2 % (c) The University of Glasgow 2006
3 % (c) The AQUA Project, Glasgow University, 1998
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 -- The above warning supression flag is a temporary kludge.
17 -- While working on this module you are encouraged to remove it and fix
18 -- any warnings in the module. See
19 -- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
23 mkDictFunId, mkDefaultMethodId,
28 mkPrimOpId, mkFCallId, mkTickBoxOpId, mkBreakPointOpId,
30 mkReboxingAlt, wrapNewTypeBody, unwrapNewTypeBody,
31 wrapFamInstBody, unwrapFamInstScrut,
32 mkUnpackCase, mkProductBox,
34 -- And some particular Ids; see below for why they are wired in
35 wiredInIds, ghcPrimIds,
36 unsafeCoerceId, realWorldPrimId, voidArgId, nullAddrId, seqId,
37 lazyId, lazyIdUnfolding, lazyIdKey,
40 rEC_CON_ERROR_ID, iRREFUT_PAT_ERROR_ID, rUNTIME_ERROR_ID,
41 nON_EXHAUSTIVE_GUARDS_ERROR_ID, nO_METHOD_BINDING_ERROR_ID,
42 pAT_ERROR_ID, eRROR_ID,
47 #include "HsVersions.h"
70 import Var ( Var, TyVar, mkCoVar)
78 import BasicTypes hiding ( SuccessFlag(..) )
86 %************************************************************************
88 \subsection{Wired in Ids}
90 %************************************************************************
94 = [ -- These error-y things are wired in because we don't yet have
95 -- a way to express in an interface file that the result type variable
96 -- is 'open'; that is can be unified with an unboxed type
98 -- [The interface file format now carry such information, but there's
99 -- no way yet of expressing at the definition site for these
100 -- error-reporting functions that they have an 'open'
101 -- result type. -- sof 1/99]
103 eRROR_ID, -- This one isn't used anywhere else in the compiler
104 -- But we still need it in wiredInIds so that when GHC
105 -- compiles a program that mentions 'error' we don't
106 -- import its type from the interface file; we just get
107 -- the Id defined here. Which has an 'open-tyvar' type.
110 iRREFUT_PAT_ERROR_ID,
111 nON_EXHAUSTIVE_GUARDS_ERROR_ID,
112 nO_METHOD_BINDING_ERROR_ID,
119 -- These Ids are exported from GHC.Prim
121 = [ -- These can't be defined in Haskell, but they have
122 -- perfectly reasonable unfoldings in Core
130 %************************************************************************
132 \subsection{Data constructors}
134 %************************************************************************
136 The wrapper for a constructor is an ordinary top-level binding that evaluates
137 any strict args, unboxes any args that are going to be flattened, and calls
140 We're going to build a constructor that looks like:
142 data (Data a, C b) => T a b = T1 !a !Int b
145 \d1::Data a, d2::C b ->
146 \p q r -> case p of { p ->
148 Con T1 [a,b] [p,q,r]}}
152 * d2 is thrown away --- a context in a data decl is used to make sure
153 one *could* construct dictionaries at the site the constructor
154 is used, but the dictionary isn't actually used.
156 * We have to check that we can construct Data dictionaries for
157 the types a and Int. Once we've done that we can throw d1 away too.
159 * We use (case p of q -> ...) to evaluate p, rather than "seq" because
160 all that matters is that the arguments are evaluated. "seq" is
161 very careful to preserve evaluation order, which we don't need
164 You might think that we could simply give constructors some strictness
165 info, like PrimOps, and let CoreToStg do the let-to-case transformation.
166 But we don't do that because in the case of primops and functions strictness
167 is a *property* not a *requirement*. In the case of constructors we need to
168 do something active to evaluate the argument.
170 Making an explicit case expression allows the simplifier to eliminate
171 it in the (common) case where the constructor arg is already evaluated.
173 Note [Wrappers for data instance tycons]
174 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
175 In the case of data instances, the wrapper also applies the coercion turning
176 the representation type into the family instance type to cast the result of
177 the wrapper. For example, consider the declarations
179 data family Map k :: * -> *
180 data instance Map (a, b) v = MapPair (Map a (Pair b v))
182 The tycon to which the datacon MapPair belongs gets a unique internal
183 name of the form :R123Map, and we call it the representation tycon.
184 In contrast, Map is the family tycon (accessible via
185 tyConFamInst_maybe). A coercion allows you to move between
186 representation and family type. It is accessible from :R123Map via
187 tyConFamilyCoercion_maybe and has kind
189 Co123Map a b v :: {Map (a, b) v :=: :R123Map a b v}
191 The wrapper and worker of MapPair get the types
194 $WMapPair :: forall a b v. Map a (Map a b v) -> Map (a, b) v
195 $WMapPair a b v = MapPair a b v `cast` sym (Co123Map a b v)
198 MapPair :: forall a b v. Map a (Map a b v) -> :R123Map a b v
200 This coercion is conditionally applied by wrapFamInstBody.
202 It's a bit more complicated if the data instance is a GADT as well!
204 data instance T [a] where
205 T1 :: forall b. b -> T [Maybe b]
207 Co7T a :: T [a] ~ :R7T a
212 $WT1 :: forall b. b -> T [Maybe b]
213 $WT1 b v = T1 (Maybe b) b (Maybe b) v
214 `cast` sym (Co7T (Maybe b))
217 T1 :: forall c b. (c ~ Maybe b) => b -> :R7T c
220 mkDataConIds :: Name -> Name -> DataCon -> DataConIds
221 mkDataConIds wrap_name wkr_name data_con
222 | isNewTyCon tycon -- Newtype, only has a worker
223 = DCIds Nothing nt_work_id
225 | any isMarkedStrict all_strict_marks -- Algebraic, needs wrapper
226 || not (null eq_spec) -- NB: LoadIface.ifaceDeclSubBndrs
227 || isFamInstTyCon tycon -- depends on this test
228 = DCIds (Just alg_wrap_id) wrk_id
230 | otherwise -- Algebraic, no wrapper
231 = DCIds Nothing wrk_id
233 (univ_tvs, ex_tvs, eq_spec,
234 eq_theta, dict_theta, orig_arg_tys, res_ty) = dataConFullSig data_con
235 tycon = dataConTyCon data_con -- The representation TyCon (not family)
237 ----------- Worker (algebraic data types only) --------------
238 -- The *worker* for the data constructor is the function that
239 -- takes the representation arguments and builds the constructor.
240 wrk_id = mkGlobalId (DataConWorkId data_con) wkr_name
241 (dataConRepType data_con) wkr_info
243 wkr_arity = dataConRepArity data_con
244 wkr_info = noCafIdInfo
245 `setArityInfo` wkr_arity
246 `setAllStrictnessInfo` Just wkr_sig
247 `setUnfoldingInfo` evaldUnfolding -- Record that it's evaluated,
250 wkr_sig = mkStrictSig (mkTopDmdType (replicate wkr_arity topDmd) cpr_info)
251 -- Note [Data-con worker strictness]
252 -- Notice that we do *not* say the worker is strict
253 -- even if the data constructor is declared strict
254 -- e.g. data T = MkT !(Int,Int)
255 -- Why? Because the *wrapper* is strict (and its unfolding has case
256 -- expresssions that do the evals) but the *worker* itself is not.
257 -- If we pretend it is strict then when we see
258 -- case x of y -> $wMkT y
259 -- the simplifier thinks that y is "sure to be evaluated" (because
260 -- $wMkT is strict) and drops the case. No, $wMkT is not strict.
262 -- When the simplifer sees a pattern
263 -- case e of MkT x -> ...
264 -- it uses the dataConRepStrictness of MkT to mark x as evaluated;
265 -- but that's fine... dataConRepStrictness comes from the data con
266 -- not from the worker Id.
268 cpr_info | isProductTyCon tycon &&
271 wkr_arity <= mAX_CPR_SIZE = retCPR
273 -- RetCPR is only true for products that are real data types;
274 -- that is, not unboxed tuples or [non-recursive] newtypes
276 ----------- Workers for newtypes --------------
277 nt_work_id = mkGlobalId (DataConWrapId data_con) wkr_name wrap_ty nt_work_info
278 nt_work_info = noCafIdInfo -- The NoCaf-ness is set by noCafIdInfo
279 `setArityInfo` 1 -- Arity 1
280 `setUnfoldingInfo` newtype_unf
281 newtype_unf = -- The assertion below is no longer correct:
282 -- there may be a dict theta rather than a singleton orig_arg_ty
283 -- ASSERT( isVanillaDataCon data_con &&
284 -- isSingleton orig_arg_tys )
286 -- No existentials on a newtype, but it can have a context
287 -- e.g. newtype Eq a => T a = MkT (...)
288 mkCompulsoryUnfolding $
289 mkLams wrap_tvs $ Lam id_arg1 $
290 wrapNewTypeBody tycon res_ty_args
293 id_arg1 = mkTemplateLocal 1
294 (if null orig_arg_tys
295 then ASSERT(not (null $ dataConDictTheta data_con)) mkPredTy $ head (dataConDictTheta data_con)
296 else head orig_arg_tys
299 ----------- Wrapper --------------
300 -- We used to include the stupid theta in the wrapper's args
301 -- but now we don't. Instead the type checker just injects these
302 -- extra constraints where necessary.
303 wrap_tvs = (univ_tvs `minusList` map fst eq_spec) ++ ex_tvs
304 res_ty_args = substTyVars (mkTopTvSubst eq_spec) univ_tvs
305 eq_tys = mkPredTys eq_theta
306 dict_tys = mkPredTys dict_theta
307 wrap_ty = mkForAllTys wrap_tvs $ mkFunTys eq_tys $ mkFunTys dict_tys $
308 mkFunTys orig_arg_tys $ res_ty
309 -- NB: watch out here if you allow user-written equality
310 -- constraints in data constructor signatures
312 ----------- Wrappers for algebraic data types --------------
313 alg_wrap_id = mkGlobalId (DataConWrapId data_con) wrap_name wrap_ty alg_wrap_info
314 alg_wrap_info = noCafIdInfo -- The NoCaf-ness is set by noCafIdInfo
315 `setArityInfo` wrap_arity
316 -- It's important to specify the arity, so that partial
317 -- applications are treated as values
318 `setUnfoldingInfo` wrap_unf
319 `setAllStrictnessInfo` Just wrap_sig
321 all_strict_marks = dataConExStricts data_con ++ dataConStrictMarks data_con
322 wrap_sig = mkStrictSig (mkTopDmdType arg_dmds cpr_info)
323 arg_dmds = map mk_dmd all_strict_marks
324 mk_dmd str | isMarkedStrict str = evalDmd
325 | otherwise = lazyDmd
326 -- The Cpr info can be important inside INLINE rhss, where the
327 -- wrapper constructor isn't inlined.
328 -- And the argument strictness can be important too; we
329 -- may not inline a contructor when it is partially applied.
331 -- data W = C !Int !Int !Int
332 -- ...(let w = C x in ...(w p q)...)...
333 -- we want to see that w is strict in its two arguments
335 wrap_unf = mkTopUnfolding $ Note InlineMe $
338 mkLams dict_args $ mkLams id_args $
339 foldr mk_case con_app
340 (zip (dict_args ++ id_args) all_strict_marks)
343 con_app _ rep_ids = wrapFamInstBody tycon res_ty_args $
344 Var wrk_id `mkTyApps` res_ty_args
346 `mkTyApps` map snd eq_spec -- Equality evidence
348 `mkVarApps` reverse rep_ids
350 (dict_args,i2) = mkLocals 1 dict_tys
351 (id_args,i3) = mkLocals i2 orig_arg_tys
353 (eq_args,_) = mkCoVarLocals i3 eq_tys
355 mkCoVarLocals i [] = ([],i)
356 mkCoVarLocals i (x:xs) = let (ys,j) = mkCoVarLocals (i+1) xs
357 y = mkCoVar (mkSysTvName (mkBuiltinUnique i) FSLIT("dc_co")) x
361 :: (Id, StrictnessMark) -- Arg, strictness
362 -> (Int -> [Id] -> CoreExpr) -- Body
363 -> Int -- Next rep arg id
364 -> [Id] -- Rep args so far, reversed
366 mk_case (arg,strict) body i rep_args
368 NotMarkedStrict -> body i (arg:rep_args)
370 | isUnLiftedType (idType arg) -> body i (arg:rep_args)
372 Case (Var arg) arg res_ty [(DEFAULT,[], body i (arg:rep_args))]
375 -> unboxProduct i (Var arg) (idType arg) the_body
377 the_body i con_args = body i (reverse con_args ++ rep_args)
379 mAX_CPR_SIZE :: Arity
381 -- We do not treat very big tuples as CPR-ish:
382 -- a) for a start we get into trouble because there aren't
383 -- "enough" unboxed tuple types (a tiresome restriction,
385 -- b) more importantly, big unboxed tuples get returned mainly
386 -- on the stack, and are often then allocated in the heap
387 -- by the caller. So doing CPR for them may in fact make
390 mkLocals i tys = (zipWith mkTemplateLocal [i..i+n-1] tys, i+n)
396 %************************************************************************
398 \subsection{Record selectors}
400 %************************************************************************
402 We're going to build a record selector unfolding that looks like this:
404 data T a b c = T1 { ..., op :: a, ...}
405 | T2 { ..., op :: a, ...}
408 sel = /\ a b c -> \ d -> case d of
413 Similarly for newtypes
415 newtype N a = MkN { unN :: a->a }
418 unN n = coerce (a->a) n
420 We need to take a little care if the field has a polymorphic type:
422 data R = R { f :: forall a. a->a }
426 f :: forall a. R -> a -> a
427 f = /\ a \ r = case r of
430 (not f :: R -> forall a. a->a, which gives the type inference mechanism
431 problems at call sites)
433 Similarly for (recursive) newtypes
435 newtype N = MkN { unN :: forall a. a->a }
437 unN :: forall b. N -> b -> b
438 unN = /\b -> \n:N -> (coerce (forall a. a->a) n)
441 Note [Naughty record selectors]
442 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
443 A "naughty" field is one for which we can't define a record
444 selector, because an existential type variable would escape. For example:
445 data T = forall a. MkT { x,y::a }
446 We obviously can't define
448 Nevertheless we *do* put a RecordSelId into the type environment
449 so that if the user tries to use 'x' as a selector we can bleat
450 helpfully, rather than saying unhelpfully that 'x' is not in scope.
451 Hence the sel_naughty flag, to identify record selectors that don't really exist.
453 In general, a field is naughty if its type mentions a type variable that
454 isn't in the result type of the constructor.
456 Note [GADT record selectors]
457 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
458 For GADTs, we require that all constructors with a common field 'f' have the same
459 result type (modulo alpha conversion). [Checked in TcTyClsDecls.checkValidTyCon]
462 T1 { f :: a } :: T [a]
463 T2 { f :: a, y :: b } :: T [a]
464 and now the selector takes that type as its argument:
465 f :: forall a. T [a] -> a
469 Note the forall'd tyvars of the selector are just the free tyvars
470 of the result type; there may be other tyvars in the constructor's
471 type (e.g. 'b' in T2).
473 Note [Selector running example]
474 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
475 It's OK to combine GADTs and type families. Here's a running example:
477 data instance T [a] where
478 T1 { fld :: b } :: T [Maybe b]
480 The representation type looks like this
482 T1 { fld :: b } :: :R7T (Maybe b)
484 and there's coercion from the family type to the representation type
485 :CoR7T a :: T [a] ~ :R7T a
487 The selector we want for fld looks like this:
489 fld :: forall b. T [Maybe b] -> b
490 fld = /\b. \(d::T [Maybe b]).
491 case d `cast` :CoR7T (Maybe b) of
494 The scrutinee of the case has type :R7T (Maybe b), which can be
495 gotten by appying the eq_spec to the univ_tvs of the data con.
498 mkRecordSelId :: TyCon -> FieldLabel -> Id
499 mkRecordSelId tycon field_label
500 -- Assumes that all fields with the same field label have the same type
501 | is_naughty = naughty_id
504 is_naughty = not (tyVarsOfType field_ty `subVarSet` data_tv_set)
505 sel_id_details = RecordSelId { sel_tycon = tycon, sel_label = field_label, sel_naughty = is_naughty }
506 -- For a data type family, the tycon is the *instance* TyCon
508 -- Escapist case here for naughty constructors
509 -- We give it no IdInfo, and a type of forall a.a (never looked at)
510 naughty_id = mkGlobalId sel_id_details field_label forall_a_a noCafIdInfo
511 forall_a_a = mkForAllTy alphaTyVar (mkTyVarTy alphaTyVar)
513 -- Normal case starts here
514 sel_id = mkGlobalId sel_id_details field_label selector_ty info
515 data_cons = tyConDataCons tycon
516 data_cons_w_field = filter has_field data_cons -- Can't be empty!
517 has_field con = field_label `elem` dataConFieldLabels con
519 con1 = ASSERT( not (null data_cons_w_field) ) head data_cons_w_field
520 (univ_tvs, _, eq_spec, _, _, _, data_ty) = dataConFullSig con1
521 -- For a data type family, the data_ty (and hence selector_ty) mentions
522 -- only the family TyCon, not the instance TyCon
523 data_tv_set = tyVarsOfType data_ty
524 data_tvs = varSetElems data_tv_set
525 field_ty = dataConFieldType con1 field_label
527 -- *Very* tiresomely, the selectors are (unnecessarily!) overloaded over
528 -- just the dictionaries in the types of the constructors that contain
529 -- the relevant field. [The Report says that pattern matching on a
530 -- constructor gives the same constraints as applying it.] Urgh.
532 -- However, not all data cons have all constraints (because of
533 -- BuildTyCl.mkDataConStupidTheta). So we need to find all the data cons
534 -- involved in the pattern match and take the union of their constraints.
535 stupid_dict_tys = mkPredTys (dataConsStupidTheta data_cons_w_field)
536 n_stupid_dicts = length stupid_dict_tys
538 (field_tyvars,pre_field_theta,field_tau) = tcSplitSigmaTy field_ty
539 field_theta = filter (not . isEqPred) pre_field_theta
540 field_dict_tys = mkPredTys field_theta
541 n_field_dict_tys = length field_dict_tys
542 -- If the field has a universally quantified type we have to
543 -- be a bit careful. Suppose we have
544 -- data R = R { op :: forall a. Foo a => a -> a }
545 -- Then we can't give op the type
546 -- op :: R -> forall a. Foo a => a -> a
547 -- because the typechecker doesn't understand foralls to the
548 -- right of an arrow. The "right" type to give it is
549 -- op :: forall a. Foo a => R -> a -> a
550 -- But then we must generate the right unfolding too:
551 -- op = /\a -> \dfoo -> \ r ->
554 -- Note that this is exactly the type we'd infer from a user defn
558 selector_ty = mkForAllTys data_tvs $ mkForAllTys field_tyvars $
559 mkFunTys stupid_dict_tys $ mkFunTys field_dict_tys $
560 mkFunTy data_ty field_tau
562 arity = 1 + n_stupid_dicts + n_field_dict_tys
564 (strict_sig, rhs_w_str) = dmdAnalTopRhs sel_rhs
565 -- Use the demand analyser to work out strictness.
566 -- With all this unpackery it's not easy!
569 `setCafInfo` caf_info
571 `setUnfoldingInfo` mkTopUnfolding rhs_w_str
572 `setAllStrictnessInfo` Just strict_sig
574 -- Allocate Ids. We do it a funny way round because field_dict_tys is
575 -- almost always empty. Also note that we use max_dict_tys
576 -- rather than n_dict_tys, because the latter gives an infinite loop:
577 -- n_dict tys depends on the_alts, which depens on arg_ids, which depends
578 -- on arity, which depends on n_dict tys. Sigh! Mega sigh!
579 stupid_dict_ids = mkTemplateLocalsNum 1 stupid_dict_tys
580 max_stupid_dicts = length (tyConStupidTheta tycon)
581 field_dict_base = max_stupid_dicts + 1
582 field_dict_ids = mkTemplateLocalsNum field_dict_base field_dict_tys
583 dict_id_base = field_dict_base + n_field_dict_tys
584 data_id = mkTemplateLocal dict_id_base data_ty
585 scrut_id = mkTemplateLocal (dict_id_base+1) scrut_ty
586 arg_base = dict_id_base + 2
588 the_alts :: [CoreAlt]
589 the_alts = map mk_alt data_cons_w_field -- Already sorted by data-con
590 no_default = length data_cons == length data_cons_w_field -- No default needed
592 default_alt | no_default = []
593 | otherwise = [(DEFAULT, [], error_expr)]
595 -- The default branch may have CAF refs, because it calls recSelError etc.
596 caf_info | no_default = NoCafRefs
597 | otherwise = MayHaveCafRefs
599 sel_rhs = mkLams data_tvs $ mkLams field_tyvars $
600 mkLams stupid_dict_ids $ mkLams field_dict_ids $
601 Lam data_id $ mk_result sel_body
603 scrut_ty_args = substTyVars (mkTopTvSubst eq_spec) univ_tvs
604 scrut_ty = mkTyConApp tycon scrut_ty_args
605 scrut = unwrapFamInstScrut tycon scrut_ty_args (Var data_id)
606 -- First coerce from the type family to the representation type
608 -- NB: A newtype always has a vanilla DataCon; no existentials etc
609 -- data_tys will simply be the dataConUnivTyVars
610 sel_body | isNewTyCon tycon = unwrapNewTypeBody tycon scrut_ty_args scrut
611 | otherwise = Case scrut scrut_id field_ty (default_alt ++ the_alts)
613 mk_result poly_result = mkVarApps (mkVarApps poly_result field_tyvars) field_dict_ids
614 -- We pull the field lambdas to the top, so we need to
615 -- apply them in the body. For example:
616 -- data T = MkT { foo :: forall a. a->a }
618 -- foo :: forall a. T -> a -> a
619 -- foo = /\a. \t:T. case t of { MkT f -> f a }
622 = ASSERT2( data_ty `tcEqType` field_ty, ppr data_con $$ ppr data_ty $$ ppr field_ty )
623 mkReboxingAlt rebox_uniqs data_con (ex_tvs ++ co_tvs ++ arg_vs) rhs
625 -- get pattern binders with types appropriately instantiated
626 arg_uniqs = map mkBuiltinUnique [arg_base..]
627 (ex_tvs, co_tvs, arg_vs) = dataConOrigInstPat arg_uniqs data_con scrut_ty_args
629 rebox_base = arg_base + length ex_tvs + length co_tvs + length arg_vs
630 rebox_uniqs = map mkBuiltinUnique [rebox_base..]
632 -- data T :: *->* where T1 { fld :: Maybe b } -> T [b]
633 -- Hence T1 :: forall a b. (a=[b]) => b -> T a
634 -- fld :: forall b. T [b] -> Maybe b
635 -- fld = /\b.\(t:T[b]). case t of
636 -- T1 b' (c : [b]=[b']) (x:Maybe b')
637 -- -> x `cast` Maybe (sym (right c))
640 -- Generate the refinement for b'=b,
641 -- and apply to (Maybe b'), to get (Maybe b)
642 Succeeded refinement = gadtRefine emptyRefinement ex_tvs co_tvs
643 the_arg_id_ty = idType the_arg_id
644 (rhs, data_ty) = case refineType refinement the_arg_id_ty of
645 Just (co, data_ty) -> (Cast (Var the_arg_id) co, data_ty)
646 Nothing -> (Var the_arg_id, the_arg_id_ty)
648 field_vs = filter (not . isPredTy . idType) arg_vs
649 the_arg_id = assoc "mkRecordSelId:mk_alt" (field_lbls `zip` field_vs) field_label
650 field_lbls = dataConFieldLabels data_con
652 error_expr = mkRuntimeErrorApp rEC_SEL_ERROR_ID field_ty full_msg
653 full_msg = showSDoc (sep [text "No match in record selector", ppr sel_id])
655 -- unbox a product type...
656 -- we will recurse into newtypes, casting along the way, and unbox at the
657 -- first product data constructor we find. e.g.
659 -- data PairInt = PairInt Int Int
660 -- newtype S = MkS PairInt
663 -- If we have e = MkT (MkS (PairInt 0 1)) and some body expecting a list of
664 -- ids, we get (modulo int passing)
666 -- case (e `cast` CoT) `cast` CoS of
667 -- PairInt a b -> body [a,b]
669 -- The Ints passed around are just for creating fresh locals
670 unboxProduct :: Int -> CoreExpr -> Type -> (Int -> [Id] -> CoreExpr) -> CoreExpr
671 unboxProduct i arg arg_ty body
674 result = mkUnpackCase the_id arg con_args boxing_con rhs
675 (_tycon, _tycon_args, boxing_con, tys) = deepSplitProductType "unboxProduct" arg_ty
676 ([the_id], i') = mkLocals i [arg_ty]
677 (con_args, i'') = mkLocals i' tys
678 rhs = body i'' con_args
680 mkUnpackCase :: Id -> CoreExpr -> [Id] -> DataCon -> CoreExpr -> CoreExpr
681 -- (mkUnpackCase x e args Con body)
683 -- case (e `cast` ...) of bndr { Con args -> body }
685 -- the type of the bndr passed in is irrelevent
686 mkUnpackCase bndr arg unpk_args boxing_con body
687 = Case cast_arg (setIdType bndr bndr_ty) (exprType body) [(DataAlt boxing_con, unpk_args, body)]
689 (cast_arg, bndr_ty) = go (idType bndr) arg
691 | (tycon, tycon_args, _, _) <- splitProductType "mkUnpackCase" ty
692 , isNewTyCon tycon && not (isRecursiveTyCon tycon)
693 = go (newTyConInstRhs tycon tycon_args)
694 (unwrapNewTypeBody tycon tycon_args arg)
695 | otherwise = (arg, ty)
698 reboxProduct :: [Unique] -- uniques to create new local binders
699 -> Type -- type of product to box
700 -> ([Unique], -- remaining uniques
701 CoreExpr, -- boxed product
702 [Id]) -- Ids being boxed into product
705 (_tycon, _tycon_args, _pack_con, con_arg_tys) = deepSplitProductType "reboxProduct" ty
707 us' = dropList con_arg_tys us
709 arg_ids = zipWith (mkSysLocal FSLIT("rb")) us con_arg_tys
711 bind_rhs = mkProductBox arg_ids ty
714 (us', bind_rhs, arg_ids)
716 mkProductBox :: [Id] -> Type -> CoreExpr
717 mkProductBox arg_ids ty
720 (tycon, tycon_args, pack_con, _con_arg_tys) = splitProductType "mkProductBox" ty
723 | isNewTyCon tycon && not (isRecursiveTyCon tycon)
724 = wrap (mkProductBox arg_ids (newTyConInstRhs tycon tycon_args))
725 | otherwise = mkConApp pack_con (map Type tycon_args ++ map Var arg_ids)
727 wrap expr = wrapNewTypeBody tycon tycon_args expr
730 -- (mkReboxingAlt us con xs rhs) basically constructs the case
731 -- alternative (con, xs, rhs)
732 -- but it does the reboxing necessary to construct the *source*
733 -- arguments, xs, from the representation arguments ys.
735 -- data T = MkT !(Int,Int) Bool
737 -- mkReboxingAlt MkT [x,b] r
738 -- = (DataAlt MkT, [y::Int,z::Int,b], let x = (y,z) in r)
740 -- mkDataAlt should really be in DataCon, but it can't because
741 -- it manipulates CoreSyn.
744 :: [Unique] -- Uniques for the new Ids
746 -> [Var] -- Source-level args, including existential dicts
750 mkReboxingAlt us con args rhs
751 | not (any isMarkedUnboxed stricts)
752 = (DataAlt con, args, rhs)
756 (binds, args') = go args stricts us
758 (DataAlt con, args', mkLets binds rhs)
761 stricts = dataConExStricts con ++ dataConStrictMarks con
763 go [] _stricts _us = ([], [])
765 -- Type variable case
766 go (arg:args) stricts us
768 = let (binds, args') = go args stricts us
769 in (binds, arg:args')
771 -- Term variable case
772 go (arg:args) (str:stricts) us
773 | isMarkedUnboxed str
775 let (binds, unpacked_args') = go args stricts us'
776 (us', bind_rhs, unpacked_args) = reboxProduct us (idType arg)
778 (NonRec arg bind_rhs : binds, unpacked_args ++ unpacked_args')
780 = let (binds, args') = go args stricts us
781 in (binds, arg:args')
785 %************************************************************************
787 \subsection{Dictionary selectors}
789 %************************************************************************
791 Selecting a field for a dictionary. If there is just one field, then
792 there's nothing to do.
794 Dictionary selectors may get nested forall-types. Thus:
797 op :: forall b. Ord b => a -> b -> b
799 Then the top-level type for op is
801 op :: forall a. Foo a =>
805 This is unlike ordinary record selectors, which have all the for-alls
806 at the outside. When dealing with classes it's very convenient to
807 recover the original type signature from the class op selector.
810 mkDictSelId :: Name -> Class -> Id
811 mkDictSelId name clas
812 = mkGlobalId (ClassOpId clas) name sel_ty info
814 sel_ty = mkForAllTys tyvars (mkFunTy (idType dict_id) (idType the_arg_id))
815 -- We can't just say (exprType rhs), because that would give a type
817 -- for a single-op class (after all, the selector is the identity)
818 -- But it's type must expose the representation of the dictionary
819 -- to get (say) C a -> (a -> a)
823 `setUnfoldingInfo` mkTopUnfolding rhs
824 `setAllStrictnessInfo` Just strict_sig
826 -- We no longer use 'must-inline' on record selectors. They'll
827 -- inline like crazy if they scrutinise a constructor
829 -- The strictness signature is of the form U(AAAVAAAA) -> T
830 -- where the V depends on which item we are selecting
831 -- It's worth giving one, so that absence info etc is generated
832 -- even if the selector isn't inlined
833 strict_sig = mkStrictSig (mkTopDmdType [arg_dmd] TopRes)
834 arg_dmd | isNewTyCon tycon = evalDmd
835 | otherwise = Eval (Prod [ if the_arg_id == id then evalDmd else Abs
838 tycon = classTyCon clas
839 [data_con] = tyConDataCons tycon
840 tyvars = dataConUnivTyVars data_con
841 arg_tys = {- ASSERT( isVanillaDataCon data_con ) -} dataConRepArgTys data_con
842 eq_theta = dataConEqTheta data_con
843 the_arg_id = assoc "MkId.mkDictSelId" (map idName (classSelIds clas) `zip` arg_ids) name
845 pred = mkClassPred clas (mkTyVarTys tyvars)
846 dict_id = mkTemplateLocal 1 $ mkPredTy pred
847 (eq_ids,n) = mkCoVarLocals 2 $ mkPredTys eq_theta
848 arg_ids = mkTemplateLocalsNum n arg_tys
850 mkCoVarLocals i [] = ([],i)
851 mkCoVarLocals i (x:xs) = let (ys,j) = mkCoVarLocals (i+1) xs
852 y = mkCoVar (mkSysTvName (mkBuiltinUnique i) FSLIT("dc_co")) x
855 rhs = mkLams tyvars (Lam dict_id rhs_body)
856 rhs_body | isNewTyCon tycon = unwrapNewTypeBody tycon (map mkTyVarTy tyvars) (Var dict_id)
857 | otherwise = Case (Var dict_id) dict_id (idType the_arg_id)
858 [(DataAlt data_con, eq_ids ++ arg_ids, Var the_arg_id)]
862 %************************************************************************
864 Wrapping and unwrapping newtypes and type families
866 %************************************************************************
869 wrapNewTypeBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
870 -- The wrapper for the data constructor for a newtype looks like this:
871 -- newtype T a = MkT (a,Int)
872 -- MkT :: forall a. (a,Int) -> T a
873 -- MkT = /\a. \(x:(a,Int)). x `cast` sym (CoT a)
874 -- where CoT is the coercion TyCon assoicated with the newtype
876 -- The call (wrapNewTypeBody T [a] e) returns the
877 -- body of the wrapper, namely
878 -- e `cast` (CoT [a])
880 -- If a coercion constructor is provided in the newtype, then we use
881 -- it, otherwise the wrap/unwrap are both no-ops
883 -- If the we are dealing with a newtype *instance*, we have a second coercion
884 -- identifying the family instance with the constructor of the newtype
885 -- instance. This coercion is applied in any case (ie, composed with the
886 -- coercion constructor of the newtype or applied by itself).
888 wrapNewTypeBody tycon args result_expr
889 = wrapFamInstBody tycon args inner
892 | Just co_con <- newTyConCo_maybe tycon
893 = mkCoerce (mkSymCoercion (mkTyConApp co_con args)) result_expr
897 -- When unwrapping, we do *not* apply any family coercion, because this will
898 -- be done via a CoPat by the type checker. We have to do it this way as
899 -- computing the right type arguments for the coercion requires more than just
900 -- a spliting operation (cf, TcPat.tcConPat).
902 unwrapNewTypeBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
903 unwrapNewTypeBody tycon args result_expr
904 | Just co_con <- newTyConCo_maybe tycon
905 = mkCoerce (mkTyConApp co_con args) result_expr
909 -- If the type constructor is a representation type of a data instance, wrap
910 -- the expression into a cast adjusting the expression type, which is an
911 -- instance of the representation type, to the corresponding instance of the
912 -- family instance type.
913 -- See Note [Wrappers for data instance tycons]
914 wrapFamInstBody :: TyCon -> [Type] -> CoreExpr -> CoreExpr
915 wrapFamInstBody tycon args body
916 | Just co_con <- tyConFamilyCoercion_maybe tycon
917 = mkCoerce (mkSymCoercion (mkTyConApp co_con args)) body
921 unwrapFamInstScrut :: TyCon -> [Type] -> CoreExpr -> CoreExpr
922 unwrapFamInstScrut tycon args scrut
923 | Just co_con <- tyConFamilyCoercion_maybe tycon
924 = mkCoerce (mkTyConApp co_con args) scrut
930 %************************************************************************
932 \subsection{Primitive operations
934 %************************************************************************
937 mkPrimOpId :: PrimOp -> Id
941 (tyvars,arg_tys,res_ty, arity, strict_sig) = primOpSig prim_op
942 ty = mkForAllTys tyvars (mkFunTys arg_tys res_ty)
943 name = mkWiredInName gHC_PRIM (primOpOcc prim_op)
944 (mkPrimOpIdUnique (primOpTag prim_op))
946 id = mkGlobalId (PrimOpId prim_op) name ty info
949 `setSpecInfo` mkSpecInfo (primOpRules prim_op name)
951 `setAllStrictnessInfo` Just strict_sig
953 -- For each ccall we manufacture a separate CCallOpId, giving it
954 -- a fresh unique, a type that is correct for this particular ccall,
955 -- and a CCall structure that gives the correct details about calling
958 -- The *name* of this Id is a local name whose OccName gives the full
959 -- details of the ccall, type and all. This means that the interface
960 -- file reader can reconstruct a suitable Id
962 mkFCallId :: Unique -> ForeignCall -> Type -> Id
963 mkFCallId uniq fcall ty
964 = ASSERT( isEmptyVarSet (tyVarsOfType ty) )
965 -- A CCallOpId should have no free type variables;
966 -- when doing substitutions won't substitute over it
967 mkGlobalId (FCallId fcall) name ty info
969 occ_str = showSDoc (braces (ppr fcall <+> ppr ty))
970 -- The "occurrence name" of a ccall is the full info about the
971 -- ccall; it is encoded, but may have embedded spaces etc!
973 name = mkFCallName uniq occ_str
977 `setAllStrictnessInfo` Just strict_sig
979 (_, tau) = tcSplitForAllTys ty
980 (arg_tys, _) = tcSplitFunTys tau
981 arity = length arg_tys
982 strict_sig = mkStrictSig (mkTopDmdType (replicate arity evalDmd) TopRes)
984 -- Tick boxes and breakpoints are both represented as TickBoxOpIds,
985 -- except for the type:
987 -- a plain HPC tick box has type (State# RealWorld)
988 -- a breakpoint Id has type forall a.a
990 -- The breakpoint Id will be applied to a list of arbitrary free variables,
991 -- which is why it needs a polymorphic type.
993 mkTickBoxOpId :: Unique -> Module -> TickBoxId -> Id
994 mkTickBoxOpId uniq mod ix = mkTickBox' uniq mod ix realWorldStatePrimTy
996 mkBreakPointOpId :: Unique -> Module -> TickBoxId -> Id
997 mkBreakPointOpId uniq mod ix = mkTickBox' uniq mod ix ty
998 where ty = mkSigmaTy [openAlphaTyVar] [] openAlphaTy
1000 mkTickBox' uniq mod ix ty = mkGlobalId (TickBoxOpId tickbox) name ty info
1002 tickbox = TickBox mod ix
1003 occ_str = showSDoc (braces (ppr tickbox))
1004 name = mkTickBoxOpName uniq occ_str
1009 %************************************************************************
1011 \subsection{DictFuns and default methods}
1013 %************************************************************************
1015 Important notes about dict funs and default methods
1016 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1017 Dict funs and default methods are *not* ImplicitIds. Their definition
1018 involves user-written code, so we can't figure out their strictness etc
1019 based on fixed info, as we can for constructors and record selectors (say).
1021 We build them as LocalIds, but with External Names. This ensures that
1022 they are taken to account by free-variable finding and dependency
1023 analysis (e.g. CoreFVs.exprFreeVars).
1025 Why shouldn't they be bound as GlobalIds? Because, in particular, if
1026 they are globals, the specialiser floats dict uses above their defns,
1027 which prevents good simplifications happening. Also the strictness
1028 analyser treats a occurrence of a GlobalId as imported and assumes it
1029 contains strictness in its IdInfo, which isn't true if the thing is
1030 bound in the same module as the occurrence.
1032 It's OK for dfuns to be LocalIds, because we form the instance-env to
1033 pass on to the next module (md_insts) in CoreTidy, afer tidying
1034 and globalising the top-level Ids.
1036 BUT make sure they are *exported* LocalIds (mkExportedLocalId) so
1037 that they aren't discarded by the occurrence analyser.
1040 mkDefaultMethodId dm_name ty = mkExportedLocalId dm_name ty
1042 mkDictFunId :: Name -- Name to use for the dict fun;
1049 mkDictFunId dfun_name inst_tyvars dfun_theta clas inst_tys
1050 = mkExportedLocalId dfun_name dfun_ty
1052 dfun_ty = mkSigmaTy inst_tyvars dfun_theta (mkDictTy clas inst_tys)
1054 {- 1 dec 99: disable the Mark Jones optimisation for the sake
1055 of compatibility with Hugs.
1056 See `types/InstEnv' for a discussion related to this.
1058 (class_tyvars, sc_theta, _, _) = classBigSig clas
1059 not_const (clas, tys) = not (isEmptyVarSet (tyVarsOfTypes tys))
1060 sc_theta' = substClasses (zipTopTvSubst class_tyvars inst_tys) sc_theta
1061 dfun_theta = case inst_decl_theta of
1062 [] -> [] -- If inst_decl_theta is empty, then we don't
1063 -- want to have any dict arguments, so that we can
1064 -- expose the constant methods.
1066 other -> nub (inst_decl_theta ++ filter not_const sc_theta')
1067 -- Otherwise we pass the superclass dictionaries to
1068 -- the dictionary function; the Mark Jones optimisation.
1070 -- NOTE the "nub". I got caught by this one:
1071 -- class Monad m => MonadT t m where ...
1072 -- instance Monad m => MonadT (EnvT env) m where ...
1073 -- Here, the inst_decl_theta has (Monad m); but so
1074 -- does the sc_theta'!
1076 -- NOTE the "not_const". I got caught by this one too:
1077 -- class Foo a => Baz a b where ...
1078 -- instance Wob b => Baz T b where..
1079 -- Now sc_theta' has Foo T
1084 %************************************************************************
1086 \subsection{Un-definable}
1088 %************************************************************************
1090 These Ids can't be defined in Haskell. They could be defined in
1091 unfoldings in the wired-in GHC.Prim interface file, but we'd have to
1092 ensure that they were definitely, definitely inlined, because there is
1093 no curried identifier for them. That's what mkCompulsoryUnfolding
1094 does. If we had a way to get a compulsory unfolding from an interface
1095 file, we could do that, but we don't right now.
1097 unsafeCoerce# isn't so much a PrimOp as a phantom identifier, that
1098 just gets expanded into a type coercion wherever it occurs. Hence we
1099 add it as a built-in Id with an unfolding here.
1101 The type variables we use here are "open" type variables: this means
1102 they can unify with both unlifted and lifted types. Hence we provide
1103 another gun with which to shoot yourself in the foot.
1106 mkWiredInIdName mod fs uniq id
1107 = mkWiredInName mod (mkOccNameFS varName fs) uniq (AnId id) UserSyntax
1109 unsafeCoerceName = mkWiredInIdName gHC_PRIM FSLIT("unsafeCoerce#") unsafeCoerceIdKey unsafeCoerceId
1110 nullAddrName = mkWiredInIdName gHC_PRIM FSLIT("nullAddr#") nullAddrIdKey nullAddrId
1111 seqName = mkWiredInIdName gHC_PRIM FSLIT("seq") seqIdKey seqId
1112 realWorldName = mkWiredInIdName gHC_PRIM FSLIT("realWorld#") realWorldPrimIdKey realWorldPrimId
1113 lazyIdName = mkWiredInIdName gHC_BASE FSLIT("lazy") lazyIdKey lazyId
1115 errorName = mkWiredInIdName gHC_ERR FSLIT("error") errorIdKey eRROR_ID
1116 recSelErrorName = mkWiredInIdName gHC_ERR FSLIT("recSelError") recSelErrorIdKey rEC_SEL_ERROR_ID
1117 runtimeErrorName = mkWiredInIdName gHC_ERR FSLIT("runtimeError") runtimeErrorIdKey rUNTIME_ERROR_ID
1118 irrefutPatErrorName = mkWiredInIdName gHC_ERR FSLIT("irrefutPatError") irrefutPatErrorIdKey iRREFUT_PAT_ERROR_ID
1119 recConErrorName = mkWiredInIdName gHC_ERR FSLIT("recConError") recConErrorIdKey rEC_CON_ERROR_ID
1120 patErrorName = mkWiredInIdName gHC_ERR FSLIT("patError") patErrorIdKey pAT_ERROR_ID
1121 noMethodBindingErrorName = mkWiredInIdName gHC_ERR FSLIT("noMethodBindingError")
1122 noMethodBindingErrorIdKey nO_METHOD_BINDING_ERROR_ID
1123 nonExhaustiveGuardsErrorName
1124 = mkWiredInIdName gHC_ERR FSLIT("nonExhaustiveGuardsError")
1125 nonExhaustiveGuardsErrorIdKey nON_EXHAUSTIVE_GUARDS_ERROR_ID
1129 -- unsafeCoerce# :: forall a b. a -> b
1131 = pcMiscPrelId unsafeCoerceName ty info
1133 info = noCafIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs
1136 ty = mkForAllTys [openAlphaTyVar,openBetaTyVar]
1137 (mkFunTy openAlphaTy openBetaTy)
1138 [x] = mkTemplateLocals [openAlphaTy]
1139 rhs = mkLams [openAlphaTyVar,openBetaTyVar,x] $
1140 Cast (Var x) (mkUnsafeCoercion openAlphaTy openBetaTy)
1142 -- nullAddr# :: Addr#
1143 -- The reason is is here is because we don't provide
1144 -- a way to write this literal in Haskell.
1146 = pcMiscPrelId nullAddrName addrPrimTy info
1148 info = noCafIdInfo `setUnfoldingInfo`
1149 mkCompulsoryUnfolding (Lit nullAddrLit)
1152 = pcMiscPrelId seqName ty info
1154 info = noCafIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs
1157 ty = mkForAllTys [alphaTyVar,openBetaTyVar]
1158 (mkFunTy alphaTy (mkFunTy openBetaTy openBetaTy))
1159 [x,y] = mkTemplateLocals [alphaTy, openBetaTy]
1160 rhs = mkLams [alphaTyVar,openBetaTyVar,x,y] (Case (Var x) x openBetaTy [(DEFAULT, [], Var y)])
1162 -- lazy :: forall a?. a? -> a? (i.e. works for unboxed types too)
1163 -- Used to lazify pseq: pseq a b = a `seq` lazy b
1165 -- Also, no strictness: by being a built-in Id, all the info about lazyId comes from here,
1166 -- not from GHC.Base.hi. This is important, because the strictness
1167 -- analyser will spot it as strict!
1169 -- Also no unfolding in lazyId: it gets "inlined" by a HACK in the worker/wrapperpass
1170 -- (see WorkWrap.wwExpr)
1171 -- We could use inline phases to do this, but that would be vulnerable to changes in
1172 -- phase numbering....we must inline precisely after strictness analysis.
1174 = pcMiscPrelId lazyIdName ty info
1177 ty = mkForAllTys [alphaTyVar] (mkFunTy alphaTy alphaTy)
1179 lazyIdUnfolding :: CoreExpr -- Used to expand 'lazyId' after strictness anal
1180 lazyIdUnfolding = mkLams [openAlphaTyVar,x] (Var x)
1182 [x] = mkTemplateLocals [openAlphaTy]
1185 @realWorld#@ used to be a magic literal, \tr{void#}. If things get
1186 nasty as-is, change it back to a literal (@Literal@).
1188 voidArgId is a Local Id used simply as an argument in functions
1189 where we just want an arg to avoid having a thunk of unlifted type.
1191 x = \ void :: State# RealWorld -> (# p, q #)
1193 This comes up in strictness analysis
1196 realWorldPrimId -- :: State# RealWorld
1197 = pcMiscPrelId realWorldName realWorldStatePrimTy
1198 (noCafIdInfo `setUnfoldingInfo` evaldUnfolding)
1199 -- The evaldUnfolding makes it look that realWorld# is evaluated
1200 -- which in turn makes Simplify.interestingArg return True,
1201 -- which in turn makes INLINE things applied to realWorld# likely
1204 voidArgId -- :: State# RealWorld
1205 = mkSysLocal FSLIT("void") voidArgIdKey realWorldStatePrimTy
1209 %************************************************************************
1211 \subsection[PrelVals-error-related]{@error@ and friends; @trace@}
1213 %************************************************************************
1215 GHC randomly injects these into the code.
1217 @patError@ is just a version of @error@ for pattern-matching
1218 failures. It knows various ``codes'' which expand to longer
1219 strings---this saves space!
1221 @absentErr@ is a thing we put in for ``absent'' arguments. They jolly
1222 well shouldn't be yanked on, but if one is, then you will get a
1223 friendly message from @absentErr@ (rather than a totally random
1226 @parError@ is a special version of @error@ which the compiler does
1227 not know to be a bottoming Id. It is used in the @_par_@ and @_seq_@
1228 templates, but we don't ever expect to generate code for it.
1232 :: Id -- Should be of type (forall a. Addr# -> a)
1233 -- where Addr# points to a UTF8 encoded string
1234 -> Type -- The type to instantiate 'a'
1235 -> String -- The string to print
1238 mkRuntimeErrorApp err_id res_ty err_msg
1239 = mkApps (Var err_id) [Type res_ty, err_string]
1241 err_string = Lit (mkStringLit err_msg)
1243 rEC_SEL_ERROR_ID = mkRuntimeErrorId recSelErrorName
1244 rUNTIME_ERROR_ID = mkRuntimeErrorId runtimeErrorName
1245 iRREFUT_PAT_ERROR_ID = mkRuntimeErrorId irrefutPatErrorName
1246 rEC_CON_ERROR_ID = mkRuntimeErrorId recConErrorName
1247 pAT_ERROR_ID = mkRuntimeErrorId patErrorName
1248 nO_METHOD_BINDING_ERROR_ID = mkRuntimeErrorId noMethodBindingErrorName
1249 nON_EXHAUSTIVE_GUARDS_ERROR_ID = mkRuntimeErrorId nonExhaustiveGuardsErrorName
1251 -- The runtime error Ids take a UTF8-encoded string as argument
1252 mkRuntimeErrorId name = pc_bottoming_Id name runtimeErrorTy
1253 runtimeErrorTy = mkSigmaTy [openAlphaTyVar] [] (mkFunTy addrPrimTy openAlphaTy)
1257 eRROR_ID = pc_bottoming_Id errorName errorTy
1260 errorTy = mkSigmaTy [openAlphaTyVar] [] (mkFunTys [mkListTy charTy] openAlphaTy)
1261 -- Notice the openAlphaTyVar. It says that "error" can be applied
1262 -- to unboxed as well as boxed types. This is OK because it never
1263 -- returns, so the return type is irrelevant.
1267 %************************************************************************
1269 \subsection{Utilities}
1271 %************************************************************************
1274 pcMiscPrelId :: Name -> Type -> IdInfo -> Id
1275 pcMiscPrelId name ty info
1276 = mkVanillaGlobal name ty info
1277 -- We lie and say the thing is imported; otherwise, we get into
1278 -- a mess with dependency analysis; e.g., core2stg may heave in
1279 -- random calls to GHCbase.unpackPS__. If GHCbase is the module
1280 -- being compiled, then it's just a matter of luck if the definition
1281 -- will be in "the right place" to be in scope.
1283 pc_bottoming_Id name ty
1284 = pcMiscPrelId name ty bottoming_info
1286 bottoming_info = vanillaIdInfo `setAllStrictnessInfo` Just strict_sig
1287 -- Do *not* mark them as NoCafRefs, because they can indeed have
1288 -- CAF refs. For example, pAT_ERROR_ID calls GHC.Err.untangle,
1289 -- which has some CAFs
1290 -- In due course we may arrange that these error-y things are
1291 -- regarded by the GC as permanently live, in which case we
1292 -- can give them NoCaf info. As it is, any function that calls
1293 -- any pc_bottoming_Id will itself have CafRefs, which bloats
1296 strict_sig = mkStrictSig (mkTopDmdType [evalDmd] BotRes)
1297 -- These "bottom" out, no matter what their arguments