2 % (c) The AQUA Project, Glasgow University, 1998
4 \section[StdIdInfo]{Standard unfoldings}
6 This module contains definitions for the IdInfo for things that
7 have a standard form, namely:
11 * method and superclass selectors
12 * primitive operations
16 mkSpecPragmaId, mkWorkerId,
18 mkDictFunId, mkDefaultMethodId,
21 mkDataConId, mkDataConWrapId,
23 mkPrimOpId, mkCCallOpId,
25 -- And some particular Ids; see below for why they are wired in
27 unsafeCoerceId, realWorldPrimId,
28 eRROR_ID, rEC_SEL_ERROR_ID, pAT_ERROR_ID, rEC_CON_ERROR_ID,
29 rEC_UPD_ERROR_ID, iRREFUT_PAT_ERROR_ID, nON_EXHAUSTIVE_GUARDS_ERROR_ID,
30 nO_METHOD_BINDING_ERROR_ID, aBSENT_ERROR_ID, pAR_ERROR_ID
33 #include "HsVersions.h"
36 import TysPrim ( openAlphaTyVars, alphaTyVar, alphaTy,
37 intPrimTy, realWorldStatePrimTy
39 import TysWiredIn ( charTy, mkListTy )
40 import PrelNames ( pREL_ERR, pREL_GHC )
41 import PrelRules ( primOpRule )
42 import Rules ( addRule )
43 import Type ( Type, ThetaType, mkDictTy, mkDictTys, mkTyConApp, mkTyVarTys,
44 mkFunTys, mkFunTy, mkSigmaTy,
45 isUnLiftedType, mkForAllTys, mkTyVarTy, tyVarsOfType,
46 splitFunTys, splitForAllTys
48 import Module ( Module )
49 import CoreUtils ( exprType, mkInlineMe )
50 import CoreUnfold ( mkTopUnfolding, mkCompulsoryUnfolding, mkOtherCon )
51 import Literal ( Literal(..) )
52 import TyCon ( TyCon, isNewTyCon, tyConTyVars, tyConDataCons,
53 tyConTheta, isProductTyCon, isDataTyCon )
54 import Class ( Class, classTyCon, classTyVars, classSelIds )
55 import Var ( Id, TyVar )
56 import VarSet ( isEmptyVarSet )
57 import Name ( mkWiredInName, mkLocalName,
58 mkWorkerOcc, mkCCallName,
59 Name, NamedThing(..), getSrcLoc
61 import OccName ( mkVarOcc )
62 import PrimOp ( PrimOp(DataToTagOp, CCallOp),
63 primOpSig, mkPrimOpIdName,
66 import Demand ( wwStrict, wwPrim, mkStrictnessInfo )
67 import DataCon ( DataCon, StrictnessMark(..),
68 dataConFieldLabels, dataConRepArity, dataConTyCon,
69 dataConArgTys, dataConRepType, dataConRepStrictness,
70 dataConInstOrigArgTys,
71 dataConName, dataConTheta,
72 dataConSig, dataConStrictMarks, dataConId,
73 maybeMarkedUnboxed, splitProductType_maybe
75 import Id ( idType, mkId,
76 mkVanillaId, mkTemplateLocals,
77 mkTemplateLocal, idCprInfo
79 import IdInfo ( IdInfo, constantIdInfo, mkIdInfo,
80 exactArity, setUnfoldingInfo, setCafInfo, setCprInfo,
81 setArityInfo, setSpecInfo, setTyGenInfo,
82 mkStrictnessInfo, setStrictnessInfo,
83 IdFlavour(..), CafInfo(..), CprInfo(..), TyGenInfo(..)
85 import FieldLabel ( mkFieldLabel, fieldLabelName,
86 firstFieldLabelTag, allFieldLabelTags, fieldLabelType
91 import Maybe ( isJust )
93 import ListSetOps ( assoc, assocMaybe )
94 import UnicodeUtil ( stringToUtf8 )
99 %************************************************************************
101 \subsection{Wired in Ids}
103 %************************************************************************
107 = [ -- These error-y things are wired in because we don't yet have
108 -- a way to express in an interface file that the result type variable
109 -- is 'open'; that is can be unified with an unboxed type
111 -- [The interface file format now carry such information, but there's
112 -- no way yet of expressing at the definition site for these
114 -- functions that they have an 'open' result type. -- sof 1/99]
118 , iRREFUT_PAT_ERROR_ID
119 , nON_EXHAUSTIVE_GUARDS_ERROR_ID
120 , nO_METHOD_BINDING_ERROR_ID
126 -- These two can't be defined in Haskell
133 %************************************************************************
135 \subsection{Easy ones}
137 %************************************************************************
140 mkSpecPragmaId occ uniq ty loc
141 = mkId (mkLocalName uniq occ loc) ty (mkIdInfo SpecPragmaId NoCafRefs)
142 -- Maybe a SysLocal? But then we'd lose the location
144 mkDefaultMethodId dm_name rec_c ty
145 = mkId dm_name ty info
147 info = constantIdInfo `setTyGenInfo` TyGenNever
148 -- type is wired-in (see comment at TcClassDcl.tcClassSig), so
149 -- do not generalise it
151 mkWorkerId :: Unique -> Id -> Type -> Id
152 -- A worker gets a local name. CoreTidy will globalise it if necessary.
153 mkWorkerId uniq unwrkr ty
154 = mkVanillaId wkr_name ty
156 wkr_name = mkLocalName uniq (mkWorkerOcc (getOccName unwrkr)) (getSrcLoc unwrkr)
159 %************************************************************************
161 \subsection{Data constructors}
163 %************************************************************************
166 mkDataConId :: Name -> DataCon -> Id
167 -- Makes the *worker* for the data constructor; that is, the function
168 -- that takes the reprsentation arguments and builds the constructor.
169 mkDataConId work_name data_con
170 = mkId work_name (dataConRepType data_con) info
172 info = mkIdInfo (DataConId data_con) NoCafRefs
173 `setArityInfo` exactArity arity
174 `setStrictnessInfo` strict_info
175 `setCprInfo` cpr_info
177 arity = dataConRepArity data_con
179 strict_info = mkStrictnessInfo (dataConRepStrictness data_con, False)
181 tycon = dataConTyCon data_con
182 cpr_info | isProductTyCon tycon &&
184 arity > 0 = ReturnsCPR
185 | otherwise = NoCPRInfo
186 -- ReturnsCPR is only true for products that are real data types;
187 -- that is, not unboxed tuples or newtypes
190 The wrapper for a constructor is an ordinary top-level binding that evaluates
191 any strict args, unboxes any args that are going to be flattened, and calls
194 We're going to build a constructor that looks like:
196 data (Data a, C b) => T a b = T1 !a !Int b
199 \d1::Data a, d2::C b ->
200 \p q r -> case p of { p ->
202 Con T1 [a,b] [p,q,r]}}
206 * d2 is thrown away --- a context in a data decl is used to make sure
207 one *could* construct dictionaries at the site the constructor
208 is used, but the dictionary isn't actually used.
210 * We have to check that we can construct Data dictionaries for
211 the types a and Int. Once we've done that we can throw d1 away too.
213 * We use (case p of q -> ...) to evaluate p, rather than "seq" because
214 all that matters is that the arguments are evaluated. "seq" is
215 very careful to preserve evaluation order, which we don't need
218 You might think that we could simply give constructors some strictness
219 info, like PrimOps, and let CoreToStg do the let-to-case transformation.
220 But we don't do that because in the case of primops and functions strictness
221 is a *property* not a *requirement*. In the case of constructors we need to
222 do something active to evaluate the argument.
224 Making an explicit case expression allows the simplifier to eliminate
225 it in the (common) case where the constructor arg is already evaluated.
228 mkDataConWrapId data_con
231 wrap_id = mkId (dataConName data_con) wrap_ty info
232 work_id = dataConId data_con
234 info = mkIdInfo (DataConWrapId data_con) NoCafRefs
235 `setUnfoldingInfo` mkTopUnfolding (mkInlineMe wrap_rhs)
236 `setCprInfo` cpr_info
237 -- The Cpr info can be important inside INLINE rhss, where the
238 -- wrapper constructor isn't inlined
239 `setArityInfo` exactArity arity
240 -- It's important to specify the arity, so that partial
241 -- applications are treated as values
242 `setTyGenInfo` TyGenNever
243 -- No point generalising its type, since it gets eagerly inlined
246 wrap_ty = mkForAllTys all_tyvars $
250 cpr_info = idCprInfo work_id
252 wrap_rhs | isNewTyCon tycon
253 = ASSERT( null ex_tyvars && null ex_dict_args && length orig_arg_tys == 1 )
254 -- No existentials on a newtype, but it can have a context
255 -- e.g. newtype Eq a => T a = MkT (...)
257 mkLams tyvars $ mkLams dict_args $ Lam id_arg1 $
258 Note (Coerce result_ty (head orig_arg_tys)) (Var id_arg1)
260 | null dict_args && all not_marked_strict strict_marks
261 = Var work_id -- The common case. Not only is this efficient,
262 -- but it also ensures that the wrapper is replaced
263 -- by the worker even when there are no args.
267 -- This is really important in rule matching,
268 -- (We could match on the wrappers,
269 -- but that makes it less likely that rules will match
270 -- when we bring bits of unfoldings together.)
272 -- NB: because of this special case, (map (:) ys) turns into
273 -- (map $w: ys), and thence into (map (\x xs. $w: x xs) ys)
274 -- in core-to-stg. The top-level defn for (:) is never used.
275 -- This is somewhat of a bore, but I'm currently leaving it
276 -- as is, so that there still is a top level curried (:) for
277 -- the interpreter to call.
280 = mkLams all_tyvars $ mkLams dict_args $
281 mkLams ex_dict_args $ mkLams id_args $
282 foldr mk_case con_app
283 (zip (ex_dict_args++id_args) strict_marks) i3 []
285 con_app i rep_ids = mkApps (Var work_id)
286 (map varToCoreExpr (all_tyvars ++ reverse rep_ids))
288 (tyvars, theta, ex_tyvars, ex_theta, orig_arg_tys, tycon) = dataConSig data_con
289 all_tyvars = tyvars ++ ex_tyvars
291 dict_tys = mkDictTys theta
292 ex_dict_tys = mkDictTys ex_theta
293 all_arg_tys = dict_tys ++ ex_dict_tys ++ orig_arg_tys
294 result_ty = mkTyConApp tycon (mkTyVarTys tyvars)
296 mkLocals i tys = (zipWith mkTemplateLocal [i..i+n-1] tys, i+n)
300 (dict_args, i1) = mkLocals 1 dict_tys
301 (ex_dict_args,i2) = mkLocals i1 ex_dict_tys
302 (id_args,i3) = mkLocals i2 orig_arg_tys
304 (id_arg1:_) = id_args -- Used for newtype only
306 strict_marks = dataConStrictMarks data_con
307 not_marked_strict NotMarkedStrict = True
308 not_marked_strict other = False
312 :: (Id, StrictnessMark) -- arg, strictness
313 -> (Int -> [Id] -> CoreExpr) -- body
314 -> Int -- next rep arg id
315 -> [Id] -- rep args so far
317 mk_case (arg,strict) body i rep_args
319 NotMarkedStrict -> body i (arg:rep_args)
321 | isUnLiftedType (idType arg) -> body i (arg:rep_args)
323 Case (Var arg) arg [(DEFAULT,[], body i (arg:rep_args))]
325 MarkedUnboxed con tys ->
326 Case (Var arg) arg [(DataAlt con, con_args,
327 body i' (reverse con_args++rep_args))]
329 (con_args,i') = mkLocals i tys
333 %************************************************************************
335 \subsection{Record selectors}
337 %************************************************************************
339 We're going to build a record selector unfolding that looks like this:
341 data T a b c = T1 { ..., op :: a, ...}
342 | T2 { ..., op :: a, ...}
345 sel = /\ a b c -> \ d -> case d of
350 Similarly for newtypes
352 newtype N a = MkN { unN :: a->a }
355 unN n = coerce (a->a) n
357 We need to take a little care if the field has a polymorphic type:
359 data R = R { f :: forall a. a->a }
363 f :: forall a. R -> a -> a
364 f = /\ a \ r = case r of
367 (not f :: R -> forall a. a->a, which gives the type inference mechanism
368 problems at call sites)
370 Similarly for newtypes
372 newtype N = MkN { unN :: forall a. a->a }
374 unN :: forall a. N -> a -> a
375 unN = /\a -> \n:N -> coerce (a->a) n
378 mkRecordSelId tycon field_label unpack_id unpackUtf8_id
379 -- Assumes that all fields with the same field label have the same type
381 -- Annoyingly, we have to pass in the unpackCString# Id, because
382 -- we can't conjure it up out of thin air
385 sel_id = mkId (fieldLabelName field_label) selector_ty info
387 field_ty = fieldLabelType field_label
388 data_cons = tyConDataCons tycon
389 tyvars = tyConTyVars tycon -- These scope over the types in
390 -- the FieldLabels of constructors of this type
391 tycon_theta = tyConTheta tycon -- The context on the data decl
392 -- eg data (Eq a, Ord b) => T a b = ...
393 (field_tyvars,field_tau) = splitForAllTys field_ty
395 data_ty = mkTyConApp tycon tyvar_tys
396 tyvar_tys = mkTyVarTys tyvars
398 -- Very tiresomely, the selectors are (unnecessarily!) overloaded over
399 -- just the dictionaries in the types of the constructors that contain
400 -- the relevant field. Urgh.
401 -- NB: this code relies on the fact that DataCons are quantified over
402 -- the identical type variables as their parent TyCon
403 dict_tys = [mkDictTy cls tys | (cls, tys) <- tycon_theta, needed_dict (cls, tys)]
404 needed_dict pred = or [ pred `elem` (dataConTheta dc)
405 | (DataAlt dc, _, _) <- the_alts]
408 selector_ty = mkForAllTys tyvars $ mkForAllTys field_tyvars $
409 mkFunTys dict_tys $ mkFunTy data_ty field_tau
411 info = mkIdInfo (RecordSelId field_label) NoCafRefs
412 `setArityInfo` exactArity (1 + length dict_tys)
413 `setUnfoldingInfo` unfolding
414 `setTyGenInfo` TyGenNever
415 -- ToDo: consider adding further IdInfo
417 unfolding = mkTopUnfolding sel_rhs
420 (data_id:dict_ids) = mkTemplateLocals (data_ty:dict_tys)
421 alts = map mk_maybe_alt data_cons
422 the_alts = catMaybes alts
423 default_alt | all isJust alts = [] -- No default needed
424 | otherwise = [(DEFAULT, [], error_expr)]
426 sel_rhs = mkLams tyvars $ mkLams field_tyvars $
427 mkLams dict_ids $ Lam data_id $
430 sel_body | isNewTyCon tycon = Note (Coerce field_tau data_ty) (Var data_id)
431 | otherwise = Case (Var data_id) data_id (the_alts ++ default_alt)
433 mk_maybe_alt data_con
434 = case maybe_the_arg_id of
436 Just the_arg_id -> Just (DataAlt data_con, real_args, expr)
438 body = mkVarApps (Var the_arg_id) field_tyvars
439 strict_marks = dataConStrictMarks data_con
440 (expr, real_args) = rebuildConArgs data_con arg_ids strict_marks body
443 arg_ids = mkTemplateLocals (dataConInstOrigArgTys data_con tyvar_tys)
444 -- The first one will shadow data_id, but who cares
445 maybe_the_arg_id = assocMaybe (field_lbls `zip` arg_ids) field_label
446 field_lbls = dataConFieldLabels data_con
448 error_expr = mkApps (Var rEC_SEL_ERROR_ID) [Type field_tau, err_string]
450 | all safeChar full_msg
451 = App (Var unpack_id) (Lit (MachStr (_PK_ full_msg)))
453 = App (Var unpackUtf8_id) (Lit (MachStr (_PK_ (stringToUtf8 (map ord full_msg)))))
455 safeChar c = c >= '\1' && c <= '\xFF'
456 -- TODO: Putting this Unicode stuff here is ugly. Find a better
457 -- generic place to make string literals. This logic is repeated
459 full_msg = showSDoc (sep [text "No match in record selector", ppr sel_id])
462 -- this rather ugly function converts the unpacked data con arguments back into
463 -- their packed form. It is almost the same as the version in DsUtils, except that
464 -- we use template locals here rather than newDsId (ToDo: merge these).
467 :: DataCon -- the con we're matching on
468 -> [Id] -- the source-level args
469 -> [StrictnessMark] -- the strictness annotations (per-arg)
470 -> CoreExpr -- the body
471 -> Int -- template local
474 rebuildConArgs con [] stricts body i = (body, [])
475 rebuildConArgs con (arg:args) stricts body i | isTyVar arg
476 = let (body', args') = rebuildConArgs con args stricts body i
478 rebuildConArgs con (arg:args) (str:stricts) body i
479 = case maybeMarkedUnboxed str of
480 Just (pack_con1, _) ->
481 case splitProductType_maybe (idType arg) of
482 Just (_, tycon_args, pack_con, con_arg_tys) ->
483 ASSERT( pack_con == pack_con1 )
484 let unpacked_args = zipWith mkTemplateLocal [i..] con_arg_tys
485 (body', real_args) = rebuildConArgs con args stricts body
486 (i + length con_arg_tys)
489 Let (NonRec arg (mkConApp pack_con
490 (map Type tycon_args ++
491 map Var unpacked_args))) body',
492 unpacked_args ++ real_args
495 _ -> let (body', args') = rebuildConArgs con args stricts body i
496 in (body', arg:args')
500 %************************************************************************
502 \subsection{Dictionary selectors}
504 %************************************************************************
506 Selecting a field for a dictionary. If there is just one field, then
507 there's nothing to do.
509 ToDo: unify with mkRecordSelId.
512 mkDictSelId :: Name -> Class -> Id
513 mkDictSelId name clas
517 sel_id = mkId name ty info
518 field_lbl = mkFieldLabel name tycon ty tag
519 tag = assoc "MkId.mkDictSelId" (classSelIds clas `zip` allFieldLabelTags) sel_id
521 info = mkIdInfo (RecordSelId field_lbl) NoCafRefs
522 `setArityInfo` exactArity 1
523 `setUnfoldingInfo` unfolding
524 `setTyGenInfo` TyGenNever
526 -- We no longer use 'must-inline' on record selectors. They'll
527 -- inline like crazy if they scrutinise a constructor
529 unfolding = mkTopUnfolding rhs
531 tyvars = classTyVars clas
533 tycon = classTyCon clas
534 [data_con] = tyConDataCons tycon
535 tyvar_tys = mkTyVarTys tyvars
536 arg_tys = dataConArgTys data_con tyvar_tys
537 the_arg_id = arg_ids !! (tag - firstFieldLabelTag)
539 dict_ty = mkDictTy clas tyvar_tys
540 (dict_id:arg_ids) = mkTemplateLocals (dict_ty : arg_tys)
542 rhs | isNewTyCon tycon = mkLams tyvars $ Lam dict_id $
543 Note (Coerce (head arg_tys) dict_ty) (Var dict_id)
544 | otherwise = mkLams tyvars $ Lam dict_id $
545 Case (Var dict_id) dict_id
546 [(DataAlt data_con, arg_ids, Var the_arg_id)]
550 %************************************************************************
552 \subsection{Primitive operations
554 %************************************************************************
557 mkPrimOpId :: PrimOp -> Id
561 (tyvars,arg_tys,res_ty, arity, strict_info) = primOpSig prim_op
562 ty = mkForAllTys tyvars (mkFunTys arg_tys res_ty)
563 name = mkPrimOpIdName prim_op
564 id = mkId name ty info
566 info = mkIdInfo (PrimOpId prim_op) NoCafRefs
568 `setArityInfo` exactArity arity
569 `setStrictnessInfo` strict_info
571 rules = addRule emptyCoreRules id (primOpRule prim_op)
574 -- For each ccall we manufacture a separate CCallOpId, giving it
575 -- a fresh unique, a type that is correct for this particular ccall,
576 -- and a CCall structure that gives the correct details about calling
579 -- The *name* of this Id is a local name whose OccName gives the full
580 -- details of the ccall, type and all. This means that the interface
581 -- file reader can reconstruct a suitable Id
583 mkCCallOpId :: Unique -> CCall -> Type -> Id
584 mkCCallOpId uniq ccall ty
585 = ASSERT( isEmptyVarSet (tyVarsOfType ty) )
586 -- A CCallOpId should have no free type variables;
587 -- when doing substitutions won't substitute over it
590 occ_str = showSDocIface (braces (pprCCallOp ccall <+> ppr ty))
591 -- The "occurrence name" of a ccall is the full info about the
592 -- ccall; it is encoded, but may have embedded spaces etc!
594 name = mkCCallName uniq occ_str
595 prim_op = CCallOp ccall
597 info = mkIdInfo (PrimOpId prim_op) NoCafRefs
598 `setArityInfo` exactArity arity
599 `setStrictnessInfo` strict_info
601 (_, tau) = splitForAllTys ty
602 (arg_tys, _) = splitFunTys tau
603 arity = length arg_tys
604 strict_info = mkStrictnessInfo (take arity (repeat wwPrim), False)
608 %************************************************************************
610 \subsection{DictFuns}
612 %************************************************************************
615 mkDictFunId :: Name -- Name to use for the dict fun;
622 mkDictFunId dfun_name clas inst_tyvars inst_tys dfun_theta
623 = mkId dfun_name dfun_ty info
625 dfun_ty = mkSigmaTy inst_tyvars dfun_theta (mkDictTy clas inst_tys)
626 info = mkIdInfo DictFunId MayHaveCafRefs
627 `setTyGenInfo` TyGenNever
628 -- type is wired-in (see comment at TcClassDcl.tcClassSig), so
629 -- do not generalise it
630 -- An imported dfun may refer to CAFs, so we assume the worst
632 {- 1 dec 99: disable the Mark Jones optimisation for the sake
633 of compatibility with Hugs.
634 See `types/InstEnv' for a discussion related to this.
636 (class_tyvars, sc_theta, _, _) = classBigSig clas
637 not_const (clas, tys) = not (isEmptyVarSet (tyVarsOfTypes tys))
638 sc_theta' = substClasses (mkTopTyVarSubst class_tyvars inst_tys) sc_theta
639 dfun_theta = case inst_decl_theta of
640 [] -> [] -- If inst_decl_theta is empty, then we don't
641 -- want to have any dict arguments, so that we can
642 -- expose the constant methods.
644 other -> nub (inst_decl_theta ++ filter not_const sc_theta')
645 -- Otherwise we pass the superclass dictionaries to
646 -- the dictionary function; the Mark Jones optimisation.
648 -- NOTE the "nub". I got caught by this one:
649 -- class Monad m => MonadT t m where ...
650 -- instance Monad m => MonadT (EnvT env) m where ...
651 -- Here, the inst_decl_theta has (Monad m); but so
652 -- does the sc_theta'!
654 -- NOTE the "not_const". I got caught by this one too:
655 -- class Foo a => Baz a b where ...
656 -- instance Wob b => Baz T b where..
657 -- Now sc_theta' has Foo T
662 %************************************************************************
664 \subsection{Un-definable}
666 %************************************************************************
668 These two can't be defined in Haskell.
670 unsafeCoerce# isn't so much a PrimOp as a phantom identifier, that
671 just gets expanded into a type coercion wherever it occurs. Hence we
672 add it as a built-in Id with an unfolding here.
674 The type variables we use here are "open" type variables: this means
675 they can unify with both unlifted and lifted types. Hence we provide
676 another gun with which to shoot yourself in the foot.
680 = pcMiscPrelId unsafeCoerceIdKey pREL_GHC SLIT("unsafeCoerce#") ty info
682 info = constantIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs
685 ty = mkForAllTys [openAlphaTyVar,openBetaTyVar]
686 (mkFunTy openAlphaTy openBetaTy)
687 [x] = mkTemplateLocals [openAlphaTy]
688 rhs = mkLams [openAlphaTyVar,openBetaTyVar,x] $
689 Note (Coerce openBetaTy openAlphaTy) (Var x)
693 @getTag#@ is another function which can't be defined in Haskell. It needs to
694 evaluate its argument and call the dataToTag# primitive.
698 = pcMiscPrelId getTagIdKey pREL_GHC SLIT("getTag#") ty info
700 info = constantIdInfo
701 `setUnfoldingInfo` mkCompulsoryUnfolding rhs
702 -- We don't provide a defn for this; you must inline it
704 ty = mkForAllTys [alphaTyVar] (mkFunTy alphaTy intPrimTy)
705 [x,y] = mkTemplateLocals [alphaTy,alphaTy]
706 rhs = mkLams [alphaTyVar,x] $
707 Case (Var x) y [ (DEFAULT, [], mkApps (Var dataToTagId) [Type alphaTy, Var y]) ]
709 dataToTagId = mkPrimOpId DataToTagOp
712 @realWorld#@ used to be a magic literal, \tr{void#}. If things get
713 nasty as-is, change it back to a literal (@Literal@).
716 realWorldPrimId -- :: State# RealWorld
717 = pcMiscPrelId realWorldPrimIdKey pREL_GHC SLIT("realWorld#")
719 (noCafIdInfo `setUnfoldingInfo` mkOtherCon [])
720 -- The mkOtherCon makes it look that realWorld# is evaluated
721 -- which in turn makes Simplify.interestingArg return True,
722 -- which in turn makes INLINE things applied to realWorld# likely
727 %************************************************************************
729 \subsection[PrelVals-error-related]{@error@ and friends; @trace@}
731 %************************************************************************
733 GHC randomly injects these into the code.
735 @patError@ is just a version of @error@ for pattern-matching
736 failures. It knows various ``codes'' which expand to longer
737 strings---this saves space!
739 @absentErr@ is a thing we put in for ``absent'' arguments. They jolly
740 well shouldn't be yanked on, but if one is, then you will get a
741 friendly message from @absentErr@ (rather than a totally random
744 @parError@ is a special version of @error@ which the compiler does
745 not know to be a bottoming Id. It is used in the @_par_@ and @_seq_@
746 templates, but we don't ever expect to generate code for it.
750 = pc_bottoming_Id errorIdKey pREL_ERR SLIT("error") errorTy
752 = generic_ERROR_ID patErrorIdKey SLIT("patError")
754 = generic_ERROR_ID recSelErrIdKey SLIT("recSelError")
756 = generic_ERROR_ID recConErrorIdKey SLIT("recConError")
758 = generic_ERROR_ID recUpdErrorIdKey SLIT("recUpdError")
760 = generic_ERROR_ID irrefutPatErrorIdKey SLIT("irrefutPatError")
761 nON_EXHAUSTIVE_GUARDS_ERROR_ID
762 = generic_ERROR_ID nonExhaustiveGuardsErrorIdKey SLIT("nonExhaustiveGuardsError")
763 nO_METHOD_BINDING_ERROR_ID
764 = generic_ERROR_ID noMethodBindingErrorIdKey SLIT("noMethodBindingError")
767 = pc_bottoming_Id absentErrorIdKey pREL_ERR SLIT("absentErr")
768 (mkSigmaTy [openAlphaTyVar] [] openAlphaTy)
771 = pcMiscPrelId parErrorIdKey pREL_ERR SLIT("parError")
772 (mkSigmaTy [openAlphaTyVar] [] openAlphaTy) noCafIdInfo
777 %************************************************************************
779 \subsection{Utilities}
781 %************************************************************************
784 pcMiscPrelId :: Unique{-IdKey-} -> Module -> FAST_STRING -> Type -> IdInfo -> Id
785 pcMiscPrelId key mod str ty info
787 name = mkWiredInName mod (mkVarOcc str) key
788 imp = mkId name ty info -- the usual case...
791 -- We lie and say the thing is imported; otherwise, we get into
792 -- a mess with dependency analysis; e.g., core2stg may heave in
793 -- random calls to GHCbase.unpackPS__. If GHCbase is the module
794 -- being compiled, then it's just a matter of luck if the definition
795 -- will be in "the right place" to be in scope.
797 pc_bottoming_Id key mod name ty
798 = pcMiscPrelId key mod name ty bottoming_info
800 bottoming_info = noCafIdInfo
801 `setStrictnessInfo` mkStrictnessInfo ([wwStrict], True)
803 -- these "bottom" out, no matter what their arguments
805 generic_ERROR_ID u n = pc_bottoming_Id u pREL_ERR n errorTy
808 noCafIdInfo = constantIdInfo `setCafInfo` NoCafRefs
810 (openAlphaTyVar:openBetaTyVar:_) = openAlphaTyVars
811 openAlphaTy = mkTyVarTy openAlphaTyVar
812 openBetaTy = mkTyVarTy openBetaTyVar
815 errorTy = mkSigmaTy [openAlphaTyVar] [] (mkFunTys [mkListTy charTy]
817 -- Notice the openAlphaTyVar. It says that "error" can be applied
818 -- to unboxed as well as boxed types. This is OK because it never
819 -- returns, so the return type is irrelevant.