%
-% (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@}
Haskell. [WDP 94/11])
\begin{code}
-#include "HsVersions.h"
-
module IdInfo (
- IdInfo, -- abstract
- noIdInfo,
- boringIdInfo,
- ppIdInfo,
- applySubstToIdInfo, apply_to_IdInfo, -- not for general use, please
-
- OptIdInfo(..), -- class; for convenience only
- -- all the *Infos herein are instances of it
-
- -- component "id infos"; also abstract:
- SrcLoc,
- getSrcLocIdInfo,
-
- ArityInfo,
- mkArityInfo, unknownArity, arityMaybe,
-
- DemandInfo,
- mkDemandInfo,
- willBeDemanded,
-
- StrictnessInfo(..), -- non-abstract
- Demand(..), -- non-abstract
-
- wwLazy, wwStrict, wwUnpack, wwPrim, wwEnum,
- indicatesWorker, nonAbsentArgs,
- mkStrictnessInfo, mkBottomStrictnessInfo,
- getWrapperArgTypeCategories,
- getWorkerId,
- workerExists,
- bottomIsGuaranteed,
-
- mkUnfolding,
- noInfo_UF, getInfo_UF, addInfo_UF, -- to avoid instance virus
-
- UpdateInfo,
- mkUpdateInfo,
- SYN_IE(UpdateSpec),
- updateInfoMaybe,
-
- DeforestInfo(..),
-
- ArgUsageInfo,
- ArgUsage(..),
- SYN_IE(ArgUsageType),
- mkArgUsageInfo,
- getArgUsage,
-
- FBTypeInfo,
- FBType(..),
- FBConsum(..),
- FBProd(..),
- mkFBTypeInfo,
- getFBType
+ IdInfo, -- Abstract
- ) where
+ vanillaIdInfo, constantIdInfo, mkIdInfo, seqIdInfo, megaSeqIdInfo,
-IMP_Ubiq()
-IMPORT_1_3(Char(toLower))
-
-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".
-
-import CmdLineOpts ( opt_OmitInterfacePragmas )
-import Maybes ( firstJust )
-import Outputable ( ifPprInterface, Outputable(..){-instances-} )
-import PprStyle ( PprStyle(..) )
-import Pretty
-import SrcLoc ( mkUnknownSrcLoc )
-import Type ( eqSimpleTy, splitFunTyExpandingDicts )
-import Unique ( pprUnique )
-import Util ( mapAccumL, panic, assertPanic, pprPanic )
-
-#ifdef REALLY_HASKELL_1_3
-ord = fromEnum :: Char -> Int
-#endif
-
-applySubstToTy = panic "IdInfo.applySubstToTy"
-showTypeCategory = panic "IdInfo.showTypeCategory"
-mkFormSummary = panic "IdInfo.mkFormSummary"
-isWrapperFor = panic "IdInfo.isWrapperFor"
-pprCoreUnfolding = panic "IdInfo.pprCoreUnfolding"
-\end{code}
+ -- Zapping
+ zapFragileInfo, zapLamInfo, zapSpecPragInfo, shortableIdInfo, copyIdInfo,
-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.
+ -- Flavour
+ IdFlavour(..), flavourInfo,
+ setNoDiscardInfo, setFlavourInfo,
+ ppFlavourInfo,
-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.
+ -- Arity
+ ArityInfo(..),
+ exactArity, atLeastArity, unknownArity, hasArity,
+ arityInfo, setArityInfo, ppArityInfo, arityLowerBound,
-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).
+ -- Strictness; imported from Demand
+ StrictnessInfo(..),
+ mkStrictnessInfo, noStrictnessInfo,
+ ppStrictnessInfo,isBottomingStrictness,
+ strictnessInfo, setStrictnessInfo,
-\begin{code}
-data IdInfo
- = IdInfo
- ArityInfo -- Its arity
+ -- Usage generalisation
+ TyGenInfo(..),
+ tyGenInfo, setTyGenInfo,
+ noTyGenInfo, isNoTyGenInfo, ppTyGenInfo, tyGenInfoString,
- DemandInfo -- Whether or not it is definitely
- -- demanded
+ -- Worker
+ WorkerInfo(..), workerExists, wrapperArity, workerId,
+ workerInfo, setWorkerInfo, ppWorkerInfo,
- SpecEnv -- Specialisations of this function which exist
+ -- Unfolding
+ unfoldingInfo, setUnfoldingInfo,
- StrictnessInfo -- Strictness properties, notably
- -- how to conjure up "worker" functions
+ -- DemandInfo
+ demandInfo, setDemandInfo,
- Unfolding -- Its unfolding; for locally-defined
- -- things, this can *only* be NoUnfolding
+ -- Inline prags
+ InlinePragInfo(..),
+ inlinePragInfo, setInlinePragInfo, pprInlinePragInfo,
+ isNeverInlinePrag, neverInlinePrag,
- UpdateInfo -- Which args should be updated
+ -- Occurrence info
+ OccInfo(..), isFragileOcc, isDeadOcc, isLoopBreaker,
+ InsideLam, OneBranch, insideLam, notInsideLam, oneBranch, notOneBranch,
+ occInfo, setOccInfo,
- DeforestInfo -- Whether its definition should be
- -- unfolded during deforestation
+ -- Specialisation
+ specInfo, setSpecInfo,
- ArgUsageInfo -- how this Id uses its arguments
+ -- CAF info
+ CafInfo(..), cafInfo, setCafInfo, ppCafInfo,
- FBTypeInfo -- the Foldr/Build W/W property of this function.
+ -- Constructed Product Result Info
+ CprInfo(..), cprInfo, setCprInfo, ppCprInfo, noCprInfo,
- SrcLoc -- Source location of definition
+ -- Lambda-bound variable info
+ LBVarInfo(..), lbvarInfo, setLBVarInfo, noLBVarInfo
+ ) where
- -- ToDo: SrcLoc is in FullNames too (could rm?) but it
- -- is needed here too for things like ConstMethodIds and the
- -- like, which don't have full-names of their own Mind you,
- -- perhaps the Name for a constant method could give the
- -- class/type involved?
-\end{code}
+#include "HsVersions.h"
-\begin{code}
-noIdInfo = IdInfo noInfo noInfo noInfo noInfo noInfo_UF
- noInfo noInfo noInfo noInfo mkUnknownSrcLoc
-
--- "boring" means: nothing to put in interface
-boringIdInfo (IdInfo UnknownArity
- UnknownDemand
- specenv
- strictness
- unfolding
- NoUpdateInfo
- Don'tDeforest
- _ {- arg_usage: currently no interface effect -}
- _ {- no f/b w/w -}
- _ {- src_loc: no effect on interfaces-}
- )
- | isNullSpecEnv specenv
- && boring_strictness strictness
- && boring_unfolding unfolding
- = True
- where
- boring_strictness NoStrictnessInfo = True
- boring_strictness BottomGuaranteed = False
- boring_strictness (StrictnessInfo wrap_args _) = all_present_WwLazies wrap_args
- boring_unfolding NoUnfolding = True
- boring_unfolding _ = False
+import CoreSyn
+import Type ( Type, usOnce )
+import PrimOp ( PrimOp )
+import Var ( Id )
+import BasicTypes ( OccInfo(..), isFragileOcc, isDeadOcc, seqOccInfo, isLoopBreaker,
+ InsideLam, insideLam, notInsideLam,
+ OneBranch, oneBranch, notOneBranch,
+ Arity
+ )
+import DataCon ( DataCon )
+import FieldLabel ( FieldLabel )
+import Type ( usOnce, usMany )
+import Demand -- Lots of stuff
+import Outputable
+import Util ( seqList )
+
+infixl 1 `setDemandInfo`,
+ `setTyGenInfo`,
+ `setStrictnessInfo`,
+ `setSpecInfo`,
+ `setArityInfo`,
+ `setInlinePragInfo`,
+ `setUnfoldingInfo`,
+ `setCprInfo`,
+ `setWorkerInfo`,
+ `setLBVarInfo`,
+ `setCafInfo`,
+ `setOccInfo`
+ -- infixl so you can say (id `set` a `set` b)
+\end{code}
-boringIdInfo _ = False
+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.
-pp_NONE = ppPStr SLIT("_N_")
-\end{code}
+ 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.
-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 srcloc)
- | isNullSpecEnv spec
- = idinfo
- | 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 srcloc
- 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)
--}
-\end{code}
+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.
-Variant of the same thing for the typechecker.
-\begin{code}
-applySubstToIdInfo s0 (IdInfo arity demand spec strictness unfold
- update deforest arg_usage fb_ww srcloc)
- = 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 srcloc) }
- 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}
+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). (@lbvarInfo@ is also a marginal
+case. KSW 1999-04).
\begin{code}
-ppIdInfo :: PprStyle
- -> Id -- The Id for which we're printing this IdInfo
- -> Bool -- True <=> print specialisations, please
- -> (Id -> Id) -- to look up "better Ids" w/ better IdInfos;
- -> IdEnv Unfolding
- -- inlining info for top-level fns in this module
- -> IdInfo -- see MkIface notes
- -> Pretty
-
-ppIdInfo sty for_this_id specs_please better_id_fn inline_env
- i@(IdInfo arity demand specenv strictness unfold update deforest arg_usage fbtype srcloc)
- | boringIdInfo i
- = ppPStr SLIT("_NI_")
+data IdInfo
+ = IdInfo {
+ flavourInfo :: IdFlavour, -- NOT OPTIONAL
+ arityInfo :: ArityInfo, -- Its arity
+ demandInfo :: Demand, -- Whether or not it is definitely demanded
+ specInfo :: CoreRules, -- Specialisations of this function which exist
+ tyGenInfo :: TyGenInfo, -- Restrictions on usage-generalisation of this Id
+ strictnessInfo :: StrictnessInfo, -- Strictness properties
+ workerInfo :: WorkerInfo, -- Pointer to Worker Function
+ unfoldingInfo :: Unfolding, -- Its unfolding
+ cafInfo :: CafInfo,
+ 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
+ }
+
+seqIdInfo :: IdInfo -> ()
+seqIdInfo (IdInfo {}) = ()
+
+megaSeqIdInfo :: IdInfo -> ()
+megaSeqIdInfo info
+ = seqFlavour (flavourInfo info) `seq`
+ seqArity (arityInfo info) `seq`
+ seqDemand (demandInfo info) `seq`
+ seqRules (specInfo info) `seq`
+ seqTyGenInfo (tyGenInfo info) `seq`
+ seqStrictnessInfo (strictnessInfo info) `seq`
+ seqWorker (workerInfo info) `seq`
+
+-- seqUnfolding (unfoldingInfo info) `seq`
+-- Omitting this improves runtimes a little, presumably because
+-- some unfoldings are not calculated at all
+
+ seqCaf (cafInfo info) `seq`
+ seqCpr (cprInfo info) `seq`
+ seqLBVar (lbvarInfo info) `seq`
+ seqOccInfo (occInfo info)
+\end{code}
+
+Setters
+
+\begin{code}
+setFlavourInfo info fl = fl `seq` info { flavourInfo = fl }
+setWorkerInfo info wk = wk `seq` info { workerInfo = wk }
+setSpecInfo info sp = 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 && isStrict (demandInfo info)
+ -- If the unfolding is a value, the demand info may
+ -- go pear-shaped, so we nuke it. Example:
+ -- let x = (a,b) in
+ -- case x of (p,q) -> h p q x
+ -- Here x is certainly demanded. But after we've nuked
+ -- the case, we'll get just
+ -- let x = (a,b) in h a b x
+ -- and now x is not demanded (I'm assuming h is lazy)
+ -- This really happens. The solution here is a bit ad hoc...
+ = info { unfoldingInfo = uf, demandInfo = wwLazy }
| otherwise
- = let
- stuff = ppCat [
- -- order is important!:
- ppInfo sty better_id_fn arity,
- ppInfo sty better_id_fn update,
- ppInfo sty better_id_fn deforest,
-
- pp_strictness sty (Just for_this_id)
- better_id_fn inline_env strictness,
-
- if bottomIsGuaranteed strictness
- then pp_NONE
- else pp_unfolding sty for_this_id inline_env unfold,
-
- if specs_please
- then pp_NONE -- ToDo -- sty (not (isDataCon for_this_id))
- -- better_id_fn inline_env (mEnvToList specenv)
- else pp_NONE,
-
- -- DemandInfo needn't be printed since it has no effect on interfaces
- ppInfo sty better_id_fn demand,
- ppInfo sty better_id_fn fbtype
- ]
- in
- case sty of
- PprInterface -> if opt_OmitInterfacePragmas
- then ppNil
- else stuff
- _ -> stuff
-\end{code}
+ -- We do *not* seq on the unfolding info, For some reason, doing so
+ -- actually increases residency significantly.
+ = info { unfoldingInfo = uf }
-%************************************************************************
-%* *
-\subsection[OptIdInfo-class]{The @OptIdInfo@ class (keeps things tidier)}
-%* *
-%************************************************************************
+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 }
-\begin{code}
-class OptIdInfo a where
- noInfo :: a
- getInfo :: IdInfo -> a
- addInfo :: IdInfo -> a -> IdInfo
- -- By default, "addInfo" will not overwrite
- -- "info" with "non-info"; look at any instance
- -- to see an example.
- ppInfo :: PprStyle -> (Id -> Id) -> a -> Pretty
+setNoDiscardInfo info = case flavourInfo info of
+ VanillaId -> info { flavourInfo = ExportedId }
+ other -> info
+zapSpecPragInfo info = case flavourInfo info of
+ SpecPragmaId -> info { flavourInfo = VanillaId }
+ other -> info
\end{code}
-%************************************************************************
-%* *
-\subsection[srcloc-IdInfo]{Source-location info in an @IdInfo@}
-%* *
-%************************************************************************
-Not used much, but...
\begin{code}
-getSrcLocIdInfo (IdInfo _ _ _ _ _ _ _ _ _ src_loc) = src_loc
+vanillaIdInfo :: IdInfo
+vanillaIdInfo = mkIdInfo VanillaId
+
+constantIdInfo :: IdInfo
+constantIdInfo = mkIdInfo ConstantId
+
+mkIdInfo :: IdFlavour -> IdInfo
+mkIdInfo flv = IdInfo {
+ flavourInfo = flv,
+ arityInfo = UnknownArity,
+ demandInfo = wwLazy,
+ specInfo = emptyCoreRules,
+ tyGenInfo = noTyGenInfo,
+ workerInfo = NoWorker,
+ strictnessInfo = NoStrictnessInfo,
+ unfoldingInfo = noUnfolding,
+ cafInfo = MayHaveCafRefs,
+ cprInfo = NoCPRInfo,
+ lbvarInfo = NoLBVarInfo,
+ inlinePragInfo = NoInlinePragInfo,
+ occInfo = NoOccInfo
+ }
\end{code}
+
%************************************************************************
%* *
-\subsection[arity-IdInfo]{Arity info about an @Id@}
+\subsection{Flavour}
%* *
%************************************************************************
\begin{code}
-data ArityInfo
- = UnknownArity -- no idea
- | ArityExactly Int -- arity is exactly this
-\end{code}
+data IdFlavour
+ = VanillaId -- Locally defined, not exported
+ | ExportedId -- Locally defined, exported
+ | SpecPragmaId -- Locally defined, RHS holds specialised call
-\begin{code}
-mkArityInfo = ArityExactly
-unknownArity = UnknownArity
+ | ConstantId -- Imported from elsewhere, or a dictionary function,
+ -- default method Id.
-arityMaybe :: ArityInfo -> Maybe Int
+ | DataConId DataCon -- The Id for a data constructor *worker*
+ | DataConWrapId DataCon -- The Id for a data constructor *wrapper*
+ -- [the only reasons we need to know is so that
+ -- a) we can suppress printing a definition in the interface file
+ -- b) when typechecking a pattern we can get from the
+ -- Id back to the data con]
+ | PrimOpId PrimOp -- The Id for a primitive operator
+ | RecordSelId FieldLabel -- The Id for a record selector
-arityMaybe UnknownArity = Nothing
-arityMaybe (ArityExactly i) = Just i
-\end{code}
-\begin{code}
-instance OptIdInfo ArityInfo where
- noInfo = UnknownArity
+ppFlavourInfo :: IdFlavour -> SDoc
+ppFlavourInfo VanillaId = empty
+ppFlavourInfo ExportedId = ptext SLIT("[Exported]")
+ppFlavourInfo SpecPragmaId = ptext SLIT("[SpecPrag]")
+ppFlavourInfo ConstantId = ptext SLIT("[Constant]")
+ppFlavourInfo (DataConId _) = ptext SLIT("[DataCon]")
+ppFlavourInfo (DataConWrapId _) = ptext SLIT("[DataConWrapper]")
+ppFlavourInfo (PrimOpId _) = ptext SLIT("[PrimOp]")
+ppFlavourInfo (RecordSelId _) = ptext SLIT("[RecSel]")
- getInfo (IdInfo arity _ _ _ _ _ _ _ _ _) = arity
+seqFlavour :: IdFlavour -> ()
+seqFlavour f = f `seq` ()
+\end{code}
- addInfo id_info UnknownArity = id_info
- addInfo (IdInfo _ a c d e f g h i j) arity = IdInfo arity a c d e f g h i j
+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.
- ppInfo sty _ UnknownArity = ifPprInterface sty pp_NONE
- ppInfo sty _ (ArityExactly arity) = ppCat [ppPStr SLIT("_A_"), ppInt arity]
-\end{code}
%************************************************************************
%* *
-\subsection[demand-IdInfo]{Demand info about an @Id@}
+\subsection[arity-IdInfo]{Arity info about an @Id@}
%* *
%************************************************************************
-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
-\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}
-mkDemandInfo :: Demand -> DemandInfo
-mkDemandInfo demand = DemandedAsPer demand
+data ArityInfo
+ = UnknownArity -- No idea
-willBeDemanded :: DemandInfo -> Bool
-willBeDemanded (DemandedAsPer demand) = isStrict demand
-willBeDemanded _ = False
-\end{code}
+ | ArityExactly Arity -- Arity is exactly this. We use this when importing a
+ -- function; it's already been compiled and we know its
+ -- arity for sure.
-\begin{code}
-instance OptIdInfo DemandInfo where
- noInfo = UnknownDemand
-
- getInfo (IdInfo _ demand _ _ _ _ _ _ _ _) = demand
-
-{- DELETED! If this line is in, there is no way to
- nuke a DemandInfo, and we have to be able to do that
- when floating let-bindings around
- addInfo id_info UnknownDemand = id_info
--}
- addInfo (IdInfo a _ c d e f g h i j) demand = IdInfo a demand c d e f g h i j
-
- ppInfo PprInterface _ _ = ppNil
- ppInfo sty _ UnknownDemand = ppStr "{-# L #-}"
- ppInfo sty _ (DemandedAsPer info)
- = ppCat [ppStr "{-#", ppStr (showList [info] ""), ppStr "#-}"]
-\end{code}
+ | ArityAtLeast Arity -- A partial application of this Id to up to n-1 value arguments
+ -- does essentially no work. That is not necessarily the
+ -- same as saying that it has n leading lambdas, because coerces
+ -- may get in the way.
-%************************************************************************
-%* *
-\subsection[specialisation-IdInfo]{Specialisation info about an @Id@}
-%* *
-%************************************************************************
+ -- functions in the module being compiled. Their arity
+ -- might increase later in the compilation process, if
+ -- an extra lambda floats up to the binding site.
+ deriving( Eq )
-See SpecEnv.lhs
+seqArity :: ArityInfo -> ()
+seqArity a = arityLowerBound a `seq` ()
-\begin{code}
-instance OptIdInfo SpecEnv where
- noInfo = nullSpecEnv
+exactArity = ArityExactly
+atLeastArity = ArityAtLeast
+unknownArity = UnknownArity
- getInfo (IdInfo _ _ spec _ _ _ _ _ _ _) = spec
+arityLowerBound :: ArityInfo -> Arity
+arityLowerBound UnknownArity = 0
+arityLowerBound (ArityAtLeast n) = n
+arityLowerBound (ArityExactly n) = n
- addInfo id_info spec | isNullSpecEnv spec = id_info
- addInfo (IdInfo a b _ d e f g h i j) spec = IdInfo a b spec d e f g h i j
+hasArity :: ArityInfo -> Bool
+hasArity UnknownArity = False
+hasArity other = True
- ppInfo sty better_id_fn spec = panic "IdInfo:ppSpecs"
--- = ppSpecs sty True better_id_fn nullIdEnv (mEnvToList spec)
+ppArityInfo UnknownArity = empty
+ppArityInfo (ArityExactly arity) = hsep [ptext SLIT("__A"), int arity]
+ppArityInfo (ArityAtLeast arity) = hsep [ptext SLIT("__AL"), int arity]
\end{code}
%************************************************************************
%* *
-\subsection[strictness-IdInfo]{Strictness info about an @Id@}
+\subsection{Inline-pragma information}
%* *
%************************************************************************
-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).
+\begin{code}
+data InlinePragInfo
+ = NoInlinePragInfo
+ | IMustNotBeINLINEd Bool -- True <=> came from an INLINE prag, False <=> came from a NOINLINE prag
+ (Maybe Int) -- Phase number from pragma, if any
+ deriving( Eq )
+ -- The True, Nothing case doesn't need to be recorded
-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.
+ -- SEE COMMENTS WITH CoreUnfold.blackListed on the
+ -- exact significance of the IMustNotBeINLINEd pragma
-\begin{code}
-data StrictnessInfo
- = NoStrictnessInfo
+isNeverInlinePrag :: InlinePragInfo -> Bool
+isNeverInlinePrag (IMustNotBeINLINEd _ Nothing) = True
+isNeverInlinePrag other = False
- | BottomGuaranteed -- This Id guarantees never to return;
- -- it is bottom regardless of its arguments.
- -- Useful for "error" and other disguised
- -- variants thereof.
+neverInlinePrag :: InlinePragInfo
+neverInlinePrag = IMustNotBeINLINEd True{-should be False? --SDM -} Nothing
- | StrictnessInfo [Demand] -- the main stuff; see below.
- (Maybe Id) -- worker's Id, if applicable.
-\end{code}
+instance Outputable InlinePragInfo where
+ -- This is now parsed in interface files
+ ppr NoInlinePragInfo = empty
+ ppr other_prag = ptext SLIT("__U") <> pprInlinePragInfo other_prag
-This type is also actually used in the strictness analyser:
-\begin{code}
-data Demand
- = WwLazy -- Argument is lazy as far as we know
- MaybeAbsent -- (does not imply worker's existence [etc]).
- -- If MaybeAbsent == True, then it is
- -- *definitely* lazy. (NB: Absence implies
- -- a worker...)
-
- | WwStrict -- Argument is strict but that's all we know
- -- (does not imply worker's existence or any
- -- calling-convention magic)
-
- | WwUnpack -- Argument is strict & a single-constructor
- [Demand] -- type; its constituent parts (whose StrictInfos
- -- are in the list) should be passed
- -- as arguments to the worker.
-
- | WwPrim -- Argument is of primitive type, therefore
- -- strict; doesn't imply existence of a worker;
- -- argument should be passed as is to worker.
-
- | WwEnum -- Argument is strict & an enumeration type;
- -- an Int# representing the tag (start counting
- -- at zero) should be passed to the worker.
- deriving (Eq, Ord)
- -- we need Eq/Ord to cross-chk update infos in interfaces
-
-type MaybeAbsent = Bool -- True <=> not even used
-
--- versions that don't worry about Absence:
-wwLazy = WwLazy False
-wwStrict = WwStrict
-wwUnpack xs = WwUnpack xs
-wwPrim = WwPrim
-wwEnum = WwEnum
+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}
-mkStrictnessInfo :: [Demand] -> Maybe Id -> StrictnessInfo
-mkStrictnessInfo [] _ = NoStrictnessInfo
-mkStrictnessInfo xs wrkr = StrictnessInfo xs wrkr
+%************************************************************************
+%* *
+\subsection[TyGen-IdInfo]{Type generalisation info about an @Id@}
+%* *
+%************************************************************************
-mkBottomStrictnessInfo = BottomGuaranteed
+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.
-bottomIsGuaranteed BottomGuaranteed = True
-bottomIsGuaranteed other = False
+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).
-getWrapperArgTypeCategories
- :: Type -- wrapper's type
- -> StrictnessInfo -- strictness info about its args
- -> Maybe String
+To indicate this property, such identifiers are marked TyGenNever.
-getWrapperArgTypeCategories _ NoStrictnessInfo = Nothing
-getWrapperArgTypeCategories _ BottomGuaranteed
- = trace "getWrapperArgTypeCategories:BottomGuaranteed!" Nothing -- wrong
-getWrapperArgTypeCategories _ (StrictnessInfo [] _) = Nothing
+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.
-getWrapperArgTypeCategories ty (StrictnessInfo arg_info _)
- = Just (mkWrapperArgTypeCategories ty arg_info)
+\begin{code}
+data TyGenInfo
+ = NoTyGenInfo -- no restriction on type generalisation
-workerExists :: StrictnessInfo -> Bool
-workerExists (StrictnessInfo _ (Just worker_id)) = True
-workerExists other = False
+ | TyGenUInfo [Maybe Type] -- restrict generalisation of this Id to
+ -- preserve specified usage annotations
-getWorkerId :: StrictnessInfo -> Id
+ | TyGenNever -- never generalise the type of this Id
-getWorkerId (StrictnessInfo _ (Just worker_id)) = worker_id
-#ifdef DEBUG
-getWorkerId junk = pprPanic "getWorkerId: " (ppInfo PprDebug (\x->x) junk)
-#endif
+ deriving ( Eq )
\end{code}
-\begin{code}
-isStrict :: Demand -> Bool
-
-isStrict WwStrict = True
-isStrict (WwUnpack _) = True
-isStrict WwPrim = True
-isStrict WwEnum = True
-isStrict _ = False
-
-nonAbsentArgs :: [Demand] -> Int
+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.
-nonAbsentArgs cmpts
- = foldr tick_non 0 cmpts
- where
- tick_non (WwLazy True) acc = acc
- tick_non other acc = acc + 1
+\begin{code}
+seqTyGenInfo :: TyGenInfo -> ()
+seqTyGenInfo NoTyGenInfo = ()
+seqTyGenInfo (TyGenUInfo us) = seqList us ()
+seqTyGenInfo TyGenNever = ()
-all_present_WwLazies :: [Demand] -> Bool
-all_present_WwLazies infos
- = and (map is_L infos)
- where
- is_L (WwLazy False) = True -- False <=> "Absent" args do *not* count!
- is_L _ = False -- (as they imply a worker)
-\end{code}
+noTyGenInfo :: TyGenInfo
+noTyGenInfo = NoTyGenInfo
-WDP 95/04: It is no longer enough to look at a list of @Demands@ for
-an ``Unpack'' or an ``Absent'' and declare a worker. We also have to
-check that @mAX_WORKER_ARGS@ hasn't been exceeded. Therefore,
-@indicatesWorker@ mirrors the process used in @mk_ww_arg_processing@
-in \tr{WwLib.lhs}. A worker is ``indicated'' when we hit an Unpack
-or an Absent {\em that we accept}.
-\begin{code}
-indicatesWorker :: [Demand] -> Bool
+isNoTyGenInfo :: TyGenInfo -> Bool
+isNoTyGenInfo NoTyGenInfo = True
+isNoTyGenInfo _ = False
-indicatesWorker dems
- = fake_mk_ww (mAX_WORKER_ARGS - nonAbsentArgs dems) dems
- where
- fake_mk_ww _ [] = False
- fake_mk_ww _ (WwLazy True : _) = True -- we accepted an Absent
- fake_mk_ww extra_args (WwUnpack cmpnts : dems)
- | extra_args_now > 0 = True -- we accepted an Unpack
- where
- extra_args_now = extra_args + 1 - nonAbsentArgs cmpnts
-
- fake_mk_ww extra_args (_ : dems)
- = fake_mk_ww extra_args dems
-\end{code}
+-- 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.
-\begin{code}
-mkWrapperArgTypeCategories
- :: Type -- wrapper's type
- -> [Demand] -- info about its arguments
- -> String -- a string saying lots about the args
-
-mkWrapperArgTypeCategories wrapper_ty wrap_info
- = case (splitFunTyExpandingDicts wrapper_ty) of { (arg_tys,_) ->
- map do_one (wrap_info `zip` (map showTypeCategory arg_tys)) }
- where
- -- ToDo: this needs FIXING UP (it was a hack anyway...)
- do_one (WwPrim, _) = 'P'
- do_one (WwEnum, _) = 'E'
- do_one (WwStrict, arg_ty_char) = arg_ty_char
- do_one (WwUnpack _, arg_ty_char)
- = if arg_ty_char `elem` "CIJFDTS"
- then toLower arg_ty_char
- else if arg_ty_char == '+' then 't'
- else trace ("mkWrapp..:funny char:"++[arg_ty_char]) '-'
- do_one (other_wrap_info, _) = '-'
-\end{code}
+ppTyGenInfo :: TyGenInfo -> SDoc
+ppTyGenInfo NoTyGenInfo = empty
+ppTyGenInfo (TyGenUInfo us) = ptext SLIT("__G") <+> text (tyGenInfoString us)
+ppTyGenInfo TyGenNever = ptext SLIT("__G N")
-Whether a worker exists depends on whether the worker has an
-absent argument, a @WwUnpack@ argument, (or @WwEnum@ ToDo???) arguments.
+tyGenInfoString us = map go us
+ where go Nothing = 'x' -- for legibility, choose
+ go (Just u) | u == usOnce = '1' -- chars with identity
+ | u == usMany = 'M' -- Z-encoding.
+ go other = pprPanic "IdInfo.tyGenInfoString: unexpected annotation" (ppr other)
-If a @WwUnpack@ argument is for an {\em abstract} type (or one that
-will be abstract outside this module), which might happen for an
-imported function, then we can't (or don't want to...) unpack the arg
-as the worker requires. Hence we have to give up altogether, and call
-the wrapper only; so under these circumstances we return \tr{False}.
+instance Outputable TyGenInfo where
+ ppr = ppTyGenInfo
-\begin{code}
-#ifdef REALLY_HASKELL_1_3
-instance Read Demand where
-#else
-instance Text Demand where
-#endif
- readList str = read_em [{-acc-}] str
- where
- read_em acc [] = [(reverse acc, "")]
- -- lower case indicates absence...
- read_em acc ('L' : xs) = read_em (WwLazy False : acc) xs
- read_em acc ('A' : xs) = read_em (WwLazy True : acc) xs
- read_em acc ('S' : xs) = read_em (WwStrict : acc) xs
- read_em acc ('P' : xs) = read_em (WwPrim : acc) xs
- read_em acc ('E' : xs) = read_em (WwEnum : acc) xs
-
- read_em acc (')' : xs) = [(reverse acc, xs)]
- read_em acc ( 'U' : '(' : xs)
- = case (read_em [] xs) of
- [(stuff, rest)] -> read_em (WwUnpack stuff : acc) rest
- _ -> panic ("Text.Demand:"++str++"::"++xs)
-
- read_em acc other = panic ("IdInfo.readem:"++other)
-
-#ifdef REALLY_HASKELL_1_3
-instance Show Demand where
-#endif
- showList wrap_args rest = (concat (map show1 wrap_args)) ++ rest
- where
- show1 (WwLazy False) = "L"
- show1 (WwLazy True) = "A"
- show1 WwStrict = "S"
- show1 WwPrim = "P"
- show1 WwEnum = "E"
- show1 (WwUnpack args)= "U(" ++ (concat (map show1 args)) ++ ")"
-
-instance Outputable Demand where
- ppr sty si = ppStr (showList [si] "")
-
-instance OptIdInfo StrictnessInfo where
- noInfo = NoStrictnessInfo
-
- getInfo (IdInfo _ _ _ strict _ _ _ _ _ _) = strict
-
- addInfo id_info NoStrictnessInfo = id_info
- addInfo (IdInfo a b d _ e f g h i j) strict = IdInfo a b d strict e f g h i j
-
- ppInfo sty better_id_fn strictness_info
- = pp_strictness sty Nothing better_id_fn nullIdEnv strictness_info
+instance Show TyGenInfo where
+ showsPrec p c = showsPrecSDoc p (ppr c)
\end{code}
-We'll omit the worker info if the thing has an explicit unfolding
-already.
-\begin{code}
-pp_strictness sty _ _ _ NoStrictnessInfo = ifPprInterface sty pp_NONE
-
-pp_strictness sty _ _ _ BottomGuaranteed = ppPStr SLIT("_S_ _!_")
-
-pp_strictness sty for_this_id_maybe better_id_fn inline_env
- info@(StrictnessInfo wrapper_args wrkr_maybe)
- = let
- (have_wrkr, wrkr_id) = case wrkr_maybe of
- Nothing -> (False, panic "ppInfo(Strictness)")
- Just xx -> (True, xx)
-
- wrkr_to_print = better_id_fn wrkr_id
- wrkr_info = getIdInfo wrkr_to_print
-
- -- if we aren't going to be able to *read* the strictness info
- -- in TcPragmas, we need not even print it.
- wrapper_args_to_use
- = if not (indicatesWorker wrapper_args) then
- wrapper_args -- no worker/wrappering in any case
- else
- case for_this_id_maybe of
- Nothing -> wrapper_args
- Just id -> if externallyVisibleId id
- && (unfoldingUnfriendlyId id || not have_wrkr) then
- -- pprTrace "IdInfo: unworker-ising:" (ppCat [ppr PprDebug have_wrkr, ppr PprDebug id]) $
- map un_workerise wrapper_args
- else
- wrapper_args
-
- id_is_worker
- = case for_this_id_maybe of
- Nothing -> False
- Just id -> isWorkerId id
-
- am_printing_iface = case sty of { PprInterface -> True ; _ -> False }
-
- pp_basic_info
- = ppBesides [ppStr "_S_ \"",
- ppStr (showList wrapper_args_to_use ""), ppStr "\""]
-
- pp_with_worker
- = ppBesides [ ppSP, ppChar '{',
- ppIdInfo sty wrkr_to_print True{-wrkr specs, yes!-} better_id_fn inline_env wrkr_info,
- ppChar '}' ]
- in
- if all_present_WwLazies wrapper_args_to_use then -- too boring
- ifPprInterface sty pp_NONE
-
- else if id_is_worker && am_printing_iface then
- pp_NONE -- we don't put worker strictness in interfaces
- -- (it can be deduced)
-
- else if not (indicatesWorker wrapper_args_to_use)
- || not have_wrkr
- || boringIdInfo wrkr_info then
- ppBeside pp_basic_info ppNil
- else
- ppBeside pp_basic_info pp_with_worker
- where
- un_workerise (WwLazy _) = WwLazy False -- avoid absence
- un_workerise (WwUnpack _) = WwStrict
- un_workerise other = other
-\end{code}
%************************************************************************
%* *
-\subsection[unfolding-IdInfo]{Unfolding info about an @Id@}
+\subsection[worker-IdInfo]{Worker info about an @Id@}
%* *
%************************************************************************
-\begin{code}
-mkUnfolding guide expr
- = CoreUnfolding (SimpleUnfolding (mkFormSummary expr)
- guide
- (occurAnalyseGlobalExpr expr))
-\end{code}
+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.
+
+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}
-noInfo_UF = NoUnfolding
-getInfo_UF (IdInfo _ _ _ _ unfolding _ _ _ _ _) = unfolding
+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.
-addInfo_UF id_info@(IdInfo a b c d e f g h i j) NoUnfolding = id_info
-addInfo_UF (IdInfo a b d e _ f g h i j) uf = IdInfo a b d e uf f g h i j
-\end{code}
+seqWorker :: WorkerInfo -> ()
+seqWorker (HasWorker id _) = id `seq` ()
+seqWorker NoWorker = ()
-\begin{code}
-pp_unfolding sty for_this_id inline_env uf_details
- = case (lookupIdEnv inline_env for_this_id) of
- Nothing -> pp uf_details
- Just dt -> pp dt
- where
- pp NoUnfolding = pp_NONE
+ppWorkerInfo NoWorker = empty
+ppWorkerInfo (HasWorker wk_id _) = ptext SLIT("__P") <+> ppr wk_id
- pp (MagicUnfolding tag _)
- = ppCat [ppPStr SLIT("_MF_"), pprUnique tag]
+noWorkerInfo = NoWorker
- pp (CoreUnfolding (SimpleUnfolding _ guide template))
- = let
- untagged = unTagBinders template
- in
- if untagged `isWrapperFor` for_this_id
- then -- pprTrace "IdInfo:isWrapperFor:" (ppAbove (ppr PprDebug for_this_id) (ppr PprDebug untagged))
- pp_NONE
- else ppCat [ppPStr SLIT("_F_"), ppr sty guide, pprCoreUnfolding untagged]
+workerExists :: WorkerInfo -> Bool
+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[CAF-IdInfo]{CAF-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}
+This information is used to build Static Reference Tables (see
+simplStg/ComputeSRT.lhs).
\begin{code}
-mkUpdateInfo = SomeUpdateInfo
+data CafInfo
+ = MayHaveCafRefs -- either:
+ -- (1) A function or static constructor
+ -- that refers to one or more CAFs,
+ -- (2) A real live CAF
-updateInfoMaybe NoUpdateInfo = Nothing
-updateInfoMaybe (SomeUpdateInfo []) = Nothing
-updateInfoMaybe (SomeUpdateInfo u) = Just u
-\end{code}
+ | NoCafRefs -- A function or static constructor
+ -- that refers to no CAFs.
-Text instance so that the update annotations can be read in.
+-- LATER: not sure how easy this is...
+-- | OneCafRef Id
-\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"
-
-instance OptIdInfo UpdateInfo where
- noInfo = NoUpdateInfo
-
- getInfo (IdInfo _ _ _ _ _ update _ _ _ _) = update
-
- addInfo id_info NoUpdateInfo = id_info
- addInfo (IdInfo a b d e f _ g h i j) upd_info = IdInfo a b d e f upd_info g h i j
-
- ppInfo sty better_id_fn NoUpdateInfo = ifPprInterface sty pp_NONE
- ppInfo sty better_id_fn (SomeUpdateInfo []) = ifPprInterface sty pp_NONE
- ppInfo sty better_id_fn (SomeUpdateInfo spec)
- = ppBeside (ppPStr SLIT("_U_ ")) (ppBesides (map ppInt spec))
-\end{code}
-
-%************************************************************************
-%* *
-\subsection[deforest-IdInfo]{Deforestation info about an @Id@}
-%* *
-%************************************************************************
-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.
+seqCaf c = c `seq` ()
-\begin{code}
-data DeforestInfo
- = Don'tDeforest -- just a bool, might extend this
- | DoDeforest -- later.
- -- deriving (Eq, Ord)
+ppCafInfo NoCafRefs = ptext SLIT("__C")
+ppCafInfo MayHaveCafRefs = empty
\end{code}
-\begin{code}
-instance OptIdInfo DeforestInfo where
- noInfo = Don'tDeforest
-
- getInfo (IdInfo _ _ _ _ _ _ deforest _ _ _) = deforest
-
- addInfo id_info Don'tDeforest = id_info
- addInfo (IdInfo a b d e f g _ h i j) deforest =
- IdInfo a b d e f g deforest h i j
-
- ppInfo sty better_id_fn Don'tDeforest
- = ifPprInterface sty pp_NONE
- ppInfo sty better_id_fn DoDeforest
- = ppPStr SLIT("_DEFOREST_")
-\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{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}
+
+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}
-mkArgUsageInfo = SomeArgUsageInfo
+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
-getArgUsage :: ArgUsageInfo -> ArgUsageType
-getArgUsage NoArgUsageInfo = []
-getArgUsage (SomeArgUsageInfo u) = u
+ -- We used to keep nested info about sub-components, but
+ -- we never used it so I threw it away
\end{code}
\begin{code}
-instance OptIdInfo ArgUsageInfo where
- noInfo = NoArgUsageInfo
+seqCpr :: CprInfo -> ()
+seqCpr ReturnsCPR = ()
+seqCpr NoCPRInfo = ()
- getInfo (IdInfo _ _ _ _ _ _ _ au _ _) = au
+noCprInfo = NoCPRInfo
- addInfo id_info NoArgUsageInfo = id_info
- addInfo (IdInfo a b d e f g h _ i j) au_info = IdInfo a b d e f g h au_info i j
+ppCprInfo NoCPRInfo = empty
+ppCprInfo ReturnsCPR = ptext SLIT("__M")
- ppInfo sty better_id_fn NoArgUsageInfo = ifPprInterface sty pp_NONE
- ppInfo sty better_id_fn (SomeArgUsageInfo []) = ifPprInterface sty pp_NONE
- ppInfo sty better_id_fn (SomeArgUsageInfo aut)
- = ppBeside (ppPStr SLIT("_L_ ")) (ppArgUsageType aut)
+instance Outputable CprInfo where
+ ppr = ppCprInfo
+instance Show CprInfo where
+ showsPrec p c = showsPrecSDoc p (ppr c)
+\end{code}
-ppArgUsage (ArgUsage n) = ppInt n
-ppArgUsage (UnknownArgUsage) = ppChar '-'
-ppArgUsageType aut = ppBesides
- [ ppChar '"' ,
- ppIntersperse ppComma (map ppArgUsage aut),
- ppChar '"' ]
-\end{code}
%************************************************************************
%* *
-\subsection[FBType-IdInfo]{Type of an expression through Foldr/build's eyes}
+\subsection[lbvar-IdInfo]{Lambda-bound var info about an @Id@}
%* *
%************************************************************************
+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.
+
+This information may be useful in optimisation, as computations may
+safely be floated inside such a lambda without risk of duplicating
+work.
+
\begin{code}
-data FBTypeInfo
- = NoFBTypeInfo
- | SomeFBTypeInfo FBType
- -- ??? deriving (Eq, Ord)
+data LBVarInfo
+ = NoLBVarInfo
-data FBType = FBType [FBConsum] FBProd deriving (Eq)
+ | 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.
-data FBConsum = FBGoodConsum | FBBadConsum deriving(Eq)
-data FBProd = FBGoodProd | FBBadProd deriving(Eq)
+seqLBVar l = l `seq` ()
\end{code}
\begin{code}
-mkFBTypeInfo = SomeFBTypeInfo
+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 == usOnce
+ = getPprStyle $ \ sty ->
+ if ifaceStyle sty
+ then empty
+ else ptext SLIT("OneShot")
+ | otherwise
+ = empty
-getFBType :: FBTypeInfo -> Maybe FBType
-getFBType NoFBTypeInfo = Nothing
-getFBType (SomeFBTypeInfo u) = Just u
+instance Outputable LBVarInfo where
+ ppr = pprLBVarInfo
+
+instance Show LBVarInfo where
+ showsPrec p c = showsPrecSDoc p (ppr c)
\end{code}
-\begin{code}
-instance OptIdInfo FBTypeInfo where
- noInfo = NoFBTypeInfo
- getInfo (IdInfo _ _ _ _ _ _ _ _ fb _) = fb
+%************************************************************************
+%* *
+\subsection{Bulk operations on IdInfo}
+%* *
+%************************************************************************
- addInfo id_info NoFBTypeInfo = id_info
- addInfo (IdInfo a b d e f g h i _ j) fb_info = IdInfo a b d e f g h i fb_info j
+zapFragileInfo is used when cloning binders, mainly in the
+simplifier. We must forget about used-once information because that
+isn't necessarily correct in the transformed program.
+Also forget specialisations and unfoldings because they would need
+substitution to be correct. (They get pinned back on separately.)
+
+\begin{code}
+zapFragileInfo :: IdInfo -> Maybe IdInfo
+zapFragileInfo info@(IdInfo {occInfo = occ,
+ workerInfo = wrkr,
+ specInfo = rules,
+ unfoldingInfo = unfolding})
+ | not (isFragileOcc occ)
+ -- We must forget about whether it was marked safe-to-inline,
+ -- because that isn't necessarily true in the simplified expression.
+ -- This is important because expressions may be re-simplified
+ -- We don't zap deadness or loop-breaker-ness.
+ -- The latter is important because it tells MkIface not to
+ -- spit out an inlining for the thing. The former doesn't
+ -- seem so important, but there's no harm.
+
+ && isEmptyCoreRules rules
+ -- Specialisations would need substituting. They get pinned
+ -- back on separately.
+
+ && not (workerExists wrkr)
+
+ && not (hasUnfolding unfolding)
+ -- This is very important; occasionally a let-bound binder is used
+ -- as a binder in some lambda, in which case its unfolding is utterly
+ -- bogus. Also the unfolding uses old binders so if we left it we'd
+ -- have to substitute it. Much better simply to give the Id a new
+ -- unfolding each time, which is what the simplifier does.
+ = Nothing
- ppInfo PprInterface _ NoFBTypeInfo = ppNil
- ppInfo sty _ NoFBTypeInfo = ifPprInterface sty pp_NONE
- ppInfo sty _ (SomeFBTypeInfo (FBType cons prod))
- = ppBeside (ppPStr SLIT("_F_ ")) (ppFBType cons prod)
+ | 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}
---ppFBType (FBType n) = ppBesides [ppInt n]
---ppFBType (UnknownFBType) = ppBesides [ppStr "-"]
---
+@zapLamInfo@ is used for lambda binders that turn out to to be
+part of an unsaturated lambda
-ppFBType cons prod = ppBesides
- ([ ppChar '"' ] ++ map ppCons cons ++ [ ppChar '-', ppProd prod, ppChar '"' ])
+\begin{code}
+zapLamInfo :: IdInfo -> Maybe IdInfo
+zapLamInfo info@(IdInfo {occInfo = occ, demandInfo = demand})
+ | is_safe_occ && not (isStrict demand)
+ = Nothing
+ | otherwise
+ = Just (info {occInfo = safe_occ,
+ demandInfo = wwLazy})
where
- ppCons FBGoodConsum = ppChar 'G'
- ppCons FBBadConsum = ppChar 'B'
- ppProd FBGoodProd = ppChar 'G'
- ppProd FBBadProd = ppChar 'B'
+ -- The "unsafe" occ info is the ones that say I'm not in a lambda
+ -- because that might not be true for an unsaturated lambda
+ is_safe_occ = case occ of
+ OneOcc in_lam once -> in_lam
+ other -> True
+
+ safe_occ = case occ of
+ OneOcc _ once -> OneOcc insideLam once
+ other -> occ
+\end{code}
+
+
+copyIdInfo is used when shorting out a top-level binding
+ f_local = BIG
+ f = f_local
+where f is exported. We are going to swizzle it around to
+ f = BIG
+ f_local = f
+
+BUT (a) we must be careful about messing up rules
+ (b) we must ensure f's IdInfo ends up right
+
+(a) Messing up the rules
+~~~~~~~~~~~~~~~~~~~~
+The example that went bad on me was this one:
+
+ iterate :: (a -> a) -> a -> [a]
+ iterate = iterateList
+
+ iterateFB c f x = x `c` iterateFB c f (f x)
+ iterateList f x = x : iterateList f (f x)
+
+ {-# RULES
+ "iterate" forall f x. iterate f x = build (\c _n -> iterateFB c f x)
+ "iterateFB" iterateFB (:) = iterateList
+ #-}
+
+This got shorted out to:
+
+ iterateList :: (a -> a) -> a -> [a]
+ iterateList = iterate
+
+ iterateFB c f x = x `c` iterateFB c f (f x)
+ iterate f x = x : iterate f (f x)
+
+ {-# RULES
+ "iterate" forall f x. iterate f x = build (\c _n -> iterateFB c f x)
+ "iterateFB" iterateFB (:) = iterate
+ #-}
+
+And now we get an infinite loop in the rule system
+ iterate f x -> build (\cn -> iterateFB c f x
+ -> iterateFB (:) f x
+ -> iterate f x
+
+Tiresome solution: don't do shorting out if f has rewrite rules.
+Hence shortableIdInfo.
+
+(b) Keeping the IdInfo right
+~~~~~~~~~~~~~~~~~~~~~~~~
+We want to move strictness/worker info from f_local to f, but keep the rest.
+Hence copyIdInfo.
+
+\begin{code}
+shortableIdInfo :: IdInfo -> Bool
+shortableIdInfo info = isEmptyCoreRules (specInfo info)
+
+copyIdInfo :: IdInfo -- f_local
+ -> IdInfo -- f (the exported one)
+ -> IdInfo -- New info for f
+copyIdInfo f_local f = f { strictnessInfo = strictnessInfo f_local,
+ workerInfo = workerInfo f_local,
+ cprInfo = cprInfo f_local
+ }
\end{code}
projects / ghc-hetmet.git / blobdiff