- primitive operations
\begin{code}
-{-# OPTIONS -fno-warn-missing-signatures #-}
--- The above warning supression flag is a temporary kludge.
--- While working on this module you are encouraged to remove it and fix
--- any warnings in the module. See
--- <http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings>
--- for details
-
module MkId (
- mkDictFunId, mkDefaultMethodId,
- mkDictSelId,
+ mkDictFunId, mkDictFunTy, mkDictSelId,
mkDataConIds,
mkPrimOpId, mkFCallId, mkTickBoxOpId, mkBreakPointOpId,
-- And some particular Ids; see below for why they are wired in
wiredInIds, ghcPrimIds,
- unsafeCoerceId, realWorldPrimId, voidArgId, nullAddrId, seqId,
- lazyId, lazyIdUnfolding, lazyIdKey,
-
- mkRuntimeErrorApp, mkImpossibleExpr,
- rEC_CON_ERROR_ID, iRREFUT_PAT_ERROR_ID, rUNTIME_ERROR_ID,
- nON_EXHAUSTIVE_GUARDS_ERROR_ID, nO_METHOD_BINDING_ERROR_ID,
- pAT_ERROR_ID, eRROR_ID, rEC_SEL_ERROR_ID,
+ unsafeCoerceName, unsafeCoerceId, realWorldPrimId,
+ voidArgId, nullAddrId, seqId, lazyId, lazyIdKey,
+ coercionTokenId,
- unsafeCoerceName
+ -- Re-export error Ids
+ module PrelRules
) where
#include "HsVersions.h"
import Rules
import TysPrim
-import TysWiredIn
+import TysWiredIn ( unitTy )
import PrelRules
import Type
-import TypeRep
import Coercion
import TcType
+import MkCore
import CoreUtils ( exprType, mkCoerce )
import CoreUnfold
import Literal
import Class
import VarSet
import Name
-import OccName
import PrimOp
import ForeignCall
import DataCon
import Id
-import Var ( Var, TyVar, mkCoVar, mkExportedLocalVar )
+import Var ( mkExportedLocalVar )
import IdInfo
-import NewDemand
+import Demand
import CoreSyn
import Unique
-import Maybes
import PrelNames
import BasicTypes hiding ( SuccessFlag(..) )
import Util
+import Pair
import Outputable
import FastString
import ListSetOps
\begin{code}
wiredInIds :: [Id]
wiredInIds
- = [
-
- eRROR_ID, -- This one isn't used anywhere else in the compiler
- -- But we still need it in wiredInIds so that when GHC
- -- compiles a program that mentions 'error' we don't
- -- import its type from the interface file; we just get
- -- the Id defined here. Which has an 'open-tyvar' type.
-
- rUNTIME_ERROR_ID,
- iRREFUT_PAT_ERROR_ID,
- nON_EXHAUSTIVE_GUARDS_ERROR_ID,
- nO_METHOD_BINDING_ERROR_ID,
- pAT_ERROR_ID,
- rEC_CON_ERROR_ID,
- rEC_SEL_ERROR_ID,
-
- lazyId
- ] ++ ghcPrimIds
+ = [lazyId]
+ ++ errorIds -- Defined in MkCore
+ ++ ghcPrimIds
-- These Ids are exported from GHC.Prim
ghcPrimIds :: [Id]
data instance T [a] where
T1 :: forall b. b -> T [Maybe b]
-Hence
- Co7T a :: T [a] ~ :R7T a
-Now we want
+Hence we translate to
-- Wrapper
$WT1 :: forall b. b -> T [Maybe b]
-- Worker
T1 :: forall c b. (c ~ Maybe b) => b -> :R7T c
+ -- Coercion from family type to representation type
+ Co7T a :: T [a] ~ :R7T a
+
\begin{code}
mkDataConIds :: Name -> Name -> DataCon -> DataConIds
mkDataConIds wrap_name wkr_name data_con
| 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
= DCIds Nothing wrk_id
where
(univ_tvs, ex_tvs, eq_spec,
- eq_theta, dict_theta, orig_arg_tys, res_ty) = dataConFullSig data_con
+ other_theta, orig_arg_tys, res_ty) = dataConFullSig data_con
tycon = dataConTyCon data_con -- The representation TyCon (not family)
----------- Worker (algebraic data types only) --------------
wkr_arity = dataConRepArity data_con
wkr_info = noCafIdInfo
- `setArityInfo` wkr_arity
- `setAllStrictnessInfo` Just wkr_sig
- `setUnfoldingInfo` evaldUnfolding -- Record that it's evaluated,
+ `setArityInfo` wkr_arity
+ `setStrictnessInfo` Just wkr_sig
+ `setUnfoldingInfo` evaldUnfolding -- Record that it's evaluated,
-- even if arity = 0
wkr_sig = mkStrictSig (mkTopDmdType (replicate wkr_arity topDmd) cpr_info)
nt_work_id = mkGlobalId (DataConWrapId data_con) wkr_name wrap_ty nt_work_info
nt_work_info = noCafIdInfo -- The NoCaf-ness is set by noCafIdInfo
`setArityInfo` 1 -- Arity 1
+ `setInlinePragInfo` alwaysInlinePragma
`setUnfoldingInfo` newtype_unf
id_arg1 = mkTemplateLocal 1 (head orig_arg_tys)
newtype_unf = ASSERT2( isVanillaDataCon data_con &&
-- extra constraints where necessary.
wrap_tvs = (univ_tvs `minusList` map fst eq_spec) ++ ex_tvs
res_ty_args = substTyVars (mkTopTvSubst eq_spec) univ_tvs
- eq_tys = mkPredTys eq_theta
- dict_tys = mkPredTys dict_theta
- wrap_ty = mkForAllTys wrap_tvs $ mkFunTys eq_tys $ mkFunTys dict_tys $
- mkFunTys orig_arg_tys $ res_ty
- -- NB: watch out here if you allow user-written equality
- -- constraints in data constructor signatures
+ ev_tys = mkPredTys other_theta
+ wrap_ty = mkForAllTys wrap_tvs $
+ mkFunTys ev_tys $
+ mkFunTys orig_arg_tys $ res_ty
----------- Wrappers for algebraic data types --------------
alg_wrap_id = mkGlobalId (DataConWrapId data_con) wrap_name wrap_ty alg_wrap_info
`setArityInfo` wrap_arity
-- It's important to specify the arity, so that partial
-- applications are treated as values
+ `setInlinePragInfo` alwaysInlinePragma
`setUnfoldingInfo` wrap_unf
- `setAllStrictnessInfo` Just wrap_sig
+ `setStrictnessInfo` Just wrap_sig
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
+ wrap_sig = mkStrictSig (mkTopDmdType wrap_arg_dmds cpr_info)
+ wrap_stricts = dropList eq_spec all_strict_marks
+ wrap_arg_dmds = map mk_dmd wrap_stricts
+ 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
-- ...(let w = C x in ...(w p q)...)...
-- we want to see that w is strict in its two arguments
- wrap_unf = mkImplicitUnfolding $ Note InlineMe $
- mkLams wrap_tvs $
- mkLams eq_args $
- mkLams dict_args $ mkLams id_args $
+ wrap_unf = mkInlineUnfolding (Just (length ev_args + length id_args)) wrap_rhs
+ wrap_rhs = mkLams wrap_tvs $
+ mkLams ev_args $
+ mkLams id_args $
foldr mk_case con_app
- (zip (dict_args ++ id_args) all_strict_marks)
+ (zip (ev_args ++ id_args) wrap_stricts)
i3 []
+ -- The ev_args is the evidence arguments *other than* the eq_spec
+ -- Because we are going to apply the eq_spec args manually in the
+ -- wrapper
con_app _ rep_ids = wrapFamInstBody tycon res_ty_args $
Var wrk_id `mkTyApps` res_ty_args
`mkVarApps` ex_tvs
- -- Equality evidence:
- `mkTyApps` map snd eq_spec
- `mkVarApps` eq_args
+ `mkCoApps` map (mkReflCo . snd) eq_spec
`mkVarApps` reverse rep_ids
- (dict_args,i2) = mkLocals 1 dict_tys
- (id_args,i3) = mkLocals i2 orig_arg_tys
- wrap_arity = i3-1
- (eq_args,_) = mkCoVarLocals i3 eq_tys
-
- mkCoVarLocals i [] = ([],i)
- mkCoVarLocals i (x:xs) = let (ys,j) = mkCoVarLocals (i+1) xs
- y = mkCoVar (mkSysTvName (mkBuiltinUnique i) (fsLit "dc_co")) x
- in (y:ys,j)
+ (ev_args,i2) = mkLocals 1 ev_tys
+ (id_args,i3) = mkLocals i2 orig_arg_tys
+ wrap_arity = i3-1
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
-- by the caller. So doing CPR for them may in fact make
-- things worse.
+mkLocals :: Int -> [Type] -> ([Id], Int)
mkLocals i tys = (zipWith mkTemplateLocal [i..i+n-1] tys, i+n)
where
n = length tys
recover the original type signature from the class op selector.
\begin{code}
-mkDictSelId :: Bool -- True <=> don't include the unfolding
- -- Little point on imports without -O, because the
- -- dictionary itself won't be visible
- -> Name -> Class -> Id
+mkDictSelId :: Bool -- True <=> don't include the unfolding
+ -- Little point on imports without -O, because the
+ -- dictionary itself won't be visible
+ -> Name -- Name of one of the *value* selectors
+ -- (dictionary superclass or method)
+ -> Class -> Id
mkDictSelId no_unf name clas
= mkGlobalId (ClassOpId clas) name sel_ty info
where
-- But it's type must expose the representation of the dictionary
-- to get (say) C a -> (a -> a)
- info = noCafIdInfo
- `setArityInfo` 1
- `setAllStrictnessInfo` Just strict_sig
- `setUnfoldingInfo` (if no_unf then noUnfolding
- else mkImplicitUnfolding rhs)
-
- -- We no longer use 'must-inline' on record selectors. They'll
- -- inline like crazy if they scrutinise a constructor
+ base_info = noCafIdInfo
+ `setArityInfo` 1
+ `setStrictnessInfo` Just strict_sig
+ `setUnfoldingInfo` (if no_unf then noUnfolding
+ else mkImplicitUnfolding rhs)
+ -- In module where class op is defined, we must add
+ -- the unfolding, even though it'll never be inlined
+ -- becuase we use that to generate a top-level binding
+ -- for the ClassOp
+
+ info | new_tycon = base_info `setInlinePragInfo` alwaysInlinePragma
+ -- See Note [Single-method classes] for why alwaysInlinePragma
+ | otherwise = base_info `setSpecInfo` mkSpecInfo [rule]
+ `setInlinePragInfo` neverInlinePragma
+ -- Add a magic BuiltinRule, and never inline it
+ -- so that the rule is always available to fire.
+ -- See Note [ClassOp/DFun selection] in TcInstDcls
+
+ n_ty_args = length tyvars
+
+ -- This is the built-in rule that goes
+ -- op (dfT d1 d2) ---> opT d1 d2
+ rule = BuiltinRule { ru_name = fsLit "Class op " `appendFS`
+ occNameFS (getOccName name)
+ , ru_fn = name
+ , ru_nargs = n_ty_args + 1
+ , ru_try = dictSelRule val_index n_ty_args }
-- The strictness signature is of the form U(AAAVAAAA) -> T
-- where the V depends on which item we are selecting
-- It's worth giving one, so that absence info etc is generated
-- even if the selector isn't inlined
strict_sig = mkStrictSig (mkTopDmdType [arg_dmd] TopRes)
- arg_dmd | isNewTyCon tycon = evalDmd
- | otherwise = Eval (Prod [ if the_arg_id == id then evalDmd else Abs
- | id <- arg_ids ])
-
- tycon = classTyCon clas
- [data_con] = tyConDataCons tycon
- tyvars = dataConUnivTyVars data_con
- arg_tys = {- ASSERT( isVanillaDataCon data_con ) -} dataConRepArgTys data_con
- eq_theta = dataConEqTheta data_con
- the_arg_id = assoc "MkId.mkDictSelId" (map idName (classSelIds clas) `zip` arg_ids) name
-
- pred = mkClassPred clas (mkTyVarTys tyvars)
- dict_id = mkTemplateLocal 1 $ mkPredTy pred
- (eq_ids,n) = mkCoVarLocals 2 $ mkPredTys eq_theta
- arg_ids = mkTemplateLocalsNum n arg_tys
-
- mkCoVarLocals i [] = ([],i)
- mkCoVarLocals i (x:xs) = let (ys,j) = mkCoVarLocals (i+1) xs
- y = mkCoVar (mkSysTvName (mkBuiltinUnique i) (fsLit "dc_co")) x
- in (y:ys,j)
+ arg_dmd | new_tycon = evalDmd
+ | otherwise = Eval (Prod [ if the_arg_id == id then evalDmd else Abs
+ | id <- arg_ids ])
+
+ tycon = classTyCon clas
+ new_tycon = isNewTyCon tycon
+ [data_con] = tyConDataCons tycon
+ tyvars = dataConUnivTyVars data_con
+ arg_tys = dataConRepArgTys data_con -- Includes the dictionary superclasses
+
+ -- 'index' is a 0-index into the *value* arguments of the dictionary
+ val_index = assoc "MkId.mkDictSelId" sel_index_prs name
+ sel_index_prs = map idName (classAllSelIds clas) `zip` [0..]
+
+ the_arg_id = arg_ids !! val_index
+ pred = mkClassPred clas (mkTyVarTys tyvars)
+ dict_id = mkTemplateLocal 1 $ mkPredTy pred
+ arg_ids = mkTemplateLocalsNum 2 arg_tys
rhs = mkLams tyvars (Lam dict_id rhs_body)
- rhs_body | isNewTyCon tycon = unwrapNewTypeBody tycon (map mkTyVarTy tyvars) (Var dict_id)
- | otherwise = Case (Var dict_id) dict_id (idType the_arg_id)
- [(DataAlt data_con, eq_ids ++ arg_ids, Var the_arg_id)]
+ rhs_body | new_tycon = unwrapNewTypeBody tycon (map mkTyVarTy tyvars) (Var dict_id)
+ | otherwise = Case (Var dict_id) dict_id (idType the_arg_id)
+ [(DataAlt data_con, arg_ids, Var the_arg_id)]
+
+dictSelRule :: Int -> Arity
+ -> IdUnfoldingFun -> [CoreExpr] -> Maybe CoreExpr
+-- Tries to persuade the argument to look like a constructor
+-- application, using exprIsConApp_maybe, and then selects
+-- from it
+-- sel_i t1..tk (D t1..tk op1 ... opm) = opi
+--
+dictSelRule val_index n_ty_args id_unf args
+ | (dict_arg : _) <- drop n_ty_args args
+ , Just (_, _, con_args) <- exprIsConApp_maybe id_unf dict_arg
+ = Just (con_args !! val_index)
+ | otherwise
+ = Nothing
\end{code}
mkReboxingAlt
:: [Unique] -- Uniques for the new Ids
-> DataCon
- -> [Var] -- Source-level args, including existential dicts
+ -> [Var] -- Source-level args, *including* all evidence vars
-> CoreExpr -- RHS
-> CoreAlt
-- Term variable case
go (arg:args) (str:stricts) us
| isMarkedUnboxed str
- =
- let (binds, unpacked_args') = go args stricts us'
+ = let (binds, unpacked_args') = go args stricts us'
(us', bind_rhs, unpacked_args) = reboxProduct us (idType arg)
in
(NonRec arg bind_rhs : binds, unpacked_args ++ unpacked_args')
-- coercion constructor of the newtype or applied by itself).
wrapNewTypeBody tycon args result_expr
- = wrapFamInstBody tycon args inner
+ = ASSERT( isNewTyCon tycon )
+ wrapFamInstBody tycon args $
+ mkCoerce (mkSymCo co) result_expr
where
- inner
- | Just co_con <- newTyConCo_maybe tycon
- = mkCoerce (mkSymCoercion (mkTyConApp co_con args)) result_expr
- | otherwise
- = result_expr
+ co = mkAxInstCo (newTyConCo tycon) args
-- When unwrapping, we do *not* apply any family coercion, because this will
-- be done via a CoPat by the type checker. We have to do it this way as
unwrapNewTypeBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
unwrapNewTypeBody tycon args result_expr
- | Just co_con <- newTyConCo_maybe tycon
- = mkCoerce (mkTyConApp co_con args) result_expr
- | otherwise
- = result_expr
+ = ASSERT( isNewTyCon tycon )
+ mkCoerce (mkAxInstCo (newTyConCo tycon) args) result_expr
-- If the type constructor is a representation type of a data instance, wrap
-- the expression into a cast adjusting the expression type, which is an
wrapFamInstBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
wrapFamInstBody tycon args body
| Just co_con <- tyConFamilyCoercion_maybe tycon
- = mkCoerce (mkSymCoercion (mkTyConApp co_con args)) body
+ = mkCoerce (mkSymCo (mkAxInstCo co_con args)) body
| otherwise
= body
unwrapFamInstScrut :: TyCon -> [Type] -> CoreExpr -> CoreExpr
unwrapFamInstScrut tycon args scrut
| Just co_con <- tyConFamilyCoercion_maybe tycon
- = mkCoerce (mkTyConApp co_con args) scrut
+ = mkCoerce (mkAxInstCo co_con args) scrut
| otherwise
= scrut
\end{code}
info = noCafIdInfo
`setSpecInfo` mkSpecInfo (primOpRules prim_op name)
`setArityInfo` arity
- `setAllStrictnessInfo` Just strict_sig
+ `setStrictnessInfo` Just strict_sig
-- For each ccall we manufacture a separate CCallOpId, giving it
-- a fresh unique, a type that is correct for this particular ccall,
info = noCafIdInfo
`setArityInfo` arity
- `setAllStrictnessInfo` Just strict_sig
+ `setStrictnessInfo` Just strict_sig
(_, tau) = tcSplitForAllTys ty
(arg_tys, _) = tcSplitFunTys tau
mkBreakPointOpId uniq mod ix = mkTickBox' uniq mod ix ty
where ty = mkSigmaTy [openAlphaTyVar] [] openAlphaTy
+mkTickBox' :: Unique -> Module -> TickBoxId -> Type -> Id
mkTickBox' uniq mod ix ty = mkGlobalId (TickBoxOpId tickbox) name ty info
where
tickbox = TickBox mod ix
that they aren't discarded by the occurrence analyser.
\begin{code}
-mkDefaultMethodId dm_name ty = mkExportedLocalId dm_name ty
-
mkDictFunId :: Name -- Name to use for the dict fun;
-> [TyVar]
-> ThetaType
-> Class
-> [Type]
-> Id
+-- Implements the DFun Superclass Invariant (see TcInstDcls)
+
+mkDictFunId dfun_name tvs theta clas tys
+ = mkExportedLocalVar (DFunId n_silent is_nt)
+ dfun_name
+ dfun_ty
+ vanillaIdInfo
+ where
+ is_nt = isNewTyCon (classTyCon clas)
+ (n_silent, dfun_ty) = mkDictFunTy tvs theta clas tys
-mkDictFunId dfun_name inst_tyvars dfun_theta clas inst_tys
- = mkExportedLocalVar DFunId dfun_name dfun_ty vanillaIdInfo
+mkDictFunTy :: [TyVar] -> ThetaType -> Class -> [Type] -> (Int, Type)
+mkDictFunTy tvs theta clas tys
+ = (length silent_theta, dfun_ty)
where
- dfun_ty = mkSigmaTy inst_tyvars dfun_theta (mkDictTy clas inst_tys)
+ dfun_ty = mkSigmaTy tvs (silent_theta ++ theta) (mkDictTy clas tys)
+ silent_theta = filterOut discard $
+ substTheta (zipTopTvSubst (classTyVars clas) tys)
+ (classSCTheta clas)
+ -- See Note [Silent Superclass Arguments]
+ discard pred = isEmptyVarSet (tyVarsOfPred pred)
+ || any (`eqPred` pred) theta
+ -- See the DFun Superclass Invariant in TcInstDcls
\end{code}
another gun with which to shoot yourself in the foot.
\begin{code}
-mkWiredInIdName mod fs uniq id
- = mkWiredInName mod (mkOccNameFS varName fs) uniq (AnId id) UserSyntax
-
-unsafeCoerceName = mkWiredInIdName gHC_PRIM (fsLit "unsafeCoerce#") unsafeCoerceIdKey unsafeCoerceId
-nullAddrName = mkWiredInIdName gHC_PRIM (fsLit "nullAddr#") nullAddrIdKey nullAddrId
-seqName = mkWiredInIdName gHC_PRIM (fsLit "seq") seqIdKey seqId
-realWorldName = mkWiredInIdName gHC_PRIM (fsLit "realWorld#") realWorldPrimIdKey realWorldPrimId
-lazyIdName = mkWiredInIdName gHC_BASE (fsLit "lazy") lazyIdKey lazyId
-
-errorName = mkWiredInIdName gHC_ERR (fsLit "error") errorIdKey eRROR_ID
-recSelErrorName = mkWiredInIdName cONTROL_EXCEPTION_BASE (fsLit "recSelError") recSelErrorIdKey rEC_SEL_ERROR_ID
-runtimeErrorName = mkWiredInIdName cONTROL_EXCEPTION_BASE (fsLit "runtimeError") runtimeErrorIdKey rUNTIME_ERROR_ID
-irrefutPatErrorName = mkWiredInIdName cONTROL_EXCEPTION_BASE (fsLit "irrefutPatError") irrefutPatErrorIdKey iRREFUT_PAT_ERROR_ID
-recConErrorName = mkWiredInIdName cONTROL_EXCEPTION_BASE (fsLit "recConError") recConErrorIdKey rEC_CON_ERROR_ID
-patErrorName = mkWiredInIdName cONTROL_EXCEPTION_BASE (fsLit "patError") patErrorIdKey pAT_ERROR_ID
-noMethodBindingErrorName = mkWiredInIdName cONTROL_EXCEPTION_BASE (fsLit "noMethodBindingError")
- noMethodBindingErrorIdKey nO_METHOD_BINDING_ERROR_ID
-nonExhaustiveGuardsErrorName
- = mkWiredInIdName cONTROL_EXCEPTION_BASE (fsLit "nonExhaustiveGuardsError")
- nonExhaustiveGuardsErrorIdKey nON_EXHAUSTIVE_GUARDS_ERROR_ID
+lazyIdName, unsafeCoerceName, nullAddrName, seqName, realWorldName, coercionTokenName :: Name
+unsafeCoerceName = mkWiredInIdName gHC_PRIM (fsLit "unsafeCoerce#") unsafeCoerceIdKey unsafeCoerceId
+nullAddrName = mkWiredInIdName gHC_PRIM (fsLit "nullAddr#") nullAddrIdKey nullAddrId
+seqName = mkWiredInIdName gHC_PRIM (fsLit "seq") seqIdKey seqId
+realWorldName = mkWiredInIdName gHC_PRIM (fsLit "realWorld#") realWorldPrimIdKey realWorldPrimId
+lazyIdName = mkWiredInIdName gHC_BASE (fsLit "lazy") lazyIdKey lazyId
+coercionTokenName = mkWiredInIdName gHC_PRIM (fsLit "coercionToken#") coercionTokenIdKey coercionTokenId
\end{code}
\begin{code}
------------------------------------------------
-- unsafeCoerce# :: forall a b. a -> b
+unsafeCoerceId :: Id
unsafeCoerceId
= pcMiscPrelId unsafeCoerceName ty info
where
- info = noCafIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs
+ info = noCafIdInfo `setInlinePragInfo` alwaysInlinePragma
+ `setUnfoldingInfo` mkCompulsoryUnfolding rhs
- ty = mkForAllTys [openAlphaTyVar,openBetaTyVar]
- (mkFunTy openAlphaTy openBetaTy)
- [x] = mkTemplateLocals [openAlphaTy]
- rhs = mkLams [openAlphaTyVar,openBetaTyVar,x] $
- Cast (Var x) (mkUnsafeCoercion openAlphaTy openBetaTy)
+ ty = mkForAllTys [argAlphaTyVar,openBetaTyVar]
+ (mkFunTy argAlphaTy openBetaTy)
+ [x] = mkTemplateLocals [argAlphaTy]
+ rhs = mkLams [argAlphaTyVar,openBetaTyVar,x] $
+ Cast (Var x) (mkUnsafeCo argAlphaTy openBetaTy)
------------------------------------------------
nullAddrId :: Id
-- a way to write this literal in Haskell.
nullAddrId = pcMiscPrelId nullAddrName addrPrimTy info
where
- info = noCafIdInfo `setUnfoldingInfo`
- mkCompulsoryUnfolding (Lit nullAddrLit)
+ info = noCafIdInfo `setInlinePragInfo` alwaysInlinePragma
+ `setUnfoldingInfo` mkCompulsoryUnfolding (Lit nullAddrLit)
------------------------------------------------
-seqId :: Id
--- 'seq' is very special. See notes with
--- See DsUtils.lhs Note [Desugaring seq (1)] and
--- Note [Desugaring seq (2)] and
--- Fixity is set in LoadIface.ghcPrimIface
+seqId :: Id -- See Note [seqId magic]
seqId = pcMiscPrelId seqName ty info
where
- info = noCafIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs
+ info = noCafIdInfo `setInlinePragInfo` alwaysInlinePragma
+ `setUnfoldingInfo` mkCompulsoryUnfolding rhs
+ `setSpecInfo` mkSpecInfo [seq_cast_rule]
- ty = mkForAllTys [alphaTyVar,openBetaTyVar]
- (mkFunTy alphaTy (mkFunTy openBetaTy openBetaTy))
- [x,y] = mkTemplateLocals [alphaTy, openBetaTy]
- rhs = mkLams [alphaTyVar,openBetaTyVar,x,y] (Case (Var x) x openBetaTy [(DEFAULT, [], Var y)])
+ ty = mkForAllTys [alphaTyVar,argBetaTyVar]
+ (mkFunTy alphaTy (mkFunTy argBetaTy argBetaTy))
+ [x,y] = mkTemplateLocals [alphaTy, argBetaTy]
+ rhs = mkLams [alphaTyVar,argBetaTyVar,x,y] (Case (Var x) x argBetaTy [(DEFAULT, [], Var y)])
+
+ -- See Note [Built-in RULES for seq]
+ seq_cast_rule = BuiltinRule { ru_name = fsLit "seq of cast"
+ , ru_fn = seqName
+ , ru_nargs = 4
+ , ru_try = match_seq_of_cast
+ }
+
+match_seq_of_cast :: IdUnfoldingFun -> [CoreExpr] -> Maybe CoreExpr
+ -- See Note [Built-in RULES for seq]
+match_seq_of_cast _ [Type _, Type res_ty, Cast scrut co, expr]
+ = Just (Var seqId `mkApps` [Type (pFst (coercionKind co)), Type res_ty,
+ scrut, expr])
+match_seq_of_cast _ _ = Nothing
------------------------------------------------
-lazyId :: Id
--- lazy :: forall a?. a? -> a? (i.e. works for unboxed types too)
--- Used to lazify pseq: pseq a b = a `seq` lazy b
---
--- Also, no strictness: by being a built-in Id, all the info about lazyId comes from here,
--- not from GHC.Base.hi. This is important, because the strictness
--- analyser will spot it as strict!
---
--- Also no unfolding in lazyId: it gets "inlined" by a HACK in the worker/wrapperpass
--- (see WorkWrap.wwExpr)
--- We could use inline phases to do this, but that would be vulnerable to changes in
--- phase numbering....we must inline precisely after strictness analysis.
+lazyId :: Id -- See Note [lazyId magic]
lazyId = pcMiscPrelId lazyIdName ty info
where
info = noCafIdInfo
ty = mkForAllTys [alphaTyVar] (mkFunTy alphaTy alphaTy)
-
-lazyIdUnfolding :: CoreExpr -- Used to expand 'lazyId' after strictness anal
-lazyIdUnfolding = mkLams [openAlphaTyVar,x] (Var x)
- where
- [x] = mkTemplateLocals [openAlphaTy]
\end{code}
+Note [seqId magic]
+~~~~~~~~~~~~~~~~~~
+'GHC.Prim.seq' is special in several ways.
+
+a) Its second arg can have an unboxed type
+ x `seq` (v +# w)
+
+b) Its fixity is set in LoadIface.ghcPrimIface
+
+c) It has quite a bit of desugaring magic.
+ See DsUtils.lhs Note [Desugaring seq (1)] and (2) and (3)
+
+d) There is some special rule handing: Note [User-defined RULES for seq]
+
+e) See Note [Typing rule for seq] in TcExpr.
+
+Note [User-defined RULES for seq]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Roman found situations where he had
+ case (f n) of _ -> e
+where he knew that f (which was strict in n) would terminate if n did.
+Notice that the result of (f n) is discarded. So it makes sense to
+transform to
+ case n of _ -> e
+
+Rather than attempt some general analysis to support this, I've added
+enough support that you can do this using a rewrite rule:
+
+ RULE "f/seq" forall n. seq (f n) e = seq n e
+
+You write that rule. When GHC sees a case expression that discards
+its result, it mentally transforms it to a call to 'seq' and looks for
+a RULE. (This is done in Simplify.rebuildCase.) As usual, the
+correctness of the rule is up to you.
+
+To make this work, we need to be careful that the magical desugaring
+done in Note [seqId magic] item (c) is *not* done on the LHS of a rule.
+Or rather, we arrange to un-do it, in DsBinds.decomposeRuleLhs.
+
+Note [Built-in RULES for seq]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+We also have the following built-in rule for seq
+
+ seq (x `cast` co) y = seq x y
+
+This eliminates unnecessary casts and also allows other seq rules to
+match more often. Notably,
+
+ seq (f x `cast` co) y --> seq (f x) y
+
+and now a user-defined rule for seq (see Note [User-defined RULES for seq])
+may fire.
+
+
+Note [lazyId magic]
+~~~~~~~~~~~~~~~~~~~
+ lazy :: forall a?. a? -> a? (i.e. works for unboxed types too)
+
+Used to lazify pseq: pseq a b = a `seq` lazy b
+
+Also, no strictness: by being a built-in Id, all the info about lazyId comes from here,
+not from GHC.Base.hi. This is important, because the strictness
+analyser will spot it as strict!
+
+Also no unfolding in lazyId: it gets "inlined" by a HACK in CorePrep.
+It's very important to do this inlining *after* unfoldings are exposed
+in the interface file. Otherwise, the unfolding for (say) pseq in the
+interface file will not mention 'lazy', so if we inline 'pseq' we'll totally
+miss the very thing that 'lazy' was there for in the first place.
+See Trac #3259 for a real world example.
+
+lazyId is defined in GHC.Base, so we don't *have* to inline it. If it
+appears un-applied, we'll end up just calling it.
+
+-------------------------------------------------------------
@realWorld#@ used to be a magic literal, \tr{void#}. If things get
nasty as-is, change it back to a literal (@Literal@).
This comes up in strictness analysis
\begin{code}
+realWorldPrimId :: Id
realWorldPrimId -- :: State# RealWorld
= pcMiscPrelId realWorldName realWorldStatePrimTy
(noCafIdInfo `setUnfoldingInfo` evaldUnfolding)
voidArgId :: Id
voidArgId -- :: State# RealWorld
= mkSysLocal (fsLit "void") voidArgIdKey realWorldStatePrimTy
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection[PrelVals-error-related]{@error@ and friends; @trace@}
-%* *
-%************************************************************************
-
-GHC randomly injects these into the code.
-
-@patError@ is just a version of @error@ for pattern-matching
-failures. It knows various ``codes'' which expand to longer
-strings---this saves space!
-
-@absentErr@ is a thing we put in for ``absent'' arguments. They jolly
-well shouldn't be yanked on, but if one is, then you will get a
-friendly message from @absentErr@ (rather than a totally random
-crash).
-@parError@ is a special version of @error@ which the compiler does
-not know to be a bottoming Id. It is used in the @_par_@ and @_seq_@
-templates, but we don't ever expect to generate code for it.
-
-\begin{code}
-mkRuntimeErrorApp
- :: Id -- Should be of type (forall a. Addr# -> a)
- -- where Addr# points to a UTF8 encoded string
- -> Type -- The type to instantiate 'a'
- -> String -- The string to print
- -> CoreExpr
-
-mkRuntimeErrorApp err_id res_ty err_msg
- = mkApps (Var err_id) [Type res_ty, err_string]
- where
- err_string = Lit (mkMachString err_msg)
-
-mkImpossibleExpr :: Type -> CoreExpr
-mkImpossibleExpr res_ty
- = mkRuntimeErrorApp rUNTIME_ERROR_ID res_ty "Impossible case alternative"
-
-rEC_SEL_ERROR_ID = mkRuntimeErrorId recSelErrorName
-rUNTIME_ERROR_ID = mkRuntimeErrorId runtimeErrorName
-iRREFUT_PAT_ERROR_ID = mkRuntimeErrorId irrefutPatErrorName
-rEC_CON_ERROR_ID = mkRuntimeErrorId recConErrorName
-pAT_ERROR_ID = mkRuntimeErrorId patErrorName
-nO_METHOD_BINDING_ERROR_ID = mkRuntimeErrorId noMethodBindingErrorName
-nON_EXHAUSTIVE_GUARDS_ERROR_ID = mkRuntimeErrorId nonExhaustiveGuardsErrorName
-
--- The runtime error Ids take a UTF8-encoded string as argument
-
-mkRuntimeErrorId :: Name -> Id
-mkRuntimeErrorId name = pc_bottoming_Id name runtimeErrorTy
-
-runtimeErrorTy :: Type
-runtimeErrorTy = mkSigmaTy [openAlphaTyVar] [] (mkFunTy addrPrimTy openAlphaTy)
+coercionTokenId :: Id -- :: () ~ ()
+coercionTokenId -- Used to replace Coercion terms when we go to STG
+ = pcMiscPrelId coercionTokenName
+ (mkTyConApp eqPredPrimTyCon [unitTy, unitTy])
+ noCafIdInfo
\end{code}
-\begin{code}
-eRROR_ID = pc_bottoming_Id errorName errorTy
-
-errorTy :: Type
-errorTy = mkSigmaTy [openAlphaTyVar] [] (mkFunTys [mkListTy charTy] openAlphaTy)
- -- Notice the openAlphaTyVar. It says that "error" can be applied
- -- to unboxed as well as boxed types. This is OK because it never
- -- returns, so the return type is irrelevant.
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection{Utilities}
-%* *
-%************************************************************************
\begin{code}
pcMiscPrelId :: Name -> Type -> IdInfo -> Id
-- random calls to GHCbase.unpackPS__. If GHCbase is the module
-- being compiled, then it's just a matter of luck if the definition
-- will be in "the right place" to be in scope.
-
-pc_bottoming_Id :: Name -> Type -> Id
--- Function of arity 1, which diverges after being given one argument
-pc_bottoming_Id name ty
- = pcMiscPrelId name ty bottoming_info
- where
- bottoming_info = vanillaIdInfo `setAllStrictnessInfo` Just strict_sig
- `setArityInfo` 1
- -- Make arity and strictness agree
-
- -- Do *not* mark them as NoCafRefs, because they can indeed have
- -- CAF refs. For example, pAT_ERROR_ID calls GHC.Err.untangle,
- -- which has some CAFs
- -- In due course we may arrange that these error-y things are
- -- regarded by the GC as permanently live, in which case we
- -- can give them NoCaf info. As it is, any function that calls
- -- any pc_bottoming_Id will itself have CafRefs, which bloats
- -- SRTs.
-
- strict_sig = mkStrictSig (mkTopDmdType [evalDmd] BotRes)
- -- These "bottom" out, no matter what their arguments
\end{code}
-
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