2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section{Tidying up Core}
7 module TidyPgm( tidyCorePgm, tidyCoreExpr ) where
9 #include "HsVersions.h"
11 import CmdLineOpts ( DynFlags, DynFlag(..), dopt )
13 import CoreUnfold ( noUnfolding, mkTopUnfolding )
14 import CoreFVs ( ruleLhsFreeIds, exprSomeFreeVars )
15 import CoreTidy ( tidyExpr, tidyVarOcc, tidyIdRules )
16 import PprCore ( pprIdRules )
17 import CoreLint ( showPass, endPass )
18 import CoreUtils ( exprArity, rhsIsStatic )
21 import Var ( Id, Var )
22 import Id ( idType, idInfo, idName, idCoreRules,
23 isExportedId, mkVanillaGlobal, isLocalId,
24 isImplicitId, idArity, setIdInfo, idCafInfo
26 import IdInfo {- loads of stuff -}
27 import NewDemand ( isBottomingSig, topSig )
28 import BasicTypes ( Arity, isNeverActive )
29 import Name ( Name, getOccName, nameOccName, mkInternalName,
30 localiseName, isExternalName, nameSrcLoc, nameParent_maybe
32 import IfaceEnv ( allocateGlobalBinder )
33 import NameEnv ( lookupNameEnv, filterNameEnv )
34 import OccName ( TidyOccEnv, initTidyOccEnv, tidyOccName )
35 import Type ( tidyTopType )
36 import Module ( Module )
37 import HscTypes ( HscEnv(..), NameCache( nsUniqs ),
38 TypeEnv, extendTypeEnvList, typeEnvIds,
39 ModGuts(..), ModGuts, TyThing(..)
41 import Maybes ( orElse )
42 import ErrUtils ( showPass, dumpIfSet_core )
43 import UniqFM ( mapUFM )
44 import UniqSupply ( splitUniqSupply, uniqFromSupply )
45 import List ( partition )
46 import Maybe ( isJust )
48 import DATA_IOREF ( IORef, readIORef, writeIORef )
49 import FastTypes hiding ( fastOr )
53 %************************************************************************
55 \subsection{What goes on}
57 %************************************************************************
63 Step 1: Figure out external Ids
64 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
65 First we figure out which Ids are "external" Ids. An
66 "external" Id is one that is visible from outside the compilation
68 a) the user exported ones
69 b) ones mentioned in the unfoldings, workers,
70 or rules of externally-visible ones
71 This exercise takes a sweep of the bindings bottom to top. Actually,
72 in Step 2 we're also going to need to know which Ids should be
73 exported with their unfoldings, so we produce not an IdSet but an
77 Step 2: Tidy the program
78 ~~~~~~~~~~~~~~~~~~~~~~~~
79 Next we traverse the bindings top to bottom. For each *top-level*
82 1. Make it into a GlobalId
84 2. Give it a system-wide Unique.
85 [Even non-exported things need system-wide Uniques because the
86 byte-code generator builds a single Name->BCO symbol table.]
88 We use the NameCache kept in the HscEnv as the
89 source of such system-wide uniques.
91 For external Ids, use the original-name cache in the NameCache
92 to ensure that the unique assigned is the same as the Id had
93 in any previous compilation run.
95 3. If it's an external Id, make it have a global Name, otherwise
96 make it have a local Name.
97 This is used by the code generator to decide whether
98 to make the label externally visible
100 4. Give external Ids a "tidy" occurrence name. This means
101 we can print them in interface files without confusing
102 "x" (unique 5) with "x" (unique 10).
104 5. Give it its UTTERLY FINAL IdInfo; in ptic,
105 * Its IdDetails becomes VanillaGlobal, reflecting the fact that
106 from now on we regard it as a global, not local, Id
108 * its unfolding, if it should have one
110 * its arity, computed from the number of visible lambdas
112 * its CAF info, computed from what is free in its RHS
115 Finally, substitute these new top-level binders consistently
116 throughout, including in unfoldings. We also tidy binders in
117 RHSs, so that they print nicely in interfaces.
120 tidyCorePgm :: HscEnv -> ModGuts -> IO ModGuts
123 mod_impl@(ModGuts { mg_module = mod,
124 mg_types = env_tc, mg_insts = insts_tc,
125 mg_binds = binds_in, mg_rules = orphans_in })
126 = do { let { dflags = hsc_dflags hsc_env
127 ; nc_var = hsc_NC hsc_env }
128 ; showPass dflags "Tidy Core"
130 ; let omit_iface_prags = dopt Opt_OmitInterfacePragmas dflags
131 ; let ext_ids = findExternalSet omit_iface_prags binds_in
132 ; let ext_rules = findExternalRules omit_iface_prags binds_in orphans_in ext_ids
133 -- findExternalRules filters ext_rules to avoid binders that
134 -- aren't externally visible; but the externally-visible binders
135 -- are computed (by findExternalSet) assuming that all orphan
136 -- rules are exported (they get their Exported flag set in the desugarer)
137 -- So in fact we may export more than we need.
138 -- (It's a sort of mutual recursion.)
140 -- We also make sure to avoid any exported binders. Consider
141 -- f{-u1-} = 1 -- Local decl
143 -- f{-u2-} = 2 -- Exported decl
145 -- The second exported decl must 'get' the name 'f', so we
146 -- have to put 'f' in the avoids list before we get to the first
147 -- decl. tidyTopId then does a no-op on exported binders.
148 ; let init_env = (initTidyOccEnv avoids, emptyVarEnv)
149 avoids = [getOccName name | bndr <- typeEnvIds env_tc,
150 let name = idName bndr,
152 -- In computing our "avoids" list, we must include
154 -- all things with global names (assigned once and for
155 -- all by the renamer)
156 -- since their names are "taken".
157 -- The type environment is a convenient source of such things.
159 ; (final_env, tidy_binds)
160 <- tidyTopBinds dflags mod nc_var ext_ids init_env binds_in
162 ; let tidy_rules = tidyIdRules final_env ext_rules
164 ; let tidy_type_env = mkFinalTypeEnv omit_iface_prags env_tc tidy_binds
166 -- Dfuns are local Ids that might have
167 -- changed their unique during tidying. Remember
168 -- to lookup the id in the TypeEnv too, because
169 -- those Ids have had their IdInfo stripped if
171 ; let (_, subst_env ) = final_env
173 case lookupVarEnv subst_env id of
174 Nothing -> dfun_panic
176 case lookupNameEnv tidy_type_env (idName id) of
180 dfun_panic = pprPanic "lookup_dfun_id" (ppr id)
182 tidy_dfun_ids = map lookup_dfun_id insts_tc
184 ; let tidy_result = mod_impl { mg_types = tidy_type_env,
185 mg_rules = tidy_rules,
186 mg_insts = tidy_dfun_ids,
187 mg_binds = tidy_binds }
189 ; endPass dflags "Tidy Core" Opt_D_dump_simpl tidy_binds
190 ; dumpIfSet_core dflags Opt_D_dump_simpl
192 (pprIdRules tidy_rules)
197 tidyCoreExpr :: CoreExpr -> IO CoreExpr
198 tidyCoreExpr expr = return (tidyExpr emptyTidyEnv expr)
202 %************************************************************************
204 \subsection{Write a new interface file}
206 %************************************************************************
209 mkFinalTypeEnv :: Bool -- Omit interface pragmas
210 -> TypeEnv -- From typechecker
211 -> [CoreBind] -- Final Ids
214 -- The competed type environment is gotten from
215 -- a) keeping the types and classes
216 -- b) removing all Ids,
217 -- c) adding Ids with correct IdInfo, including unfoldings,
218 -- gotten from the bindings
219 -- From (c) we keep only those Ids with External names;
220 -- the CoreTidy pass makes sure these are all and only
221 -- the externally-accessible ones
222 -- This truncates the type environment to include only the
223 -- exported Ids and things needed from them, which saves space
225 -- However, we do keep things like constructors, which should not appear
226 -- in interface files, because they are needed by importing modules when
227 -- using the compilation manager
229 mkFinalTypeEnv omit_iface_prags type_env tidy_binds
230 = extendTypeEnvList (filterNameEnv keep_it type_env) final_ids
232 final_ids = [ AnId (strip_id_info id)
233 | bind <- tidy_binds,
234 id <- bindersOf bind,
235 isExternalName (idName id)]
238 | omit_iface_prags = id `setIdInfo` vanillaIdInfo
240 -- If the interface file has no pragma info then discard all
243 -- This is not so important for *this* module, but it's
244 -- vital for ghc --make:
245 -- subsequent compilations must not see (e.g.) the arity if
246 -- the interface file does not contain arity
247 -- If they do, they'll exploit the arity; then the arity might
248 -- change, but the iface file doesn't change => recompilation
249 -- does not happen => disaster
251 -- This IdInfo will live long-term in the Id => vanillaIdInfo makes
252 -- a conservative assumption about Caf-hood
254 -- We're not worried about occurrences of these Ids in unfoldings,
255 -- because in OmitInterfacePragmas mode we're stripping all the
256 -- unfoldings anyway.
258 -- We keep implicit Ids, because they won't appear
259 -- in the bindings from which final_ids are derived!
260 keep_it (AnId id) = isImplicitId id -- Remove all Ids except implicit ones
261 keep_it other = True -- Keep all TyCons and Classes
265 findExternalRules :: Bool -- Omit interface pragmas
267 -> [IdCoreRule] -- Orphan rules
268 -> IdEnv a -- Ids that are exported, so we need their rules
270 -- The complete rules are gotten by combining
271 -- a) the orphan rules
272 -- b) rules embedded in the top-level Ids
273 findExternalRules omit_iface_prags binds orphan_rules ext_ids
274 | omit_iface_prags = []
276 = filter (not . internal_rule) (orphan_rules ++ local_rules)
279 | id <- bindersOfBinds binds,
280 id `elemVarEnv` ext_ids,
281 rule <- idCoreRules id
283 internal_rule (IdCoreRule id is_orphan rule)
285 -- We can't print builtin rules in interface files
286 -- Since they are built in, an importing module
287 -- will have access to them anyway
289 || (not is_orphan && internal_id id)
290 -- Rule for an Id in this module; internal if the
291 -- Id is not exported
293 || any internal_id (varSetElems (ruleLhsFreeIds rule))
294 -- Don't export a rule whose LHS mentions an Id that
295 -- is completely internal (i.e. not visible to an
298 internal_id id = not (id `elemVarEnv` ext_ids)
301 %************************************************************************
303 \subsection{Step 1: finding externals}
305 %************************************************************************
308 findExternalSet :: Bool -- Omit interface pragmas
310 -> IdEnv Bool -- In domain => external
311 -- Range = True <=> show unfolding
312 -- Step 1 from the notes above
313 findExternalSet omit_iface_prags binds
314 = foldr find emptyVarEnv binds
316 find (NonRec id rhs) needed
317 | need_id needed id = addExternal omit_iface_prags (id,rhs) needed
319 find (Rec prs) needed = find_prs prs needed
321 -- For a recursive group we have to look for a fixed point
323 | null needed_prs = needed
324 | otherwise = find_prs other_prs new_needed
326 (needed_prs, other_prs) = partition (need_pr needed) prs
327 new_needed = foldr (addExternal omit_iface_prags) needed needed_prs
329 -- The 'needed' set contains the Ids that are needed by earlier
330 -- interface file emissions. If the Id isn't in this set, and isn't
331 -- exported, there's no need to emit anything
332 need_id needed_set id = id `elemVarEnv` needed_set || isExportedId id
333 need_pr needed_set (id,rhs) = need_id needed_set id
335 addExternal :: Bool -> (Id,CoreExpr) -> IdEnv Bool -> IdEnv Bool
336 -- The Id is needed; extend the needed set
337 -- with it and its dependents (free vars etc)
338 addExternal omit_iface_prags (id,rhs) needed
339 = extendVarEnv (foldVarSet add_occ needed new_needed_ids)
342 add_occ id needed = extendVarEnv needed id False
343 -- "False" because we don't know we need the Id's unfolding
344 -- We'll override it later when we find the binding site
346 new_needed_ids | omit_iface_prags = emptyVarSet
347 | otherwise = worker_ids `unionVarSet`
348 unfold_ids `unionVarSet`
352 dont_inline = isNeverActive (inlinePragInfo idinfo)
353 loop_breaker = isLoopBreaker (occInfo idinfo)
354 bottoming_fn = isBottomingSig (newStrictnessInfo idinfo `orElse` topSig)
355 spec_ids = rulesRhsFreeVars (specInfo idinfo)
356 worker_info = workerInfo idinfo
358 -- Stuff to do with the Id's unfolding
359 -- The simplifier has put an up-to-date unfolding
360 -- in the IdInfo, but the RHS will do just as well
361 unfolding = unfoldingInfo idinfo
362 rhs_is_small = not (neverUnfold unfolding)
364 -- We leave the unfolding there even if there is a worker
365 -- In GHCI the unfolding is used by importers
366 -- When writing an interface file, we omit the unfolding
367 -- if there is a worker
368 show_unfold = not bottoming_fn && -- Not necessary
371 rhs_is_small -- Small enough
373 unfold_ids | show_unfold = exprSomeFreeVars isLocalId rhs
374 | otherwise = emptyVarSet
376 worker_ids = case worker_info of
377 HasWorker work_id _ -> unitVarSet work_id
378 otherwise -> emptyVarSet
382 %************************************************************************
384 \subsection{Step 2: top-level tidying}
386 %************************************************************************
390 -- TopTidyEnv: when tidying we need to know
391 -- * nc_var: The NameCache, containing a unique supply and any pre-ordained Names.
392 -- These may have arisen because the
393 -- renamer read in an interface file mentioning M.$wf, say,
394 -- and assigned it unique r77. If, on this compilation, we've
395 -- invented an Id whose name is $wf (but with a different unique)
396 -- we want to rename it to have unique r77, so that we can do easy
397 -- comparisons with stuff from the interface file
399 -- * occ_env: The TidyOccEnv, which tells us which local occurrences
402 -- * subst_env: A Var->Var mapping that substitutes the new Var for the old
404 tidyTopBinds :: DynFlags
406 -> IORef NameCache -- For allocating new unique names
407 -> IdEnv Bool -- Domain = Ids that should be external
408 -- True <=> their unfolding is external too
409 -> TidyEnv -> [CoreBind]
410 -> IO (TidyEnv, [CoreBind])
411 tidyTopBinds dflags mod nc_var ext_ids tidy_env []
412 = return (tidy_env, [])
414 tidyTopBinds dflags mod nc_var ext_ids tidy_env (b:bs)
415 = do { (tidy_env1, b') <- tidyTopBind dflags mod nc_var ext_ids tidy_env b
416 ; (tidy_env2, bs') <- tidyTopBinds dflags mod nc_var ext_ids tidy_env1 bs
417 ; return (tidy_env2, b':bs') }
419 ------------------------
420 tidyTopBind :: DynFlags
422 -> IORef NameCache -- For allocating new unique names
423 -> IdEnv Bool -- Domain = Ids that should be external
424 -- True <=> their unfolding is external too
425 -> TidyEnv -> CoreBind
426 -> IO (TidyEnv, CoreBind)
428 tidyTopBind dflags mod nc_var ext_ids tidy_env1@(occ_env1,subst1) (NonRec bndr rhs)
429 = do { (occ_env2, name') <- tidyTopName mod nc_var ext_ids occ_env1 bndr
430 ; let { (bndr', rhs') = tidyTopPair ext_ids tidy_env2 caf_info name' (bndr, rhs)
431 ; subst2 = extendVarEnv subst1 bndr bndr'
432 ; tidy_env2 = (occ_env2, subst2) }
433 ; return (tidy_env2, NonRec bndr' rhs') }
435 caf_info = hasCafRefs dflags subst1 (idArity bndr) rhs
437 tidyTopBind dflags mod nc_var ext_ids tidy_env1@(occ_env1,subst1) (Rec prs)
438 = do { (occ_env2, names') <- tidyTopNames mod nc_var ext_ids occ_env1 bndrs
439 ; let { prs' = zipWith (tidyTopPair ext_ids tidy_env2 caf_info)
441 ; subst2 = extendVarEnvList subst1 (bndrs `zip` map fst prs')
442 ; tidy_env2 = (occ_env2, subst2) }
443 ; return (tidy_env2, Rec prs') }
447 -- the CafInfo for a recursive group says whether *any* rhs in
448 -- the group may refer indirectly to a CAF (because then, they all do).
450 | or [ mayHaveCafRefs (hasCafRefs dflags subst1 (idArity bndr) rhs)
451 | (bndr,rhs) <- prs ] = MayHaveCafRefs
452 | otherwise = NoCafRefs
454 --------------------------------------------------------------------
456 -- This is where we set names to local/global based on whether they really are
457 -- externally visible (see comment at the top of this module). If the name
458 -- was previously local, we have to give it a unique occurrence name if
459 -- we intend to externalise it.
460 tidyTopNames mod nc_var ext_ids occ_env [] = return (occ_env, [])
461 tidyTopNames mod nc_var ext_ids occ_env (id:ids)
462 = do { (occ_env1, name) <- tidyTopName mod nc_var ext_ids occ_env id
463 ; (occ_env2, names) <- tidyTopNames mod nc_var ext_ids occ_env1 ids
464 ; return (occ_env2, name:names) }
466 tidyTopName :: Module -> IORef NameCache -> VarEnv Bool -> TidyOccEnv
467 -> Id -> IO (TidyOccEnv, Name)
468 tidyTopName mod nc_var ext_ids occ_env id
469 | global && internal = return (occ_env, localiseName name)
471 | global && external = return (occ_env, name)
472 -- Global names are assumed to have been allocated by the renamer,
473 -- so they already have the "right" unique
474 -- And it's a system-wide unique too
476 -- Now we get to the real reason that all this is in the IO Monad:
477 -- we have to update the name cache in a nice atomic fashion
479 | local && internal = do { nc <- readIORef nc_var
480 ; let (nc', new_local_name) = mk_new_local nc
481 ; writeIORef nc_var nc'
482 ; return (occ_env', new_local_name) }
483 -- Even local, internal names must get a unique occurrence, because
484 -- if we do -split-objs we externalise the name later, in the code generator
486 -- Similarly, we must make sure it has a system-wide Unique, because
487 -- the byte-code generator builds a system-wide Name->BCO symbol table
489 | local && external = do { nc <- readIORef nc_var
490 ; let (nc', new_external_name) = mk_new_external nc
491 ; writeIORef nc_var nc'
492 ; return (occ_env', new_external_name) }
495 external = id `elemVarEnv` ext_ids
496 global = isExternalName name
498 internal = not external
499 mb_parent = nameParent_maybe name
500 loc = nameSrcLoc name
502 (occ_env', occ') = tidyOccName occ_env (nameOccName name)
504 mk_new_local nc = (nc { nsUniqs = us2 }, mkInternalName uniq occ' loc)
506 (us1, us2) = splitUniqSupply (nsUniqs nc)
507 uniq = uniqFromSupply us1
509 mk_new_external nc = allocateGlobalBinder nc mod occ' mb_parent loc
510 -- If we want to externalise a currently-local name, check
511 -- whether we have already assigned a unique for it.
512 -- If so, use it; if not, extend the table.
513 -- All this is done by allcoateGlobalBinder.
514 -- This is needed when *re*-compiling a module in GHCi; we want to
515 -- use the same name for externally-visible things as we did before.
518 -----------------------------------------------------------
519 tidyTopPair :: VarEnv Bool
520 -> TidyEnv -- The TidyEnv is used to tidy the IdInfo
521 -- It is knot-tied: don't look at it!
524 -> (Id, CoreExpr) -- Binder and RHS before tidying
526 -- This function is the heart of Step 2
527 -- The rec_tidy_env is the one to use for the IdInfo
528 -- It's necessary because when we are dealing with a recursive
529 -- group, a variable late in the group might be mentioned
530 -- in the IdInfo of one early in the group
532 tidyTopPair ext_ids rhs_tidy_env caf_info name' (bndr, rhs)
533 = ASSERT(isLocalId bndr) -- "all Ids defined in this module are local
534 -- until the CoreTidy phase" --GHC comentary
537 bndr' = mkVanillaGlobal name' ty' idinfo'
538 ty' = tidyTopType (idType bndr)
539 rhs' = tidyExpr rhs_tidy_env rhs
540 idinfo' = tidyTopIdInfo rhs_tidy_env (isJust maybe_external)
541 (idInfo bndr) unfold_info arity
544 -- Expose an unfolding if ext_ids tells us to
545 -- Remember that ext_ids maps an Id to a Bool:
546 -- True to show the unfolding, False to hide it
547 maybe_external = lookupVarEnv ext_ids bndr
548 show_unfold = maybe_external `orElse` False
549 unfold_info | show_unfold = mkTopUnfolding rhs'
550 | otherwise = noUnfolding
552 -- Usually the Id will have an accurate arity on it, because
553 -- the simplifier has just run, but not always.
554 -- One case I found was when the last thing the simplifier
555 -- did was to let-bind a non-atomic argument and then float
556 -- it to the top level. So it seems more robust just to
558 arity = exprArity rhs
561 -- tidyTopIdInfo creates the final IdInfo for top-level
562 -- binders. There are two delicate pieces:
564 -- * Arity. After CoreTidy, this arity must not change any more.
565 -- Indeed, CorePrep must eta expand where necessary to make
566 -- the manifest arity equal to the claimed arity.
568 -- * CAF info. This must also remain valid through to code generation.
569 -- We add the info here so that it propagates to all
570 -- occurrences of the binders in RHSs, and hence to occurrences in
571 -- unfoldings, which are inside Ids imported by GHCi. Ditto RULES.
572 -- CoreToStg makes use of this when constructing SRTs.
574 tidyTopIdInfo tidy_env is_external idinfo unfold_info arity caf_info
575 | not is_external -- For internal Ids (not externally visible)
576 = vanillaIdInfo -- we only need enough info for code generation
577 -- Arity and strictness info are enough;
578 -- c.f. CoreTidy.tidyLetBndr
579 `setCafInfo` caf_info
581 `setAllStrictnessInfo` newStrictnessInfo idinfo
583 | otherwise -- Externally-visible Ids get the whole lot
585 `setCafInfo` caf_info
587 `setAllStrictnessInfo` newStrictnessInfo idinfo
588 `setInlinePragInfo` inlinePragInfo idinfo
589 `setUnfoldingInfo` unfold_info
590 `setWorkerInfo` tidyWorker tidy_env (workerInfo idinfo)
591 -- NB: we throw away the Rules
592 -- They have already been extracted by findExternalRules
596 ------------ Worker --------------
597 tidyWorker tidy_env (HasWorker work_id wrap_arity)
598 = HasWorker (tidyVarOcc tidy_env work_id) wrap_arity
599 tidyWorker tidy_env other
603 %************************************************************************
605 \subsection{Figuring out CafInfo for an expression}
607 %************************************************************************
609 hasCafRefs decides whether a top-level closure can point into the dynamic heap.
610 We mark such things as `MayHaveCafRefs' because this information is
611 used to decide whether a particular closure needs to be referenced
614 There are two reasons for setting MayHaveCafRefs:
615 a) The RHS is a CAF: a top-level updatable thunk.
616 b) The RHS refers to something that MayHaveCafRefs
618 Possible improvement: In an effort to keep the number of CAFs (and
619 hence the size of the SRTs) down, we could also look at the expression and
620 decide whether it requires a small bounded amount of heap, so we can ignore
621 it as a CAF. In these cases however, we would need to use an additional
622 CAF list to keep track of non-collectable CAFs.
625 hasCafRefs :: DynFlags -> VarEnv Var -> Arity -> CoreExpr -> CafInfo
626 hasCafRefs dflags p arity expr
627 | is_caf || mentions_cafs = MayHaveCafRefs
628 | otherwise = NoCafRefs
630 mentions_cafs = isFastTrue (cafRefs p expr)
631 is_caf = not (arity > 0 || rhsIsStatic dflags expr)
632 -- NB. we pass in the arity of the expression, which is expected
633 -- to be calculated by exprArity. This is because exprArity
634 -- knows how much eta expansion is going to be done by
635 -- CorePrep later on, and we don't want to duplicate that
636 -- knowledge in rhsIsStatic below.
639 -- imported Ids first:
640 | not (isLocalId id) = fastBool (mayHaveCafRefs (idCafInfo id))
641 -- now Ids local to this module:
643 case lookupVarEnv p id of
644 Just id' -> fastBool (mayHaveCafRefs (idCafInfo id'))
645 Nothing -> fastBool False
647 cafRefs p (Lit l) = fastBool False
648 cafRefs p (App f a) = fastOr (cafRefs p f) (cafRefs p) a
649 cafRefs p (Lam x e) = cafRefs p e
650 cafRefs p (Let b e) = fastOr (cafRefss p (rhssOfBind b)) (cafRefs p) e
652 cafRefs p (Case e bndr _ alts) = fastOr (cafRefs p e) (cafRefss p) (rhssOfAlts alts)
653 cafRefs p (Note n e) = cafRefs p e
654 cafRefs p (Type t) = fastBool False
656 cafRefss p [] = fastBool False
657 cafRefss p (e:es) = fastOr (cafRefs p e) (cafRefss p) es
659 -- hack for lazy-or over FastBool.
660 fastOr a f x = fastBool (isFastTrue a || isFastTrue (f x))