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,
21 mkPrimOpId, mkFCallId,
23 mkReboxingAlt, mkNewTypeBody,
25 -- And some particular Ids; see below for why they are wired in
26 wiredInIds, ghcPrimIds,
27 unsafeCoerceId, realWorldPrimId, voidArgId, nullAddrId, seqId,
28 lazyId, lazyIdUnfolding, lazyIdKey,
31 rEC_CON_ERROR_ID, iRREFUT_PAT_ERROR_ID, rUNTIME_ERROR_ID,
32 nON_EXHAUSTIVE_GUARDS_ERROR_ID, nO_METHOD_BINDING_ERROR_ID,
36 #include "HsVersions.h"
39 import BasicTypes ( Arity, StrictnessMark(..), isMarkedUnboxed, isMarkedStrict )
40 import TysPrim ( openAlphaTyVars, alphaTyVar, alphaTy, betaTyVar, betaTy,
41 intPrimTy, realWorldStatePrimTy, addrPrimTy
43 import TysWiredIn ( charTy, mkListTy )
44 import PrelRules ( primOpRules )
45 import Rules ( addRule )
46 import TcType ( Type, ThetaType, mkDictTy, mkPredTys, mkTyConApp,
47 mkTyVarTys, mkClassPred, tcEqPred,
48 mkFunTys, mkFunTy, mkSigmaTy, tcSplitSigmaTy,
49 isUnLiftedType, mkForAllTys, mkTyVarTy, tyVarsOfType,
50 tcSplitFunTys, tcSplitForAllTys, mkPredTy
52 import CoreUtils ( exprType )
53 import CoreUnfold ( mkTopUnfolding, mkCompulsoryUnfolding, mkOtherCon )
54 import Literal ( Literal(..), nullAddrLit )
55 import TyCon ( TyCon, isNewTyCon, tyConTyVars, tyConDataCons,
56 tyConTheta, isProductTyCon, isDataTyCon, isRecursiveTyCon )
57 import Class ( Class, classTyCon, classTyVars, classSelIds )
58 import Var ( Id, TyVar, Var )
59 import VarSet ( isEmptyVarSet )
60 import Name ( mkFCallName, Name )
61 import PrimOp ( PrimOp(DataToTagOp), primOpSig, mkPrimOpIdName )
62 import ForeignCall ( ForeignCall )
63 import DataCon ( DataCon,
64 dataConFieldLabels, dataConRepArity, dataConTyCon,
65 dataConArgTys, dataConRepType,
67 dataConName, dataConTheta,
68 dataConSig, dataConStrictMarks, dataConWorkId,
71 import Id ( idType, mkGlobalId, mkVanillaGlobal, mkSysLocal, mkLocalId,
72 mkTemplateLocals, mkTemplateLocalsNum, setIdLocalExported,
73 mkTemplateLocal, idNewStrictness, idName
75 import IdInfo ( IdInfo, noCafIdInfo, hasCafIdInfo,
77 setArityInfo, setSpecInfo, setCafInfo,
79 GlobalIdDetails(..), CafInfo(..)
81 import NewDemand ( mkStrictSig, strictSigResInfo, DmdResult(..),
82 mkTopDmdType, topDmd, evalDmd, lazyDmd, retCPR,
83 Demand(..), Demands(..) )
84 import FieldLabel ( mkFieldLabel, fieldLabelName,
85 firstFieldLabelTag, allFieldLabelTags, fieldLabelType
87 import DmdAnal ( dmdAnalTopRhs )
89 import Unique ( mkBuiltinUnique )
92 import Maybe ( isJust )
93 import Util ( dropList, isSingleton )
96 import ListSetOps ( assoc, assocMaybe )
97 import UnicodeUtil ( stringToUtf8 )
101 %************************************************************************
103 \subsection{Wired in Ids}
105 %************************************************************************
109 = [ -- These error-y things are wired in because we don't yet have
110 -- a way to express in an interface file that the result type variable
111 -- is 'open'; that is can be unified with an unboxed type
113 -- [The interface file format now carry such information, but there's
114 -- no way yet of expressing at the definition site for these
115 -- error-reporting functions that they have an 'open'
116 -- result type. -- sof 1/99]
118 eRROR_ID, -- This one isn't used anywhere else in the compiler
119 -- But we still need it in wiredInIds so that when GHC
120 -- compiles a program that mentions 'error' we don't
121 -- import its type from the interface file; we just get
122 -- the Id defined here. Which has an 'open-tyvar' type.
125 iRREFUT_PAT_ERROR_ID,
126 nON_EXHAUSTIVE_GUARDS_ERROR_ID,
127 nO_METHOD_BINDING_ERROR_ID,
134 -- These Ids are exported from GHC.Prim
136 = [ -- These can't be defined in Haskell, but they have
137 -- perfectly reasonable unfoldings in Core
145 %************************************************************************
147 \subsection{Data constructors}
149 %************************************************************************
152 mkDataConId :: Name -> DataCon -> Id
153 -- Makes the *worker* for the data constructor; that is, the function
154 -- that takes the reprsentation arguments and builds the constructor.
155 mkDataConId work_name data_con
156 = mkGlobalId (DataConId data_con) work_name (dataConRepType data_con) info
160 `setAllStrictnessInfo` Just strict_sig
162 arity = dataConRepArity data_con
164 strict_sig = mkStrictSig (mkTopDmdType (replicate arity topDmd) cpr_info)
165 -- Notice that we do *not* say the worker is strict
166 -- even if the data constructor is declared strict
167 -- e.g. data T = MkT !(Int,Int)
168 -- Why? Because the *wrapper* is strict (and its unfolding has case
169 -- expresssions that do the evals) but the *worker* itself is not.
170 -- If we pretend it is strict then when we see
171 -- case x of y -> $wMkT y
172 -- the simplifier thinks that y is "sure to be evaluated" (because
173 -- $wMkT is strict) and drops the case. No, $wMkT is not strict.
175 -- When the simplifer sees a pattern
176 -- case e of MkT x -> ...
177 -- it uses the dataConRepStrictness of MkT to mark x as evaluated;
178 -- but that's fine... dataConRepStrictness comes from the data con
179 -- not from the worker Id.
181 tycon = dataConTyCon data_con
182 cpr_info | isProductTyCon tycon &&
185 arity <= mAX_CPR_SIZE = retCPR
187 -- RetCPR is only true for products that are real data types;
188 -- that is, not unboxed tuples or [non-recursive] newtypes
190 mAX_CPR_SIZE :: Arity
192 -- We do not treat very big tuples as CPR-ish:
193 -- a) for a start we get into trouble because there aren't
194 -- "enough" unboxed tuple types (a tiresome restriction,
196 -- b) more importantly, big unboxed tuples get returned mainly
197 -- on the stack, and are often then allocated in the heap
198 -- by the caller. So doing CPR for them may in fact make
202 The wrapper for a constructor is an ordinary top-level binding that evaluates
203 any strict args, unboxes any args that are going to be flattened, and calls
206 We're going to build a constructor that looks like:
208 data (Data a, C b) => T a b = T1 !a !Int b
211 \d1::Data a, d2::C b ->
212 \p q r -> case p of { p ->
214 Con T1 [a,b] [p,q,r]}}
218 * d2 is thrown away --- a context in a data decl is used to make sure
219 one *could* construct dictionaries at the site the constructor
220 is used, but the dictionary isn't actually used.
222 * We have to check that we can construct Data dictionaries for
223 the types a and Int. Once we've done that we can throw d1 away too.
225 * We use (case p of q -> ...) to evaluate p, rather than "seq" because
226 all that matters is that the arguments are evaluated. "seq" is
227 very careful to preserve evaluation order, which we don't need
230 You might think that we could simply give constructors some strictness
231 info, like PrimOps, and let CoreToStg do the let-to-case transformation.
232 But we don't do that because in the case of primops and functions strictness
233 is a *property* not a *requirement*. In the case of constructors we need to
234 do something active to evaluate the argument.
236 Making an explicit case expression allows the simplifier to eliminate
237 it in the (common) case where the constructor arg is already evaluated.
240 mkDataConWrapId data_con
241 = mkGlobalId (DataConWrapId data_con) (dataConName data_con) wrap_ty info
243 work_id = dataConWorkId data_con
246 `setUnfoldingInfo` wrap_unf
247 -- The NoCaf-ness is set by noCafIdInfo
249 -- It's important to specify the arity, so that partial
250 -- applications are treated as values
251 `setAllStrictnessInfo` Just wrap_sig
253 wrap_sig = mkStrictSig (mkTopDmdType arg_dmds res_info)
254 res_info = strictSigResInfo (idNewStrictness work_id)
255 arg_dmds = map mk_dmd strict_marks
256 mk_dmd str | isMarkedStrict str = evalDmd
257 | otherwise = lazyDmd
258 -- The Cpr info can be important inside INLINE rhss, where the
259 -- wrapper constructor isn't inlined.
260 -- And the argument strictness can be important too; we
261 -- may not inline a contructor when it is partially applied.
263 -- data W = C !Int !Int !Int
264 -- ...(let w = C x in ...(w p q)...)...
265 -- we want to see that w is strict in its two arguments
267 wrap_unf | isNewTyCon tycon
268 = ASSERT( null ex_tyvars && null ex_dict_args && isSingleton orig_arg_tys )
269 -- No existentials on a newtype, but it can have a context
270 -- e.g. newtype Eq a => T a = MkT (...)
271 mkTopUnfolding $ Note InlineMe $
272 mkLams tyvars $ Lam id_arg1 $
273 mkNewTypeBody tycon result_ty (Var id_arg1)
275 | not (any isMarkedStrict strict_marks)
276 = mkCompulsoryUnfolding (Var work_id)
277 -- The common case. Not only is this efficient,
278 -- but it also ensures that the wrapper is replaced
279 -- by the worker even when there are no args.
283 -- This is really important in rule matching,
284 -- (We could match on the wrappers,
285 -- but that makes it less likely that rules will match
286 -- when we bring bits of unfoldings together.)
288 -- NB: because of this special case, (map (:) ys) turns into
289 -- (map $w: ys). The top-level defn for (:) is never used.
290 -- This is somewhat of a bore, but I'm currently leaving it
291 -- as is, so that there still is a top level curried (:) for
292 -- the interpreter to call.
295 = mkTopUnfolding $ Note InlineMe $
297 mkLams ex_dict_args $ mkLams id_args $
298 foldr mk_case con_app
299 (zip (ex_dict_args++id_args) strict_marks) i3 []
301 con_app i rep_ids = mkApps (Var work_id)
302 (map varToCoreExpr (all_tyvars ++ reverse rep_ids))
304 (tyvars, _, ex_tyvars, ex_theta, orig_arg_tys, tycon) = dataConSig data_con
305 all_tyvars = tyvars ++ ex_tyvars
307 ex_dict_tys = mkPredTys ex_theta
308 all_arg_tys = ex_dict_tys ++ orig_arg_tys
309 result_ty = mkTyConApp tycon (mkTyVarTys tyvars)
311 wrap_ty = mkForAllTys all_tyvars (mkFunTys all_arg_tys result_ty)
312 -- We used to include the stupid theta in the wrapper's args
313 -- but now we don't. Instead the type checker just injects these
314 -- extra constraints where necessary.
316 mkLocals i tys = (zipWith mkTemplateLocal [i..i+n-1] tys, i+n)
320 (ex_dict_args,i2) = mkLocals 1 ex_dict_tys
321 (id_args,i3) = mkLocals i2 orig_arg_tys
323 (id_arg1:_) = id_args -- Used for newtype only
325 strict_marks = dataConStrictMarks data_con
328 :: (Id, StrictnessMark) -- Arg, strictness
329 -> (Int -> [Id] -> CoreExpr) -- Body
330 -> Int -- Next rep arg id
331 -> [Id] -- Rep args so far, reversed
333 mk_case (arg,strict) body i rep_args
335 NotMarkedStrict -> body i (arg:rep_args)
337 | isUnLiftedType (idType arg) -> body i (arg:rep_args)
339 Case (Var arg) arg [(DEFAULT,[], body i (arg:rep_args))]
342 -> case splitProductType "do_unbox" (idType arg) of
343 (tycon, tycon_args, con, tys) ->
344 Case (Var arg) arg [(DataAlt con, con_args,
345 body i' (reverse con_args ++ rep_args))]
347 (con_args, i') = mkLocals i tys
351 %************************************************************************
353 \subsection{Record selectors}
355 %************************************************************************
357 We're going to build a record selector unfolding that looks like this:
359 data T a b c = T1 { ..., op :: a, ...}
360 | T2 { ..., op :: a, ...}
363 sel = /\ a b c -> \ d -> case d of
368 Similarly for newtypes
370 newtype N a = MkN { unN :: a->a }
373 unN n = coerce (a->a) n
375 We need to take a little care if the field has a polymorphic type:
377 data R = R { f :: forall a. a->a }
381 f :: forall a. R -> a -> a
382 f = /\ a \ r = case r of
385 (not f :: R -> forall a. a->a, which gives the type inference mechanism
386 problems at call sites)
388 Similarly for (recursive) newtypes
390 newtype N = MkN { unN :: forall a. a->a }
392 unN :: forall b. N -> b -> b
393 unN = /\b -> \n:N -> (coerce (forall a. a->a) n)
396 mkRecordSelId tycon field_label
397 -- Assumes that all fields with the same field label have the same type
399 -- Annoyingly, we have to pass in the unpackCString# Id, because
400 -- we can't conjure it up out of thin air
403 sel_id = mkGlobalId (RecordSelId field_label) (fieldLabelName field_label) selector_ty info
404 field_ty = fieldLabelType field_label
405 data_cons = tyConDataCons tycon
406 tyvars = tyConTyVars tycon -- These scope over the types in
407 -- the FieldLabels of constructors of this type
408 data_ty = mkTyConApp tycon tyvar_tys
409 tyvar_tys = mkTyVarTys tyvars
411 -- Very tiresomely, the selectors are (unnecessarily!) overloaded over
412 -- just the dictionaries in the types of the constructors that contain
413 -- the relevant field. [The Report says that pattern matching on a
414 -- constructor gives the same constraints as applying it.] Urgh.
416 -- However, not all data cons have all constraints (because of
417 -- TcTyDecls.thinContext). So we need to find all the data cons
418 -- involved in the pattern match and take the union of their constraints.
420 -- NB: this code relies on the fact that DataCons are quantified over
421 -- the identical type variables as their parent TyCon
422 tycon_theta = tyConTheta tycon -- The context on the data decl
423 -- eg data (Eq a, Ord b) => T a b = ...
424 needed_preds = [pred | (DataAlt dc, _, _) <- the_alts, pred <- dataConTheta dc]
425 dict_tys = map mkPredTy (nubBy tcEqPred needed_preds)
426 n_dict_tys = length dict_tys
428 (field_tyvars,field_theta,field_tau) = tcSplitSigmaTy field_ty
429 field_dict_tys = map mkPredTy field_theta
430 n_field_dict_tys = length field_dict_tys
431 -- If the field has a universally quantified type we have to
432 -- be a bit careful. Suppose we have
433 -- data R = R { op :: forall a. Foo a => a -> a }
434 -- Then we can't give op the type
435 -- op :: R -> forall a. Foo a => a -> a
436 -- because the typechecker doesn't understand foralls to the
437 -- right of an arrow. The "right" type to give it is
438 -- op :: forall a. Foo a => R -> a -> a
439 -- But then we must generate the right unfolding too:
440 -- op = /\a -> \dfoo -> \ r ->
443 -- Note that this is exactly the type we'd infer from a user defn
447 selector_ty = mkForAllTys tyvars $ mkForAllTys field_tyvars $
448 mkFunTys dict_tys $ mkFunTys field_dict_tys $
449 mkFunTy data_ty field_tau
451 arity = 1 + n_dict_tys + n_field_dict_tys
453 (strict_sig, rhs_w_str) = dmdAnalTopRhs sel_rhs
454 -- Use the demand analyser to work out strictness.
455 -- With all this unpackery it's not easy!
458 `setCafInfo` caf_info
460 `setUnfoldingInfo` mkTopUnfolding rhs_w_str
461 `setAllStrictnessInfo` Just strict_sig
463 -- Allocate Ids. We do it a funny way round because field_dict_tys is
464 -- almost always empty. Also note that we use length_tycon_theta
465 -- rather than n_dict_tys, because the latter gives an infinite loop:
466 -- n_dict tys depends on the_alts, which depens on arg_ids, which depends
467 -- on arity, which depends on n_dict tys. Sigh! Mega sigh!
468 field_dict_base = length tycon_theta + 1
469 dict_id_base = field_dict_base + n_field_dict_tys
470 field_base = dict_id_base + 1
471 dict_ids = mkTemplateLocalsNum 1 dict_tys
472 field_dict_ids = mkTemplateLocalsNum field_dict_base field_dict_tys
473 data_id = mkTemplateLocal dict_id_base data_ty
475 alts = map mk_maybe_alt data_cons
476 the_alts = catMaybes alts
478 no_default = all isJust alts -- No default needed
479 default_alt | no_default = []
480 | otherwise = [(DEFAULT, [], error_expr)]
482 -- The default branch may have CAF refs, because it calls recSelError etc.
483 caf_info | no_default = NoCafRefs
484 | otherwise = MayHaveCafRefs
486 sel_rhs = mkLams tyvars $ mkLams field_tyvars $
487 mkLams dict_ids $ mkLams field_dict_ids $
488 Lam data_id $ sel_body
490 sel_body | isNewTyCon tycon = mk_result (mkNewTypeBody tycon field_ty (Var data_id))
491 | otherwise = Case (Var data_id) data_id (default_alt ++ the_alts)
493 mk_result poly_result = mkVarApps (mkVarApps poly_result field_tyvars) field_dict_ids
494 -- We pull the field lambdas to the top, so we need to
495 -- apply them in the body. For example:
496 -- data T = MkT { foo :: forall a. a->a }
498 -- foo :: forall a. T -> a -> a
499 -- foo = /\a. \t:T. case t of { MkT f -> f a }
501 mk_maybe_alt data_con
502 = case maybe_the_arg_id of
504 Just the_arg_id -> Just (mkReboxingAlt uniqs data_con arg_ids body)
506 body = mk_result (Var the_arg_id)
508 arg_ids = mkTemplateLocalsNum field_base (dataConOrigArgTys data_con)
509 -- No need to instantiate; same tyvars in datacon as tycon
511 unpack_base = field_base + length arg_ids
512 uniqs = map mkBuiltinUnique [unpack_base..]
514 -- arity+1 avoids all shadowing
515 maybe_the_arg_id = assocMaybe (field_lbls `zip` arg_ids) field_label
516 field_lbls = dataConFieldLabels data_con
518 error_expr = mkRuntimeErrorApp rEC_SEL_ERROR_ID field_tau full_msg
519 full_msg = showSDoc (sep [text "No match in record selector", ppr sel_id])
522 -- (mkReboxingAlt us con xs rhs) basically constructs the case
523 -- alternative (con, xs, rhs)
524 -- but it does the reboxing necessary to construct the *source*
525 -- arguments, xs, from the representation arguments ys.
527 -- data T = MkT !(Int,Int) Bool
529 -- mkReboxingAlt MkT [x,b] r
530 -- = (DataAlt MkT, [y::Int,z::Int,b], let x = (y,z) in r)
532 -- mkDataAlt should really be in DataCon, but it can't because
533 -- it manipulates CoreSyn.
536 :: [Unique] -- Uniques for the new Ids
538 -> [Var] -- Source-level args
542 mkReboxingAlt us con args rhs
543 | not (any isMarkedUnboxed stricts)
544 = (DataAlt con, args, rhs)
548 (binds, args') = go args stricts us
550 (DataAlt con, args', mkLets binds rhs)
553 stricts = dataConStrictMarks con
555 go [] stricts us = ([], [])
557 -- Type variable case
558 go (arg:args) stricts us
560 = let (binds, args') = go args stricts us
561 in (binds, arg:args')
563 -- Term variable case
564 go (arg:args) (str:stricts) us
565 | isMarkedUnboxed str
567 (_, tycon_args, pack_con, con_arg_tys)
568 = splitProductType "mkReboxingAlt" (idType arg)
570 unpacked_args = zipWith (mkSysLocal FSLIT("rb")) us con_arg_tys
571 (binds, args') = go args stricts (dropList con_arg_tys us)
572 con_app = mkConApp pack_con (map Type tycon_args ++ map Var unpacked_args)
574 (NonRec arg con_app : binds, unpacked_args ++ args')
577 = let (binds, args') = go args stricts us
578 in (binds, arg:args')
582 %************************************************************************
584 \subsection{Dictionary selectors}
586 %************************************************************************
588 Selecting a field for a dictionary. If there is just one field, then
589 there's nothing to do.
591 Dictionary selectors may get nested forall-types. Thus:
594 op :: forall b. Ord b => a -> b -> b
596 Then the top-level type for op is
598 op :: forall a. Foo a =>
602 This is unlike ordinary record selectors, which have all the for-alls
603 at the outside. When dealing with classes it's very convenient to
604 recover the original type signature from the class op selector.
606 ToDo: unify with mkRecordSelId?
609 mkDictSelId :: Name -> Class -> Id
610 mkDictSelId name clas
611 = mkGlobalId (RecordSelId field_lbl) name sel_ty info
613 sel_ty = mkForAllTys tyvars (mkFunTy (idType dict_id) (idType the_arg_id))
614 -- We can't just say (exprType rhs), because that would give a type
616 -- for a single-op class (after all, the selector is the identity)
617 -- But it's type must expose the representation of the dictionary
618 -- to gat (say) C a -> (a -> a)
620 field_lbl = mkFieldLabel name tycon sel_ty tag
621 tag = assoc "MkId.mkDictSelId" (map idName (classSelIds clas) `zip` allFieldLabelTags) name
625 `setUnfoldingInfo` mkTopUnfolding rhs
626 `setAllStrictnessInfo` Just strict_sig
628 -- We no longer use 'must-inline' on record selectors. They'll
629 -- inline like crazy if they scrutinise a constructor
631 -- The strictness signature is of the form U(AAAVAAAA) -> T
632 -- where the V depends on which item we are selecting
633 -- It's worth giving one, so that absence info etc is generated
634 -- even if the selector isn't inlined
635 strict_sig = mkStrictSig (mkTopDmdType [arg_dmd] TopRes)
636 arg_dmd | isNewTyCon tycon = evalDmd
637 | otherwise = Eval (Prod [ if the_arg_id == id then evalDmd else Abs
640 tyvars = classTyVars clas
642 tycon = classTyCon clas
643 [data_con] = tyConDataCons tycon
644 tyvar_tys = mkTyVarTys tyvars
645 arg_tys = dataConArgTys data_con tyvar_tys
646 the_arg_id = arg_ids !! (tag - firstFieldLabelTag)
648 pred = mkClassPred clas tyvar_tys
649 (dict_id:arg_ids) = mkTemplateLocals (mkPredTy pred : arg_tys)
651 rhs | isNewTyCon tycon = mkLams tyvars $ Lam dict_id $
652 mkNewTypeBody tycon (head arg_tys) (Var dict_id)
653 | otherwise = mkLams tyvars $ Lam dict_id $
654 Case (Var dict_id) dict_id
655 [(DataAlt data_con, arg_ids, Var the_arg_id)]
657 mkNewTypeBody tycon result_ty result_expr
658 -- Adds a coerce where necessary
659 -- Used for both wrapping and unwrapping
660 | isRecursiveTyCon tycon -- Recursive case; use a coerce
661 = Note (Coerce result_ty (exprType result_expr)) result_expr
662 | otherwise -- Normal case
667 %************************************************************************
669 \subsection{Primitive operations
671 %************************************************************************
674 mkPrimOpId :: PrimOp -> Id
678 (tyvars,arg_tys,res_ty, arity, strict_sig) = primOpSig prim_op
679 ty = mkForAllTys tyvars (mkFunTys arg_tys res_ty)
680 name = mkPrimOpIdName prim_op
681 id = mkGlobalId (PrimOpId prim_op) name ty info
686 `setAllStrictnessInfo` Just strict_sig
688 rules = foldl (addRule id) emptyCoreRules (primOpRules prim_op)
691 -- For each ccall we manufacture a separate CCallOpId, giving it
692 -- a fresh unique, a type that is correct for this particular ccall,
693 -- and a CCall structure that gives the correct details about calling
696 -- The *name* of this Id is a local name whose OccName gives the full
697 -- details of the ccall, type and all. This means that the interface
698 -- file reader can reconstruct a suitable Id
700 mkFCallId :: Unique -> ForeignCall -> Type -> Id
701 mkFCallId uniq fcall ty
702 = ASSERT( isEmptyVarSet (tyVarsOfType ty) )
703 -- A CCallOpId should have no free type variables;
704 -- when doing substitutions won't substitute over it
705 mkGlobalId (FCallId fcall) name ty info
707 occ_str = showSDoc (braces (ppr fcall <+> ppr ty))
708 -- The "occurrence name" of a ccall is the full info about the
709 -- ccall; it is encoded, but may have embedded spaces etc!
711 name = mkFCallName uniq occ_str
715 `setAllStrictnessInfo` Just strict_sig
717 (_, tau) = tcSplitForAllTys ty
718 (arg_tys, _) = tcSplitFunTys tau
719 arity = length arg_tys
720 strict_sig = mkStrictSig (mkTopDmdType (replicate arity evalDmd) TopRes)
724 %************************************************************************
726 \subsection{DictFuns and default methods}
728 %************************************************************************
730 Important notes about dict funs and default methods
731 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
732 Dict funs and default methods are *not* ImplicitIds. Their definition
733 involves user-written code, so we can't figure out their strictness etc
734 based on fixed info, as we can for constructors and record selectors (say).
736 We build them as GlobalIds, but when in the module where they are
737 bound, we turn the Id at the *binding site* into an exported LocalId.
738 This ensures that they are taken to account by free-variable finding
739 and dependency analysis (e.g. CoreFVs.exprFreeVars). The simplifier
740 will propagate the LocalId to all occurrence sites.
742 Why shouldn't they be bound as GlobalIds? Because, in particular, if
743 they are globals, the specialiser floats dict uses above their defns,
744 which prevents good simplifications happening. Also the strictness
745 analyser treats a occurrence of a GlobalId as imported and assumes it
746 contains strictness in its IdInfo, which isn't true if the thing is
747 bound in the same module as the occurrence.
749 It's OK for dfuns to be LocalIds, because we form the instance-env to
750 pass on to the next module (md_insts) in CoreTidy, afer tidying
751 and globalising the top-level Ids.
753 BUT make sure they are *exported* LocalIds (setIdLocalExported) so
754 that they aren't discarded by the occurrence analyser.
757 mkDefaultMethodId dm_name ty
758 = setIdLocalExported (mkLocalId dm_name ty)
760 mkDictFunId :: Name -- Name to use for the dict fun;
767 mkDictFunId dfun_name inst_tyvars dfun_theta clas inst_tys
768 = setIdLocalExported (mkLocalId dfun_name dfun_ty)
770 dfun_ty = mkSigmaTy inst_tyvars dfun_theta (mkDictTy clas inst_tys)
772 {- 1 dec 99: disable the Mark Jones optimisation for the sake
773 of compatibility with Hugs.
774 See `types/InstEnv' for a discussion related to this.
776 (class_tyvars, sc_theta, _, _) = classBigSig clas
777 not_const (clas, tys) = not (isEmptyVarSet (tyVarsOfTypes tys))
778 sc_theta' = substClasses (mkTopTyVarSubst class_tyvars inst_tys) sc_theta
779 dfun_theta = case inst_decl_theta of
780 [] -> [] -- If inst_decl_theta is empty, then we don't
781 -- want to have any dict arguments, so that we can
782 -- expose the constant methods.
784 other -> nub (inst_decl_theta ++ filter not_const sc_theta')
785 -- Otherwise we pass the superclass dictionaries to
786 -- the dictionary function; the Mark Jones optimisation.
788 -- NOTE the "nub". I got caught by this one:
789 -- class Monad m => MonadT t m where ...
790 -- instance Monad m => MonadT (EnvT env) m where ...
791 -- Here, the inst_decl_theta has (Monad m); but so
792 -- does the sc_theta'!
794 -- NOTE the "not_const". I got caught by this one too:
795 -- class Foo a => Baz a b where ...
796 -- instance Wob b => Baz T b where..
797 -- Now sc_theta' has Foo T
802 %************************************************************************
804 \subsection{Un-definable}
806 %************************************************************************
808 These Ids can't be defined in Haskell. They could be defined in
809 unfoldings in the wired-in GHC.Prim interface file, but we'd have to
810 ensure that they were definitely, definitely inlined, because there is
811 no curried identifier for them. That's what mkCompulsoryUnfolding
812 does. If we had a way to get a compulsory unfolding from an interface
813 file, we could do that, but we don't right now.
815 unsafeCoerce# isn't so much a PrimOp as a phantom identifier, that
816 just gets expanded into a type coercion wherever it occurs. Hence we
817 add it as a built-in Id with an unfolding here.
819 The type variables we use here are "open" type variables: this means
820 they can unify with both unlifted and lifted types. Hence we provide
821 another gun with which to shoot yourself in the foot.
824 -- unsafeCoerce# :: forall a b. a -> b
826 = pcMiscPrelId unsafeCoerceName ty info
828 info = noCafIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs
831 ty = mkForAllTys [openAlphaTyVar,openBetaTyVar]
832 (mkFunTy openAlphaTy openBetaTy)
833 [x] = mkTemplateLocals [openAlphaTy]
834 rhs = mkLams [openAlphaTyVar,openBetaTyVar,x] $
835 Note (Coerce openBetaTy openAlphaTy) (Var x)
837 -- nullAddr# :: Addr#
838 -- The reason is is here is because we don't provide
839 -- a way to write this literal in Haskell.
841 = pcMiscPrelId nullAddrName addrPrimTy info
843 info = noCafIdInfo `setUnfoldingInfo`
844 mkCompulsoryUnfolding (Lit nullAddrLit)
847 = pcMiscPrelId seqName ty info
849 info = noCafIdInfo `setUnfoldingInfo` mkCompulsoryUnfolding rhs
852 ty = mkForAllTys [alphaTyVar,openBetaTyVar]
853 (mkFunTy alphaTy (mkFunTy openBetaTy openBetaTy))
854 [x,y] = mkTemplateLocals [alphaTy, openBetaTy]
855 rhs = mkLams [alphaTyVar,openBetaTyVar,x,y] (Case (Var x) x [(DEFAULT, [], Var y)])
857 -- lazy :: forall a?. a? -> a? (i.e. works for unboxed types too)
858 -- Used to lazify pseq: pseq a b = a `seq` lazy b
859 -- No unfolding: it gets "inlined" by the worker/wrapper pass
860 -- Also, no strictness: by being a built-in Id, it overrides all
861 -- the info in PrelBase.hi. This is important, because the strictness
862 -- analyser will spot it as strict!
864 = pcMiscPrelId lazyIdName ty info
867 ty = mkForAllTys [alphaTyVar] (mkFunTy alphaTy alphaTy)
869 lazyIdUnfolding :: CoreExpr -- Used to expand LazyOp after strictness anal
870 lazyIdUnfolding = mkLams [openAlphaTyVar,x] (Var x)
872 [x] = mkTemplateLocals [openAlphaTy]
875 @realWorld#@ used to be a magic literal, \tr{void#}. If things get
876 nasty as-is, change it back to a literal (@Literal@).
878 voidArgId is a Local Id used simply as an argument in functions
879 where we just want an arg to avoid having a thunk of unlifted type.
881 x = \ void :: State# RealWorld -> (# p, q #)
883 This comes up in strictness analysis
886 realWorldPrimId -- :: State# RealWorld
887 = pcMiscPrelId realWorldName realWorldStatePrimTy
888 (noCafIdInfo `setUnfoldingInfo` mkOtherCon [])
889 -- The mkOtherCon makes it look that realWorld# is evaluated
890 -- which in turn makes Simplify.interestingArg return True,
891 -- which in turn makes INLINE things applied to realWorld# likely
894 voidArgId -- :: State# RealWorld
895 = mkSysLocal FSLIT("void") voidArgIdKey realWorldStatePrimTy
899 %************************************************************************
901 \subsection[PrelVals-error-related]{@error@ and friends; @trace@}
903 %************************************************************************
905 GHC randomly injects these into the code.
907 @patError@ is just a version of @error@ for pattern-matching
908 failures. It knows various ``codes'' which expand to longer
909 strings---this saves space!
911 @absentErr@ is a thing we put in for ``absent'' arguments. They jolly
912 well shouldn't be yanked on, but if one is, then you will get a
913 friendly message from @absentErr@ (rather than a totally random
916 @parError@ is a special version of @error@ which the compiler does
917 not know to be a bottoming Id. It is used in the @_par_@ and @_seq_@
918 templates, but we don't ever expect to generate code for it.
922 :: Id -- Should be of type (forall a. Addr# -> a)
923 -- where Addr# points to a UTF8 encoded string
924 -> Type -- The type to instantiate 'a'
925 -> String -- The string to print
928 mkRuntimeErrorApp err_id res_ty err_msg
929 = mkApps (Var err_id) [Type res_ty, err_string]
931 err_string = Lit (MachStr (mkFastString (stringToUtf8 err_msg)))
933 rEC_SEL_ERROR_ID = mkRuntimeErrorId recSelErrorName
934 rUNTIME_ERROR_ID = mkRuntimeErrorId runtimeErrorName
935 iRREFUT_PAT_ERROR_ID = mkRuntimeErrorId irrefutPatErrorName
936 rEC_CON_ERROR_ID = mkRuntimeErrorId recConErrorName
937 nON_EXHAUSTIVE_GUARDS_ERROR_ID = mkRuntimeErrorId nonExhaustiveGuardsErrorName
938 pAT_ERROR_ID = mkRuntimeErrorId patErrorName
939 nO_METHOD_BINDING_ERROR_ID = mkRuntimeErrorId noMethodBindingErrorName
941 -- The runtime error Ids take a UTF8-encoded string as argument
942 mkRuntimeErrorId name = pc_bottoming_Id name runtimeErrorTy
943 runtimeErrorTy = mkSigmaTy [openAlphaTyVar] [] (mkFunTy addrPrimTy openAlphaTy)
947 eRROR_ID = pc_bottoming_Id errorName errorTy
950 errorTy = mkSigmaTy [openAlphaTyVar] [] (mkFunTys [mkListTy charTy] openAlphaTy)
951 -- Notice the openAlphaTyVar. It says that "error" can be applied
952 -- to unboxed as well as boxed types. This is OK because it never
953 -- returns, so the return type is irrelevant.
957 %************************************************************************
959 \subsection{Utilities}
961 %************************************************************************
964 pcMiscPrelId :: Name -> Type -> IdInfo -> Id
965 pcMiscPrelId name ty info
966 = mkVanillaGlobal name ty info
967 -- We lie and say the thing is imported; otherwise, we get into
968 -- a mess with dependency analysis; e.g., core2stg may heave in
969 -- random calls to GHCbase.unpackPS__. If GHCbase is the module
970 -- being compiled, then it's just a matter of luck if the definition
971 -- will be in "the right place" to be in scope.
973 pc_bottoming_Id name ty
974 = pcMiscPrelId name ty bottoming_info
976 bottoming_info = hasCafIdInfo `setAllStrictnessInfo` Just strict_sig
977 -- Do *not* mark them as NoCafRefs, because they can indeed have
978 -- CAF refs. For example, pAT_ERROR_ID calls GHC.Err.untangle,
979 -- which has some CAFs
980 -- In due course we may arrange that these error-y things are
981 -- regarded by the GC as permanently live, in which case we
982 -- can give them NoCaf info. As it is, any function that calls
983 -- any pc_bottoming_Id will itself have CafRefs, which bloats
986 strict_sig = mkStrictSig (mkTopDmdType [evalDmd] BotRes)
987 -- These "bottom" out, no matter what their arguments
989 (openAlphaTyVar:openBetaTyVar:_) = openAlphaTyVars
990 openAlphaTy = mkTyVarTy openAlphaTyVar
991 openBetaTy = mkTyVarTy openBetaTyVar