Id, DictId,
-- Simple construction
- mkVanillaId, mkImportedId, mkSysLocal, mkUserLocal,
- mkTemplateLocals, mkWildId, mkUserId,
+ mkGlobalId, mkLocalId, mkLocalIdWithInfo,
+ mkSysLocal, mkUserLocal, mkVanillaGlobal,
+ mkTemplateLocals, mkTemplateLocalsNum, mkWildId, mkTemplateLocal,
+ mkWorkerId, mkExportedLocalId,
-- Taking an Id apart
- idName, idType, idUnique, idInfo, idDetails,
- idPrimRep, isId,
+ idName, idType, idUnique, idInfo,
+ isId, globalIdDetails, idPrimRep,
recordSelectorFieldLabel,
-- Modifying an Id
- setIdName, setIdUnique, setIdType, setIdInfo,
+ setIdName, setIdUnique, Id.setIdType, setIdExported, setIdNotExported,
+ setIdInfo, lazySetIdInfo, modifyIdInfo, maybeModifyIdInfo,
+ zapLamIdInfo, zapDemandIdInfo,
-- Predicates
- omitIfaceSigForId,
- externallyVisibleId,
- idFreeTyVars,
+ isImplicitId, isDeadBinder, isDictId,
+ isExportedId, isLocalId, isGlobalId,
+ isRecordSelector, isNaughtyRecordSelector,
+ isClassOpId_maybe,
+ isPrimOpId, isPrimOpId_maybe,
+ isFCallId, isFCallId_maybe,
+ isDataConWorkId, isDataConWorkId_maybe, isDataConId_maybe, idDataCon,
+ isBottomingId, idIsFrom,
+ hasNoBinding,
-- Inline pragma stuff
- getInlinePragma, setInlinePragma, modifyInlinePragma,
- idWantsToBeINLINEd, idMustBeINLINEd, idMustNotBeINLINEd,
- isSpecPragmaId,
-
+ idInlinePragma, setInlinePragma, modifyInlinePragma,
- isRecordSelector,
- isPrimitiveId_maybe, isDataConId_maybe,
- isConstantId,
- isBottomingId, idAppIsBottom,
+
+ -- One shot lambda stuff
+ isOneShotBndr, isOneShotLambda, isStateHackType,
+ setOneShotLambda, clearOneShotLambda,
-- IdInfo stuff
setIdUnfolding,
setIdArity,
- setIdDemandInfo,
- setIdStrictness,
+ setIdNewDemandInfo,
+ setIdNewStrictness, zapIdNewStrictness,
+ setIdWorkerInfo,
setIdSpecialisation,
- setIdUpdateInfo,
setIdCafInfo,
-
- getIdArity,
- getIdDemandInfo,
- getIdStrictness,
- getIdUnfolding,
- getIdSpecialisation,
- getIdUpdateInfo,
- getIdCafInfo
+ setIdOccInfo,
+
+#ifdef OLD_STRICTNESS
+ idDemandInfo,
+ idStrictness,
+ idCprInfo,
+ setIdStrictness,
+ setIdDemandInfo,
+ setIdCprInfo,
+#endif
+
+ idArity,
+ idNewDemandInfo, idNewDemandInfo_maybe,
+ idNewStrictness, idNewStrictness_maybe,
+ idWorkerInfo,
+ idUnfolding,
+ idSpecialisation, idCoreRules,
+ idCafInfo,
+ idLBVarInfo,
+ idOccInfo,
+
+#ifdef OLD_STRICTNESS
+ newStrictnessFromOld -- Temporary
+#endif
) where
#include "HsVersions.h"
-import {-# SOURCE #-} CoreUnfold ( Unfolding )
-import Var ( Id, DictId, VarDetails(..),
- isId, mkId,
- idName, idType, idUnique, idInfo, idDetails,
- setIdName, setVarType, setIdUnique, setIdInfo, modifyIdInfo,
- externallyVisibleId
+import CoreSyn ( Unfolding, CoreRule )
+import BasicTypes ( Arity )
+import Var ( Id, DictId,
+ isId, isExportedId, isLocalId,
+ idName, idType, idUnique, idInfo, isGlobalId,
+ setIdName, setIdType, setIdUnique,
+ setIdExported, setIdNotExported,
+ setIdInfo, lazySetIdInfo, modifyIdInfo,
+ maybeModifyIdInfo,
+ globalIdDetails
)
-import VarSet
-import Type ( Type, tyVarsOfType, typePrimRep, addFreeTyVars )
-import IdInfo
-import Demand ( Demand )
-import Name ( Name, OccName,
- mkSysLocalName, mkLocalName,
- isWiredInName
- )
-import Const ( Con(..) )
-import PrimRep ( PrimRep )
-import PrimOp ( PrimOp )
-import FieldLabel ( FieldLabel(..) )
+import qualified Var ( mkLocalId, mkGlobalId, mkExportedLocalId )
+import TyCon ( FieldLabel, TyCon )
+import Type ( Type, typePrimRep, addFreeTyVars, seqType,
+ splitTyConApp_maybe, PrimRep )
+import TcType ( isDictTy )
+import TysPrim ( statePrimTyCon )
+import IdInfo
+
+#ifdef OLD_STRICTNESS
+import qualified Demand ( Demand )
+#endif
+import DataCon ( DataCon, isUnboxedTupleCon )
+import NewDemand ( Demand, StrictSig, topDmd, topSig, isBottomingSig )
+import Name ( Name, OccName, nameIsLocalOrFrom,
+ mkSystemVarName, mkInternalName, getOccName,
+ getSrcLoc )
+import Module ( Module )
+import OccName ( mkWorkerOcc )
+import Maybes ( orElse )
import SrcLoc ( SrcLoc )
-import Unique ( Unique, mkBuiltinUnique, getBuiltinUniques )
import Outputable
+import Unique ( Unique, mkBuiltinUnique )
+import FastString ( FastString )
+import StaticFlags ( opt_NoStateHack )
+-- infixl so you can say (id `set` a `set` b)
infixl 1 `setIdUnfolding`,
`setIdArity`,
- `setIdDemandInfo`,
- `setIdStrictness`,
+ `setIdNewDemandInfo`,
+ `setIdNewStrictness`,
+ `setIdWorkerInfo`,
`setIdSpecialisation`,
- `setIdUpdateInfo`,
- `setInlinePragma`
- -- infixl so you can say (id `set` a `set` b)
+ `setInlinePragma`,
+ `idCafInfo`
+#ifdef OLD_STRICTNESS
+ ,`idCprInfo`
+ ,`setIdStrictness`
+ ,`setIdDemandInfo`
+#endif
\end{code}
%* *
%************************************************************************
+Absolutely all Ids are made by mkId. It is just like Var.mkId,
+but in addition it pins free-tyvar-info onto the Id's type,
+where it can easily be found.
+
\begin{code}
-mkVanillaId :: Name -> Type -> Id
-mkVanillaId name ty = mkId name (addFreeTyVars ty) VanillaId noIdInfo
+mkLocalIdWithInfo :: Name -> Type -> IdInfo -> Id
+mkLocalIdWithInfo name ty info = Var.mkLocalId name (addFreeTyVars ty) info
-mkImportedId :: Name -> Type -> IdInfo -> Id
-mkImportedId name ty info = mkId name (addFreeTyVars ty) VanillaId info
+mkExportedLocalId :: Name -> Type -> Id
+mkExportedLocalId name ty = Var.mkExportedLocalId name (addFreeTyVars ty) vanillaIdInfo
-mkUserId :: Name -> Type -> Id
-mkUserId name ty = mkVanillaId name ty
+mkGlobalId :: GlobalIdDetails -> Name -> Type -> IdInfo -> Id
+mkGlobalId details name ty info = Var.mkGlobalId details name (addFreeTyVars ty) info
+\end{code}
+
+\begin{code}
+mkLocalId :: Name -> Type -> Id
+mkLocalId name ty = mkLocalIdWithInfo name ty vanillaIdInfo
-- SysLocal: for an Id being created by the compiler out of thin air...
-- UserLocal: an Id with a name the user might recognize...
-mkUserLocal :: OccName -> Unique -> Type -> SrcLoc -> Id
-mkSysLocal :: FAST_STRING -> Unique -> Type -> Id
+mkUserLocal :: OccName -> Unique -> Type -> SrcLoc -> Id
+mkSysLocal :: FastString -> Unique -> Type -> Id
+mkVanillaGlobal :: Name -> Type -> IdInfo -> Id
+
+mkSysLocal fs uniq ty = mkLocalId (mkSystemVarName uniq fs) ty
-mkSysLocal fs uniq ty = mkVanillaId (mkSysLocalName uniq fs) ty
-mkUserLocal occ uniq ty loc = mkVanillaId (mkLocalName uniq occ loc) ty
+mkUserLocal occ uniq ty loc = mkLocalId (mkInternalName uniq occ loc) ty
+mkVanillaGlobal = mkGlobalId VanillaGlobal
\end{code}
Make some local @Ids@ for a template @CoreExpr@. These have bogus
@Uniques@, but that's OK because the templates are supposed to be
instantiated before use.
-
+
\begin{code}
-- "Wild Id" typically used when you need a binder that you don't expect to use
mkWildId :: Type -> Id
-mkWildId ty = mkSysLocal SLIT("wild") (mkBuiltinUnique 1) ty
+mkWildId ty = mkSysLocal FSLIT("wild") (mkBuiltinUnique 1) ty
+
+mkWorkerId :: Unique -> Id -> Type -> Id
+-- A worker gets a local name. CoreTidy will externalise it if necessary.
+mkWorkerId uniq unwrkr ty
+ = mkLocalId wkr_name ty
+ where
+ wkr_name = mkInternalName uniq (mkWorkerOcc (getOccName unwrkr)) (getSrcLoc unwrkr)
-- "Template locals" typically used in unfoldings
mkTemplateLocals :: [Type] -> [Id]
-mkTemplateLocals tys = zipWith (mkSysLocal SLIT("tpl"))
- (getBuiltinUniques (length tys))
- tys
+mkTemplateLocals tys = zipWith mkTemplateLocal [1..] tys
+
+mkTemplateLocalsNum :: Int -> [Type] -> [Id]
+-- The Int gives the starting point for unique allocation
+mkTemplateLocalsNum n tys = zipWith mkTemplateLocal [n..] tys
+
+mkTemplateLocal :: Int -> Type -> Id
+mkTemplateLocal i ty = mkSysLocal FSLIT("tpl") (mkBuiltinUnique i) ty
\end{code}
%************************************************************************
\begin{code}
-idFreeTyVars :: Id -> TyVarSet
-idFreeTyVars id = tyVarsOfType (idType id)
-
setIdType :: Id -> Type -> Id
-- Add free tyvar info to the type
-setIdType id ty = setVarType id (addFreeTyVars ty)
+setIdType id ty = seqType ty `seq` Var.setIdType id (addFreeTyVars ty)
idPrimRep :: Id -> PrimRep
idPrimRep id = typePrimRep (idType id)
\end{code}
-omitIfaceSigForId tells whether an Id's info is implied by other declarations,
-so we don't need to put its signature in an interface file, even if it's mentioned
-in some other interface unfolding.
-
-\begin{code}
-omitIfaceSigForId :: Id -> Bool
-omitIfaceSigForId id
- | isWiredInName (idName id)
- = True
-
- | otherwise
- = case idDetails id of
- RecordSelId _ -> True -- Includes dictionary selectors
- ConstantId _ -> True
- -- ConstantIds are implied by their type or class decl;
- -- remember that all type and class decls appear in the interface file.
- -- The dfun id must *not* be omitted, because it carries version info for
- -- the instance decl
-
- other -> False -- Don't omit!
-\end{code}
%************************************************************************
%* *
%************************************************************************
\begin{code}
-recordSelectorFieldLabel :: Id -> FieldLabel
-recordSelectorFieldLabel id = case idDetails id of
- RecordSelId lbl -> lbl
+recordSelectorFieldLabel :: Id -> (TyCon, FieldLabel)
+recordSelectorFieldLabel id = case globalIdDetails id of
+ RecordSelId tycon lbl _ -> (tycon,lbl)
+ other -> panic "recordSelectorFieldLabel"
-isRecordSelector id = case idDetails id of
- RecordSelId lbl -> True
+isRecordSelector id = case globalIdDetails id of
+ RecordSelId {} -> True
other -> False
-isPrimitiveId_maybe id = case idDetails id of
- ConstantId (PrimOp op) -> Just op
- other -> Nothing
+isNaughtyRecordSelector id = case globalIdDetails id of
+ RecordSelId { sel_naughty = n } -> n
+ other -> False
+
+isClassOpId_maybe id = case globalIdDetails id of
+ ClassOpId cls -> Just cls
+ _other -> Nothing
+
+isPrimOpId id = case globalIdDetails id of
+ PrimOpId op -> True
+ other -> False
-isDataConId_maybe id = case idDetails id of
- ConstantId (DataCon con) -> Just con
- other -> Nothing
+isPrimOpId_maybe id = case globalIdDetails id of
+ PrimOpId op -> Just op
+ other -> Nothing
-isConstantId id = case idDetails id of
- ConstantId _ -> True
+isFCallId id = case globalIdDetails id of
+ FCallId call -> True
other -> False
+
+isFCallId_maybe id = case globalIdDetails id of
+ FCallId call -> Just call
+ other -> Nothing
+
+isDataConWorkId id = case globalIdDetails id of
+ DataConWorkId _ -> True
+ other -> False
+
+isDataConWorkId_maybe id = case globalIdDetails id of
+ DataConWorkId con -> Just con
+ other -> Nothing
+
+isDataConId_maybe :: Id -> Maybe DataCon
+isDataConId_maybe id = case globalIdDetails id of
+ DataConWorkId con -> Just con
+ DataConWrapId con -> Just con
+ other -> Nothing
+
+idDataCon :: Id -> DataCon
+-- Get from either the worker or the wrapper to the DataCon
+-- Currently used only in the desugarer
+-- INVARIANT: idDataCon (dataConWrapId d) = d
+-- (Remember, dataConWrapId can return either the wrapper or the worker.)
+idDataCon id = case globalIdDetails id of
+ DataConWorkId con -> con
+ DataConWrapId con -> con
+ other -> pprPanic "idDataCon" (ppr id)
+
+
+isDictId :: Id -> Bool
+isDictId id = isDictTy (idType id)
+
+-- hasNoBinding returns True of an Id which may not have a
+-- binding, even though it is defined in this module.
+-- Data constructor workers used to be things of this kind, but
+-- they aren't any more. Instead, we inject a binding for
+-- them at the CorePrep stage.
+-- EXCEPT: unboxed tuples, which definitely have no binding
+hasNoBinding id = case globalIdDetails id of
+ PrimOpId _ -> True
+ FCallId _ -> True
+ DataConWorkId dc -> isUnboxedTupleCon dc
+ other -> False
+
+isImplicitId :: Id -> Bool
+ -- isImplicitId tells whether an Id's info is implied by other
+ -- declarations, so we don't need to put its signature in an interface
+ -- file, even if it's mentioned in some other interface unfolding.
+isImplicitId id
+ = case globalIdDetails id of
+ RecordSelId {} -> True
+ FCallId _ -> True
+ PrimOpId _ -> True
+ ClassOpId _ -> True
+ DataConWorkId _ -> True
+ DataConWrapId _ -> True
+ -- These are are implied by their type or class decl;
+ -- remember that all type and class decls appear in the interface file.
+ -- The dfun id is not an implicit Id; it must *not* be omitted, because
+ -- it carries version info for the instance decl
+ other -> False
+
+idIsFrom :: Module -> Id -> Bool
+idIsFrom mod id = nameIsLocalOrFrom mod (idName id)
+\end{code}
+
+\begin{code}
+isDeadBinder :: Id -> Bool
+isDeadBinder bndr | isId bndr = isDeadOcc (idOccInfo bndr)
+ | otherwise = False -- TyVars count as not dead
\end{code}
\begin{code}
---------------------------------
-- ARITY
-getIdArity :: Id -> ArityInfo
-getIdArity id = arityInfo (idInfo id)
+idArity :: Id -> Arity
+idArity id = arityInfo (idInfo id)
-setIdArity :: Id -> ArityInfo -> Id
-setIdArity id arity = modifyIdInfo id (arity `setArityInfo`)
+setIdArity :: Id -> Arity -> Id
+setIdArity id arity = modifyIdInfo (`setArityInfo` arity) id
+#ifdef OLD_STRICTNESS
---------------------------------
- -- STRICTNESS
-getIdStrictness :: Id -> StrictnessInfo
-getIdStrictness id = strictnessInfo (idInfo id)
+ -- (OLD) STRICTNESS
+idStrictness :: Id -> StrictnessInfo
+idStrictness id = strictnessInfo (idInfo id)
setIdStrictness :: Id -> StrictnessInfo -> Id
-setIdStrictness id strict_info = modifyIdInfo id (strict_info `setStrictnessInfo`)
+setIdStrictness id strict_info = modifyIdInfo (`setStrictnessInfo` strict_info) id
+#endif
-- isBottomingId returns true if an application to n args would diverge
isBottomingId :: Id -> Bool
-isBottomingId id = isBottomingStrictness (strictnessInfo (idInfo id))
+isBottomingId id = isBottomingSig (idNewStrictness id)
-idAppIsBottom :: Id -> Int -> Bool
-idAppIsBottom id n = appIsBottom (strictnessInfo (idInfo id)) n
+idNewStrictness_maybe :: Id -> Maybe StrictSig
+idNewStrictness :: Id -> StrictSig
+
+idNewStrictness_maybe id = newStrictnessInfo (idInfo id)
+idNewStrictness id = idNewStrictness_maybe id `orElse` topSig
+
+setIdNewStrictness :: Id -> StrictSig -> Id
+setIdNewStrictness id sig = modifyIdInfo (`setNewStrictnessInfo` Just sig) id
+
+zapIdNewStrictness :: Id -> Id
+zapIdNewStrictness id = modifyIdInfo (`setNewStrictnessInfo` Nothing) id
+
+ ---------------------------------
+ -- WORKER ID
+idWorkerInfo :: Id -> WorkerInfo
+idWorkerInfo id = workerInfo (idInfo id)
+
+setIdWorkerInfo :: Id -> WorkerInfo -> Id
+setIdWorkerInfo id work_info = modifyIdInfo (`setWorkerInfo` work_info) id
---------------------------------
-- UNFOLDING
-getIdUnfolding :: Id -> Unfolding
-getIdUnfolding id = unfoldingInfo (idInfo id)
+idUnfolding :: Id -> Unfolding
+idUnfolding id = unfoldingInfo (idInfo id)
setIdUnfolding :: Id -> Unfolding -> Id
-setIdUnfolding id unfolding = modifyIdInfo id (unfolding `setUnfoldingInfo`)
+setIdUnfolding id unfolding = modifyIdInfo (`setUnfoldingInfo` unfolding) id
+#ifdef OLD_STRICTNESS
---------------------------------
- -- DEMAND
-getIdDemandInfo :: Id -> Demand
-getIdDemandInfo id = demandInfo (idInfo id)
+ -- (OLD) DEMAND
+idDemandInfo :: Id -> Demand.Demand
+idDemandInfo id = demandInfo (idInfo id)
-setIdDemandInfo :: Id -> Demand -> Id
-setIdDemandInfo id demand_info = modifyIdInfo id (demand_info `setDemandInfo`)
+setIdDemandInfo :: Id -> Demand.Demand -> Id
+setIdDemandInfo id demand_info = modifyIdInfo (`setDemandInfo` demand_info) id
+#endif
- ---------------------------------
- -- UPDATE INFO
-getIdUpdateInfo :: Id -> UpdateInfo
-getIdUpdateInfo id = updateInfo (idInfo id)
+idNewDemandInfo_maybe :: Id -> Maybe NewDemand.Demand
+idNewDemandInfo :: Id -> NewDemand.Demand
-setIdUpdateInfo :: Id -> UpdateInfo -> Id
-setIdUpdateInfo id upd_info = modifyIdInfo id (upd_info `setUpdateInfo`)
+idNewDemandInfo_maybe id = newDemandInfo (idInfo id)
+idNewDemandInfo id = newDemandInfo (idInfo id) `orElse` NewDemand.topDmd
+
+setIdNewDemandInfo :: Id -> NewDemand.Demand -> Id
+setIdNewDemandInfo id dmd = modifyIdInfo (`setNewDemandInfo` Just dmd) id
---------------------------------
-- SPECIALISATION
-getIdSpecialisation :: Id -> IdSpecEnv
-getIdSpecialisation id = specInfo (idInfo id)
+idSpecialisation :: Id -> SpecInfo
+idSpecialisation id = specInfo (idInfo id)
+
+idCoreRules :: Id -> [CoreRule]
+idCoreRules id = specInfoRules (idSpecialisation id)
-setIdSpecialisation :: Id -> IdSpecEnv -> Id
-setIdSpecialisation id spec_info = modifyIdInfo id (spec_info `setSpecInfo`)
+setIdSpecialisation :: Id -> SpecInfo -> Id
+setIdSpecialisation id spec_info = modifyIdInfo (`setSpecInfo` spec_info) id
---------------------------------
-- CAF INFO
-getIdCafInfo :: Id -> CafInfo
-getIdCafInfo id = cafInfo (idInfo id)
+idCafInfo :: Id -> CafInfo
+#ifdef OLD_STRICTNESS
+idCafInfo id = case cgInfo (idInfo id) of
+ NoCgInfo -> pprPanic "idCafInfo" (ppr id)
+ info -> cgCafInfo info
+#else
+idCafInfo id = cafInfo (idInfo id)
+#endif
setIdCafInfo :: Id -> CafInfo -> Id
-setIdCafInfo id caf_info = modifyIdInfo id (caf_info `setCafInfo`)
+setIdCafInfo id caf_info = modifyIdInfo (`setCafInfo` caf_info) id
+
+ ---------------------------------
+ -- CPR INFO
+#ifdef OLD_STRICTNESS
+idCprInfo :: Id -> CprInfo
+idCprInfo id = cprInfo (idInfo id)
+
+setIdCprInfo :: Id -> CprInfo -> Id
+setIdCprInfo id cpr_info = modifyIdInfo (`setCprInfo` cpr_info) id
+#endif
+
+ ---------------------------------
+ -- Occcurrence INFO
+idOccInfo :: Id -> OccInfo
+idOccInfo id = occInfo (idInfo id)
+
+setIdOccInfo :: Id -> OccInfo -> Id
+setIdOccInfo id occ_info = modifyIdInfo (`setOccInfo` occ_info) id
\end{code}
OK not to if optimisation is switched off.
\begin{code}
-getInlinePragma :: Id -> InlinePragInfo
-getInlinePragma id = inlinePragInfo (idInfo id)
+idInlinePragma :: Id -> InlinePragInfo
+idInlinePragma id = inlinePragInfo (idInfo id)
setInlinePragma :: Id -> InlinePragInfo -> Id
-setInlinePragma id prag = modifyIdInfo id (setInlinePragInfo prag)
+setInlinePragma id prag = modifyIdInfo (`setInlinePragInfo` prag) id
modifyInlinePragma :: Id -> (InlinePragInfo -> InlinePragInfo) -> Id
-modifyInlinePragma id fn = modifyIdInfo id (\info -> setInlinePragInfo (fn (inlinePragInfo info)) info)
-
-idWantsToBeINLINEd :: Id -> Bool
-idWantsToBeINLINEd id = case getInlinePragma id of
- IWantToBeINLINEd -> True
- IMustBeINLINEd -> True
- other -> False
-
-idMustNotBeINLINEd id = case getInlinePragma id of
- IMustNotBeINLINEd -> True
- IAmASpecPragmaId -> True
- IAmALoopBreaker -> True
- other -> False
-
-idMustBeINLINEd id = case getInlinePragma id of
- IMustBeINLINEd -> True
- other -> False
-
-isSpecPragmaId id = case getInlinePragma id of
- IAmASpecPragmaId -> True
- other -> False
+modifyInlinePragma id fn = modifyIdInfo (\info -> info `setInlinePragInfo` (fn (inlinePragInfo info))) id
\end{code}
+
+
+ ---------------------------------
+ -- ONE-SHOT LAMBDAS
+\begin{code}
+idLBVarInfo :: Id -> LBVarInfo
+idLBVarInfo id = lbvarInfo (idInfo id)
+
+isOneShotBndr :: Id -> Bool
+-- This one is the "business end", called externally.
+-- Its main purpose is to encapsulate the Horrible State Hack
+isOneShotBndr id = isOneShotLambda id || (isStateHackType (idType id))
+
+isStateHackType :: Type -> Bool
+isStateHackType ty
+ | opt_NoStateHack
+ = False
+ | otherwise
+ = case splitTyConApp_maybe ty of
+ Just (tycon,_) -> tycon == statePrimTyCon
+ other -> False
+ -- This is a gross hack. It claims that
+ -- every function over realWorldStatePrimTy is a one-shot
+ -- function. This is pretty true in practice, and makes a big
+ -- difference. For example, consider
+ -- a `thenST` \ r -> ...E...
+ -- The early full laziness pass, if it doesn't know that r is one-shot
+ -- will pull out E (let's say it doesn't mention r) to give
+ -- let lvl = E in a `thenST` \ r -> ...lvl...
+ -- When `thenST` gets inlined, we end up with
+ -- let lvl = E in \s -> case a s of (r, s') -> ...lvl...
+ -- and we don't re-inline E.
+ --
+ -- It would be better to spot that r was one-shot to start with, but
+ -- I don't want to rely on that.
+ --
+ -- Another good example is in fill_in in PrelPack.lhs. We should be able to
+ -- spot that fill_in has arity 2 (and when Keith is done, we will) but we can't yet.
+
+
+-- The OneShotLambda functions simply fiddle with the IdInfo flag
+isOneShotLambda :: Id -> Bool
+isOneShotLambda id = case idLBVarInfo id of
+ IsOneShotLambda -> True
+ NoLBVarInfo -> False
+
+setOneShotLambda :: Id -> Id
+setOneShotLambda id = modifyIdInfo (`setLBVarInfo` IsOneShotLambda) id
+
+clearOneShotLambda :: Id -> Id
+clearOneShotLambda id
+ | isOneShotLambda id = modifyIdInfo (`setLBVarInfo` NoLBVarInfo) id
+ | otherwise = id
+
+-- But watch out: this may change the type of something else
+-- f = \x -> e
+-- If we change the one-shot-ness of x, f's type changes
+\end{code}
+
+\begin{code}
+zapLamIdInfo :: Id -> Id
+zapLamIdInfo id = maybeModifyIdInfo zapLamInfo id
+
+zapDemandIdInfo id = maybeModifyIdInfo zapDemandInfo id
+\end{code}
+
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