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, isUnboxedTupleTyCon )
54 import Class ( Class, classTyCon, classTyVars, classSelIds )
55 import Var ( Id, TyVar )
56 import VarSet ( isEmptyVarSet )
57 import Name ( mkDerivedName, mkWiredInName, mkLocalName,
58 mkWorkerOcc, mkCCallName,
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, vanillaIdInfo, 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)
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 = vanillaIdInfo `setTyGenInfo` TyGenNever
148 -- type is wired-in (see comment at TcClassDcl.tcClassSig), so
149 -- do not generalise it
151 mkWorkerId uniq unwrkr ty
152 = mkVanillaId (mkDerivedName mkWorkerOcc (getName unwrkr) uniq) ty
155 %************************************************************************
157 \subsection{Data constructors}
159 %************************************************************************
162 mkDataConId :: Name -> DataCon -> Id
163 -- Makes the *worker* for the data constructor; that is, the function
164 -- that takes the reprsentation arguments and builds the constructor.
165 mkDataConId work_name data_con
166 = mkId work_name (dataConRepType data_con) info
168 info = mkIdInfo (DataConId data_con)
169 `setArityInfo` exactArity arity
170 `setStrictnessInfo` strict_info
171 `setCprInfo` cpr_info
173 arity = dataConRepArity data_con
175 strict_info = mkStrictnessInfo (dataConRepStrictness data_con, False)
177 cpr_info | isProductTyCon tycon &&
178 not (isUnboxedTupleTyCon tycon) &&
179 arity > 0 = ReturnsCPR
180 | otherwise = NoCPRInfo
182 tycon = dataConTyCon data_con
183 -- Newtypes don't have a worker at all
185 -- If we are a product with 0 args we must be void(like)
186 -- We can't create an unboxed tuple with 0 args for this
187 -- and since Void has only one, constant value it should
188 -- just mean returning a pointer to a pre-existing cell.
189 -- So we won't really gain from doing anything fancy
190 -- and we treat this case as Top.
193 The wrapper for a constructor is an ordinary top-level binding that evaluates
194 any strict args, unboxes any args that are going to be flattened, and calls
197 We're going to build a constructor that looks like:
199 data (Data a, C b) => T a b = T1 !a !Int b
202 \d1::Data a, d2::C b ->
203 \p q r -> case p of { p ->
205 Con T1 [a,b] [p,q,r]}}
209 * d2 is thrown away --- a context in a data decl is used to make sure
210 one *could* construct dictionaries at the site the constructor
211 is used, but the dictionary isn't actually used.
213 * We have to check that we can construct Data dictionaries for
214 the types a and Int. Once we've done that we can throw d1 away too.
216 * We use (case p of q -> ...) to evaluate p, rather than "seq" because
217 all that matters is that the arguments are evaluated. "seq" is
218 very careful to preserve evaluation order, which we don't need
221 You might think that we could simply give constructors some strictness
222 info, like PrimOps, and let CoreToStg do the let-to-case transformation.
223 But we don't do that because in the case of primops and functions strictness
224 is a *property* not a *requirement*. In the case of constructors we need to
225 do something active to evaluate the argument.
227 Making an explicit case expression allows the simplifier to eliminate
228 it in the (common) case where the constructor arg is already evaluated.
231 mkDataConWrapId data_con
234 wrap_id = mkId (dataConName data_con) wrap_ty info
235 work_id = dataConId data_con
237 info = mkIdInfo (DataConWrapId data_con)
238 `setUnfoldingInfo` mkTopUnfolding (mkInlineMe wrap_rhs)
239 `setCprInfo` cpr_info
240 -- The Cpr info can be important inside INLINE rhss, where the
241 -- wrapper constructor isn't inlined
242 `setArityInfo` exactArity arity
243 -- It's important to specify the arity, so that partial
244 -- applications are treated as values
245 `setCafInfo` NoCafRefs
246 -- The wrapper Id ends up in STG code as an argument,
247 -- sometimes before its definition, so we want to
248 -- signal that it has no CAFs
249 `setTyGenInfo` TyGenNever
250 -- No point generalising its type, since it gets eagerly inlined
253 wrap_ty = mkForAllTys all_tyvars $
257 cpr_info = idCprInfo work_id
259 wrap_rhs | isNewTyCon tycon
260 = ASSERT( null ex_tyvars && null ex_dict_args && length orig_arg_tys == 1 )
261 -- No existentials on a newtype, but it can have a context
262 -- e.g. newtype Eq a => T a = MkT (...)
264 mkLams tyvars $ mkLams dict_args $ Lam id_arg1 $
265 Note (Coerce result_ty (head orig_arg_tys)) (Var id_arg1)
267 | null dict_args && all not_marked_strict strict_marks
268 = Var work_id -- The common case. Not only is this efficient,
269 -- but it also ensures that the wrapper is replaced
270 -- by the worker even when there are no args.
274 -- This is really important in rule matching,
275 -- (We could match on the wrappers,
276 -- but that makes it less likely that rules will match
277 -- when we bring bits of unfoldings together.)
279 -- NB: because of this special case, (map (:) ys) turns into
280 -- (map $w: ys), and thence into (map (\x xs. $w: x xs) ys)
281 -- in core-to-stg. The top-level defn for (:) is never used.
282 -- This is somewhat of a bore, but I'm currently leaving it
283 -- as is, so that there still is a top level curried (:) for
284 -- the interpreter to call.
287 = mkLams all_tyvars $ mkLams dict_args $
288 mkLams ex_dict_args $ mkLams id_args $
289 foldr mk_case con_app
290 (zip (ex_dict_args++id_args) strict_marks) i3 []
292 con_app i rep_ids = mkApps (Var work_id)
293 (map varToCoreExpr (all_tyvars ++ reverse rep_ids))
295 (tyvars, theta, ex_tyvars, ex_theta, orig_arg_tys, tycon) = dataConSig data_con
296 all_tyvars = tyvars ++ ex_tyvars
298 dict_tys = mkDictTys theta
299 ex_dict_tys = mkDictTys ex_theta
300 all_arg_tys = dict_tys ++ ex_dict_tys ++ orig_arg_tys
301 result_ty = mkTyConApp tycon (mkTyVarTys tyvars)
303 mkLocals i tys = (zipWith mkTemplateLocal [i..i+n-1] tys, i+n)
307 (dict_args, i1) = mkLocals 1 dict_tys
308 (ex_dict_args,i2) = mkLocals i1 ex_dict_tys
309 (id_args,i3) = mkLocals i2 orig_arg_tys
311 (id_arg1:_) = id_args -- Used for newtype only
313 strict_marks = dataConStrictMarks data_con
314 not_marked_strict NotMarkedStrict = True
315 not_marked_strict other = False
319 :: (Id, StrictnessMark) -- arg, strictness
320 -> (Int -> [Id] -> CoreExpr) -- body
321 -> Int -- next rep arg id
322 -> [Id] -- rep args so far
324 mk_case (arg,strict) body i rep_args
326 NotMarkedStrict -> body i (arg:rep_args)
328 | isUnLiftedType (idType arg) -> body i (arg:rep_args)
330 Case (Var arg) arg [(DEFAULT,[], body i (arg:rep_args))]
332 MarkedUnboxed con tys ->
333 Case (Var arg) arg [(DataAlt con, con_args,
334 body i' (reverse con_args++rep_args))]
336 (con_args,i') = mkLocals i tys
340 %************************************************************************
342 \subsection{Record selectors}
344 %************************************************************************
346 We're going to build a record selector unfolding that looks like this:
348 data T a b c = T1 { ..., op :: a, ...}
349 | T2 { ..., op :: a, ...}
352 sel = /\ a b c -> \ d -> case d of
357 Similarly for newtypes
359 newtype N a = MkN { unN :: a->a }
362 unN n = coerce (a->a) n
364 We need to take a little care if the field has a polymorphic type:
366 data R = R { f :: forall a. a->a }
370 f :: forall a. R -> a -> a
371 f = /\ a \ r = case r of
374 (not f :: R -> forall a. a->a, which gives the type inference mechanism
375 problems at call sites)
377 Similarly for newtypes
379 newtype N = MkN { unN :: forall a. a->a }
381 unN :: forall a. N -> a -> a
382 unN = /\a -> \n:N -> coerce (a->a) n
385 mkRecordSelId tycon field_label unpack_id unpackUtf8_id
386 -- Assumes that all fields with the same field label have the same type
388 -- Annoyingly, we have to pass in the unpackCString# Id, because
389 -- we can't conjure it up out of thin air
392 sel_id = mkId (fieldLabelName field_label) selector_ty info
394 field_ty = fieldLabelType field_label
395 data_cons = tyConDataCons tycon
396 tyvars = tyConTyVars tycon -- These scope over the types in
397 -- the FieldLabels of constructors of this type
398 tycon_theta = tyConTheta tycon -- The context on the data decl
399 -- eg data (Eq a, Ord b) => T a b = ...
400 (field_tyvars,field_tau) = splitForAllTys field_ty
402 data_ty = mkTyConApp tycon tyvar_tys
403 tyvar_tys = mkTyVarTys tyvars
405 -- Very tiresomely, the selectors are (unnecessarily!) overloaded over
406 -- just the dictionaries in the types of the constructors that contain
407 -- the relevant field. Urgh.
408 -- NB: this code relies on the fact that DataCons are quantified over
409 -- the identical type variables as their parent TyCon
410 dict_tys = [mkDictTy cls tys | (cls, tys) <- tycon_theta, needed_dict (cls, tys)]
411 needed_dict pred = or [ pred `elem` (dataConTheta dc)
412 | (DataAlt dc, _, _) <- the_alts]
415 selector_ty = mkForAllTys tyvars $ mkForAllTys field_tyvars $
416 mkFunTys dict_tys $ mkFunTy data_ty field_tau
418 info = mkIdInfo (RecordSelId field_label)
419 `setArityInfo` exactArity (1 + length dict_tys)
420 `setUnfoldingInfo` unfolding
421 `setCafInfo` NoCafRefs
422 `setTyGenInfo` TyGenNever
423 -- ToDo: consider adding further IdInfo
425 unfolding = mkTopUnfolding sel_rhs
428 (data_id:dict_ids) = mkTemplateLocals (data_ty:dict_tys)
429 alts = map mk_maybe_alt data_cons
430 the_alts = catMaybes alts
431 default_alt | all isJust alts = [] -- No default needed
432 | otherwise = [(DEFAULT, [], error_expr)]
434 sel_rhs = mkLams tyvars $ mkLams field_tyvars $
435 mkLams dict_ids $ Lam data_id $
438 sel_body | isNewTyCon tycon = Note (Coerce field_tau data_ty) (Var data_id)
439 | otherwise = Case (Var data_id) data_id (the_alts ++ default_alt)
441 mk_maybe_alt data_con
442 = case maybe_the_arg_id of
444 Just the_arg_id -> Just (DataAlt data_con, real_args, expr)
446 body = mkVarApps (Var the_arg_id) field_tyvars
447 strict_marks = dataConStrictMarks data_con
448 (expr, real_args) = rebuildConArgs data_con arg_ids strict_marks body
451 arg_ids = mkTemplateLocals (dataConInstOrigArgTys data_con tyvar_tys)
452 -- The first one will shadow data_id, but who cares
453 maybe_the_arg_id = assocMaybe (field_lbls `zip` arg_ids) field_label
454 field_lbls = dataConFieldLabels data_con
456 error_expr = mkApps (Var rEC_SEL_ERROR_ID) [Type field_tau, err_string]
458 | all safeChar full_msg
459 = App (Var unpack_id) (Lit (MachStr (_PK_ full_msg)))
461 = App (Var unpackUtf8_id) (Lit (MachStr (_PK_ (stringToUtf8 (map ord full_msg)))))
463 safeChar c = c >= '\1' && c <= '\xFF'
464 -- TODO: Putting this Unicode stuff here is ugly. Find a better
465 -- generic place to make string literals. This logic is repeated
467 full_msg = showSDoc (sep [text "No match in record selector", ppr sel_id])
470 -- this rather ugly function converts the unpacked data con arguments back into
471 -- their packed form. It is almost the same as the version in DsUtils, except that
472 -- we use template locals here rather than newDsId (ToDo: merge these).
475 :: DataCon -- the con we're matching on
476 -> [Id] -- the source-level args
477 -> [StrictnessMark] -- the strictness annotations (per-arg)
478 -> CoreExpr -- the body
479 -> Int -- template local
482 rebuildConArgs con [] stricts body i = (body, [])
483 rebuildConArgs con (arg:args) stricts body i | isTyVar arg
484 = let (body', args') = rebuildConArgs con args stricts body i
486 rebuildConArgs con (arg:args) (str:stricts) body i
487 = case maybeMarkedUnboxed str of
488 Just (pack_con1, _) ->
489 case splitProductType_maybe (idType arg) of
490 Just (_, tycon_args, pack_con, con_arg_tys) ->
491 ASSERT( pack_con == pack_con1 )
492 let unpacked_args = zipWith mkTemplateLocal [i..] con_arg_tys
493 (body', real_args) = rebuildConArgs con args stricts body
494 (i + length con_arg_tys)
497 Let (NonRec arg (mkConApp pack_con
498 (map Type tycon_args ++
499 map Var unpacked_args))) body',
500 unpacked_args ++ real_args
503 _ -> let (body', args') = rebuildConArgs con args stricts body i
504 in (body', arg:args')
508 %************************************************************************
510 \subsection{Dictionary selectors}
512 %************************************************************************
514 Selecting a field for a dictionary. If there is just one field, then
515 there's nothing to do.
517 ToDo: unify with mkRecordSelId.
520 mkDictSelId :: Name -> Class -> Id
521 mkDictSelId name clas
525 sel_id = mkId name ty info
526 field_lbl = mkFieldLabel name tycon ty tag
527 tag = assoc "MkId.mkDictSelId" (classSelIds clas `zip` allFieldLabelTags) sel_id
529 info = mkIdInfo (RecordSelId field_lbl)
530 `setArityInfo` exactArity 1
531 `setUnfoldingInfo` unfolding
532 `setCafInfo` NoCafRefs
533 `setTyGenInfo` TyGenNever
535 -- We no longer use 'must-inline' on record selectors. They'll
536 -- inline like crazy if they scrutinise a constructor
538 unfolding = mkTopUnfolding rhs
540 tyvars = classTyVars clas
542 tycon = classTyCon clas
543 [data_con] = tyConDataCons tycon
544 tyvar_tys = mkTyVarTys tyvars
545 arg_tys = dataConArgTys data_con tyvar_tys
546 the_arg_id = arg_ids !! (tag - firstFieldLabelTag)
548 dict_ty = mkDictTy clas tyvar_tys
549 (dict_id:arg_ids) = mkTemplateLocals (dict_ty : arg_tys)
551 rhs | isNewTyCon tycon = mkLams tyvars $ Lam dict_id $
552 Note (Coerce (head arg_tys) dict_ty) (Var dict_id)
553 | otherwise = mkLams tyvars $ Lam dict_id $
554 Case (Var dict_id) dict_id
555 [(DataAlt data_con, arg_ids, Var the_arg_id)]
559 %************************************************************************
561 \subsection{Primitive operations
563 %************************************************************************
566 mkPrimOpId :: PrimOp -> Id
570 (tyvars,arg_tys,res_ty, arity, strict_info) = primOpSig prim_op
571 ty = mkForAllTys tyvars (mkFunTys arg_tys res_ty)
572 name = mkPrimOpIdName prim_op
573 id = mkId name ty info
575 info = mkIdInfo (PrimOpId prim_op)
577 `setArityInfo` exactArity arity
578 `setStrictnessInfo` strict_info
580 rules = addRule emptyCoreRules id (primOpRule prim_op)
583 -- For each ccall we manufacture a separate CCallOpId, giving it
584 -- a fresh unique, a type that is correct for this particular ccall,
585 -- and a CCall structure that gives the correct details about calling
588 -- The *name* of this Id is a local name whose OccName gives the full
589 -- details of the ccall, type and all. This means that the interface
590 -- file reader can reconstruct a suitable Id
592 mkCCallOpId :: Unique -> CCall -> Type -> Id
593 mkCCallOpId uniq ccall ty
594 = ASSERT( isEmptyVarSet (tyVarsOfType ty) )
595 -- A CCallOpId should have no free type variables;
596 -- when doing substitutions won't substitute over it
599 occ_str = showSDocIface (braces (pprCCallOp ccall <+> ppr ty))
600 -- The "occurrence name" of a ccall is the full info about the
601 -- ccall; it is encoded, but may have embedded spaces etc!
603 name = mkCCallName uniq occ_str
604 prim_op = CCallOp ccall
606 info = mkIdInfo (PrimOpId prim_op)
607 `setArityInfo` exactArity arity
608 `setStrictnessInfo` strict_info
610 (_, tau) = splitForAllTys ty
611 (arg_tys, _) = splitFunTys tau
612 arity = length arg_tys
613 strict_info = mkStrictnessInfo (take arity (repeat wwPrim), False)
617 %************************************************************************
619 \subsection{DictFuns}
621 %************************************************************************
624 mkDictFunId :: Name -- Name to use for the dict fun;
631 mkDictFunId dfun_name clas inst_tyvars inst_tys dfun_theta
632 = mkId dfun_name dfun_ty info
634 dfun_ty = mkSigmaTy inst_tyvars dfun_theta (mkDictTy clas inst_tys)
635 info = vanillaIdInfo `setTyGenInfo` TyGenNever
636 -- type is wired-in (see comment at TcClassDcl.tcClassSig), so
637 -- do not generalise it
639 {- 1 dec 99: disable the Mark Jones optimisation for the sake
640 of compatibility with Hugs.
641 See `types/InstEnv' for a discussion related to this.
643 (class_tyvars, sc_theta, _, _) = classBigSig clas
644 not_const (clas, tys) = not (isEmptyVarSet (tyVarsOfTypes tys))
645 sc_theta' = substClasses (mkTopTyVarSubst class_tyvars inst_tys) sc_theta
646 dfun_theta = case inst_decl_theta of
647 [] -> [] -- If inst_decl_theta is empty, then we don't
648 -- want to have any dict arguments, so that we can
649 -- expose the constant methods.
651 other -> nub (inst_decl_theta ++ filter not_const sc_theta')
652 -- Otherwise we pass the superclass dictionaries to
653 -- the dictionary function; the Mark Jones optimisation.
655 -- NOTE the "nub". I got caught by this one:
656 -- class Monad m => MonadT t m where ...
657 -- instance Monad m => MonadT (EnvT env) m where ...
658 -- Here, the inst_decl_theta has (Monad m); but so
659 -- does the sc_theta'!
661 -- NOTE the "not_const". I got caught by this one too:
662 -- class Foo a => Baz a b where ...
663 -- instance Wob b => Baz T b where..
664 -- Now sc_theta' has Foo T
669 %************************************************************************
671 \subsection{Un-definable}
673 %************************************************************************
675 These two can't be defined in Haskell.
677 unsafeCoerce# isn't so much a PrimOp as a phantom identifier, that
678 just gets expanded into a type coercion wherever it occurs. Hence we
679 add it as a built-in Id with an unfolding here.
681 The type variables we use here are "open" type variables: this means
682 they can unify with both unlifted and lifted types. Hence we provide
683 another gun with which to shoot yourself in the foot.
687 = pcMiscPrelId unsafeCoerceIdKey pREL_GHC SLIT("unsafeCoerce#") ty info
690 `setUnfoldingInfo` mkCompulsoryUnfolding rhs
693 ty = mkForAllTys [openAlphaTyVar,openBetaTyVar]
694 (mkFunTy openAlphaTy openBetaTy)
695 [x] = mkTemplateLocals [openAlphaTy]
696 rhs = mkLams [openAlphaTyVar,openBetaTyVar,x] $
697 Note (Coerce openBetaTy openAlphaTy) (Var x)
701 @getTag#@ is another function which can't be defined in Haskell. It needs to
702 evaluate its argument and call the dataToTag# primitive.
706 = pcMiscPrelId getTagIdKey pREL_GHC SLIT("getTag#") ty info
709 `setUnfoldingInfo` mkCompulsoryUnfolding rhs
710 -- We don't provide a defn for this; you must inline it
712 ty = mkForAllTys [alphaTyVar] (mkFunTy alphaTy intPrimTy)
713 [x,y] = mkTemplateLocals [alphaTy,alphaTy]
714 rhs = mkLams [alphaTyVar,x] $
715 Case (Var x) y [ (DEFAULT, [], mkApps (Var dataToTagId) [Type alphaTy, Var y]) ]
717 dataToTagId = mkPrimOpId DataToTagOp
720 @realWorld#@ used to be a magic literal, \tr{void#}. If things get
721 nasty as-is, change it back to a literal (@Literal@).
724 realWorldPrimId -- :: State# RealWorld
725 = pcMiscPrelId realWorldPrimIdKey pREL_GHC SLIT("realWorld#")
727 (noCafIdInfo `setUnfoldingInfo` mkOtherCon [])
728 -- The mkOtherCon makes it look that realWorld# is evaluated
729 -- which in turn makes Simplify.interestingArg return True,
730 -- which in turn makes INLINE things applied to realWorld# likely
735 %************************************************************************
737 \subsection[PrelVals-error-related]{@error@ and friends; @trace@}
739 %************************************************************************
741 GHC randomly injects these into the code.
743 @patError@ is just a version of @error@ for pattern-matching
744 failures. It knows various ``codes'' which expand to longer
745 strings---this saves space!
747 @absentErr@ is a thing we put in for ``absent'' arguments. They jolly
748 well shouldn't be yanked on, but if one is, then you will get a
749 friendly message from @absentErr@ (rather than a totally random
752 @parError@ is a special version of @error@ which the compiler does
753 not know to be a bottoming Id. It is used in the @_par_@ and @_seq_@
754 templates, but we don't ever expect to generate code for it.
758 = pc_bottoming_Id errorIdKey pREL_ERR SLIT("error") errorTy
760 = generic_ERROR_ID patErrorIdKey SLIT("patError")
762 = generic_ERROR_ID recSelErrIdKey SLIT("recSelError")
764 = generic_ERROR_ID recConErrorIdKey SLIT("recConError")
766 = generic_ERROR_ID recUpdErrorIdKey SLIT("recUpdError")
768 = generic_ERROR_ID irrefutPatErrorIdKey SLIT("irrefutPatError")
769 nON_EXHAUSTIVE_GUARDS_ERROR_ID
770 = generic_ERROR_ID nonExhaustiveGuardsErrorIdKey SLIT("nonExhaustiveGuardsError")
771 nO_METHOD_BINDING_ERROR_ID
772 = generic_ERROR_ID noMethodBindingErrorIdKey SLIT("noMethodBindingError")
775 = pc_bottoming_Id absentErrorIdKey pREL_ERR SLIT("absentErr")
776 (mkSigmaTy [openAlphaTyVar] [] openAlphaTy)
779 = pcMiscPrelId parErrorIdKey pREL_ERR SLIT("parError")
780 (mkSigmaTy [openAlphaTyVar] [] openAlphaTy) noCafIdInfo
785 %************************************************************************
787 \subsection{Utilities}
789 %************************************************************************
792 pcMiscPrelId :: Unique{-IdKey-} -> Module -> FAST_STRING -> Type -> IdInfo -> Id
793 pcMiscPrelId key mod str ty info
795 name = mkWiredInName mod (mkVarOcc str) key
796 imp = mkId name ty info -- the usual case...
799 -- We lie and say the thing is imported; otherwise, we get into
800 -- a mess with dependency analysis; e.g., core2stg may heave in
801 -- random calls to GHCbase.unpackPS__. If GHCbase is the module
802 -- being compiled, then it's just a matter of luck if the definition
803 -- will be in "the right place" to be in scope.
805 pc_bottoming_Id key mod name ty
806 = pcMiscPrelId key mod name ty bottoming_info
808 bottoming_info = noCafIdInfo
809 `setStrictnessInfo` mkStrictnessInfo ([wwStrict], True)
811 -- these "bottom" out, no matter what their arguments
813 generic_ERROR_ID u n = pc_bottoming_Id u pREL_ERR n errorTy
816 noCafIdInfo = vanillaIdInfo `setCafInfo` NoCafRefs
818 (openAlphaTyVar:openBetaTyVar:_) = openAlphaTyVars
819 openAlphaTy = mkTyVarTy openAlphaTyVar
820 openBetaTy = mkTyVarTy openBetaTyVar
823 errorTy = mkSigmaTy [openAlphaTyVar] [] (mkFunTys [mkListTy charTy]
825 -- Notice the openAlphaTyVar. It says that "error" can be applied
826 -- to unboxed as well as boxed types. This is OK because it never
827 -- returns, so the return type is irrelevant.