Warning about useless UNPACK pragmas wasn't as easy as I thought.
I did quite a bit of refactoring, which improved the code by refining
the types somewhat. In particular notice that in DataCon, we have
dcStrictMarks :: [HsBang]
dcRepStrictness :: [StrictnessMarks]
The former relates to the *source-code* annotation, the latter to
GHC's representation choice.
EP(..),
- StrictnessMark(..), isMarkedUnboxed, isMarkedStrict,
+ HsBang(..), isBanged, isMarkedUnboxed,
+ StrictnessMark(..), isMarkedStrict,
CompilerPhase,
Activation(..), isActive, isNeverActive, isAlwaysActive, isEarlyActive,
e.g. data T = MkT !Int !(Bool,Bool)
\begin{code}
-data StrictnessMark -- Used in interface decls only
- = MarkedStrict
- | MarkedUnboxed
- | NotMarkedStrict
- deriving( Eq )
+-------------------------
+-- HsBang describes what the *programmer* wrote
+-- This info is retained in the DataCon.dcStrictMarks field
+data HsBang = HsNoBang
-isMarkedUnboxed :: StrictnessMark -> Bool
-isMarkedUnboxed MarkedUnboxed = True
-isMarkedUnboxed _ = False
+ | HsStrict
-isMarkedStrict :: StrictnessMark -> Bool
-isMarkedStrict NotMarkedStrict = False
-isMarkedStrict _ = True -- All others are strict
+ | HsUnpack -- {-# UNPACK #-} ! (GHC extension, meaning "unbox")
+
+ | HsUnpackFailed -- An UNPACK pragma that we could not make
+ -- use of, because the type isn't unboxable;
+ -- equivalant to HsStrict except for checkValidDataCon
+ deriving (Eq, Data, Typeable)
+
+instance Outputable HsBang where
+ ppr HsNoBang = empty
+ ppr HsStrict = char '!'
+ ppr HsUnpack = ptext (sLit "{-# UNPACK #-} !")
+ ppr HsUnpackFailed = ptext (sLit "{-# UNPACK (failed) #-} !")
+
+isBanged :: HsBang -> Bool
+isBanged HsNoBang = False
+isBanged _ = True
+
+isMarkedUnboxed :: HsBang -> Bool
+isMarkedUnboxed HsUnpack = True
+isMarkedUnboxed _ = False
+
+-------------------------
+-- StrictnessMark is internal only, used to indicate strictness
+-- of the DataCon *worker* fields
+data StrictnessMark = MarkedStrict | NotMarkedStrict
instance Outputable StrictnessMark where
ppr MarkedStrict = ptext (sLit "!")
- ppr MarkedUnboxed = ptext (sLit "!!")
- ppr NotMarkedStrict = ptext (sLit "_")
+ ppr NotMarkedStrict = empty
+
+isMarkedStrict :: StrictnessMark -> Bool
+isMarkedStrict NotMarkedStrict = False
+isMarkedStrict _ = True -- All others are strict
\end{code}
-- The OrigResTy is T [a], but the dcRepTyCon might be :T123
-- Now the strictness annotations and field labels of the constructor
- dcStrictMarks :: [StrictnessMark],
+ dcStrictMarks :: [HsBang],
-- Strictness annotations as decided by the compiler.
-- Does *not* include the existential dictionaries
-- length = dataConSourceArity dataCon
-- | Build a new data constructor
mkDataCon :: Name
-> Bool -- ^ Is the constructor declared infix?
- -> [StrictnessMark] -- ^ Strictness annotations written in the source file
+ -> [HsBang] -- ^ Strictness annotations written in the source file
-> [FieldLabel] -- ^ Field labels for the constructor, if it is a record,
-- otherwise empty
-> [TyVar] -- ^ Universally quantified type variables
eqSpecPreds :: [(TyVar,Type)] -> ThetaType
eqSpecPreds spec = [ mkEqPred (mkTyVarTy tv, ty) | (tv,ty) <- spec ]
-mk_dict_strict_mark :: PredType -> StrictnessMark
-mk_dict_strict_mark pred | isStrictPred pred = MarkedStrict
- | otherwise = NotMarkedStrict
+mk_dict_strict_mark :: PredType -> HsBang
+mk_dict_strict_mark pred | isStrictPred pred = HsStrict
+ | otherwise = HsNoBang
\end{code}
\begin{code}
-- | The strictness markings decided on by the compiler. Does not include those for
-- existential dictionaries. The list is in one-to-one correspondence with the arity of the 'DataCon'
-dataConStrictMarks :: DataCon -> [StrictnessMark]
+dataConStrictMarks :: DataCon -> [HsBang]
dataConStrictMarks = dcStrictMarks
-- | Strictness of /existential/ arguments only
-dataConExStricts :: DataCon -> [StrictnessMark]
+dataConExStricts :: DataCon -> [HsBang]
-- Usually empty, so we don't bother to cache this
dataConExStricts dc = map mk_dict_strict_mark $ dcDictTheta dc
Nothing -> pprPanic (str ++ ": not a product") (pprType ty)
-- | Compute the representation type strictness and type suitable for a 'DataCon'
-computeRep :: [StrictnessMark] -- ^ Original argument strictness
+computeRep :: [HsBang] -- ^ Original argument strictness
-> [Type] -- ^ Original argument types
-> ([StrictnessMark], -- Representation arg strictness
[Type]) -- And type
computeRep stricts tys
= unzip $ concat $ zipWithEqual "computeRep" unbox stricts tys
where
- unbox NotMarkedStrict ty = [(NotMarkedStrict, ty)]
- unbox MarkedStrict ty = [(MarkedStrict, ty)]
- unbox MarkedUnboxed ty = zipEqual "computeRep" (dataConRepStrictness arg_dc) arg_tys
- where
- (_tycon, _tycon_args, arg_dc, arg_tys)
- = deepSplitProductType "unbox_strict_arg_ty" ty
+ unbox HsNoBang ty = [(NotMarkedStrict, ty)]
+ unbox HsStrict ty = [(MarkedStrict, ty)]
+ unbox HsUnpackFailed ty = [(MarkedStrict, ty)]
+ unbox HsUnpack ty = zipEqual "computeRep" (dataConRepStrictness arg_dc) arg_tys
+ where
+ (_tycon, _tycon_args, arg_dc, arg_tys)
+ = deepSplitProductType "unbox_strict_arg_ty" ty
\end{code}
| isNewTyCon tycon -- Newtype, only has a worker
= DCIds Nothing nt_work_id
- | any isMarkedStrict all_strict_marks -- Algebraic, needs wrapper
- || not (null eq_spec) -- NB: LoadIface.ifaceDeclSubBndrs
- || isFamInstTyCon tycon -- depends on this test
+ | any isBanged all_strict_marks -- Algebraic, needs wrapper
+ || not (null eq_spec) -- NB: LoadIface.ifaceDeclSubBndrs
+ || isFamInstTyCon tycon -- depends on this test
= DCIds (Just alg_wrap_id) wrk_id
| otherwise -- Algebraic, no wrapper
all_strict_marks = dataConExStricts data_con ++ dataConStrictMarks data_con
wrap_sig = mkStrictSig (mkTopDmdType arg_dmds cpr_info)
arg_dmds = map mk_dmd all_strict_marks
- mk_dmd str | isMarkedStrict str = evalDmd
- | otherwise = lazyDmd
+ mk_dmd str | isBanged str = evalDmd
+ | otherwise = lazyDmd
-- The Cpr info can be important inside INLINE rhss, where the
-- wrapper constructor isn't inlined.
-- And the argument strictness can be important too; we
in (y:ys,j)
mk_case
- :: (Id, StrictnessMark) -- Arg, strictness
+ :: (Id, HsBang) -- Arg, strictness
-> (Int -> [Id] -> CoreExpr) -- Body
-> Int -- Next rep arg id
-> [Id] -- Rep args so far, reversed
-> CoreExpr
mk_case (arg,strict) body i rep_args
= case strict of
- NotMarkedStrict -> body i (arg:rep_args)
- MarkedStrict
- | isUnLiftedType (idType arg) -> body i (arg:rep_args)
- | otherwise ->
- Case (Var arg) arg res_ty [(DEFAULT,[], body i (arg:rep_args))]
-
- MarkedUnboxed
- -> unboxProduct i (Var arg) (idType arg) the_body
+ HsNoBang -> body i (arg:rep_args)
+ HsUnpack -> unboxProduct i (Var arg) (idType arg) the_body
where
the_body i con_args = body i (reverse con_args ++ rep_args)
+ _other -- HsUnpackFailed and HsStrict
+ | isUnLiftedType (idType arg) -> body i (arg:rep_args)
+ | otherwise -> Case (Var arg) arg res_ty
+ [(DEFAULT,[], body i (arg:rep_args))]
mAX_CPR_SIZE :: Arity
mAX_CPR_SIZE = 10
type LBangType name = Located (BangType name)
type BangType name = HsType name -- Bangs are in the HsType data type
-data HsBang = HsNoBang -- Only used as a return value for getBangStrictness,
- -- never appears on a HsBangTy
- | HsStrict -- !
- | HsUnbox -- {-# UNPACK #-} ! (GHC extension, meaning "unbox")
- deriving (Data, Typeable)
-
-instance Outputable HsBang where
- ppr (HsNoBang) = empty
- ppr (HsStrict) = char '!'
- ppr (HsUnbox) = ptext (sLit "!!")
-
getBangType :: LHsType a -> LHsType a
getBangType (L _ (HsBangTy _ ty)) = ty
getBangType ty = ty
d <- get bh
return (InlinePragma a b c d)
-instance Binary StrictnessMark where
- put_ bh MarkedStrict = putByte bh 0
- put_ bh MarkedUnboxed = putByte bh 1
- put_ bh NotMarkedStrict = putByte bh 2
+instance Binary HsBang where
+ put_ bh HsNoBang = putByte bh 0
+ put_ bh HsStrict = putByte bh 1
+ put_ bh HsUnpack = putByte bh 2
+ put_ bh HsUnpackFailed = putByte bh 3
get bh = do
h <- getByte bh
case h of
- 0 -> do return MarkedStrict
- 1 -> do return MarkedUnboxed
- _ -> do return NotMarkedStrict
+ 0 -> do return HsNoBang
+ 1 -> do return HsStrict
+ 2 -> do return HsUnpack
+ _ -> do return HsUnpackFailed
instance Binary Boxity where
put_ bh Boxed = putByte bh 0
------------------------------------------------------
buildDataCon :: Name -> Bool
- -> [StrictnessMark]
+ -> [HsBang]
-> [Name] -- Field labels
-> [TyVar] -> [TyVar] -- Univ and ext
-> [(TyVar,Type)] -- Equality spec
; dict_con <- buildDataCon datacon_name
False -- Not declared infix
- (map (const NotMarkedStrict) args)
+ (map (const HsNoBang) args)
[{- No fields -}]
tvs [{- no existentials -}]
[{- No GADT equalities -}] [{- No theta -}]
ifConCtxt :: IfaceContext, -- Non-stupid context
ifConArgTys :: [IfaceType], -- Arg types
ifConFields :: [OccName], -- ...ditto... (field labels)
- ifConStricts :: [StrictnessMark]} -- Empty (meaning all lazy),
+ ifConStricts :: [HsBang]} -- Empty (meaning all lazy),
-- or 1-1 corresp with arg tys
data IfaceInst
if is_infix then ptext (sLit "Infix") else empty,
if has_wrap then ptext (sLit "HasWrapper") else empty,
ppUnless (null strs) $
- nest 4 (ptext (sLit "Stricts:") <+> hsep (map ppr strs)),
+ nest 4 (ptext (sLit "Stricts:") <+> hsep (map ppr_bang strs)),
ppUnless (null fields) $
nest 4 (ptext (sLit "Fields:") <+> hsep (map ppr fields))]
where
+ ppr_bang HsNoBang = char '_' -- Want to see these
+ ppr_bang bang = ppr bang
+
main_payload = ppr name <+> dcolon <+>
pprIfaceForAllPart (univ_tvs ++ ex_tvs) (eq_ctxt ++ ctxt) pp_tau
freeNamesSub :: (Fixity,[IfaceRule]) -> NameSet
freeNamesSub (_,rules) = unionManyNameSets (map freeNamesIfRule rules)
+instance Outputable IfaceDeclExtras where
+ ppr IfaceOtherDeclExtras = empty
+ ppr (IfaceIdExtras fix rules) = ppr_id_extras fix rules
+ ppr (IfaceSynExtras fix) = ppr fix
+ ppr (IfaceDataExtras fix insts stuff) = vcat [ppr fix, ppr_insts insts,
+ ppr_id_extras_s stuff]
+ ppr (IfaceClassExtras fix insts stuff) = vcat [ppr fix, ppr_insts insts,
+ ppr_id_extras_s stuff]
+
+ppr_insts :: [IfaceInstABI] -> SDoc
+ppr_insts _ = ptext (sLit "<insts>")
+
+ppr_id_extras_s :: [(Fixity, [IfaceRule])] -> SDoc
+ppr_id_extras_s stuff = vcat [ppr_id_extras f r | (f,r)<- stuff]
+
+ppr_id_extras :: Fixity -> [IfaceRule] -> SDoc
+ppr_id_extras fix rules = ppr fix $$ vcat (map ppr rules)
+
-- This instance is used only to compute fingerprints
instance Binary IfaceDeclExtras where
get _bh = panic "no get for IfaceDeclExtras"
pp_tau = foldr add (ppr res_ty) tys_w_strs
add str_ty pp_ty = pprParendBangTy str_ty <+> arrow <+> pp_ty
- pprParendBangTy (strict,ty)
- | GHC.isMarkedStrict strict = char '!' <> GHC.pprParendType ty
- | otherwise = GHC.pprParendType ty
+ pprParendBangTy (bang,ty) = ppr bang <> GHC.pprParendType ty
- pprBangTy strict ty
- | GHC.isMarkedStrict strict = char '!' <> ppr ty
- | otherwise = ppr ty
+ pprBangTy bang ty = ppr bang <> ppr ty
maybe_show_label (lbl,(strict,tp))
| show_label lbl = Just (ppr lbl <+> dcolon <+> pprBangTy strict tp)
strict_mark :: { Located HsBang }
: '!' { L1 HsStrict }
- | '{-# UNPACK' '#-}' '!' { LL HsUnbox }
+ | '{-# UNPACK' '#-}' '!' { LL HsUnpack }
-- A ctype is a for-all type
ctype :: { LHsType RdrName }
mkTupleTyCon, mkAlgTyCon, tyConName,
TyConParent(NoParentTyCon) )
-import BasicTypes ( Arity, RecFlag(..), Boxity(..), isBoxed,
- StrictnessMark(..) )
+import BasicTypes ( Arity, RecFlag(..), Boxity(..), isBoxed, HsBang(..) )
import Type ( Type, mkTyConTy, mkTyConApp, mkTyVarTy, mkTyVarTys,
TyThing(..) )
= data_con
where
data_con = mkDataCon dc_name declared_infix
- (map (const NotMarkedStrict) arg_tys)
+ (map (const HsNoBang) arg_tys)
[] -- No labelled fields
tyvars
[] -- No existential type variables
checkMissingFields data_con rbinds
| null field_labels -- Not declared as a record;
-- But C{} is still valid if no strict fields
- = if any isMarkedStrict field_strs then
+ = if any isBanged field_strs then
-- Illegal if any arg is strict
addErrTc (missingStrictFields data_con [])
else
where
missing_s_fields
= [ fl | (fl, str) <- field_info,
- isMarkedStrict str,
+ isBanged str,
not (fl `elem` field_names_used)
]
missing_ns_fields
= [ fl | (fl, str) <- field_info,
- not (isMarkedStrict str),
+ not (isBanged str),
not (fl `elem` field_names_used)
]
conv_dir BasicTypes.InfixL = TH.InfixL
conv_dir BasicTypes.InfixN = TH.InfixN
-reifyStrict :: BasicTypes.StrictnessMark -> TH.Strict
-reifyStrict MarkedStrict = TH.IsStrict
-reifyStrict MarkedUnboxed = TH.IsStrict
-reifyStrict NotMarkedStrict = TH.NotStrict
+reifyStrict :: BasicTypes.HsBang -> TH.Strict
+reifyStrict bang | isBanged bang = TH.IsStrict
+ | otherwise = TH.NotStrict
------------------------------
noTH :: LitString -> SDoc -> TcM a
-------------------
tcConArg :: Bool -- True <=> -funbox-strict_fields
-> LHsType Name
- -> TcM (TcType, StrictnessMark)
+ -> TcM (TcType, HsBang)
tcConArg unbox_strict bty
= do { arg_ty <- tcHsBangType bty
; let bang = getBangStrictness bty
- ; strict_mark <- chooseBoxingStrategy unbox_strict arg_ty bang
+ ; let strict_mark = chooseBoxingStrategy unbox_strict arg_ty bang
; return (arg_ty, strict_mark) }
-- We attempt to unbox/unpack a strict field when either:
--
-- We have turned off unboxing of newtypes because coercions make unboxing
-- and reboxing more complicated
-chooseBoxingStrategy :: Bool -> TcType -> HsBang -> TcM StrictnessMark
+chooseBoxingStrategy :: Bool -> TcType -> HsBang -> HsBang
chooseBoxingStrategy unbox_strict_fields arg_ty bang
= case bang of
- HsNoBang -> return NotMarkedStrict
- HsUnbox | can_unbox arg_ty -> return MarkedUnboxed
- | otherwise -> do { addWarnTc cant_unbox_msg
- ; return MarkedStrict }
- HsStrict | unbox_strict_fields
- , can_unbox arg_ty -> return MarkedUnboxed
- _ -> return MarkedStrict
+ HsNoBang -> HsNoBang
+ HsUnpack -> can_unbox HsUnpackFailed arg_ty
+ HsStrict | unbox_strict_fields -> can_unbox HsStrict arg_ty
+ | otherwise -> HsStrict
+ HsUnpackFailed -> pprPanic "chooseBoxingStrategy" (ppr arg_ty)
+ -- Source code never has shtes
where
- -- we can unbox if the type is a chain of newtypes with a product tycon
- -- at the end
- can_unbox arg_ty = case splitTyConApp_maybe arg_ty of
- Nothing -> False
- Just (arg_tycon, tycon_args) ->
- not (isRecursiveTyCon arg_tycon) && -- Note [Recusive unboxing]
- isProductTyCon arg_tycon &&
- (if isNewTyCon arg_tycon then
- can_unbox (newTyConInstRhs arg_tycon tycon_args)
- else True)
-
- cant_unbox_msg = ptext (sLit "Ignoring unusable UNPACK pragma")
+ can_unbox :: HsBang -> TcType -> HsBang
+ -- Returns HsUnpack if we can unpack arg_ty
+ -- fail_bang if we know what arg_ty is but we can't unpack it
+ -- HsStrict if it's abstract, so we don't know whether or not we can unbox it
+ can_unbox fail_bang arg_ty
+ = case splitTyConApp_maybe arg_ty of
+ Nothing -> fail_bang
+
+ Just (arg_tycon, tycon_args)
+ | isAbstractTyCon arg_tycon -> HsStrict
+ -- See Note [Don't complain about UNPACK on abstract TyCons]
+ | not (isRecursiveTyCon arg_tycon) -- Note [Recusive unboxing]
+ , isProductTyCon arg_tycon
+ -- We can unbox if the type is a chain of newtypes
+ -- with a product tycon at the end
+ -> if isNewTyCon arg_tycon
+ then can_unbox fail_bang (newTyConInstRhs arg_tycon tycon_args)
+ else HsUnpack
+
+ | otherwise -> fail_bang
\end{code}
+Note [Don't complain about UNPACK on abstract TyCons]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+We are going to complain about UnpackFailed, but if we say
+ data T = MkT {-# UNPACK #-} !Wobble
+and Wobble is a newtype imported from a module that was compiled
+without optimisation, we don't want to complain. Because it might
+be fine when optimsation is on. I think this happens when Haddock
+is working over (say) GHC souce files.
+
Note [Recursive unboxing]
~~~~~~~~~~~~~~~~~~~~~~~~~
Be careful not to try to unbox this!
-- Reason: it's really the argument of an equality constraint
; checkValidType ctxt (dataConUserType con)
; when (isNewTyCon tc) (checkNewDataCon con)
+ ; mapM_ check_bang (dataConStrictMarks con `zip` [1..])
}
where
ctxt = ConArgCtxt (dataConName con)
+ check_bang (HsUnpackFailed, n) = addWarnTc (cant_unbox_msg n)
+ check_bang _ = return ()
+
+ cant_unbox_msg n = sep [ ptext (sLit "Ignoring unusable UNPACK pragma on the")
+ , speakNth n <+> ptext (sLit "argument of") <+> quotes (ppr con)]
-------------------------------
checkNewDataCon :: DataCon -> TcM ()
-- Return type is (T a b c)
; checkTc (null ex_tvs && null eq_theta && null dict_theta) (newtypeExError con)
-- No existentials
- ; checkTc (not (any isMarkedStrict (dataConStrictMarks con)))
+ ; checkTc (not (any isBanged (dataConStrictMarks con)))
(newtypeStrictError con)
-- No strictness
}
import OccName
import Id
import MkId
-import BasicTypes ( StrictnessMark(..), boolToRecFlag,
+import BasicTypes ( HsBang(..), boolToRecFlag,
alwaysInlinePragma, dfunInlinePragma )
import Var ( Var, TyVar, varType )
import Name ( Name, getOccName )
liftDs $ buildDataCon name'
False -- not infix
- (map (const NotMarkedStrict) arg_tys)
+ (map (const HsNoBang) arg_tys)
[] -- no labelled fields
univ_tvs
[] -- no existential tvs for now
liftDs $ buildDataCon dc_name
False -- not infix
- (map (const NotMarkedStrict) comp_tys)
+ (map (const HsNoBang) comp_tys)
[] -- no field labels
tvs
[] -- no existentials
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