2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
6 ***************************
8 ***************************
10 * We attach binding levels to Core bindings, in preparation for floating
11 outwards (@FloatOut@).
13 * We also let-ify many expressions (notably case scrutinees), so they
14 will have a fighting chance of being floated sensible.
16 * We clone the binders of any floatable let-binding, so that when it is
17 floated out it will be unique. (This used to be done by the simplifier
18 but the latter now only ensures that there's no shadowing.)
19 NOTE: Very tiresomely, we must apply this substitution to
20 the rules stored inside a variable too.
22 We do *not* clone top-level bindings, because some of them must not change,
23 but we *do* clone bindings that are heading for the top level
26 case x of wild { p -> ...wild... }
27 we substitute x for wild in the RHS of the case alternatives:
28 case x of wild { p -> ...x... }
29 This means that a sub-expression involving x is not "trapped" inside the RHS.
30 And it's not inconvenient because we already have a substitution.
38 incMinorLvl, ltMajLvl, ltLvl, isTopLvl
41 #include "HsVersions.h"
45 import CoreUtils ( exprType, exprIsTrivial, exprIsBottom )
46 import CoreFVs -- all of it
47 import Id ( Id, idType, idFreeTyVars, mkSysLocal, isOneShotLambda, modifyIdInfo,
48 idSpecialisation, idWorkerInfo, setIdInfo
50 import IdInfo ( workerExists, vanillaIdInfo )
51 import Var ( Var, TyVar, setVarUnique )
55 import Name ( getOccName )
56 import OccName ( occNameUserString )
57 import Type ( isUnLiftedType, mkPiType, Type )
58 import BasicTypes ( TopLevelFlag(..) )
62 import Util ( sortLt, isSingleton, count )
66 %************************************************************************
68 \subsection{Level numbers}
70 %************************************************************************
73 data Level = Level Int -- Level number of enclosing lambdas
74 Int -- Number of big-lambda and/or case expressions between
75 -- here and the nearest enclosing lambda
78 The {\em level number} on a (type-)lambda-bound variable is the
79 nesting depth of the (type-)lambda which binds it. The outermost lambda
80 has level 1, so (Level 0 0) means that the variable is bound outside any lambda.
82 On an expression, it's the maximum level number of its free
83 (type-)variables. On a let(rec)-bound variable, it's the level of its
84 RHS. On a case-bound variable, it's the number of enclosing lambdas.
86 Top-level variables: level~0. Those bound on the RHS of a top-level
87 definition but ``before'' a lambda; e.g., the \tr{x} in (levels shown
90 a_0 = let b_? = ... in
91 x_1 = ... b ... in ...
94 The main function @lvlExpr@ carries a ``context level'' (@ctxt_lvl@).
95 That's meant to be the level number of the enclosing binder in the
96 final (floated) program. If the level number of a sub-expression is
97 less than that of the context, then it might be worth let-binding the
98 sub-expression so that it will indeed float. This context level starts
102 type LevelledExpr = TaggedExpr Level
103 type LevelledArg = TaggedArg Level
104 type LevelledBind = TaggedBind Level
106 tOP_LEVEL = Level 0 0
108 incMajorLvl :: Level -> Level
109 incMajorLvl (Level major minor) = Level (major+1) 0
111 incMinorLvl :: Level -> Level
112 incMinorLvl (Level major minor) = Level major (minor+1)
114 maxLvl :: Level -> Level -> Level
115 maxLvl l1@(Level maj1 min1) l2@(Level maj2 min2)
116 | (maj1 > maj2) || (maj1 == maj2 && min1 > min2) = l1
119 ltLvl :: Level -> Level -> Bool
120 ltLvl (Level maj1 min1) (Level maj2 min2)
121 = (maj1 < maj2) || (maj1 == maj2 && min1 < min2)
123 ltMajLvl :: Level -> Level -> Bool
124 -- Tells if one level belongs to a difft *lambda* level to another
125 ltMajLvl (Level maj1 _) (Level maj2 _) = maj1 < maj2
127 isTopLvl :: Level -> Bool
128 isTopLvl (Level 0 0) = True
129 isTopLvl other = False
131 instance Outputable Level where
132 ppr (Level maj min) = hcat [ char '<', int maj, char ',', int min, char '>' ]
135 %************************************************************************
137 \subsection{Main level-setting code}
139 %************************************************************************
142 setLevels :: Bool -- True <=> float lambdas to top level
147 setLevels float_lams binds us
148 = initLvl us (do_them binds)
150 -- "do_them"'s main business is to thread the monad along
151 -- It gives each top binding the same empty envt, because
152 -- things unbound in the envt have level number zero implicitly
153 do_them :: [CoreBind] -> LvlM [LevelledBind]
155 do_them [] = returnLvl []
157 = lvlTopBind init_env b `thenLvl` \ (lvld_bind, _) ->
158 do_them bs `thenLvl` \ lvld_binds ->
159 returnLvl (lvld_bind : lvld_binds)
161 init_env = initialEnv float_lams
163 lvlTopBind env (NonRec binder rhs)
164 = lvlBind TopLevel tOP_LEVEL env (AnnNonRec binder (freeVars rhs))
165 -- Rhs can have no free vars!
167 lvlTopBind env (Rec pairs)
168 = lvlBind TopLevel tOP_LEVEL env (AnnRec [(b,freeVars rhs) | (b,rhs) <- pairs])
171 %************************************************************************
173 \subsection{Setting expression levels}
175 %************************************************************************
178 lvlExpr :: Level -- ctxt_lvl: Level of enclosing expression
179 -> LevelEnv -- Level of in-scope names/tyvars
180 -> CoreExprWithFVs -- input expression
181 -> LvlM LevelledExpr -- Result expression
184 The @ctxt_lvl@ is, roughly, the level of the innermost enclosing
185 binder. Here's an example
187 v = \x -> ...\y -> let r = case (..x..) of
191 When looking at the rhs of @r@, @ctxt_lvl@ will be 1 because that's
192 the level of @r@, even though it's inside a level-2 @\y@. It's
193 important that @ctxt_lvl@ is 1 and not 2 in @r@'s rhs, because we
194 don't want @lvlExpr@ to turn the scrutinee of the @case@ into an MFE
195 --- because it isn't a *maximal* free expression.
197 If there were another lambda in @r@'s rhs, it would get level-2 as well.
200 lvlExpr _ _ (_, AnnType ty) = returnLvl (Type ty)
201 lvlExpr _ env (_, AnnVar v) = returnLvl (lookupVar env v)
202 lvlExpr _ env (_, AnnLit lit) = returnLvl (Lit lit)
204 lvlExpr ctxt_lvl env (_, AnnApp fun arg)
205 = lvlExpr ctxt_lvl env fun `thenLvl` \ fun' ->
206 lvlMFE False ctxt_lvl env arg `thenLvl` \ arg' ->
207 returnLvl (App fun' arg')
209 lvlExpr ctxt_lvl env (_, AnnNote InlineMe expr)
210 -- Don't float anything out of an InlineMe
211 = lvlExpr tOP_LEVEL env expr `thenLvl` \ expr' ->
212 returnLvl (Note InlineMe expr')
214 lvlExpr ctxt_lvl env (_, AnnNote note expr)
215 = lvlExpr ctxt_lvl env expr `thenLvl` \ expr' ->
216 returnLvl (Note note expr')
218 -- We don't split adjacent lambdas. That is, given
220 -- we don't float to give
221 -- \x -> let v = x+y in \y -> (v,y)
222 -- Why not? Because partial applications are fairly rare, and splitting
223 -- lambdas makes them more expensive.
225 lvlExpr ctxt_lvl env expr@(_, AnnLam bndr rhs)
226 = lvlMFE True new_lvl new_env body `thenLvl` \ new_body ->
227 returnLvl (glue_binders new_bndrs expr new_body)
229 (bndrs, body) = collect_binders expr
230 (new_lvl, new_bndrs) = lvlLamBndrs ctxt_lvl bndrs
231 new_env = extendLvlEnv env new_bndrs
233 lvlExpr ctxt_lvl env (_, AnnLet bind body)
234 = lvlBind NotTopLevel ctxt_lvl env bind `thenLvl` \ (bind', new_env) ->
235 lvlExpr ctxt_lvl new_env body `thenLvl` \ body' ->
236 returnLvl (Let bind' body')
238 lvlExpr ctxt_lvl env (_, AnnCase expr case_bndr alts)
239 = lvlMFE True ctxt_lvl env expr `thenLvl` \ expr' ->
241 alts_env = extendCaseBndrLvlEnv env expr' case_bndr incd_lvl
243 mapLvl (lvl_alt alts_env) alts `thenLvl` \ alts' ->
244 returnLvl (Case expr' (case_bndr, incd_lvl) alts')
246 expr_type = exprType (deAnnotate expr)
247 incd_lvl = incMinorLvl ctxt_lvl
249 lvl_alt alts_env (con, bs, rhs)
250 = lvlMFE True incd_lvl new_env rhs `thenLvl` \ rhs' ->
251 returnLvl (con, bs', rhs')
253 bs' = [ (b, incd_lvl) | b <- bs ]
254 new_env = extendLvlEnv alts_env bs'
259 go rev_bndrs (_, AnnLam b e) = go (b:rev_bndrs) e
260 go rev_bndrs (_, AnnNote n e) = go rev_bndrs e
261 go rev_bndrs rhs = (reverse rev_bndrs, rhs)
262 -- Ignore notes, because we don't want to split
263 -- a lambda like this (\x -> coerce t (\s -> ...))
264 -- This happens quite a bit in state-transformer programs
266 -- glue_binders puts the lambda back together
267 glue_binders (b:bs) (_, AnnLam _ e) body = Lam b (glue_binders bs e body)
268 glue_binders bs (_, AnnNote n e) body = Note n (glue_binders bs e body)
269 glue_binders [] e body = body
272 @lvlMFE@ is just like @lvlExpr@, except that it might let-bind
273 the expression, so that it can itself be floated.
276 lvlMFE :: Bool -- True <=> strict context [body of case or let]
277 -> Level -- Level of innermost enclosing lambda/tylam
278 -> LevelEnv -- Level of in-scope names/tyvars
279 -> CoreExprWithFVs -- input expression
280 -> LvlM LevelledExpr -- Result expression
282 lvlMFE strict_ctxt ctxt_lvl env (_, AnnType ty)
283 = returnLvl (Type ty)
285 lvlMFE strict_ctxt ctxt_lvl env ann_expr@(fvs, _)
286 | isUnLiftedType ty -- Can't let-bind it
287 || not (dest_lvl `ltMajLvl` ctxt_lvl) -- Does not escape a value lambda
288 -- A decision to float entails let-binding this thing, and we only do
289 -- that if we'll escape a value lambda. I considered doing it if it
290 -- would make the thing go to top level, but I found things like
291 -- concat = /\ a -> foldr ..a.. (++) []
292 -- was getting turned into
293 -- concat = /\ a -> lvl a
294 -- lvl = /\ a -> foldr ..a.. (++) []
295 -- which is pretty stupid. So for now at least, I don't let-bind things
296 -- simply because they could go to top level.
297 || exprIsTrivial expr -- Is trivial
298 || (strict_ctxt && exprIsBottom expr) -- Strict context and is bottom
299 = -- Don't float it out
300 lvlExpr ctxt_lvl env ann_expr
302 | otherwise -- Float it out!
303 = lvlFloatRhs abs_vars dest_lvl env ann_expr `thenLvl` \ expr' ->
304 newLvlVar "lvl" abs_vars ty `thenLvl` \ var ->
305 returnLvl (Let (NonRec (var,dest_lvl) expr')
306 (mkVarApps (Var var) abs_vars))
308 expr = deAnnotate ann_expr
310 dest_lvl = destLevel env fvs (isFunction ann_expr)
311 abs_vars = abstractVars dest_lvl env fvs
315 %************************************************************************
317 \subsection{Bindings}
319 %************************************************************************
321 The binding stuff works for top level too.
324 lvlBind :: TopLevelFlag -- Used solely to decide whether to clone
325 -> Level -- Context level; might be Top even for bindings nested in the RHS
326 -- of a top level binding
329 -> LvlM (LevelledBind, LevelEnv)
331 lvlBind top_lvl ctxt_lvl env (AnnNonRec bndr rhs@(rhs_fvs,_))
333 = -- No type abstraction; clone existing binder
334 lvlExpr ctxt_lvl env rhs `thenLvl` \ rhs' ->
335 cloneVar top_lvl env bndr dest_lvl `thenLvl` \ (env', bndr') ->
336 returnLvl (NonRec (bndr', dest_lvl) rhs', env')
339 = -- Yes, type abstraction; create a new binder, extend substitution, etc
340 lvlFloatRhs abs_vars dest_lvl env rhs `thenLvl` \ rhs' ->
341 newPolyBndrs dest_lvl env abs_vars [bndr] `thenLvl` \ (env', [bndr']) ->
342 returnLvl (NonRec (bndr', dest_lvl) rhs', env')
345 bind_fvs = rhs_fvs `unionVarSet` idFreeVars bndr
346 abs_vars = abstractVars dest_lvl env bind_fvs
348 dest_lvl | isUnLiftedType (idType bndr) = destLevel env bind_fvs False `maxLvl` Level 1 0
349 | otherwise = destLevel env bind_fvs (isFunction rhs)
350 -- Hack alert! We do have some unlifted bindings, for cheap primops, and
351 -- it is ok to float them out; but not to the top level. If they would otherwise
352 -- go to the top level, we pin them inside the topmost lambda
357 lvlBind top_lvl ctxt_lvl env (AnnRec pairs)
359 = cloneVars top_lvl env bndrs dest_lvl `thenLvl` \ (new_env, new_bndrs) ->
360 mapLvl (lvlExpr ctxt_lvl new_env) rhss `thenLvl` \ new_rhss ->
361 returnLvl (Rec ((new_bndrs `zip` repeat dest_lvl) `zip` new_rhss), new_env)
363 | isSingleton pairs && count isId abs_vars > 1
364 = -- Special case for self recursion where there are
365 -- several variables carried around: build a local loop:
366 -- poly_f = \abs_vars. \lam_vars . letrec f = \lam_vars. rhs in f lam_vars
367 -- This just makes the closures a bit smaller. If we don't do
368 -- this, allocation rises significantly on some programs
370 -- We could elaborate it for the case where there are several
371 -- mutually functions, but it's quite a bit more complicated
373 -- This all seems a bit ad hoc -- sigh
375 (bndr,rhs) = head pairs
376 (rhs_lvl, abs_vars_w_lvls) = lvlLamBndrs dest_lvl abs_vars
377 rhs_env = extendLvlEnv env abs_vars_w_lvls
379 cloneVar NotTopLevel rhs_env bndr rhs_lvl `thenLvl` \ (rhs_env', new_bndr) ->
381 (lam_bndrs, rhs_body) = collect_binders rhs
382 (body_lvl, new_lam_bndrs) = lvlLamBndrs rhs_lvl lam_bndrs
383 body_env = extendLvlEnv rhs_env' new_lam_bndrs
385 lvlExpr body_lvl body_env rhs_body `thenLvl` \ new_rhs_body ->
386 newPolyBndrs dest_lvl env abs_vars [bndr] `thenLvl` \ (poly_env, [poly_bndr]) ->
387 returnLvl (Rec [((poly_bndr,dest_lvl), mkLams abs_vars_w_lvls $
388 glue_binders new_lam_bndrs rhs $
389 Let (Rec [((new_bndr,rhs_lvl), mkLams new_lam_bndrs new_rhs_body)])
390 (mkVarApps (Var new_bndr) lam_bndrs))],
394 = newPolyBndrs dest_lvl env abs_vars bndrs `thenLvl` \ (new_env, new_bndrs) ->
395 mapLvl (lvlFloatRhs abs_vars dest_lvl new_env) rhss `thenLvl` \ new_rhss ->
396 returnLvl (Rec ((new_bndrs `zip` repeat dest_lvl) `zip` new_rhss), new_env)
399 (bndrs,rhss) = unzip pairs
401 -- Finding the free vars of the binding group is annoying
402 bind_fvs = (unionVarSets [ idFreeVars bndr `unionVarSet` rhs_fvs
403 | (bndr, (rhs_fvs,_)) <- pairs])
407 dest_lvl = destLevel env bind_fvs (all isFunction rhss)
408 abs_vars = abstractVars dest_lvl env bind_fvs
410 ----------------------------------------------------
411 -- Three help functons for the type-abstraction case
413 lvlFloatRhs abs_vars dest_lvl env rhs
414 = lvlExpr rhs_lvl rhs_env rhs `thenLvl` \ rhs' ->
415 returnLvl (mkLams abs_vars_w_lvls rhs')
417 (rhs_lvl, abs_vars_w_lvls) = lvlLamBndrs dest_lvl abs_vars
418 rhs_env = extendLvlEnv env abs_vars_w_lvls
422 %************************************************************************
424 \subsection{Deciding floatability}
426 %************************************************************************
429 lvlLamBndrs :: Level -> [CoreBndr] -> (Level, [(CoreBndr, Level)])
430 -- Compute the levels for the binders of a lambda group
434 lvlLamBndrs lvl bndrs
435 = go (incMinorLvl lvl)
436 False -- Havn't bumped major level in this group
439 go old_lvl bumped_major rev_lvld_bndrs (bndr:bndrs)
440 | isId bndr && -- Go to the next major level if this is a value binder,
441 not bumped_major && -- and we havn't already gone to the next level (one jump per group)
442 not (isOneShotLambda bndr) -- and it isn't a one-shot lambda
443 = go new_lvl True ((bndr,new_lvl) : rev_lvld_bndrs) bndrs
446 = go old_lvl bumped_major ((bndr,old_lvl) : rev_lvld_bndrs) bndrs
449 new_lvl = incMajorLvl old_lvl
451 go old_lvl _ rev_lvld_bndrs []
452 = (old_lvl, reverse rev_lvld_bndrs)
453 -- a lambda like this (\x -> coerce t (\s -> ...))
454 -- This happens quite a bit in state-transformer programs
458 abstractVars :: Level -> LevelEnv -> VarSet -> [Var]
459 -- Find the variables in fvs, free vars of the target expresion,
460 -- whose level is less than than the supplied level
461 -- These are the ones we are going to abstract out
462 abstractVars dest_lvl env fvs
463 = uniq (sortLt lt [var | fv <- varSetElems fvs, var <- absVarsOf dest_lvl env fv])
465 -- Sort the variables so we don't get
466 -- mixed-up tyvars and Ids; it's just messy
467 v1 `lt` v2 = case (isId v1, isId v2) of
468 (True, False) -> False
469 (False, True) -> True
470 other -> v1 < v2 -- Same family
471 uniq :: [Var] -> [Var]
472 -- Remove adjacent duplicates; the sort will have brought them together
473 uniq (v1:v2:vs) | v1 == v2 = uniq (v2:vs)
474 | otherwise = v1 : uniq (v2:vs)
477 -- Destintion level is the max Id level of the expression
478 -- (We'll abstract the type variables, if any.)
479 destLevel :: LevelEnv -> VarSet -> Bool -> Level
480 destLevel env fvs is_function
482 && is_function = tOP_LEVEL -- Send functions to top level; see
483 -- the comments with isFunction
484 | otherwise = maxIdLevel env fvs
486 isFunction :: CoreExprWithFVs -> Bool
487 -- The idea here is that we want to float *functions* to
488 -- the top level. This saves no work, but
489 -- (a) it can make the host function body a lot smaller,
490 -- and hence inlinable.
491 -- (b) it can also save allocation when the function is recursive:
492 -- h = \x -> letrec f = \y -> ...f...y...x...
495 -- f = \x y -> ...(f x)...y...x...
497 -- No allocation for f now.
498 -- We may only want to do this if there are sufficiently few free
499 -- variables. We certainly only want to do it for values, and not for
500 -- constructors. So the simple thing is just to look for lambdas
501 isFunction (_, AnnLam b e) | isId b = True
502 | otherwise = isFunction e
503 isFunction (_, AnnNote n e) = isFunction e
504 isFunction other = False
508 %************************************************************************
510 \subsection{Free-To-Level Monad}
512 %************************************************************************
515 type LevelEnv = (Bool, -- True <=> Float lambdas too
516 VarEnv Level, -- Domain is *post-cloned* TyVars and Ids
517 SubstEnv, -- Domain is pre-cloned Ids
518 IdEnv ([Var], LevelledExpr)) -- Domain is pre-cloned Ids
519 -- We clone let-bound variables so that they are still
520 -- distinct when floated out; hence the SubstEnv/IdEnv.
521 -- We also use these envs when making a variable polymorphic
522 -- because we want to float it out past a big lambda.
524 -- The two Envs always implement the same mapping, but the
525 -- SubstEnv maps to CoreExpr and the IdEnv to LevelledExpr
526 -- Since the range is always a variable or type application,
527 -- there is never any difference between the two, but sadly
528 -- the types differ. The SubstEnv is used when substituting in
529 -- a variable's IdInfo; the IdEnv when we find a Var.
531 -- In addition the IdEnv records a list of tyvars free in the
532 -- type application, just so we don't have to call freeVars on
533 -- the type application repeatedly.
535 -- The domain of the both envs is *pre-cloned* Ids, though
537 -- The domain of the VarEnv Level is the *post-cloned* Ids
539 initialEnv :: Bool -> LevelEnv
540 initialEnv float_lams = (float_lams, emptyVarEnv, emptySubstEnv, emptyVarEnv)
542 floatLams :: LevelEnv -> Bool
543 floatLams (float_lams, _, _, _) = float_lams
545 extendLvlEnv :: LevelEnv -> [(Var,Level)] -> LevelEnv
546 -- Used when *not* cloning
547 extendLvlEnv (float_lams, lvl_env, subst_env, id_env) prs
548 = (float_lams, foldl add lvl_env prs, subst_env, id_env)
550 add env (v,l) = extendVarEnv env v l
552 -- extendCaseBndrLvlEnv adds the mapping case-bndr->scrut-var if it can
553 extendCaseBndrLvlEnv env scrut case_bndr lvl
555 Var v -> extendCloneLvlEnv lvl env [(case_bndr, v)]
556 other -> extendLvlEnv env [(case_bndr,lvl)]
558 extendPolyLvlEnv dest_lvl (float_lams, lvl_env, subst_env, id_env) abs_vars bndr_pairs
560 foldl add_lvl lvl_env bndr_pairs,
561 foldl add_subst subst_env bndr_pairs,
562 foldl add_id id_env bndr_pairs)
564 add_lvl env (v,v') = extendVarEnv env v' dest_lvl
565 add_subst env (v,v') = extendSubstEnv env v (DoneEx (mkVarApps (Var v') abs_vars))
566 add_id env (v,v') = extendVarEnv env v ((v':abs_vars), mkVarApps (Var v') abs_vars)
568 extendCloneLvlEnv lvl (float_lams, lvl_env, subst_env, id_env) bndr_pairs
570 foldl add_lvl lvl_env bndr_pairs,
571 foldl add_subst subst_env bndr_pairs,
572 foldl add_id id_env bndr_pairs)
574 add_lvl env (v,v') = extendVarEnv env v' lvl
575 add_subst env (v,v') = extendSubstEnv env v (DoneEx (Var v'))
576 add_id env (v,v') = extendVarEnv env v ([v'], Var v')
579 maxIdLevel :: LevelEnv -> VarSet -> Level
580 maxIdLevel (_, lvl_env,_,id_env) var_set
581 = foldVarSet max_in tOP_LEVEL var_set
583 max_in in_var lvl = foldr max_out lvl (case lookupVarEnv id_env in_var of
584 Just (abs_vars, _) -> abs_vars
588 | isId out_var = case lookupVarEnv lvl_env out_var of
589 Just lvl' -> maxLvl lvl' lvl
591 | otherwise = lvl -- Ignore tyvars in *maxIdLevel*
593 lookupVar :: LevelEnv -> Id -> LevelledExpr
594 lookupVar (_, _, _, id_env) v = case lookupVarEnv id_env v of
595 Just (_, expr) -> expr
598 absVarsOf :: Level -> LevelEnv -> Var -> [Var]
599 -- If f is free in the exression, and f maps to poly_f a b c in the
600 -- current substitution, then we must report a b c as candidate type
602 absVarsOf dest_lvl (_, lvl_env, _, id_env) v
604 = [final_av | av <- lookup_avs v, abstract_me av, final_av <- add_tyvars av]
607 = if abstract_me v then [v] else []
610 abstract_me v = case lookupVarEnv lvl_env v of
611 Just lvl -> dest_lvl `ltLvl` lvl
614 lookup_avs v = case lookupVarEnv id_env v of
615 Just (abs_vars, _) -> abs_vars
618 -- We are going to lambda-abstract, so nuke any IdInfo,
619 -- and add the tyvars of the Id
620 add_tyvars v | isId v = zap v : varSetElems (idFreeTyVars v)
623 zap v = WARN( workerExists (idWorkerInfo v)
624 || not (isEmptyCoreRules (idSpecialisation v)),
625 text "absVarsOf: discarding info on" <+> ppr v )
626 setIdInfo v vanillaIdInfo
630 type LvlM result = UniqSM result
639 newPolyBndrs dest_lvl env abs_vars bndrs
640 = getUniquesUs (length bndrs) `thenLvl` \ uniqs ->
642 new_bndrs = zipWith mk_poly_bndr bndrs uniqs
644 returnLvl (extendPolyLvlEnv dest_lvl env abs_vars (bndrs `zip` new_bndrs), new_bndrs)
646 mk_poly_bndr bndr uniq = mkSysLocal (_PK_ str) uniq poly_ty
648 str = "poly_" ++ occNameUserString (getOccName bndr)
649 poly_ty = foldr mkPiType (idType bndr) abs_vars
653 -> [CoreBndr] -> Type -- Abstract wrt these bndrs
655 newLvlVar str vars body_ty
656 = getUniqueUs `thenLvl` \ uniq ->
657 returnUs (mkSysLocal (_PK_ str) uniq (foldr mkPiType body_ty vars))
659 -- The deeply tiresome thing is that we have to apply the substitution
660 -- to the rules inside each Id. Grr. But it matters.
662 cloneVar :: TopLevelFlag -> LevelEnv -> Id -> Level -> LvlM (LevelEnv, Id)
663 cloneVar TopLevel env v lvl
664 = returnUs (env, v) -- Don't clone top level things
665 cloneVar NotTopLevel env v lvl
666 = getUniqueUs `thenLvl` \ uniq ->
668 v' = setVarUnique v uniq
669 v'' = subst_id_info env v'
670 env' = extendCloneLvlEnv lvl env [(v,v'')]
674 cloneVars :: TopLevelFlag -> LevelEnv -> [Id] -> Level -> LvlM (LevelEnv, [Id])
675 cloneVars TopLevel env vs lvl
676 = returnUs (env, vs) -- Don't clone top level things
677 cloneVars NotTopLevel env vs lvl
678 = getUniquesUs (length vs) `thenLvl` \ uniqs ->
680 vs' = zipWith setVarUnique vs uniqs
681 vs'' = map (subst_id_info env') vs'
682 env' = extendCloneLvlEnv lvl env (vs `zip` vs'')
684 returnUs (env', vs'')
686 subst_id_info (_, _, subst_env, _) v
687 = modifyIdInfo (\info -> substIdInfo subst info info) v
689 subst = mkSubst emptyVarSet subst_env