2 % (c) The AQUA Project, Glasgow University, 1993-1996
4 \section[SimplEnv]{Environment stuff for the simplifier}
7 #include "HsVersions.h"
11 pprSimplEnv, -- debugging only
13 replaceInEnvs, nullInEnvs,
15 extendTyEnv, extendTyEnvList,
18 extendIdEnvWithAtom, extendIdEnvWithAtomList,
19 extendIdEnvWithInlining,
20 extendIdEnvWithClone, extendIdEnvWithClones,
23 extendUnfoldEnvGivenRhs,
24 extendUnfoldEnvGivenFormDetails,
25 extendUnfoldEnvGivenConstructor,
27 lookupUnfolding, filterUnfoldEnvForInlines,
29 getSwitchChecker, switchIsSet,
35 SimplEnv, EnclosingCcDetails(..),
36 InIdEnv(..), IdVal(..), InTypeEnv(..),
37 UnfoldEnv, UnfoldItem, UnfoldConApp,
39 InId(..), InBinder(..), InBinding(..), InType(..),
40 OutId(..), OutBinder(..), OutBinding(..), OutType(..),
42 InExpr(..), InAlts(..), InDefault(..), InArg(..),
43 OutExpr(..), OutAlts(..), OutDefault(..), OutArg(..)
45 -- and to make the interface self-sufficient...
50 import SmplLoop -- breaks the MagicUFs / SimplEnv loop
52 import BinderInfo ( BinderInfo{-instances-} )
53 import CmdLineOpts ( switchIsOn, intSwitchSet, SimplifierSwitch(..), SwitchResult )
55 import CoreUnfold ( UnfoldingDetails(..), mkGenForm, modifyUnfoldingDetails,
56 calcUnfoldingGuidance, UnfoldingGuidance(..),
57 mkFormSummary, FormSummary
59 import FiniteMap -- lots of things
60 import Id ( idType, getIdUnfolding, getIdStrictness,
62 nullIdEnv, growIdEnvList, rngIdEnv, lookupIdEnv,
63 addOneToIdEnv, modifyIdEnv,
64 IdEnv(..), IdSet(..), GenId )
65 import IdInfo ( StrictnessInfo )
66 import Literal ( isNoRepLit, Literal{-instances-} )
67 import Name ( isLocallyDefined )
68 import Outputable ( Outputable(..){-instances-} )
69 import PprCore -- various instances
70 import PprStyle ( PprStyle(..) )
71 import PprType ( GenType, GenTyVar )
73 import Type ( getAppDataTyCon, applyTypeEnvToTy )
74 import TyVar ( nullTyVarEnv, addOneToIdEnv, addOneToTyVarEnv,
76 TyVarEnv(..), GenTyVar{-instance Eq-}
78 import Unique ( Unique{-instance Outputable-} )
79 import UniqSet -- lots of things
80 import Usage ( UVar(..), GenUsage{-instances-} )
81 import Util ( zipEqual, panic, assertPanic )
83 type TypeEnv = TyVarEnv Type
84 addToUFM_Directly = panic "addToUFM_Directly (SimplEnv)"
85 bottomIsGuaranteed = panic "bottomIsGuaranteed (SimplEnv)"
86 cmpType = panic "cmpType (SimplEnv)"
87 exprSmallEnoughToDup = panic "exprSmallEnoughToDup (SimplEnv)"
88 lookupDirectlyUFM = panic "lookupDirectlyUFM (SimplEnv)"
89 manifestlyWHNF = panic "manifestlyWHNF (SimplEnv)"
90 occurAnalyseExpr = panic "occurAnalyseExpr (SimplEnv)"
91 oneSafeOcc = panic "oneSafeOcc (SimplEnv)"
92 oneTextualOcc = panic "oneTextualOcc (SimplEnv)"
93 simplIdWantsToBeINLINEd = panic "simplIdWantsToBeINLINEd (SimplEnv)"
94 uNFOLDING_CREATION_THRESHOLD = panic "uNFOLDING_CREATION_THRESHOLD (SimplEnv)"
95 ufmToList = panic "ufmToList (SimplEnv)"
98 %************************************************************************
100 \subsection[Simplify-types]{Type declarations}
102 %************************************************************************
105 %************************************************************************
107 \subsubsection{The @SimplEnv@ type}
109 %************************************************************************
112 INVARIANT: we assume {\em no shadowing}. (ToDo: How can we ASSERT
113 this? WDP 94/06) This allows us to neglect keeping everything paired
114 with its static environment.
116 The environment contains bindings for all
118 {\em locally-defined}
121 For such things, any unfolding is found in the environment, not in the
122 Id. Unfoldings in the Id itself are used only for imported things
123 (otherwise we get trouble because we have to simplify the unfoldings
124 inside the Ids, etc.).
131 EnclosingCcDetails -- the enclosing cost-centre (when profiling)
133 InTypeEnv -- For cloning types
134 -- Domain is all in-scope type variables
142 -- (Could omit the exported top-level guys,
143 -- since their names mustn't change; and ditto
144 -- the non-exported top-level guys which you
145 -- don't want to macro-expand, since their
146 -- names need not change.)
150 UnfoldEnv -- Domain is any *OutIds*, including imports
151 -- where we know something more than the
152 -- interface file tells about their value (see
155 nullSimplEnv :: SwitchChecker -> SimplEnv
158 = SimplEnv sw_chkr NoEnclosingCcDetails nullTyVarEnv nullIdEnv null_unfold_env
160 pprSimplEnv (SimplEnv _ _ ty_env id_env (UFE unfold_env _ _))
162 ppStr "** Type Env ** ????????", -- ppr PprDebug ty_env,
163 ppSP, ppStr "** Id Env ** ?????????",
164 -- ppAboves [ pp_id_entry x | x <- getIdEnvMapping id_env ],
165 ppSP, ppStr "** Unfold Env **",
166 ppAboves [ pp_uf_entry x | x <- rngIdEnv unfold_env ]
169 pp_id_entry (v, idval)
170 = ppCat [ppr PprDebug v, ppStr "=>",
172 InlineIt _ _ e -> ppCat [ppStr "InlineIt:", ppr PprDebug e]
173 ItsAnAtom a -> ppCat [ppStr "Atom:", ppr PprDebug a]
176 pp_uf_entry (UnfoldItem v form encl_cc)
177 = ppCat [ppr PprDebug v, ppStr "=>",
179 NoUnfoldingDetails -> ppStr "NoUnfoldingDetails"
180 LitForm l -> ppCat [ppStr "Lit:", ppr PprDebug l]
181 OtherLitForm ls -> ppCat [ppStr "Other lit:", ppInterleave (ppStr ", ")
182 [ppr PprDebug l | l <- ls]]
183 ConForm c a -> ppCat [ppStr "Con:", ppr PprDebug c, ppr PprDebug a]
184 OtherConForm cs -> ppCat [ppStr "OtherCon:", ppInterleave (ppStr ", ")
185 [ppr PprDebug c | c <- cs]]
186 GenForm t w e g -> ppCat [ppStr "UF:", ppr PprDebug t, ppr PprDebug w,
187 ppr PprDebug g, ppr PprDebug e]
188 MagicForm s _ -> ppCat [ppStr "Magic:", ppr PprDebug s]
192 %************************************************************************
194 \subsubsection{The @IdVal@ type (for the ``IdEnv'')}
196 %************************************************************************
198 The unfoldings for imported things are mostly kept within the Id
199 itself; nevertheless, they {\em can} get into the @UnfoldEnv@. For
200 example, suppose \tr{x} is imported, and we have
205 Then within \tr{<body>}, we know that \tr{x} is a pair with components
209 type InIdEnv = IdEnv IdVal -- Maps InIds to their value
212 = InlineIt InIdEnv InTypeEnv InExpr
213 -- No binding of the Id is left;
214 -- You *have* to replace any occurences
215 -- of the id with this expression.
216 -- Rather like a macro, really
217 -- NB: the InIdEnv/InTypeEnv is necessary to prevent
218 -- name caputure. Consider:
223 -- If x gets an InlineIt, we must remember
224 -- the correct binding for y.
226 | ItsAnAtom OutArg -- Used either (a) to record the cloned Id
227 -- or (b) if the orig defn is a let-binding, and
228 -- the RHS of the let simplifies to an atom,
229 -- we just bind the variable to that atom, and
233 %************************************************************************
235 \subsubsection{The @UnfoldEnv@ type}
237 %************************************************************************
239 The @UnfoldEnv@ contains information about the value of some of the
240 in-scope identifiers. It obeys the following invariant:
242 If the @UnfoldEnv@ contains information, it is safe to use it!
244 In particular, if the @UnfoldEnv@ contains details of an unfolding of
245 an Id, then it's safe to use the unfolding. If, for example, the Id
246 is used many times, then its unfolding won't be put in the UnfoldEnv
249 The @UnfoldEnv@ (used to be [WDP 94/06]) a simple association list
250 because (a)~it's small, and (b)~we need to search its {\em range} as
254 data UnfoldItem -- a glorified triple...
255 = UnfoldItem OutId -- key: used in lookForConstructor
256 UnfoldingDetails -- for that Id
257 EnclosingCcDetails -- so that if we do an unfolding,
258 -- we can "wrap" it in the CC
259 -- that was in force.
261 data UnfoldConApp -- yet another glorified triple
262 = UCA OutId -- same fields as ConForm
265 data UnfoldEnv -- yup, a glorified triple...
266 = UFE (IdEnv UnfoldItem) -- Maps an OutId => its UnfoldItem
267 IdSet -- The Ids in the domain of the env
268 -- which have details (GenForm True ...)
269 -- i.e., they claim they are duplicatable.
270 -- These are the ones we have to worry
271 -- about when adding new items to the
273 (FiniteMap UnfoldConApp OutId)
274 -- Maps applications of constructors (to
275 -- types & atoms) back to OutIds that are
276 -- bound to them; i.e., this is a reversed
277 -- mapping for (part of) the main IdEnv
280 null_unfold_env = UFE nullIdEnv emptyUniqSet emptyFM
283 The @UnfoldEnv@ type. We expect on the whole that an @UnfoldEnv@ will
284 be small, because it contains bindings only for those things whose
285 form or unfolding is known. Basically it maps @Id@ to their
286 @UnfoldingDetails@ (and @EnclosingCcDetails@---boring...), but we also
287 need to search it associatively, to look for @Id@s which have a given
290 We implement it with @IdEnvs@, possibly overkill, but sometimes these
291 things silently grow quite big.... Here are some local functions used
292 elsewhere in the module:
295 grow_unfold_env :: UnfoldEnv -> OutId -> UnfoldingDetails -> EnclosingCcDetails -> UnfoldEnv
296 lookup_unfold_env :: UnfoldEnv -> OutId -> UnfoldingDetails
297 lookup_unfold_env_encl_cc
298 :: UnfoldEnv -> OutId -> EnclosingCcDetails
300 grow_unfold_env full_u_env id NoUnfoldingDetails _ = full_u_env
302 grow_unfold_env (UFE u_env interesting_ids con_apps) id
303 uf_details@(GenForm True _ _ _) encl_cc
304 -- Only interested in Ids which have a "dangerous" unfolding; that is
305 -- one that claims to have a single occurrence.
306 = UFE (addOneToIdEnv u_env id (UnfoldItem id uf_details encl_cc))
307 (addOneToUniqSet interesting_ids id)
310 grow_unfold_env (UFE u_env interesting_ids con_apps) id uf_details encl_cc
311 = UFE (addOneToIdEnv u_env id (UnfoldItem id uf_details encl_cc))
318 -> case (lookupFM con_apps entry) of
319 Just _ -> con_apps -- unchanged; we hang onto what we have
320 Nothing -> addToFM con_apps entry id
322 entry = UCA con vargs
324 not_a_constructor -> con_apps -- unchanged
326 addto_unfold_env (UFE u_env interesting_ids con_apps) extra_items
327 = ASSERT(not (any constructor_form_in_those extra_items))
328 -- otherwise, we'd need to change con_apps
329 UFE (growIdEnvList u_env extra_items) interesting_ids con_apps
331 constructor_form_in_those (_, UnfoldItem _ (ConForm _ _) _) = True
332 constructor_form_in_those _ = False
334 rng_unfold_env (UFE u_env _ _) = rngIdEnv u_env
336 get_interesting_ids (UFE _ interesting_ids _) = interesting_ids
338 foldr_unfold_env fun (UFE u_env interesting_ids con_apps) stuff
339 = UFE (foldr fun u_env stuff) interesting_ids con_apps
341 lookup_unfold_env (UFE u_env _ _) id
342 = case (lookupIdEnv u_env id) of
343 Nothing -> NoUnfoldingDetails
344 Just (UnfoldItem _ uf _) -> uf
346 lookup_unfold_env_encl_cc (UFE u_env _ _) id
347 = case (lookupIdEnv u_env id) of
348 Nothing -> NoEnclosingCcDetails
349 Just (UnfoldItem _ _ encl_cc) -> encl_cc
351 lookup_conapp (UFE _ _ con_apps) con args
352 = lookupFM con_apps (UCA con args)
354 modify_unfold_env (UFE u_env interesting_ids con_apps) zapper id
355 = UFE (modifyIdEnv u_env zapper id) interesting_ids con_apps
357 -- If the current binding claims to be a "unique" one, then
359 modifyItem :: Bool -> BinderInfo -> UnfoldItem -> UnfoldItem
361 modifyItem ok_to_dup occ_info (UnfoldItem id details enc_cc)
362 = UnfoldItem id (modifyUnfoldingDetails ok_to_dup occ_info details) enc_cc
365 The main thing about @UnfoldConApp@ is that it has @Ord@ defined on
366 it, so we can use it for a @FiniteMap@ key.
368 instance Eq UnfoldConApp where
369 a == b = case cmp_app a b of { EQ_ -> True; _ -> False }
370 a /= b = case cmp_app a b of { EQ_ -> False; _ -> True }
372 instance Ord UnfoldConApp where
373 a <= b = case cmp_app a b of { LT_ -> True; EQ_ -> True; GT__ -> False }
374 a < b = case cmp_app a b of { LT_ -> True; EQ_ -> False; GT__ -> False }
375 a >= b = case cmp_app a b of { LT_ -> False; EQ_ -> True; GT__ -> True }
376 a > b = case cmp_app a b of { LT_ -> False; EQ_ -> False; GT__ -> True }
377 _tagCmp a b = case cmp_app a b of { LT_ -> _LT; EQ_ -> _EQ; GT__ -> _GT }
379 instance Ord3 UnfoldConApp where
382 cmp_app (UCA c1 as1) (UCA c2 as2)
383 = case (c1 `cmp` c2) of
386 _ -> cmp_lists cmp_atom as1 as2
388 cmp_lists cmp_item [] [] = EQ_
389 cmp_lists cmp_item (x:xs) [] = GT_
390 cmp_lists cmp_item [] (y:ys) = LT_
391 cmp_lists cmp_item (x:xs) (y:ys)
392 = case cmp_item x y of { EQ_ -> cmp_lists cmp_item xs ys; other -> other }
394 cmp_atom (VarArg x) (VarArg y) = x `cmp` y
395 cmp_atom (VarArg _) _ = LT_
396 cmp_atom (LitArg x) (LitArg y)
397 = case _tagCmp x y of { _LT -> LT_; _EQ -> EQ_; GT__ -> GT_ }
398 cmp_atom (LitArg _) _ = GT_
401 %************************************************************************
403 \subsubsection{The @EnclosingCcDetails@ type}
405 %************************************************************************
408 data EnclosingCcDetails
409 = NoEnclosingCcDetails
410 | EnclosingCC CostCentre
413 %************************************************************************
415 \subsubsection{The ``InXXX'' and ``OutXXX'' type synonyms}
417 %************************************************************************
420 type InId = Id -- Not yet cloned
421 type InBinder = (InId, BinderInfo)
422 type InType = Type -- Ditto
423 type InBinding = SimplifiableCoreBinding
424 type InExpr = SimplifiableCoreExpr
425 type InAlts = SimplifiableCoreCaseAlts
426 type InDefault = SimplifiableCoreCaseDefault
427 type InArg = SimplifiableCoreArg
429 type OutId = Id -- Cloned
431 type OutType = Type -- Cloned
432 type OutBinding = CoreBinding
433 type OutExpr = CoreExpr
434 type OutAlts = CoreCaseAlts
435 type OutDefault = CoreCaseDefault
436 type OutArg = CoreArg
441 type SwitchChecker = SimplifierSwitch -> SwitchResult
444 %************************************************************************
446 \subsection{@SimplEnv@ handling}
448 %************************************************************************
450 %************************************************************************
452 \subsubsection{Command-line switches}
454 %************************************************************************
457 getSwitchChecker :: SimplEnv -> SwitchChecker
458 getSwitchChecker (SimplEnv chkr _ _ _ _) = chkr
460 switchIsSet :: SimplEnv -> SimplifierSwitch -> Bool
461 switchIsSet (SimplEnv chkr _ _ _ _) switch
462 = switchIsOn chkr switch
465 %************************************************************************
467 \subsubsection{The ``enclosing cost-centre''}
469 %************************************************************************
472 setEnclosingCC :: SimplEnv -> EnclosingCcDetails -> SimplEnv
474 setEnclosingCC (SimplEnv chkr _ ty_env id_env unfold_env) encl_cc
475 = SimplEnv chkr encl_cc ty_env id_env unfold_env
478 %************************************************************************
480 \subsubsection{The @TypeEnv@ part}
482 %************************************************************************
485 type InTypeEnv = TypeEnv -- Maps InTyVars to OutTypes
487 extendTyEnv :: SimplEnv -> TyVar -> Type -> SimplEnv
488 extendTyEnv (SimplEnv chkr encl_cc ty_env id_env unfold_env) tyvar ty
489 = SimplEnv chkr encl_cc new_ty_env id_env unfold_env
491 new_ty_env = addOneToTyVarEnv ty_env tyvar ty
493 extendTyEnvList :: SimplEnv -> [(TyVar,Type)] -> SimplEnv
494 extendTyEnvList (SimplEnv chkr encl_cc ty_env id_env unfold_env) pairs
495 = SimplEnv chkr encl_cc new_ty_env id_env unfold_env
497 new_ty_env = growTyVarEnvList ty_env pairs
499 simplTy (SimplEnv _ _ ty_env _ _) ty = applyTypeEnvToTy ty_env ty
500 simplTyInId (SimplEnv _ _ ty_env _ _) id = applyTypeEnvToId ty_env id
503 @replaceInEnvs@ is used to install saved type and id envs
504 when pulling an un-simplified expression out of the environment, which
505 was saved with its environments.
508 nullInEnvs = (nullTyVarEnv, nullIdEnv) :: (InTypeEnv,InIdEnv)
510 replaceInEnvs :: SimplEnv -> (InTypeEnv,InIdEnv) -> SimplEnv
512 replaceInEnvs (SimplEnv chkr encl_cc ty_env id_env unfold_env)
513 (new_ty_env, new_id_env)
514 = SimplEnv chkr encl_cc new_ty_env new_id_env unfold_env
517 %************************************************************************
519 \subsubsection{The ``Id env'' part}
521 %************************************************************************
526 -> InBinder -> OutArg
529 extendIdEnvWithAtom (SimplEnv chkr encl_cc ty_env id_env unfold_env) (in_id,occ_info) atom@(LitArg lit)
530 = SimplEnv chkr encl_cc ty_env new_id_env unfold_env
532 new_id_env = addOneToIdEnv id_env in_id (ItsAnAtom atom)
534 extendIdEnvWithAtom (SimplEnv chkr encl_cc ty_env id_env unfold_env)
535 (in_id, occ_info) atom@(VarArg out_id)
536 = SimplEnv chkr encl_cc ty_env new_id_env new_unfold_env
538 new_id_env = addOneToIdEnv id_env in_id (ItsAnAtom atom)
540 new_unfold_env = modify_unfold_env
542 (modifyItem ok_to_dup occ_info)
544 -- Modify binding for in_id
545 -- NO! modify out_id, because its the info on the
546 -- atom that interest's us.
548 ok_to_dup = switchIsOn chkr SimplOkToDupCode
550 extendIdEnvWithAtomList
552 -> [(InBinder, OutArg)]
554 extendIdEnvWithAtomList = foldr (\ (bndr,val) env -> extendIdEnvWithAtom env bndr val)
556 extendIdEnvWithInlining
557 :: SimplEnv -- The Env to modify
558 -> SimplEnv -- The Env to record in the inlining. Usually the
559 -- same as the previous one, except in the recursive case
560 -> InBinder -> InExpr
563 extendIdEnvWithInlining (SimplEnv chkr encl_cc ty_env id_env unfold_env)
564 ~(SimplEnv _ _ inline_ty_env inline_id_env _ )
567 = SimplEnv chkr encl_cc ty_env new_id_env unfold_env
569 new_id_env = addOneToIdEnv id_env in_id (InlineIt inline_id_env inline_ty_env expr)
573 -> InBinder -- Old binder; binderinfo ignored
574 -> OutId -- Its new clone, as an Id
577 extendIdEnvWithClone (SimplEnv chkr encl_cc ty_env id_env unfold_env)
579 = SimplEnv chkr encl_cc ty_env new_id_env unfold_env
581 new_id_env = addOneToIdEnv id_env in_id (ItsAnAtom (VarArg out_id))
583 extendIdEnvWithClones -- Like extendIdEnvWithClone
589 extendIdEnvWithClones (SimplEnv chkr encl_cc ty_env id_env unfold_env)
591 = SimplEnv chkr encl_cc ty_env new_id_env unfold_env
593 new_id_env = growIdEnvList id_env (in_ids `zipEqual` out_vals)
594 in_ids = [id | (id,_) <- in_binders]
595 out_vals = [ItsAnAtom (VarArg out_id) | out_id <- out_ids]
597 lookupId :: SimplEnv -> Id -> Maybe IdVal
599 lookupId (SimplEnv _ _ _ id_env _) id
601 = lookupIdEnv id_env id
603 = case (lookupIdEnv id_env id) of
605 xxx -> --false!: ASSERT(not (isLocallyDefined id))
610 %************************************************************************
612 \subsubsection{The @UnfoldEnv@}
614 %************************************************************************
617 extendUnfoldEnvGivenFormDetails
623 extendUnfoldEnvGivenFormDetails
624 env@(SimplEnv chkr encl_cc ty_env id_env unfold_env)
627 NoUnfoldingDetails -> env
628 good_details -> SimplEnv chkr encl_cc ty_env id_env new_unfold_env
630 new_unfold_env = grow_unfold_env unfold_env id good_details encl_cc
632 extendUnfoldEnvGivenConstructor -- specialised variant
634 -> OutId -- bind this to...
635 -> Id -> [OutId] -- "con <tys-to-be-invented> args"
638 extendUnfoldEnvGivenConstructor env var con args
640 -- conjure up the types to which the con should be applied
641 scrut_ty = idType var
642 (_, ty_args, _) = getAppDataTyCon scrut_ty
644 extendUnfoldEnvGivenFormDetails
645 env var (ConForm con (map VarArg args))
649 @extendUnfoldEnvGivenRhs@ records in the UnfoldEnv info about the RHS
650 of a new binding. There is a horrid case we have to take care about,
651 due to Andr\'e Santos:
653 type Array_type b = Array Int b;
654 type Descr_type = (Int,Int);
656 tabulate :: (Int -> x) -> Descr_type -> Array_type x;
657 tabulate f (l,u) = listArray (l,u) [f i | i <- [l..u]];
661 f_aareorder::(Array_type Int) -> (Array_type t1) -> Array_type t1;
662 f_aareorder a_index a_ar=
664 f_aareorder' a_i= a_ar ! (a_index ! a_i)
665 } in tabulate f_aareorder' (bounds a_ar);
666 r_index=tabulate ((+) 1) (1,1);
667 arr = listArray (1,1) a_xs;
668 arg = f_aareorder r_index arr
671 Now, when the RHS of arg gets simplified, we inline f_aareorder to get
673 arg = let f_aareorder' a_i = arr ! (r_index ! a_i)
674 in tabulate f_aareorder' (bounds arr)
676 Note that r_index is not inlined, because it was bound to a_index which
677 occurs inside a lambda.
679 Alas, if elems is inlined, so that (elems arg) becomes (case arg of ...),
680 then arg is inlined. IF WE USE THE NEW VERSION OF arg, and re-occurrence
681 analyse it, we won't spot the inside-lambda property of r_index, so r_index
682 will get inlined inside the lambda. AARGH.
684 Solution: when we occurrence-analyse the new RHS we have to go back
685 and modify the info recorded in the UnfoldEnv for the free vars
686 of the RHS. In the example we'd go back and record that r_index is now used
690 extendUnfoldEnvGivenRhs
693 -> OutId -- Note: *must* be an "out" Id (post-cloning)
694 -> OutExpr -- Its rhs (*simplified*)
697 extendUnfoldEnvGivenRhs env@(SimplEnv chkr encl_cc ty_env id_env unfold_env)
698 binder@(_,occ_info) out_id rhs
699 = SimplEnv chkr encl_cc ty_env id_env new_unfold_env
701 -- Occurrence-analyse the RHS
702 (fv_occ_info, template) = occurAnalyseExpr {-test:nullIdEnv-} interesting_fvs rhs
704 interesting_fvs = get_interesting_ids unfold_env
706 -- Compute unfolding details
707 details = case rhs of
708 Var v -> panic "Vars already dealt with"
709 Lit lit | isNoRepLit lit -> LitForm lit
710 | otherwise -> panic "non-noRep Lits already dealt with"
712 Con con args -> ConForm con args
714 other -> mkGenForm ok_to_dup occ_info
715 (mkFormSummary (getIdStrictness out_id) rhs)
718 -- Compute resulting unfold env
719 new_unfold_env = case details of
720 NoUnfoldingDetails -> unfold_env
721 GenForm _ _ _ _ -> unfold_env2{-test: unfold_env1 -}
724 -- Add unfolding to unfold env
725 unfold_env1 = grow_unfold_env unfold_env out_id details encl_cc
727 -- Modify unfoldings of free vars of rhs, based on their
728 -- occurrence info in the rhs [see notes above]
729 unfold_env2 = foldr_unfold_env modify unfold_env1 (ufmToList fv_occ_info)
731 modify :: (Unique, BinderInfo) -> IdEnv UnfoldItem -> IdEnv UnfoldItem
732 modify (u, occ_info) env
733 = case (lookupDirectlyUFM env u) of
734 Nothing -> env -- ToDo: can this happen?
735 Just xx -> addToUFM_Directly env u (modifyItem ok_to_dup occ_info xx)
737 -- Compute unfolding guidance
738 guidance = if simplIdWantsToBeINLINEd out_id env
740 else calcUnfoldingGuidance True{-sccs OK-} bOMB_OUT_SIZE rhs
742 bOMB_OUT_SIZE = case (intSwitchSet chkr SimplUnfoldingCreationThreshold) of
743 Nothing -> uNFOLDING_CREATION_THRESHOLD
746 ok_to_dup = switchIsOn chkr SimplOkToDupCode
747 || exprSmallEnoughToDup rhs
748 -- [Andy] added, Jun 95
750 {- Reinstated AJG Jun 95; This is needed
751 --example that does not (currently) work
752 --without this extention
765 Omitted SLPJ Feb 95; should, I claim, be unnecessary
766 -- is_really_small looks for things like f a b c
767 -- but making sure there are not *too* many arguments.
768 -- (This is brought to you by *ANDY* Magic Constants, Inc.)
770 = case collectArgs new_rhs of
771 (Var _, _, _, xs) -> length xs < 10
777 lookupUnfolding :: SimplEnv -> Id -> UnfoldingDetails
779 lookupUnfolding (SimplEnv _ _ _ _ unfold_env) var
780 | not (isLocallyDefined var) -- Imported, so look inside the id
783 | otherwise -- Locally defined, so look in the envt.
784 -- There'll be nothing inside the Id.
785 = lookup_unfold_env unfold_env var
788 We need to remove any @GenForm@ bindings from the UnfoldEnv for
789 the RHS of an Id which has an INLINE pragma.
792 filterUnfoldEnvForInlines :: SimplEnv -> SimplEnv
794 filterUnfoldEnvForInlines env@(SimplEnv chkr encl_cc ty_env id_env unfold_env)
795 = SimplEnv chkr encl_cc ty_env id_env new_unfold_env
797 new_unfold_env = null_unfold_env
798 -- This version is really simple. INLINEd things are going to
799 -- be inlined wherever they are used, and then all the
800 -- UnfoldEnv stuff will take effect. Meanwhile, there isn't
801 -- much point in doing anything to the as-yet-un-INLINEd rhs.
803 -- Andy disagrees! Example:
804 -- all xs = foldr (&&) True xs
805 -- any p = all . map p {-# INLINE any #-}
807 -- Problem: any won't get deforested, and so if it's exported and
808 -- the importer doesn't use the inlining, (eg passes it as an arg)
809 -- then we won't get deforestation at all.
811 -- So he'd like not to filter the unfold env at all. But that's a disaster:
814 -- let f = \pq -> BIG
816 -- let g = \y -> f y y
818 -- in ...g...g...g...g...g...
820 -- Now, if that's the ONLY occurrence of f, it will be inlined inside g,
821 -- and thence copied multiple times when g is inlined.
824 ======================
826 In @lookForConstructor@ we used (before Apr 94) to have a special case
827 for nullary constructors:
830 = -- Don't re-use nullary constructors; it's a waste. Consider
838 -- Here the False in the second case will get replace by "a", hardly
843 but now we only do constructor re-use in let-bindings the special
844 case isn't necessary any more.
847 lookForConstructor (SimplEnv _ _ _ _ unfold_env) con args
848 = lookup_conapp unfold_env con args