyser.) - -This information is only used within a module, it is not exported -(obviously). - \begin{code} -data DemandInfo - = UnknownDemand - | DemandedAsPer Demand +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 + + -- SEE COMMENTS WITH CoreUnfold.blackListed on the + -- exact significance of the IMustNotBeINLINEd pragma + +isNeverInlinePrag :: InlinePragInfo -> Bool +isNeverInlinePrag (IMustNotBeINLINEd _ Nothing) = True +isNeverInlinePrag other = False + +neverInlinePrag :: InlinePragInfo +neverInlinePrag = IMustNotBeINLINEd True{-should be False? --SDM -} Nothing + +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} -\begin{code} -noDemandInfo = UnknownDemand -mkDemandInfo :: Demand -> DemandInfo -mkDemandInfo demand = DemandedAsPer demand +%************************************************************************ +%* * +\subsection[TyGen-IdInfo]{Type generalisation info about an @Id@} +%* * +%************************************************************************ -willBeDemanded :: DemandInfo -> Bool -willBeDemanded (DemandedAsPer demand) = isStrict demand -willBeDemanded _ = False -\end{code} +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} -demandInfo (IdInfo _ demand _ _ _ _ _ _ _) = demand +data TyGenInfo + = NoTyGenInfo -- no restriction on type generalisation -addDemandInfo (IdInfo a _ c d e f g h i) demand = IdInfo a demand c d e f g h i + | TyGenUInfo [Maybe Type] -- restrict generalisation of this Id to + -- preserve specified usage annotations -ppDemandInfo PprInterface _ = empty -ppDemandInfo sty UnknownDemand = text "{-# L #-}" -ppDemandInfo sty (DemandedAsPer info) = hsep [text "{-#", text (showList [info] ""), text "#-}"] + | TyGenNever -- never generalise the type of this Id \end{code} -%************************************************************************ -%* * -\subsection[specialisation-IdInfo]{Specialisation info about an @Id@} -%* * -%************************************************************************ - -See SpecEnv.lhs +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} -specInfo (IdInfo _ _ spec _ _ _ _ _ _) = spec - -addSpecInfo id_info spec | isNullSpecEnv spec = id_info -addSpecInfo (IdInfo a b _ d e f g h i) spec = IdInfo a b spec d e f g h i +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 `eqUsage` usOnce = '1' -- chars with identity + | u `eqUsage` 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[strictness-IdInfo]{Strictness info about an @Id@} +\subsection[worker-IdInfo]{Worker 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; (b)~the {\em existence} of a ``worker'' -version of the function; and (c)~the type signature of that worker (if -it exists); i.e. its calling convention. +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. -\begin{code} -data StrictnessInfo bdee - = NoStrictnessInfo - - | BottomGuaranteed -- This Id guarantees never to return; - -- it is bottom regardless of its arguments. - -- Useful for "error" and other disguised - -- variants thereof. - - | StrictnessInfo [Demand] -- The main stuff; see below. - (Maybe (bdee,[bdee])) -- Worker's Id, if applicable, and a list of the constructors - -- mentioned by the wrapper. This is necessary so that the - -- renamer can slurp them in. Without this info, the renamer doesn't - -- know which data types to slurp in concretely. Remember, for - -- strict things we don't put the unfolding in the interface file, to save space. - -- This constructor list allows the renamer to behave much as if the - -- unfolding *was* in the interface file. - -- - -- This field might be Nothing even for a strict fn because the strictness info - -- might say just "SSS" or something; so there's no w/w split. -\end{code} - -\begin{code} -mkStrictnessInfo :: [Demand] -> Maybe (bdee,[bdee]) -> StrictnessInfo bdee +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. -mkStrictnessInfo xs wrkr - | all is_lazy xs = NoStrictnessInfo -- Uninteresting - | otherwise = StrictnessInfo xs wrkr - where - is_lazy (WwLazy False) = True -- NB "Absent" args do *not* count! - is_lazy _ = False -- (as they imply a worker) +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. -noStrictnessInfo = NoStrictnessInfo -mkBottomStrictnessInfo = BottomGuaranteed +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). -bottomIsGuaranteed BottomGuaranteed = True -bottomIsGuaranteed other = False +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". -strictnessInfo (IdInfo _ _ _ strict _ _ _ _ _) = strict +\begin{code} -addStrictnessInfo id_info NoStrictnessInfo = id_info -addStrictnessInfo (IdInfo a b d _ e f g h i) strict = IdInfo a b d strict e f g h i +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. -ppStrictnessInfo sty NoStrictnessInfo = empty -ppStrictnessInfo sty BottomGuaranteed = ptext SLIT("_bot_") +seqWorker :: WorkerInfo -> () +seqWorker (HasWorker id _) = id `seq` () +seqWorker NoWorker = () -ppStrictnessInfo sty (StrictnessInfo wrapper_args wrkr_maybe) - = hsep [ptext SLIT("_S_"), text (showList wrapper_args ""), pp_wrkr] - where - pp_wrkr = case wrkr_maybe of - Nothing -> empty - Just (wrkr,cons) | ifaceStyle sty && - not (null cons) -> pprId sty wrkr <+> braces (hsep (map (pprId sty) cons)) - | otherwise -> pprId sty wrkr -\end{code} +ppWorkerInfo NoWorker = empty +ppWorkerInfo (HasWorker wk_id _) = ptext SLIT("__P") <+> ppr wk_id +workerExists :: WorkerInfo -> Bool +workerExists NoWorker = False +workerExists (HasWorker _ _) = True -\begin{code} -workerExists :: StrictnessInfo bdee -> Bool -workerExists (StrictnessInfo _ (Just worker_id)) = True -workerExists other = False +workerId :: WorkerInfo -> Id +workerId (HasWorker id _) = id -getWorkerId_maybe :: StrictnessInfo bdee -> Maybe bdee -getWorkerId_maybe (StrictnessInfo _ (Just (wrkr,_))) = Just wrkr -getWorkerId_maybe other = Nothing +wrapperArity :: WorkerInfo -> Arity +wrapperArity (HasWorker _ a) = a \end{code} %************************************************************************ %* * -\subsection[unfolding-IdInfo]{Unfolding info about an @Id@} +\subsection[CG-IdInfo]{Code generator-related information} %* * %************************************************************************ +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} -unfoldInfo (IdInfo _ _ _ _ unfolding _ _ _ _) = unfolding +data CgInfo = CgInfo + !Arity -- Exact arity for calling purposes + !CafInfo +#ifdef DEBUG + | 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 +#else +noCgInfo = panic "NoCgInfo!" +#endif -addUnfoldInfo (IdInfo a b d e _ f g h i) uf = IdInfo a b d e uf f g h i -\end{code} +cgArity (CgInfo arity _) = arity +cgCafInfo (CgInfo _ caf_info) = caf_info -%************************************************************************ -%* * -\subsection[update-IdInfo]{Update-analysis info about an @Id@} -%* * -%************************************************************************ +setCafInfo info caf_info = + case cgInfo info of { CgInfo arity _ -> + info `setCgInfo` CgInfo arity caf_info } -\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} +setCgArity info arity = + case cgInfo info of { CgInfo _ caf_info -> + info `setCgInfo` CgInfo arity caf_info } -\begin{code} -mkUpdateInfo = SomeUpdateInfo +cgMayHaveCafRefs (CgInfo _ caf_info) = mayHaveCafRefs caf_info -updateInfoMaybe NoUpdateInfo = Nothing -updateInfoMaybe (SomeUpdateInfo []) = Nothing -updateInfoMaybe (SomeUpdateInfo u) = Just u -\end{code} +seqCg c = c `seq` () -- fields are strict anyhow -Text instance so that the update annotations can be read in. +vanillaCgInfo = CgInfo 0 MayHaveCafRefs -- Definitely safe -\begin{code} -#ifdef REALLY_HASKELL_1_3 -instance Read UpdateInfo where -#else -instance Text UpdateInfo where -#endif - readsPrec p s | null s = panic "IdInfo: empty update pragma?!" - | otherwise = [(SomeUpdateInfo (map ok_digit s),"")] - where - ok_digit c | c >= '0' && c <= '2' = ord c - ord '0' - | otherwise = panic "IdInfo: not a digit while reading update pragma" +-- CafInfo is used to build Static Reference Tables (see simplStg/SRT.lhs). -updateInfo (IdInfo _ _ _ _ _ update _ _ _) = update +data CafInfo + = MayHaveCafRefs -- either: + -- (1) A function or static constructor + -- that refers to one or more CAFs, + -- (2) A real live CAF -addUpdateInfo id_info NoUpdateInfo = id_info -addUpdateInfo (IdInfo a b d e f _ g h i) upd_info = IdInfo a b d e f upd_info g h i + | NoCafRefs -- A function or static constructor + -- that refers to no CAFs. -ppUpdateInfo sty NoUpdateInfo = empty -ppUpdateInfo sty (SomeUpdateInfo []) = empty -ppUpdateInfo sty (SomeUpdateInfo spec) = (<>) (ptext SLIT("_U_ ")) (hcat (map int spec)) -\end{code} +mayHaveCafRefs MayHaveCafRefs = True +mayHaveCafRefs _ = False -%************************************************************************ -%* * -\subsection[deforest-IdInfo]{Deforestation info about an @Id@} -%* * -%************************************************************************ +seqCaf c = c `seq` () -The deforest info says whether this Id is to be unfolded during -deforestation. Therefore, when the deforest pragma is true, we must -also have the unfolding information available for this Id. +pprCgInfo (CgInfo arity caf_info) = ppArity arity <+> ppCafInfo caf_info -\begin{code} -data DeforestInfo - = Don'tDeforest -- just a bool, might extend this - | DoDeforest -- later. - -- deriving (Eq, Ord) +ppArity 0 = empty +ppArity n = hsep [ptext SLIT("__A"), int n] + +ppCafInfo NoCafRefs = ptext SLIT("__C") +ppCafInfo MayHaveCafRefs = empty \end{code} \begin{code} -deforestInfo (IdInfo _ _ _ _ _ _ deforest _ _) = deforest - -addDeforestInfo id_info Don'tDeforest = id_info -addDeforestInfo (IdInfo a b d e f g _ h i) deforest = IdInfo a b d e f g deforest h i +type CgInfoEnv = NameEnv CgInfo -ppDeforestInfo sty Don'tDeforest = empty -ppDeforestInfo sty DoDeforest = ptext SLIT("_DEFOREST_") +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} + %************************************************************************ %* * -\subsection[argUsage-IdInfo]{Argument Usage info about an @Id@} +\subsection[cpr-IdInfo]{Constructed Product Result info about an @Id@} %* * %************************************************************************ -\begin{code} -data ArgUsageInfo - = NoArgUsageInfo - | SomeArgUsageInfo ArgUsageType - -- ??? deriving (Eq, Ord) - -data ArgUsage = ArgUsage Int -- number of arguments (is linear!) - | UnknownArgUsage -type ArgUsageType = [ArgUsage] -- c_1 -> ... -> BLOB -\end{code} +If the @Id@ is a function then it may have CPR info. A CPR analysis +phase detects whether: -\begin{code} -mkArgUsageInfo [] = NoArgUsageInfo -mkArgUsageInfo au = SomeArgUsageInfo au +\begin{enumerate} +\item +The function's return value has a product type, i.e. an algebraic type +with a single constructor. Examples of such types are tuples and boxed +primitive values. +\item +The function always 'constructs' the value that it is returning. It +must do this on every path through, and it's OK if it calls another +function which constructs the result. +\end{enumerate} -getArgUsage :: ArgUsageInfo -> ArgUsageType -getArgUsage NoArgUsageInfo = [] -getArgUsage (SomeArgUsageInfo u) = u +If this is the case then we store a template which tells us the +function has the CPR property and which components of the result are +also CPRs. + +\begin{code} +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 + + -- We used to keep nested info about sub-components, but + -- we never used it so I threw it away \end{code} \begin{code} -argUsageInfo (IdInfo _ _ _ _ _ _ _ au _) = au +seqCpr :: CprInfo -> () +seqCpr ReturnsCPR = () +seqCpr NoCPRInfo = () -addArgUsageInfo id_info NoArgUsageInfo = id_info -addArgUsageInfo (IdInfo a b d e f g h _ i) au_info = IdInfo a b d e f g h au_info i +noCprInfo = NoCPRInfo -ppArgUsageInfo sty NoArgUsageInfo = empty -ppArgUsageInfo sty (SomeArgUsageInfo aut) = (<>) (ptext SLIT("_L_ ")) (ppArgUsageType aut) +ppCprInfo NoCPRInfo = empty +ppCprInfo ReturnsCPR = ptext SLIT("__M") -ppArgUsage (ArgUsage n) = int n -ppArgUsage (UnknownArgUsage) = char '-' +instance Outputable CprInfo where + ppr = ppCprInfo -ppArgUsageType aut = hcat - [ char '"' , - hcat (punctuate comma (map ppArgUsage aut)), - char '"' ] +instance Show CprInfo where + showsPrec p c = showsPrecSDoc p (ppr c) \end{code} + %************************************************************************ %* * -\subsection[FBType-IdInfo]{Type of an expression through Foldr/build's eyes} +\subsection[lbvar-IdInfo]{Lambda-bound var info about an @Id@} %* * %************************************************************************ -\begin{code} -data FBTypeInfo - = NoFBTypeInfo - | SomeFBTypeInfo FBType +If the @Id@ is a lambda-bound variable then it may have lambda-bound +var info. The usage analysis (UsageSP) detects whether the lambda +binding this var is a ``one-shot'' lambda; that is, whether it is +applied at most once. -data FBType = FBType [FBConsum] FBProd deriving (Eq) +This information may be useful in optimisation, as computations may +safely be floated inside such a lambda without risk of duplicating +work. -data FBConsum = FBGoodConsum | FBBadConsum deriving(Eq) -data FBProd = FBGoodProd | FBBadProd deriving(Eq) +\begin{code} +data LBVarInfo + = NoLBVarInfo + + | 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. + +seqLBVar l = l `seq` () \end{code} \begin{code} -mkFBTypeInfo = SomeFBTypeInfo +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 (LBVarInfo u) | u `eqUsage` 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} +%* * +%************************************************************************ -getFBType :: FBTypeInfo -> Maybe FBType -getFBType NoFBTypeInfo = Nothing -getFBType (SomeFBTypeInfo u) = Just u +@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, newDemandInfo = demand}) + | is_safe_occ && not (isStrictDmd demand) + = Nothing + | otherwise + = Just (info {occInfo = safe_occ, + newDemandInfo = Lazy}) + 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} \begin{code} -fbTypeInfo (IdInfo _ _ _ _ _ _ _ _ fb) = fb +zapDemandInfo :: IdInfo -> Maybe IdInfo +zapDemandInfo info@(IdInfo {newDemandInfo = demand}) + | not (isStrictDmd demand) = Nothing + | otherwise = Just (info {newDemandInfo = Lazy}) +\end{code} -addFBTypeInfo id_info NoFBTypeInfo = id_info -addFBTypeInfo (IdInfo a b d e f g h i _) fb_info = IdInfo a b d e f g h i fb_info -ppFBTypeInfo sty NoFBTypeInfo = empty -ppFBTypeInfo sty (SomeFBTypeInfo (FBType cons prod)) - = (<>) (ptext SLIT("_F_ ")) (ppFBType cons prod) +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. -ppFBType cons prod = hcat - ([ char '"' ] ++ map ppCons cons ++ [ char '-', ppProd prod, char '"' ]) - where - ppCons FBGoodConsum = char 'G' - ppCons FBBadConsum = char 'B' - ppProd FBGoodProd = char 'G' - ppProd FBBadProd = char 'B' +\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}