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 mkDictFunId, mkDefaultMethodId,
19 mkDataConId, mkDataConWrapId,
20 mkRecordSelId, rebuildConArgs,
21 mkPrimOpId, mkFCallId,
23 -- And some particular Ids; see below for why they are wired in
25 unsafeCoerceId, realWorldPrimId, voidArgId, nullAddrId,
26 eRROR_ID, eRROR_CSTRING_ID, rEC_SEL_ERROR_ID, pAT_ERROR_ID, rEC_CON_ERROR_ID,
27 rEC_UPD_ERROR_ID, iRREFUT_PAT_ERROR_ID, nON_EXHAUSTIVE_GUARDS_ERROR_ID,
28 nO_METHOD_BINDING_ERROR_ID, aBSENT_ERROR_ID, pAR_ERROR_ID
31 #include "HsVersions.h"
34 import BasicTypes ( Arity, StrictnessMark(..), isMarkedUnboxed, isMarkedStrict )
35 import TysPrim ( openAlphaTyVars, alphaTyVar, alphaTy, betaTyVar, betaTy,
36 intPrimTy, realWorldStatePrimTy, addrPrimTy
38 import TysWiredIn ( charTy, mkListTy )
39 import PrelRules ( primOpRules )
40 import Rules ( addRule )
41 import TcType ( Type, ThetaType, mkDictTy, mkPredTys, mkTyConApp,
42 mkTyVarTys, mkClassPred, tcEqPred,
43 mkFunTys, mkFunTy, mkSigmaTy, tcSplitSigmaTy,
44 isUnLiftedType, mkForAllTys, mkTyVarTy, tyVarsOfType,
45 tcSplitFunTys, tcSplitForAllTys, mkPredTy
47 import Module ( Module )
48 import CoreUtils ( mkInlineMe, exprType )
49 import CoreUnfold ( mkTopUnfolding, mkCompulsoryUnfolding, mkOtherCon )
50 import Literal ( Literal(..), nullAddrLit )
51 import TyCon ( TyCon, isNewTyCon, tyConTyVars, tyConDataCons,
52 tyConTheta, isProductTyCon, isDataTyCon, isRecursiveTyCon )
53 import Class ( Class, classTyCon, classTyVars, classSelIds )
54 import Var ( Id, TyVar )
55 import VarSet ( isEmptyVarSet )
56 import Name ( mkWiredInName, mkFCallName, Name )
57 import OccName ( mkVarOcc )
58 import PrimOp ( PrimOp(DataToTagOp), primOpSig, mkPrimOpIdName )
59 import ForeignCall ( ForeignCall )
60 import DataCon ( DataCon,
61 dataConFieldLabels, dataConRepArity, dataConTyCon,
62 dataConArgTys, dataConRepType,
63 dataConInstOrigArgTys,
64 dataConName, dataConTheta,
65 dataConSig, dataConStrictMarks, dataConId,
68 import Id ( idType, mkGlobalId, mkVanillaGlobal, mkSysLocal,
69 mkTemplateLocals, mkTemplateLocalsNum,
70 mkTemplateLocal, idNewStrictness, idName
72 import IdInfo ( IdInfo, noCafNoTyGenIdInfo,
74 setArityInfo, setSpecInfo, setCgInfo, setCafInfo,
75 newStrictnessFromOld, setAllStrictnessInfo,
76 GlobalIdDetails(..), CafInfo(..), CprInfo(..),
79 import NewDemand ( mkStrictSig, strictSigResInfo, DmdResult(..),
80 mkTopDmdType, topDmd, evalDmd, lazyDmd,
81 Demand(..), Demands(..) )
82 import FieldLabel ( mkFieldLabel, fieldLabelName,
83 firstFieldLabelTag, allFieldLabelTags, fieldLabelType
85 import DmdAnal ( dmdAnalTopRhs )
87 import Unique ( mkBuiltinUnique )
90 import Maybe ( isJust )
91 import Util ( dropList, isSingleton )
93 import ListSetOps ( assoc, assocMaybe )
94 import UnicodeUtil ( stringToUtf8 )
98 %************************************************************************
100 \subsection{Wired in Ids}
102 %************************************************************************
106 = [ -- These error-y things are wired in because we don't yet have
107 -- a way to express in an interface file that the result type variable
108 -- is 'open'; that is can be unified with an unboxed type
110 -- [The interface file format now carry such information, but there's
111 -- no way yet of expressing at the definition site for these
112 -- error-reporting functions that they have an 'open'
113 -- result type. -- sof 1/99]
118 , iRREFUT_PAT_ERROR_ID
119 , nON_EXHAUSTIVE_GUARDS_ERROR_ID
120 , nO_METHOD_BINDING_ERROR_ID
126 -- These can't be defined in Haskell, but they have
127 -- perfectly reasonable unfoldings in Core
136 %************************************************************************
138 \subsection{Data constructors}
140 %************************************************************************
143 mkDataConId :: Name -> DataCon -> Id
144 -- Makes the *worker* for the data constructor; that is, the function
145 -- that takes the reprsentation arguments and builds the constructor.
146 mkDataConId work_name data_con
147 = mkGlobalId (DataConId data_con) work_name (dataConRepType data_con) info
149 info = noCafNoTyGenIdInfo
151 `setAllStrictnessInfo` Just strict_sig
153 arity = dataConRepArity data_con
155 strict_sig = mkStrictSig (mkTopDmdType (replicate arity topDmd) cpr_info)
156 -- Notice that we do *not* say the worker is strict
157 -- even if the data constructor is declared strict
158 -- e.g. data T = MkT !(Int,Int)
159 -- Why? Because the *wrapper* is strict (and its unfolding has case
160 -- expresssions that do the evals) but the *worker* itself is not.
161 -- If we pretend it is strict then when we see
162 -- case x of y -> $wMkT y
163 -- the simplifier thinks that y is "sure to be evaluated" (because
164 -- $wMkT is strict) and drops the case. No, $wMkT is not strict.
166 -- When the simplifer sees a pattern
167 -- case e of MkT x -> ...
168 -- it uses the dataConRepStrictness of MkT to mark x as evaluated;
169 -- but that's fine... dataConRepStrictness comes from the data con
170 -- not from the worker Id.
172 tycon = dataConTyCon data_con
173 cpr_info | isProductTyCon tycon &&
176 arity <= mAX_CPR_SIZE = RetCPR
178 -- RetCPR is only true for products that are real data types;
179 -- that is, not unboxed tuples or [non-recursive] newtypes
181 mAX_CPR_SIZE :: Arity
183 -- We do not treat very big tuples as CPR-ish:
184 -- a) for a start we get into trouble because there aren't
185 -- "enough" unboxed tuple types (a tiresome restriction,
187 -- b) more importantly, big unboxed tuples get returned mainly
188 -- on the stack, and are often then allocated in the heap
189 -- by the caller. So doing CPR for them may in fact make
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
232 = mkGlobalId (DataConWrapId data_con) (dataConName data_con) wrap_ty info
234 work_id = dataConId data_con
236 info = noCafNoTyGenIdInfo
237 `setUnfoldingInfo` wrap_unf
238 -- The NoCaf-ness is set by noCafNoTyGenIdInfo
240 -- It's important to specify the arity, so that partial
241 -- applications are treated as values
242 `setAllStrictnessInfo` Just wrap_sig
244 wrap_ty = mkForAllTys all_tyvars (mkFunTys all_arg_tys result_ty)
246 wrap_sig = mkStrictSig (mkTopDmdType arg_dmds res_info)
247 res_info = strictSigResInfo (idNewStrictness work_id)
248 arg_dmds = [Abs | d <- dict_args] ++ map mk_dmd strict_marks
249 mk_dmd str | isMarkedStrict str = evalDmd
250 | otherwise = lazyDmd
251 -- The Cpr info can be important inside INLINE rhss, where the
252 -- wrapper constructor isn't inlined.
253 -- And the argument strictness can be important too; we
254 -- may not inline a contructor when it is partially applied.
256 -- data W = C !Int !Int !Int
257 -- ...(let w = C x in ...(w p q)...)...
258 -- we want to see that w is strict in its two arguments
260 wrap_unf | isNewTyCon tycon
261 = ASSERT( null ex_tyvars && null ex_dict_args && isSingleton orig_arg_tys )
262 -- No existentials on a newtype, but it can have a context
263 -- e.g. newtype Eq a => T a = MkT (...)
264 mkTopUnfolding $ Note InlineMe $
265 mkLams tyvars $ mkLams dict_args $ Lam id_arg1 $
266 mkNewTypeBody tycon result_ty (Var id_arg1)
268 | null dict_args && not (any isMarkedStrict strict_marks)
269 = mkCompulsoryUnfolding (Var work_id)
270 -- The common case. Not only is this efficient,
271 -- but it also ensures that the wrapper is replaced
272 -- by the worker even when there are no args.
276 -- This is really important in rule matching,
277 -- (We could match on the wrappers,
278 -- but that makes it less likely that rules will match
279 -- when we bring bits of unfoldings together.)
281 -- NB: because of this special case, (map (:) ys) turns into
282 -- (map $w: ys). The top-level defn for (:) is never used.
283 -- This is somewhat of a bore, but I'm currently leaving it
284 -- as is, so that there still is a top level curried (:) for
285 -- the interpreter to call.
288 = mkTopUnfolding $ Note InlineMe $
289 mkLams all_tyvars $ mkLams dict_args $
290 mkLams ex_dict_args $ mkLams id_args $
291 foldr mk_case con_app
292 (zip (ex_dict_args++id_args) strict_marks) i3 []
294 con_app i rep_ids = mkApps (Var work_id)
295 (map varToCoreExpr (all_tyvars ++ reverse rep_ids))
297 (tyvars, theta, ex_tyvars, ex_theta, orig_arg_tys, tycon) = dataConSig data_con
298 all_tyvars = tyvars ++ ex_tyvars
300 dict_tys = mkPredTys theta
301 ex_dict_tys = mkPredTys ex_theta
302 all_arg_tys = dict_tys ++ ex_dict_tys ++ orig_arg_tys
303 result_ty = mkTyConApp tycon (mkTyVarTys tyvars)
305 mkLocals i tys = (zipWith mkTemplateLocal [i..i+n-1] tys, i+n)
309 (dict_args, i1) = mkLocals 1 dict_tys
310 (ex_dict_args,i2) = mkLocals i1 ex_dict_tys
311 (id_args,i3) = mkLocals i2 orig_arg_tys
313 (id_arg1:_) = id_args -- Used for newtype only
315 strict_marks = dataConStrictMarks data_con
318 :: (Id, StrictnessMark) -- Arg, strictness
319 -> (Int -> [Id] -> CoreExpr) -- Body
320 -> Int -- Next rep arg id
321 -> [Id] -- Rep args so far, reversed
323 mk_case (arg,strict) body i rep_args
325 NotMarkedStrict -> body i (arg:rep_args)
327 | isUnLiftedType (idType arg) -> body i (arg:rep_args)
329 Case (Var arg) arg [(DEFAULT,[], body i (arg:rep_args))]
332 -> case splitProductType "do_unbox" (idType arg) of
333 (tycon, tycon_args, con, tys) ->
334 Case (Var arg) arg [(DataAlt con, con_args,
335 body i' (reverse con_args ++ rep_args))]
337 (con_args, i') = mkLocals i tys
341 %************************************************************************
343 \subsection{Record selectors}
345 %************************************************************************
347 We're going to build a record selector unfolding that looks like this:
349 data T a b c = T1 { ..., op :: a, ...}
350 | T2 { ..., op :: a, ...}
353 sel = /\ a b c -> \ d -> case d of
358 Similarly for newtypes
360 newtype N a = MkN { unN :: a->a }
363 unN n = coerce (a->a) n
365 We need to take a little care if the field has a polymorphic type:
367 data R = R { f :: forall a. a->a }
371 f :: forall a. R -> a -> a
372 f = /\ a \ r = case r of
375 (not f :: R -> forall a. a->a, which gives the type inference mechanism
376 problems at call sites)
378 Similarly for newtypes
380 newtype N = MkN { unN :: forall a. a->a }
382 unN :: forall a. N -> a -> a
383 unN = /\a -> \n:N -> coerce (a->a) n
386 mkRecordSelId tycon field_label unpack_id unpackUtf8_id
387 -- Assumes that all fields with the same field label have the same type
389 -- Annoyingly, we have to pass in the unpackCString# Id, because
390 -- we can't conjure it up out of thin air
393 sel_id = mkGlobalId (RecordSelId field_label) (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 data_ty = mkTyConApp tycon tyvar_tys
399 tyvar_tys = mkTyVarTys tyvars
401 tycon_theta = tyConTheta tycon -- The context on the data decl
402 -- eg data (Eq a, Ord b) => T a b = ...
403 dict_tys = [mkPredTy pred | pred <- tycon_theta,
405 needed_dict pred = or [ tcEqPred pred p
406 | (DataAlt dc, _, _) <- the_alts, p <- dataConTheta dc]
407 n_dict_tys = length dict_tys
409 (field_tyvars,field_theta,field_tau) = tcSplitSigmaTy field_ty
410 field_dict_tys = map mkPredTy field_theta
411 n_field_dict_tys = length field_dict_tys
412 -- If the field has a universally quantified type we have to
413 -- be a bit careful. Suppose we have
414 -- data R = R { op :: forall a. Foo a => a -> a }
415 -- Then we can't give op the type
416 -- op :: R -> forall a. Foo a => a -> a
417 -- because the typechecker doesn't understand foralls to the
418 -- right of an arrow. The "right" type to give it is
419 -- op :: forall a. Foo a => R -> a -> a
420 -- But then we must generate the right unfolding too:
421 -- op = /\a -> \dfoo -> \ r ->
424 -- Note that this is exactly the type we'd infer from a user defn
427 -- Very tiresomely, the selectors are (unnecessarily!) overloaded over
428 -- just the dictionaries in the types of the constructors that contain
429 -- the relevant field. Urgh.
430 -- NB: this code relies on the fact that DataCons are quantified over
431 -- the identical type variables as their parent TyCon
434 selector_ty = mkForAllTys tyvars $ mkForAllTys field_tyvars $
435 mkFunTys dict_tys $ mkFunTys field_dict_tys $
436 mkFunTy data_ty field_tau
438 arity = 1 + n_dict_tys + n_field_dict_tys
440 (strict_sig, rhs_w_str) = dmdAnalTopRhs sel_rhs
441 -- Use the demand analyser to work out strictness.
442 -- With all this unpackery it's not easy!
444 info = noCafNoTyGenIdInfo
445 `setCafInfo` caf_info
447 `setUnfoldingInfo` mkTopUnfolding rhs_w_str
448 `setAllStrictnessInfo` Just strict_sig
450 -- Allocate Ids. We do it a funny way round because field_dict_tys is
451 -- almost always empty. Also note that we use length_tycon_theta
452 -- rather than n_dict_tys, because the latter gives an infinite loop:
453 -- n_dict tys depends on the_alts, which depens on arg_ids, which depends
454 -- on arity, which depends on n_dict tys. Sigh! Mega sigh!
455 field_dict_base = length tycon_theta + 1
456 dict_id_base = field_dict_base + n_field_dict_tys
457 field_base = dict_id_base + 1
458 dict_ids = mkTemplateLocalsNum 1 dict_tys
459 field_dict_ids = mkTemplateLocalsNum field_dict_base field_dict_tys
460 data_id = mkTemplateLocal dict_id_base data_ty
462 alts = map mk_maybe_alt data_cons
463 the_alts = catMaybes alts
465 no_default = all isJust alts -- No default needed
466 default_alt | no_default = []
467 | otherwise = [(DEFAULT, [], error_expr)]
469 -- the default branch may have CAF refs, because it calls recSelError etc.
470 caf_info | no_default = NoCafRefs
471 | otherwise = MayHaveCafRefs
473 sel_rhs = mkLams tyvars $ mkLams field_tyvars $
474 mkLams dict_ids $ mkLams field_dict_ids $
475 Lam data_id $ sel_body
477 sel_body | isNewTyCon tycon = mkNewTypeBody tycon field_tau (mk_result data_id)
478 | otherwise = Case (Var data_id) data_id (default_alt ++ the_alts)
480 mk_result result_id = mkVarApps (mkVarApps (Var result_id) field_tyvars) field_dict_ids
481 -- We pull the field lambdas to the top, so we need to
482 -- apply them in the body. For example:
483 -- data T = MkT { foo :: forall a. a->a }
485 -- foo :: forall a. T -> a -> a
486 -- foo = /\a. \t:T. case t of { MkT f -> f a }
488 mk_maybe_alt data_con
489 = case maybe_the_arg_id of
491 Just the_arg_id -> Just (DataAlt data_con, real_args, mkLets binds body)
493 body = mk_result the_arg_id
494 strict_marks = dataConStrictMarks data_con
495 (binds, real_args) = rebuildConArgs arg_ids strict_marks
496 (map mkBuiltinUnique [unpack_base..])
498 arg_ids = mkTemplateLocalsNum field_base (dataConInstOrigArgTys data_con tyvar_tys)
500 unpack_base = field_base + length arg_ids
502 -- arity+1 avoids all shadowing
503 maybe_the_arg_id = assocMaybe (field_lbls `zip` arg_ids) field_label
504 field_lbls = dataConFieldLabels data_con
506 error_expr = mkApps (Var rEC_SEL_ERROR_ID) [Type field_tau, err_string]
508 | all safeChar full_msg
509 = App (Var unpack_id) (Lit (MachStr (_PK_ full_msg)))
511 = App (Var unpackUtf8_id) (Lit (MachStr (_PK_ (stringToUtf8 (map ord full_msg)))))
513 safeChar c = c >= '\1' && c <= '\xFF'
514 -- TODO: Putting this Unicode stuff here is ugly. Find a better
515 -- generic place to make string literals. This logic is repeated
517 full_msg = showSDoc (sep [text "No match in record selector", ppr sel_id])
520 -- This rather ugly function converts the unpacked data con
521 -- arguments back into their packed form.
524 :: [Id] -- Source-level args
525 -> [StrictnessMark] -- Strictness annotations (per-arg)
526 -> [Unique] -- Uniques for the new Ids
527 -> ([CoreBind], [Id]) -- A binding for each source-level arg, plus
528 -- a list of the representation-level arguments
529 -- e.g. data T = MkT Int !Int
531 -- rebuild [x::Int, y::Int] [Not, Unbox]
532 -- = ([ y = I# t ], [x,t])
534 rebuildConArgs [] stricts us = ([], [])
536 -- Type variable case
537 rebuildConArgs (arg:args) stricts us
539 = let (binds, args') = rebuildConArgs args stricts us
540 in (binds, arg:args')
542 -- Term variable case
543 rebuildConArgs (arg:args) (str:stricts) us
544 | isMarkedUnboxed str
548 (_, tycon_args, pack_con, con_arg_tys)
549 = splitProductType "rebuildConArgs" arg_ty
551 unpacked_args = zipWith (mkSysLocal SLIT("rb")) us con_arg_tys
552 (binds, args') = rebuildConArgs args stricts (dropList con_arg_tys us)
553 con_app = mkConApp pack_con (map Type tycon_args ++ map Var unpacked_args)
555 (NonRec arg con_app : binds, unpacked_args ++ args')
558 = let (binds, args') = rebuildConArgs args stricts us
559 in (binds, arg:args')
563 %************************************************************************
565 \subsection{Dictionary selectors}
567 %************************************************************************
569 Selecting a field for a dictionary. If there is just one field, then
570 there's nothing to do.
572 ToDo: unify with mkRecordSelId.
575 mkDictSelId :: Name -> Class -> Id
576 mkDictSelId name clas
577 = mkGlobalId (RecordSelId field_lbl) name sel_ty info
579 sel_ty = mkForAllTys tyvars (mkFunTy (idType dict_id) (idType the_arg_id))
580 -- We can't just say (exprType rhs), because that would give a type
582 -- for a single-op class (after all, the selector is the identity)
583 -- But it's type must expose the representation of the dictionary
584 -- to gat (say) C a -> (a -> a)
586 field_lbl = mkFieldLabel name tycon sel_ty tag
587 tag = assoc "MkId.mkDictSelId" (map idName (classSelIds clas) `zip` allFieldLabelTags) name
589 info = noCafNoTyGenIdInfo
591 `setUnfoldingInfo` mkTopUnfolding rhs
592 `setAllStrictnessInfo` Just strict_sig
594 -- We no longer use 'must-inline' on record selectors. They'll
595 -- inline like crazy if they scrutinise a constructor
597 -- The strictness signature is of the form U(AAAVAAAA) -> T
598 -- where the V depends on which item we are selecting
599 -- It's worth giving one, so that absence info etc is generated
600 -- even if the selector isn't inlined
601 strict_sig = mkStrictSig (mkTopDmdType [arg_dmd] TopRes)
602 arg_dmd | isNewTyCon tycon = evalDmd
603 | otherwise = Eval (Prod [ if the_arg_id == id then evalDmd else Abs
606 tyvars = classTyVars clas
608 tycon = classTyCon clas
609 [data_con] = tyConDataCons tycon
610 tyvar_tys = mkTyVarTys tyvars
611 arg_tys = dataConArgTys data_con tyvar_tys
612 the_arg_id = arg_ids !! (tag - firstFieldLabelTag)
614 pred = mkClassPred clas tyvar_tys
615 (dict_id:arg_ids) = mkTemplateLocals (mkPredTy pred : arg_tys)
617 rhs | isNewTyCon tycon = mkLams tyvars $ Lam dict_id $
618 mkNewTypeBody tycon (head arg_tys) (Var dict_id)
619 | otherwise = mkLams tyvars $ Lam dict_id $
620 Case (Var dict_id) dict_id
621 [(DataAlt data_con, arg_ids, Var the_arg_id)]
623 mkNewTypeBody tycon result_ty result_expr
624 -- Adds a coerce where necessary
625 -- Used for both wrapping and unwrapping
626 | isRecursiveTyCon tycon -- Recursive case; use a coerce
627 = Note (Coerce result_ty (exprType result_expr)) result_expr
628 | otherwise -- Normal case
633 %************************************************************************
635 \subsection{Primitive operations
637 %************************************************************************
640 mkPrimOpId :: PrimOp -> Id
644 (tyvars,arg_tys,res_ty, arity, strict_info) = primOpSig prim_op
645 ty = mkForAllTys tyvars (mkFunTys arg_tys res_ty)
646 name = mkPrimOpIdName prim_op
647 id = mkGlobalId (PrimOpId prim_op) name ty info
649 info = noCafNoTyGenIdInfo
652 `setAllStrictnessInfo` Just (newStrictnessFromOld name arity strict_info NoCPRInfo)
653 -- Until we modify the primop generation code
655 rules = foldl (addRule id) emptyCoreRules (primOpRules prim_op)
658 -- For each ccall we manufacture a separate CCallOpId, giving it
659 -- a fresh unique, a type that is correct for this particular ccall,
660 -- and a CCall structure that gives the correct details about calling
663 -- The *name* of this Id is a local name whose OccName gives the full
664 -- details of the ccall, type and all. This means that the interface
665 -- file reader can reconstruct a suitable Id
667 mkFCallId :: Unique -> ForeignCall -> Type -> Id
668 mkFCallId uniq fcall ty
669 = ASSERT( isEmptyVarSet (tyVarsOfType ty) )
670 -- A CCallOpId should have no free type variables;
671 -- when doing substitutions won't substitute over it
672 mkGlobalId (FCallId fcall) name ty info
674 occ_str = showSDocIface (braces (ppr fcall <+> ppr ty))
675 -- The "occurrence name" of a ccall is the full info about the
676 -- ccall; it is encoded, but may have embedded spaces etc!
678 name = mkFCallName uniq occ_str
680 info = noCafNoTyGenIdInfo
682 `setAllStrictnessInfo` Just strict_sig
684 (_, tau) = tcSplitForAllTys ty
685 (arg_tys, _) = tcSplitFunTys tau
686 arity = length arg_tys
687 strict_sig = mkStrictSig (mkTopDmdType (replicate arity evalDmd) TopRes)
691 %************************************************************************
693 \subsection{DictFuns and default methods}
695 %************************************************************************
697 Important notes about dict funs and default methods
698 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
699 Dict funs and default methods are *not* ImplicitIds. Their definition
700 involves user-written code, so we can't figure out their strictness etc
701 based on fixed info, as we can for constructors and record selectors (say).
703 We build them as GlobalIds, but when in the module where they are
704 bound, we turn the Id at the *binding site* into an exported LocalId.
705 This ensures that they are taken to account by free-variable finding
706 and dependency analysis (e.g. CoreFVs.exprFreeVars). The simplifier
707 will propagate the LocalId to all occurrence sites.
709 Why shouldn't they be bound as GlobalIds? Because, in particular, if
710 they are globals, the specialiser floats dict uses above their defns,
711 which prevents good simplifications happening. Also the strictness
712 analyser treats a occurrence of a GlobalId as imported and assumes it
713 contains strictness in its IdInfo, which isn't true if the thing is
714 bound in the same module as the occurrence.
716 It's OK for dfuns to be LocalIds, because we form the instance-env to
717 pass on to the next module (md_insts) in CoreTidy, afer tidying
718 and globalising the top-level Ids.
720 BUT make sure they are *exported* LocalIds (setIdLocalExported) so
721 that they aren't discarded by the occurrence analyser.
724 mkDefaultMethodId dm_name ty = mkVanillaGlobal dm_name ty noCafNoTyGenIdInfo
726 mkDictFunId :: Name -- Name to use for the dict fun;
733 mkDictFunId dfun_name clas inst_tyvars inst_tys dfun_theta
734 = mkVanillaGlobal dfun_name dfun_ty noCafNoTyGenIdInfo
736 dfun_ty = mkSigmaTy inst_tyvars dfun_theta (mkDictTy clas inst_tys)
738 {- 1 dec 99: disable the Mark Jones optimisation for the sake
739 of compatibility with Hugs.
740 See `types/InstEnv' for a discussion related to this.
742 (class_tyvars, sc_theta, _, _) = classBigSig clas
743 not_const (clas, tys) = not (isEmptyVarSet (tyVarsOfTypes tys))
744 sc_theta' = substClasses (mkTopTyVarSubst class_tyvars inst_tys) sc_theta
745 dfun_theta = case inst_decl_theta of
746 [] -> [] -- If inst_decl_theta is empty, then we don't
747 -- want to have any dict arguments, so that we can
748 -- expose the constant methods.
750 other -> nub (inst_decl_theta ++ filter not_const sc_theta')
751 -- Otherwise we pass the superclass dictionaries to
752 -- the dictionary function; the Mark Jones optimisation.
754 -- NOTE the "nub". I got caught by this one:
755 -- class Monad m => MonadT t m where ...
756 -- instance Monad m => MonadT (EnvT env) m where ...
757 -- Here, the inst_decl_theta has (Monad m); but so
758 -- does the sc_theta'!
760 -- NOTE the "not_const". I got caught by this one too:
761 -- class Foo a => Baz a b where ...
762 -- instance Wob b => Baz T b where..
763 -- Now sc_theta' has Foo T
768 %************************************************************************
770 \subsection{Un-definable}
772 %************************************************************************
774 These Ids can't be defined in Haskell. They could be defined in
775 unfoldings in PrelGHC.hi-boot, but we'd have to ensure that they
776 were definitely, definitely inlined, because there is no curried
777 identifier for them. That's what mkCompulsoryUnfolding does.
778 If we had a way to get a compulsory unfolding from an interface file,
779 we could do that, but we don't right now.
781 unsafeCoerce# isn't so much a PrimOp as a phantom identifier, that
782 just gets expanded into a type coercion wherever it occurs. Hence we
783 add it as a built-in Id with an unfolding here.
785 The type variables we use here are "open" type variables: this means
786 they can unify with both unlifted and lifted types. Hence we provide
787 another gun with which to shoot yourself in the foot.
790 -- unsafeCoerce# :: forall a b. a -> b
792 = pcMiscPrelId unsafeCoerceIdKey pREL_GHC SLIT("unsafeCoerce#") ty info
794 info = noCafNoTyGenIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs
797 ty = mkForAllTys [openAlphaTyVar,openBetaTyVar]
798 (mkFunTy openAlphaTy openBetaTy)
799 [x] = mkTemplateLocals [openAlphaTy]
800 rhs = mkLams [openAlphaTyVar,openBetaTyVar,x] $
801 Note (Coerce openBetaTy openAlphaTy) (Var x)
803 -- nullAddr# :: Addr#
804 -- The reason is is here is because we don't provide
805 -- a way to write this literal in Haskell.
807 = pcMiscPrelId nullAddrIdKey pREL_GHC SLIT("nullAddr#") addrPrimTy info
809 info = noCafNoTyGenIdInfo `setUnfoldingInfo`
810 mkCompulsoryUnfolding (Lit nullAddrLit)
813 = pcMiscPrelId seqIdKey pREL_GHC SLIT("seq") ty info
815 info = noCafNoTyGenIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs
818 ty = mkForAllTys [alphaTyVar,betaTyVar]
819 (mkFunTy alphaTy (mkFunTy betaTy betaTy))
820 [x,y] = mkTemplateLocals [alphaTy, betaTy]
821 rhs = mkLams [alphaTyVar,betaTyVar,x,y] (Case (Var x) x [(DEFAULT, [], Var y)])
824 @getTag#@ is another function which can't be defined in Haskell. It needs to
825 evaluate its argument and call the dataToTag# primitive.
829 = pcMiscPrelId getTagIdKey pREL_GHC SLIT("getTag#") ty info
831 info = noCafNoTyGenIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs
832 -- We don't provide a defn for this; you must inline it
834 ty = mkForAllTys [alphaTyVar] (mkFunTy alphaTy intPrimTy)
835 [x,y] = mkTemplateLocals [alphaTy,alphaTy]
836 rhs = mkLams [alphaTyVar,x] $
837 Case (Var x) y [ (DEFAULT, [], mkApps (Var dataToTagId) [Type alphaTy, Var y]) ]
839 dataToTagId = mkPrimOpId DataToTagOp
842 @realWorld#@ used to be a magic literal, \tr{void#}. If things get
843 nasty as-is, change it back to a literal (@Literal@).
845 voidArgId is a Local Id used simply as an argument in functions
846 where we just want an arg to avoid having a thunk of unlifted type.
848 x = \ void :: State# RealWorld -> (# p, q #)
850 This comes up in strictness analysis
853 realWorldPrimId -- :: State# RealWorld
854 = pcMiscPrelId realWorldPrimIdKey pREL_GHC SLIT("realWorld#")
856 (noCafNoTyGenIdInfo `setUnfoldingInfo` mkOtherCon [])
857 -- The mkOtherCon makes it look that realWorld# is evaluated
858 -- which in turn makes Simplify.interestingArg return True,
859 -- which in turn makes INLINE things applied to realWorld# likely
862 voidArgId -- :: State# RealWorld
863 = mkSysLocal SLIT("void") voidArgIdKey realWorldStatePrimTy
867 %************************************************************************
869 \subsection[PrelVals-error-related]{@error@ and friends; @trace@}
871 %************************************************************************
873 GHC randomly injects these into the code.
875 @patError@ is just a version of @error@ for pattern-matching
876 failures. It knows various ``codes'' which expand to longer
877 strings---this saves space!
879 @absentErr@ is a thing we put in for ``absent'' arguments. They jolly
880 well shouldn't be yanked on, but if one is, then you will get a
881 friendly message from @absentErr@ (rather than a totally random
884 @parError@ is a special version of @error@ which the compiler does
885 not know to be a bottoming Id. It is used in the @_par_@ and @_seq_@
886 templates, but we don't ever expect to generate code for it.
890 = pc_bottoming_Id errorIdKey pREL_ERR SLIT("error") errorTy
892 = pc_bottoming_Id errorCStringIdKey pREL_ERR SLIT("errorCString")
893 (mkSigmaTy [openAlphaTyVar] [] (mkFunTy addrPrimTy openAlphaTy))
895 = generic_ERROR_ID patErrorIdKey SLIT("patError")
897 = generic_ERROR_ID recSelErrIdKey SLIT("recSelError")
899 = generic_ERROR_ID recConErrorIdKey SLIT("recConError")
901 = generic_ERROR_ID recUpdErrorIdKey SLIT("recUpdError")
903 = generic_ERROR_ID irrefutPatErrorIdKey SLIT("irrefutPatError")
904 nON_EXHAUSTIVE_GUARDS_ERROR_ID
905 = generic_ERROR_ID nonExhaustiveGuardsErrorIdKey SLIT("nonExhaustiveGuardsError")
906 nO_METHOD_BINDING_ERROR_ID
907 = generic_ERROR_ID noMethodBindingErrorIdKey SLIT("noMethodBindingError")
910 = pc_bottoming_Id absentErrorIdKey pREL_ERR SLIT("absentErr")
911 (mkSigmaTy [openAlphaTyVar] [] openAlphaTy)
914 = pcMiscPrelId parErrorIdKey pREL_ERR SLIT("parError")
915 (mkSigmaTy [openAlphaTyVar] [] openAlphaTy) noCafNoTyGenIdInfo
919 %************************************************************************
921 \subsection{Utilities}
923 %************************************************************************
926 pcMiscPrelId :: Unique{-IdKey-} -> Module -> FAST_STRING -> Type -> IdInfo -> Id
927 pcMiscPrelId key mod str ty info
929 name = mkWiredInName mod (mkVarOcc str) key
930 imp = mkVanillaGlobal name ty info -- the usual case...
933 -- We lie and say the thing is imported; otherwise, we get into
934 -- a mess with dependency analysis; e.g., core2stg may heave in
935 -- random calls to GHCbase.unpackPS__. If GHCbase is the module
936 -- being compiled, then it's just a matter of luck if the definition
937 -- will be in "the right place" to be in scope.
939 pc_bottoming_Id key mod name ty
940 = pcMiscPrelId key mod name ty bottoming_info
942 strict_sig = mkStrictSig (mkTopDmdType [evalDmd] BotRes)
943 bottoming_info = noCafNoTyGenIdInfo `setAllStrictnessInfo` Just strict_sig
944 -- these "bottom" out, no matter what their arguments
946 generic_ERROR_ID u n = pc_bottoming_Id u pREL_ERR n errorTy
948 (openAlphaTyVar:openBetaTyVar:_) = openAlphaTyVars
949 openAlphaTy = mkTyVarTy openAlphaTyVar
950 openBetaTy = mkTyVarTy openBetaTyVar
953 errorTy = mkSigmaTy [openAlphaTyVar] [] (mkFunTys [mkListTy charTy]
955 -- Notice the openAlphaTyVar. It says that "error" can be applied
956 -- to unboxed as well as boxed types. This is OK because it never
957 -- returns, so the return type is irrelevant.