\begin{code}
module NewDemand(
- Demand(..), Keepity(..), Deferredness(..),
- topDmd, lazyDmd, seqDmd, evalDmd, isStrictDmd, isAbsentDmd,
+ Demand(..), Keepity(..),
+ mkSeq, topDmd, lazyDmd, seqDmd, evalDmd, isStrictDmd, defer,
- DmdType(..), topDmdType, mkDmdType, mkTopDmdType,
+ DmdType(..), topDmdType, botDmdType, mkDmdType, mkTopDmdType,
dmdTypeDepth, dmdTypeRes,
DmdEnv, emptyDmdEnv,
DmdResult(..), isBotRes, returnsCPR,
#include "HsVersions.h"
import BasicTypes ( Arity )
-import Var ( Id )
import VarEnv ( VarEnv, emptyVarEnv )
import UniqFM ( ufmToList )
-import qualified Demand
import Outputable
\end{code}
instance Show StrictSig where
show (StrictSig ty) = showSDoc (ppr ty)
-mkStrictSig :: Id -> Arity -> DmdType -> StrictSig
-mkStrictSig id arity dmd_ty
- = WARN( arity /= dmdTypeDepth dmd_ty, ppr id <+> (ppr arity $$ ppr dmd_ty) )
- StrictSig dmd_ty
+mkStrictSig :: DmdType -> StrictSig
+mkStrictSig dmd_ty = StrictSig dmd_ty
splitStrictSig :: StrictSig -> ([Demand], DmdResult)
splitStrictSig (StrictSig (DmdType _ dmds res)) = (dmds, res)
= Lazy -- L; used for unlifted types too, so that
-- A `lub` L = L
| Abs -- A
+
| Call Demand -- C(d)
| Eval -- V
- | Seq Keepity -- S/U(ds)
- Deferredness
- [Demand]
+ | Seq Keepity -- S/U/D(ds)
+ [Demand] -- S(ds) = L `both` U(ds)
+ -- D(ds) = A `lub` U(ds)
+ -- *** Invariant: these demands are never Bot or Abs
+ -- *** Invariant: if all demands are Abs, get []
+
| Err -- X
| Bot -- B
deriving( Eq )
-- Equality needed for fixpoints in DmdAnal
-data Deferredness = Now | Defer
- deriving( Eq )
-
-data Keepity = Keep | Drop
+data Keepity = Keep | Drop | Defer
deriving( Eq )
+mkSeq :: Keepity -> [Demand] -> Demand
+mkSeq k ds | all is_absent ds = Seq k []
+ | otherwise = Seq k ds
+ where
+ is_absent Abs = True
+ is_absent d = False
+
+defer :: Demand -> Demand
+-- Computes (Abs `lub` d)
+-- For the Bot case consider
+-- f x y = if ... then x else error x
+-- Then for y we get Abs `lub` Bot, and we really
+-- want Abs overall
+defer Bot = Abs
+defer Abs = Abs
+defer (Seq Keep ds) = Lazy
+defer (Seq _ ds) = Seq Defer ds
+defer d = Lazy
+
topDmd, lazyDmd, seqDmd :: Demand
-topDmd = Lazy -- The most uninformative demand
+topDmd = Lazy -- The most uninformative demand
lazyDmd = Lazy
-seqDmd = Seq Keep Now [] -- Polymorphic seq demand
+seqDmd = Seq Keep [] -- Polymorphic seq demand
evalDmd = Eval
isStrictDmd :: Demand -> Bool
-isStrictDmd Bot = True
-isStrictDmd Err = True
-isStrictDmd (Seq _ Now _) = True
-isStrictDmd Eval = True
-isStrictDmd (Call _) = True
-isStrictDmd other = False
-
-isAbsentDmd :: Demand -> Bool
-isAbsentDmd Bot = True
-isAbsentDmd Err = True
-isAbsentDmd Abs = True
-isAbsentDmd other = False
+isStrictDmd Bot = True
+isStrictDmd Err = True
+isStrictDmd (Seq _ _) = True
+isStrictDmd Eval = True
+isStrictDmd (Call _) = True
+isStrictDmd other = False
instance Outputable Demand where
- ppr Lazy = char 'L'
- ppr Abs = char 'A'
- ppr Eval = char 'V'
- ppr Err = char 'X'
- ppr Bot = char 'B'
- ppr (Call d) = char 'C' <> parens (ppr d)
- ppr (Seq k l []) = ppr k <> ppr l
- ppr (Seq k l ds) = ppr k <> ppr l <> parens (hcat (map ppr ds))
-
-instance Outputable Deferredness where
- ppr Now = empty
- ppr Defer = char '*'
+ ppr Lazy = char 'L'
+ ppr Abs = char 'A'
+ ppr Eval = char 'V'
+ ppr Err = char 'X'
+ ppr Bot = char 'B'
+ ppr (Call d) = char 'C' <> parens (ppr d)
+ ppr (Seq k []) = ppr k
+ ppr (Seq k ds) = ppr k <> parens (hcat (map ppr ds))
instance Outputable Keepity where
- ppr Keep = char 'S'
- ppr Drop = char 'U'
+ ppr Keep = char 'S'
+ ppr Drop = char 'U'
+ ppr Defer = char 'D'
\end{code}
-----------------
\begin{code}
-module DmdAnal ( dmdAnalPgm, both {- needed by WwLib -} ) where
+module DmdAnal ( dmdAnalPgm, dmdAnalTopRhs,
+ both {- needed by WwLib -}
+ ) where
#include "HsVersions.h"
import CmdLineOpts ( DynFlags, DynFlag(..), opt_MaxWorkerArgs )
import NewDemand -- All of it
import CoreSyn
+import PprCore
import CoreUtils ( exprIsValue, exprArity )
import DataCon ( dataConTyCon )
import TyCon ( isProductTyCon, isRecursiveTyCon )
-import Id ( Id, idType, idDemandInfo,
+import Id ( Id, idType, idDemandInfo,
isDataConId, isImplicitId, isGlobalId,
idNewStrictness, idNewStrictness_maybe, getNewStrictness, setIdNewStrictness,
idNewDemandInfo, setIdNewDemandInfo, newStrictnessFromOld )
(sigs', Rec pairs')
\end{code}
+\begin{code}
+dmdAnalTopRhs :: CoreExpr -> (StrictSig, CoreExpr)
+-- Analyse the RHS and return
+-- a) appropriate strictness info
+-- b) the unfolding (decorated with stricntess info)
+dmdAnalTopRhs rhs
+ = (sig, rhs')
+ where
+ arity = exprArity rhs
+ (rhs_ty, rhs') = dmdAnal emptySigEnv (vanillaCall arity) rhs
+ (_, sig) = mkSigTy rhs rhs_ty
+\end{code}
%************************************************************************
%* *
dmdAnal :: SigEnv -> Demand -> CoreExpr -> (DmdType, CoreExpr)
dmdAnal sigs Abs e = (topDmdType, e)
+dmdAnal sigs Bot e = (botDmdType, e)
dmdAnal sigs Lazy e = let
(res_ty, e') = dmdAnal sigs Eval e
-- The insight is, of course, that a demand on y is a demand on the
-- scrutinee, so we need to `both` it with the scrut demand
- scrut_dmd = Seq Drop Now [idNewDemandInfo b | b <- bndrs', isId b]
+ scrut_dmd = mkSeq Drop [idNewDemandInfo b | b <- bndrs', isId b]
`both`
idNewDemandInfo case_bndr'
-> [(Id,CoreExpr)]
-> (SigEnv, DmdEnv, [(Id,CoreExpr)])
loop n sigs pairs
- | all (same_sig sigs sigs') bndrs = (sigs', lazy_fv, pairs')
+ | all (same_sig sigs sigs') bndrs
+ = (sigs', lazy_fv, pairs')
-- Note: use pairs', not pairs. pairs' is the result of
-- processing the RHSs with sigs (= sigs'), whereas pairs
-- is the result of processing the RHSs with the *previous*
-- iteration of sigs.
- | n >= 5 = pprTrace "dmdFix" (ppr n <+> (vcat
+ | n >= 5 = pprTrace "dmdFix loop" (ppr n <+> (vcat
[ text "Sigs:" <+> ppr [(id,lookup sigs id, lookup sigs' id) | (id,_) <- pairs],
text "env:" <+> ppr (ufmToList sigs),
- text "binds:" <+> ppr pairs]))
+ text "binds:" <+> pprCoreBinding (Rec pairs)]))
(loop (n+1) sigs' pairs')
- | otherwise = {- pprTrace "dmdFixLoop" (ppr id_sigs) -} (loop (n+1) sigs' pairs')
+ | otherwise = loop (n+1) sigs' pairs'
where
-- Use the new signature to do the next pair
-- The occurrence analyser has arranged them in a good order
where
arity = exprArity rhs -- The idArity may not be up to date
(rhs_ty, rhs') = dmdAnal sigs (vanillaCall arity) rhs
- (lazy_fv, sig_ty) = mkSigTy id arity rhs rhs_ty
+ (lazy_fv, sig_ty) = WARN( arity /= dmdTypeDepth rhs_ty, ppr id )
+ mkSigTy rhs rhs_ty
id' = id `setIdNewStrictness` sig_ty
sigs' = extendSigEnv top_lvl sigs id sig_ty
\end{code}
%************************************************************************
\begin{code}
-mkSigTy :: Id -> Arity -> CoreExpr -> DmdType -> (DmdEnv, StrictSig)
+mkSigTy :: CoreExpr -> DmdType -> (DmdEnv, StrictSig)
-- Take a DmdType and turn it into a StrictSig
-mkSigTy id arity rhs (DmdType fv dmds res)
- = (lazy_fv, mkStrictSig id arity dmd_ty)
+mkSigTy rhs (DmdType fv dmds res)
+ = (lazy_fv, mkStrictSig dmd_ty)
where
dmd_ty = DmdType strict_fv final_dmds res'
-- DmdType, because that makes fixpointing very slow --- the
-- DmdType gets full of lazy demands that are slow to converge.
- lazified_dmds = map lazify dmds
+ lazified_dmds = map funArgDemand dmds
-- Get rid of defers in the arguments
final_dmds = setUnpackStrategy lazified_dmds
-- Set the unpacking strategy
- res' = case (dmds, res) of
- ([], RetCPR) | not (exprIsValue rhs) -> TopRes
- other -> res
+ res' = case res of
+ RetCPR | not (exprIsValue rhs) -> TopRes
+ other -> res
-- If the rhs is a thunk, we forget the CPR info, because
-- it is presumably shared (else it would have been inlined, and
-- so we'd lose sharing if w/w'd it into a function.
-> [Demand]
-> (Int, [Demand]) -- Args remaining after subcomponents of [Demand] are unpacked
- go n (Seq keep _ cs : ds)
- | n' >= 0 = Seq keep Now cs' `cons` go n'' ds
+ go n (Seq keep cs : ds)
+ | n' >= 0 = Seq keep cs' `cons` go n'' ds
| otherwise = Eval `cons` go n ds
where
(n'',cs') = go n' cs
splitDmdTy :: DmdType -> (Demand, DmdType)
-- Split off one function argument
splitDmdTy (DmdType fv (dmd:dmds) res_ty) = (dmd, DmdType fv dmds res_ty)
-splitDmdTy ty@(DmdType fv [] TopRes) = (topDmd, ty)
-splitDmdTy ty@(DmdType fv [] BotRes) = (Abs, ty)
+splitDmdTy ty@(DmdType fv [] TopRes) = (Lazy, ty)
+splitDmdTy ty@(DmdType fv [] BotRes) = (Bot, ty)
+ -- NB: Bot not Abs
+splitDmdTy (DmdType fv [] RetCPR) = panic "splitDmdTy"
-- We already have a suitable demand on all
-- free vars, so no need to add more!
-splitDmdTy (DmdType fv [] RetCPR) = panic "splitDmdTy"
\end{code}
\begin{code}
| otherwise = DmdType (extendVarEnv fv var dmd) ds res
addLazyFVs (DmdType fv ds res) lazy_fvs
- = DmdType (plusUFM_C both fv lazy_fvs) ds res
+ = DmdType both_fv1 ds res
+ where
+ both_fv = (plusUFM_C both fv lazy_fvs)
+ both_fv1 = modifyEnv (isBotRes res) (`both` Bot) lazy_fvs fv both_fv
+ -- This modifyEnv is vital. Consider
+ -- let f = \x -> (x,y)
+ -- in error (f 3)
+ -- Here, y is treated as a lazy-fv of f, but we must `both` that L
+ -- demand with the bottom coming up from 'error'
+ --
+ -- I got a loop in the fixpointer without this, due to an interaction
+ -- with the lazy_fv filtering in mkSigTy. Roughly, it was
+ -- letrec f n x
+ -- = letrec g y = x `fatbar`
+ -- letrec h z = z + ...g...
+ -- in h (f (n-1) x)
+ -- in ...
+ -- In the initial iteration for f, f=Bot
+ -- Suppose h is found to be strict in z, but the occurrence of g in its RHS
+ -- is lazy. Now consider the fixpoint iteration for g, esp the demands it
+ -- places on its free variables. Suppose it places none. Then the
+ -- x `fatbar` ...call to h...
+ -- will give a x->V demand for x. That turns into a L demand for x,
+ -- which floats out of the defn for h. Without the modifyEnv, that
+ -- L demand doesn't get both'd with the Bot coming up from the inner
+ -- call to f. So we just get an L demand for x for g.
+ --
+ -- A better way to say this is that the lazy-fv filtering should give the
+ -- same answer as putting the lazy fv demands in the function's type.
annotateBndr :: DmdType -> Var -> (DmdType, Var)
-- The returned env has the var deleted
-- No effect on the argument demands
annotateBndr dmd_ty@(DmdType fv ds res) var
| isTyVar var = (dmd_ty, var)
- | otherwise = (DmdType fv' ds res, setIdNewDemandInfo var dmd)
+ | otherwise = (DmdType fv' ds res, setIdNewDemandInfo var hacked_dmd)
where
(fv', dmd) = removeFV fv var res
+ hacked_dmd | isUnLiftedType (idType var) = unliftedDemand dmd
+ | otherwise = dmd
annotateBndrs = mapAccumR annotateBndr
(DmdType fv' (hacked_dmd:ds) res, setIdNewDemandInfo id hacked_dmd)
where
(fv', dmd) = removeFV fv id res
- hacked_dmd = case dmd of
- Bot -> Abs
- Err -> Abs
- other -> dmd
- -- This gross hack is needed because otherwise we label
+ hacked_dmd | isUnLiftedType (idType id) = unliftedDemand dmd
+ | otherwise = funArgDemand dmd
+ -- This call to funArgDemand is vital, because otherwise we label
-- a lambda binder with demand 'B'. But in terms of calling
-- conventions that's Abs, because we don't pass it. But
-- when we do a w/w split we get
------ DATA CONSTRUCTOR
| isDataConId var, -- Data constructor
- Seq k Now ds <- res_dmd, -- and the demand looks inside its fields
+ Seq k ds <- res_dmd, -- and the demand looks inside its fields
let StrictSig dmd_ty = idNewStrictness var, -- It must have a strictness sig
let DmdType _ con_ds con_res = dmd_ty
= if length con_ds == length ds then -- Saturated, so unleash the demand
-- ds can be empty, when we are just seq'ing the thing
let
arg_ds = case k of
- Keep -> zipWith lub ds con_ds
- Drop -> ds
+ Keep -> zipWith lub ds con_ds
+ Drop -> ds
+ Defer -> ds
-- Important! If we Keep the constructor application, then
-- we need the demands the constructor places (usually lazy)
-- If not, we don't need to. For example:
-- For example, f = let ... in \x -> x
-- We don't want to get a stricness type V->T for f.
-defer :: Demand -> Demand
-defer = lub Abs
+---------------
+bothLazy :: Demand -> Demand
+bothLazy = both Lazy
+bothLazy_s :: [Demand] -> [Demand]
+bothLazy_s = map bothLazy
-lazify :: Demand -> Demand
+funArgDemand :: Demand -> Demand
-- The 'Defer' demands are just Lazy at function boundaries
-- Ugly! Ask John how to improve it.
-lazify (Seq k Defer ds) = Lazy
-lazify (Seq k Now ds) = Seq k Now (map lazify ds)
-lazify Bot = Abs -- Don't pass args that are consumed by bottom/err
-lazify Err = Abs
-lazify d = d
+funArgDemand (Seq Defer ds) = Lazy
+funArgDemand (Seq k ds) = Seq k (map funArgDemand ds)
+funArgDemand Err = Eval -- Args passed to a bottoming function
+funArgDemand Bot = Abs -- Don't pass args that are consumed by bottom/err
+funArgDemand d = d
+
+unliftedDemand :: Demand -> Demand
+-- Same idea, but for unlifted types the domain is much simpler:
+-- Either we use it (Lazy) or we don't (Abs)
+unliftedDemand Bot = Abs
+unliftedDemand Abs = Abs
+unliftedDemand other = Lazy
\end{code}
\begin{code}
squashDmdEnv (StrictSig (DmdType fv ds res)) = StrictSig (DmdType emptyDmdEnv ds res)
\end{code}
-
-%************************************************************************
-%* *
-\subsection{LUB and BOTH}
-%* *
-%************************************************************************
-
\begin{code}
-lub :: Demand -> Demand -> Demand
-
-lub Bot d = d
-
-lub Lazy d = Lazy
-
-lub Err Bot = Err
-lub Err d = d
-
-lub Abs Bot = Abs -- E.g f x y = if ... then x else error x
- -- Then for y we get Abs `lub` Bot, and we really
- -- want Abs overall
-lub Abs Err = Abs
-lub Abs Abs = Abs
-lub Abs (Seq k _ ds) = Seq k Defer ds -- Very important ('radicals' example)
-lub Abs d = Lazy
-
-lub Eval Abs = Lazy
-lub Eval Lazy = Lazy
-
-lub Eval (Seq k Now ds) = Eval -- Urk! Is this monotonic?
- -- Was (incorrectly):
- -- lub Eval (Seq k Now ds) = Seq Keep Now ds
- -- Incorrect because
- -- Eval `lub` U(VV) is not S(VV)
- -- (because the components aren't necessarily evaluated)
- --
- -- Was (correctly, but pessimistically):
- -- lub Eval (Seq k Now ds) = Eval
- -- Pessimistic because
- -- f n [] = n
- -- f n (x:xs) = f (n+x) xs
- -- Here we want to do better than just V for n. It's
- -- unboxed in the (x:xs) case, and we might be prepared to
- -- rebox it in the [] case.
- -- To achieve this we could perhaps consider Eval to be equivalent to
- -- U(L), or S(A)
-
-lub Eval (Seq k Defer ds) = Lazy
-lub Eval d = Eval
-
-lub (Call d1) (Call d2) = Call (lub d1 d2)
-
-lub (Seq k1 l1 ds1) (Seq k2 l2 ds2) = Seq (k1 `vee` k2) (l1 `or_defer` l2) (lubs ds1 ds2)
-
--- The last clauses deal with the remaining cases for Call and Seq
-lub d1@(Call _) d2@(Seq _ _ _) = pprPanic "lub" (ppr d1 $$ ppr d2)
-lub d1 d2 = lub d2 d1
-
--- A Seq can have an empty list of demands, in the polymorphic case.
-lubs [] ds2 = ds2
-lubs ds1 [] = ds1
-lubs ds1 ds2 = ASSERT( length ds1 == length ds2 ) zipWith lub ds1 ds2
-
-or_defer Now Now = Now
-or_defer _ _ = Defer
-
-------------------------
-- Consider (if x then y else []) with demand V
-- Then the first branch gives {y->V} and the second
= DmdType lub_fv2 (zipWith lub ds1 ds2) (r1 `lubRes` r2)
where
lub_fv = plusUFM_C lub fv1 fv2
- lub_fv1 = modifyEnv (not (isBotRes r1)) (Abs `lub`) fv2 fv1 lub_fv
- lub_fv2 = modifyEnv (not (isBotRes r2)) (Abs `lub`) fv1 fv2 lub_fv1
+ lub_fv1 = modifyEnv (not (isBotRes r1)) defer fv2 fv1 lub_fv
+ lub_fv2 = modifyEnv (not (isBotRes r2)) defer fv1 fv2 lub_fv1
-- lub is the identity for Bot
--------------------------
+-----------------------------------
+-- (t1 `bothType` t2) takes the argument/result info from t1,
+-- using t2 just for its free-var info
+bothType (DmdType fv1 ds1 r1) (DmdType fv2 ds2 r2)
+ = DmdType both_fv2 ds1 (r1 `bothRes` r2)
+ where
+ both_fv = plusUFM_C both fv1 fv2
+ both_fv1 = modifyEnv (isBotRes r1) (`both` Bot) fv2 fv1 both_fv
+ both_fv2 = modifyEnv (isBotRes r2) (`both` Bot) fv1 fv2 both_fv1
+ -- both is the identity for Abs
+\end{code}
+
+
+\begin{code}
lubRes BotRes r = r
lubRes r BotRes = r
lubRes RetCPR RetCPR = RetCPR
lubRes r1 r2 = TopRes
------------------------------------
-vee :: Keepity -> Keepity -> Keepity
-vee Drop Drop = Drop
-vee k1 k2 = Keep
-
------------------------------------
-both :: Demand -> Demand -> Demand
-
--- The normal one
--- both Bot d = Bot
-
--- The experimental one
--- The idea is that (error x) places on x
--- both demand Bot (like on all free vars)
--- and demand Eval (for the arg to error)
--- and we want the result to be Eval.
-both Bot Bot = Bot
-both Bot Abs = Bot
-both Bot d = d
-
-both Abs d = d
+-- If either diverges, the whole thing does
+-- Otherwise take CPR info from the first
+bothRes BotRes r2 = BotRes
+bothRes r1 BotRes = BotRes
+bothRes r1 r2 = r1
+\end{code}
-both Err Bot = Err
-both Err Abs = Err
-both Err d = d
-
-both Lazy Bot = Lazy
-both Lazy Abs = Lazy
-both Lazy Err = Lazy
-both Lazy (Seq k l ds) = Seq Keep l ds
-both Lazy d = d
- -- Notice that the Seq case ensures that we have the
- -- boxed value. The equation originally said
- -- both (Seq k Now ds) = Seq Keep Now ds
- -- but it's important that the Keep is switched on even
- -- for a deferred demand. Otherwise a (Seq Drop Now [])
- -- might both'd with the result, and then we won't pass
- -- the boxed value. Here's an example:
- -- (x-1) `seq` (x+1, x)
- -- From the (x+1, x) we get (U*(V) `both` L), which must give S*(V)
- -- From (x-1) we get U(V). Combining, we must get S(V).
- -- If we got U*(V) from the pair, we'd end up with U(V), and that
- -- can be a disaster if a component of the data structure is absent.
- -- [Disaster = enter an absent argument.]
-
-both Eval (Seq k l ds) = Seq Keep Now ds
-both Eval (Call d) = Call d
-both Eval d = Eval
-
-both (Seq k1 Defer ds1) (Seq k2 Defer ds2) = Seq (k1 `vee` k2) Defer (boths ds1 ds2)
-both (Seq k1 l1 ds1) (Seq k2 l2 ds2) = Seq (k1 `vee` k2) Now (boths ds1' ds2')
- where
- ds1' = case l1 of { Now -> ds1; Defer -> map defer ds1 }
- ds2' = case l2 of { Now -> ds2; Defer -> map defer ds2 }
-
-both (Call d1) (Call d2) = Call (d1 `both` d2)
-
--- The last clauses deal with the remaining cases for Call and Seq
-both d1@(Call _) d2@(Seq _ _ _) = pprPanic "both" (ppr d1 $$ ppr d2)
-both d1 d2 = both d2 d1
+\begin{code}
+-- A Seq can have an empty list of demands, in the polymorphic case.
+lubs [] ds2 = ds2
+lubs ds1 [] = ds1
+lubs ds1 ds2 = ASSERT( length ds1 == length ds2 ) zipWith lub ds1 ds2
-----------------------------------
-- A Seq can have an empty list of demands, in the polymorphic case.
boths [] ds2 = ds2
boths ds1 [] = ds1
boths ds1 ds2 = ASSERT( length ds1 == length ds2 ) zipWith both ds1 ds2
-
------------------------------------
--- (t1 `bothType` t2) takes the argument/result info from t1,
--- using t2 just for its free-var info
-bothType (DmdType fv1 ds1 r1) (DmdType fv2 ds2 r2)
- = DmdType both_fv2 ds1 r1
- where
- both_fv = plusUFM_C both fv1 fv2
- both_fv1 = modifyEnv (isBotRes r1) (`both` Bot) fv2 fv1 both_fv
- both_fv2 = modifyEnv (isBotRes r2) (`both` Bot) fv1 fv2 both_fv1
- -- both is the identity for Abs
\end{code}
\begin{code}
%************************************************************************
%* *
+\subsection{LUB and BOTH}
+%* *
+%************************************************************************
+
+
+\begin{code}
+lub :: Demand -> Demand -> Demand
+
+lub Bot d = d
+
+lub Err Bot = Err
+lub Err d = d
+
+lub Lazy d = Lazy
+
+lub Abs d = defer d
+
+lub Eval Abs = Lazy
+lub Eval Lazy = Lazy
+lub Eval (Seq Drop ds) | not (null ds) = Seq Drop [Lazy | d <- ds]
+lub Eval d = Eval
+ -- For the Seq case, consier
+ -- f n [] = n
+ -- f n (x:xs) = f (n+x) xs
+ -- Here we want to do better than just V for n. It's
+ -- unboxed in the (x:xs) case, and we might be prepared to
+ -- rebox it in the [] case.
+ -- But if we don't use *any* of the components, give up
+ -- and revert to V
+
+lub (Call d1) (Call d2) = Call (lub d1 d2)
+lub d1@(Call _) d2 = d2 `lub` d1
+
+lub (Seq k1 ds1) (Seq k2 ds2)
+ = Seq (k1 `lub_keep` k2) (lub_ds k1 ds1 k2 ds2)
+ where
+ ------------------
+ lub_ds Keep ds1 Keep ds2 = ds1 `lubs` ds2
+ lub_ds Keep ds1 non_keep ds2 | null ds1 = [Lazy | d <- ds2]
+ | otherwise = bothLazy_s ds1 `lubs` ds2
+
+ lub_ds non_keep ds1 Keep ds2 | null ds2 = [Lazy | d <- ds1]
+ | otherwise = ds1 `lubs` bothLazy_s ds2
+
+ lub_ds k1 ds1 k2 ds2 = ds1 `lubs` ds2
+
+ ------------------
+ lub_keep Keep k = k
+
+ lub_keep Drop Defer = Defer
+ lub_keep Drop k = Drop
+
+ lub_keep Defer k = Defer
+
+lub d1@(Seq _ _) d2 = d2 `lub` d1
+
+---------------
+both :: Demand -> Demand -> Demand
+
+both Bot Bot = Bot
+both Bot Abs = Bot
+both Bot d = Err
+
+both Err d = Err
+
+both Abs d = d
+
+both Lazy Bot = Err
+both Lazy Err = Err
+both Lazy Eval = Eval
+both Lazy (Call d) = Call d
+both Lazy (Seq Defer ds) = Lazy
+both Lazy (Seq k ds) = Seq Keep ds
+both Lazy d = Lazy
+
+-- For the (Eval `both` Bot) case, consider
+-- f x = error x
+-- From 'error' itself we get demand Bot on x
+-- From the arg demand on x we get Eval
+-- So we want Eval `both` Bot to be Err.
+-- That's what Err is *for*
+both Eval Bot = Err
+both Eval Err = Err
+both Eval (Seq k ds) = Seq Keep ds
+both Eval d = Eval
+
+both (Call d1) (Call d2) = Call (d1 `both` d2)
+both d1@(Call _) d2 = d2 `both` d1
+
+both (Seq k1 ds1) (Seq k2 ds2)
+ = Seq (k1 `both_keep` k2) (both_ds k1 ds1 k2 ds2)
+ where
+ ----------------
+ both_keep Keep k2 = Keep
+
+ both_keep Drop Keep = Keep
+ both_keep Drop k2 = Drop
+
+ both_keep Defer k2 = k2
+
+ ----------------
+ both_ds Defer ds1 Defer ds2 = ds1 `boths` ds2
+ both_ds Defer ds1 non_defer ds2 = map defer ds1 `boths` ds2
+
+ both_ds non_defer ds1 Defer ds2 = ds1 `boths` map defer ds2
+
+ both_ds k1 ds1 k2 ds2 = ds1 `boths` ds2
+
+both d1@(Seq _ _) d2 = d2 `both` d1
+\end{code}
+
+
+%************************************************************************
+%* *
\subsection{Miscellaneous
%* *
%************************************************************************
where
message word = text word <+> text "demand for" <+> ppr id <+> info
info = (text "Old" <+> ppr old) $$ (text "New" <+> ppr new)
- new = lazify (idNewDemandInfo id) -- Lazify to avoid spurious improvements
+ new = funArgDemand (idNewDemandInfo id) -- FunArgDemand to avoid spurious improvements
old = newDemand (idDemandInfo id)
new_better = new `betterDemand` old
old_better = old `betterDemand` new
)
import IdInfo ( vanillaIdInfo )
import DataCon ( splitProductType_maybe, splitProductType )
-import NewDemand ( Demand(..), Keepity(..), DmdResult(..), isAbsentDmd )
+import NewDemand ( Demand(..), Keepity(..), DmdResult(..) )
import DmdAnal ( both )
import PrelInfo ( realWorldPrimId, aBSENT_ERROR_ID, eRROR_CSTRING_ID )
import TysPrim ( realWorldStatePrimTy )
-- but *with* lambdas
mkWWstr res_ty wrap_args
- = mk_ww_str wrap_args `thenUs` \ (work_args, take_apart, put_together) ->
+ = mk_ww_str_s wrap_args `thenUs` \ (work_args, take_apart, put_together) ->
let
work_dmds = [idNewDemandInfo v | v <- work_args, isId v]
apply_to args fn = mkVarApps fn args
take_apart . applyToVars [realWorldPrimId] . apply_to work_args,
mkLams work_args . Lam void_arg . put_together)
- -- Empty case
-mk_ww_str []
- = returnUs ([],
- \ wrapper_body -> wrapper_body,
- \ worker_body -> worker_body)
+----------------------
+nop_fn body = body
+----------------------
+mk_ww_str_s []
+ = returnUs ([], nop_fn, nop_fn)
-mk_ww_str (arg : ds)
+mk_ww_str_s (arg : args)
+ = mk_ww_str arg `thenUs` \ (args1, wrap_fn1, work_fn1) ->
+ mk_ww_str_s args `thenUs` \ (args2, wrap_fn2, work_fn2) ->
+ returnUs (args1 ++ args2, wrap_fn1 . wrap_fn2, work_fn1 . work_fn2)
+
+
+----------------------
+mk_ww_str arg
| isTyVar arg
- = mk_ww_str ds `thenUs` \ (worker_args, wrap_fn, work_fn) ->
- returnUs (arg : worker_args, wrap_fn, work_fn)
+ = returnUs ([arg], nop_fn, nop_fn)
| otherwise
= case idNewDemandInfo arg of
-- though, because it's not so easy to manufacture a placeholder
-- We'll see if this turns out to be a problem
Abs | not (isUnLiftedType (idType arg)) ->
- mk_ww_str ds `thenUs` \ (worker_args, wrap_fn, work_fn) ->
- returnUs (worker_args, wrap_fn, mk_absent_let arg . work_fn)
+ returnUs ([], nop_fn, mk_absent_let arg)
-- Seq and keep
- Seq _ _ cs
- | all isAbsentDmd cs
- -> mk_ww_str ds `thenUs` \ (worker_args, wrap_fn, work_fn) ->
- let
+ Seq _ []
+ -> let
arg_w_unf = arg `setIdUnfolding` mkOtherCon []
-- Tell the worker arg that it's sure to be evaluated
-- so that internal seqs can be dropped
in
- returnUs (arg_w_unf : worker_args, mk_seq_case arg . wrap_fn, work_fn)
+ returnUs ([arg_w_unf], mk_seq_case arg, nop_fn)
-- Pass the arg, anyway, even if it is in theory discarded
-- Consider
-- f x y = x `seq` y
-- But the Evald flag is pretty wierd, and I worry that it might disappear
-- during simplification, so for now I've just nuked this whole case
-
-- Unpack case
- Seq keep _ cs
+ Seq keep cs
| Just (arg_tycon, tycon_arg_tys, data_con, inst_con_arg_tys)
<- splitProductType_maybe (idType arg)
-> getUniquesUs `thenUs` \ uniqs ->
unpk_args = zipWith mk_ww_local uniqs inst_con_arg_tys
unpk_args_w_ds = zipWithEqual "mk_ww_str" set_worker_arg_info unpk_args cs'
unbox_fn = mk_unpk_case arg unpk_args data_con arg_tycon
- rebox_fn = mk_pk_let arg data_con tycon_arg_tys unpk_args
+ rebox_fn = Let (NonRec arg con_app)
+ con_app = mkConApp data_con (map Type tycon_arg_tys ++ map Var unpk_args)
cs' = case keep of
Keep -> map (DmdAnal.both Lazy) cs -- Careful! Now we don't pass
-- S(LA) --> U(LL)
Drop -> cs
in
- mk_ww_str (unpk_args_w_ds ++ ds) `thenUs` \ (worker_args, wrap_fn, work_fn) ->
+ mk_ww_str_s unpk_args_w_ds `thenUs` \ (worker_args, wrap_fn, work_fn) ->
-- case keep of
-- Keep -> returnUs (arg : worker_args, unbox_fn . wrap_fn, work_fn)
| otherwise ->
WARN( True, ppr arg )
- mk_ww_str ds `thenUs` \ (worker_args, wrap_fn, work_fn) ->
- returnUs (arg : worker_args, wrap_fn, work_fn)
+ returnUs ([arg], nop_fn, nop_fn)
-- Other cases
- other_demand ->
- mk_ww_str ds `thenUs` \ (worker_args, wrap_fn, work_fn) ->
- returnUs (arg : worker_args, wrap_fn, work_fn)
+ other_demand -> returnUs ([arg], nop_fn, nop_fn)
+
where
-- If the wrapper argument is a one-shot lambda, then
-- so should (all) the corresponding worker arguments be
-- like (x+y) `seq` ....
sanitiseCaseBndr id = id `setIdInfo` vanillaIdInfo
-mk_pk_let arg boxing_con con_tys unpk_args body
- = Let (NonRec arg (mkConApp boxing_con con_args)) body
- where
- con_args = map Type con_tys ++ map Var unpk_args
-
mk_ww_local uniq ty = mkSysLocal SLIT("ww") uniq ty
\end{code}
projects / ghc-hetmet.git / commitdiff