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 -- But it returns True regardless if l1 is the top level
126 -- We always like to float to the top!
127 ltMajLvl (Level 0 0) _ = True
128 ltMajLvl (Level maj1 _) (Level maj2 _) = maj1 < maj2
130 isTopLvl :: Level -> Bool
131 isTopLvl (Level 0 0) = True
132 isTopLvl other = False
134 instance Outputable Level where
135 ppr (Level maj min) = hcat [ char '<', int maj, char ',', int min, char '>' ]
138 %************************************************************************
140 \subsection{Main level-setting code}
142 %************************************************************************
145 setLevels :: Bool -- True <=> float lambdas to top level
150 setLevels float_lams binds us
151 = initLvl us (do_them binds)
153 -- "do_them"'s main business is to thread the monad along
154 -- It gives each top binding the same empty envt, because
155 -- things unbound in the envt have level number zero implicitly
156 do_them :: [CoreBind] -> LvlM [LevelledBind]
158 do_them [] = returnLvl []
160 = lvlTopBind init_env b `thenLvl` \ (lvld_bind, _) ->
161 do_them bs `thenLvl` \ lvld_binds ->
162 returnLvl (lvld_bind : lvld_binds)
164 init_env = initialEnv float_lams
166 lvlTopBind env (NonRec binder rhs)
167 = lvlBind TopLevel tOP_LEVEL env (AnnNonRec binder (freeVars rhs))
168 -- Rhs can have no free vars!
170 lvlTopBind env (Rec pairs)
171 = lvlBind TopLevel tOP_LEVEL env (AnnRec [(b,freeVars rhs) | (b,rhs) <- pairs])
174 %************************************************************************
176 \subsection{Setting expression levels}
178 %************************************************************************
181 lvlExpr :: Level -- ctxt_lvl: Level of enclosing expression
182 -> LevelEnv -- Level of in-scope names/tyvars
183 -> CoreExprWithFVs -- input expression
184 -> LvlM LevelledExpr -- Result expression
187 The @ctxt_lvl@ is, roughly, the level of the innermost enclosing
188 binder. Here's an example
190 v = \x -> ...\y -> let r = case (..x..) of
194 When looking at the rhs of @r@, @ctxt_lvl@ will be 1 because that's
195 the level of @r@, even though it's inside a level-2 @\y@. It's
196 important that @ctxt_lvl@ is 1 and not 2 in @r@'s rhs, because we
197 don't want @lvlExpr@ to turn the scrutinee of the @case@ into an MFE
198 --- because it isn't a *maximal* free expression.
200 If there were another lambda in @r@'s rhs, it would get level-2 as well.
203 lvlExpr _ _ (_, AnnType ty) = returnLvl (Type ty)
204 lvlExpr _ env (_, AnnVar v) = returnLvl (lookupVar env v)
205 lvlExpr _ env (_, AnnLit lit) = returnLvl (Lit lit)
207 lvlExpr ctxt_lvl env (_, AnnApp fun arg)
208 = lvl_fun fun `thenLvl` \ fun' ->
209 lvlMFE False ctxt_lvl env arg `thenLvl` \ arg' ->
210 returnLvl (App fun' arg')
212 lvl_fun (_, AnnCase _ _ _) = lvlMFE True ctxt_lvl env fun
213 lvl_fun other = lvlExpr ctxt_lvl env fun
214 -- We don't do MFE on partial applications generally,
215 -- but we do if the function is big and hairy, like a case
217 lvlExpr ctxt_lvl env (_, AnnNote InlineMe expr)
218 -- Don't float anything out of an InlineMe
219 = lvlExpr tOP_LEVEL env expr `thenLvl` \ expr' ->
220 returnLvl (Note InlineMe expr')
222 lvlExpr ctxt_lvl env (_, AnnNote note expr)
223 = lvlExpr ctxt_lvl env expr `thenLvl` \ expr' ->
224 returnLvl (Note note expr')
226 -- We don't split adjacent lambdas. That is, given
228 -- we don't float to give
229 -- \x -> let v = x+y in \y -> (v,y)
230 -- Why not? Because partial applications are fairly rare, and splitting
231 -- lambdas makes them more expensive.
233 lvlExpr ctxt_lvl env expr@(_, AnnLam bndr rhs)
234 = lvlMFE True new_lvl new_env body `thenLvl` \ new_body ->
235 returnLvl (glue_binders new_bndrs expr new_body)
237 (bndrs, body) = collect_binders expr
238 (new_lvl, new_bndrs) = lvlLamBndrs ctxt_lvl bndrs
239 new_env = extendLvlEnv env new_bndrs
241 lvlExpr ctxt_lvl env (_, AnnLet bind body)
242 = lvlBind NotTopLevel ctxt_lvl env bind `thenLvl` \ (bind', new_env) ->
243 lvlExpr ctxt_lvl new_env body `thenLvl` \ body' ->
244 returnLvl (Let bind' body')
246 lvlExpr ctxt_lvl env (_, AnnCase expr case_bndr alts)
247 = lvlMFE True ctxt_lvl env expr `thenLvl` \ expr' ->
249 alts_env = extendCaseBndrLvlEnv env expr' case_bndr incd_lvl
251 mapLvl (lvl_alt alts_env) alts `thenLvl` \ alts' ->
252 returnLvl (Case expr' (case_bndr, incd_lvl) alts')
254 expr_type = exprType (deAnnotate expr)
255 incd_lvl = incMinorLvl ctxt_lvl
257 lvl_alt alts_env (con, bs, rhs)
258 = lvlMFE True incd_lvl new_env rhs `thenLvl` \ rhs' ->
259 returnLvl (con, bs', rhs')
261 bs' = [ (b, incd_lvl) | b <- bs ]
262 new_env = extendLvlEnv alts_env bs'
267 go rev_bndrs (_, AnnLam b e) = go (b:rev_bndrs) e
268 go rev_bndrs (_, AnnNote n e) = go rev_bndrs e
269 go rev_bndrs rhs = (reverse rev_bndrs, rhs)
270 -- Ignore notes, because we don't want to split
271 -- a lambda like this (\x -> coerce t (\s -> ...))
272 -- This happens quite a bit in state-transformer programs
274 -- glue_binders puts the lambda back together
275 glue_binders (b:bs) (_, AnnLam _ e) body = Lam b (glue_binders bs e body)
276 glue_binders bs (_, AnnNote n e) body = Note n (glue_binders bs e body)
277 glue_binders [] e body = body
280 @lvlMFE@ is just like @lvlExpr@, except that it might let-bind
281 the expression, so that it can itself be floated.
284 lvlMFE :: Bool -- True <=> strict context [body of case or let]
285 -> Level -- Level of innermost enclosing lambda/tylam
286 -> LevelEnv -- Level of in-scope names/tyvars
287 -> CoreExprWithFVs -- input expression
288 -> LvlM LevelledExpr -- Result expression
290 lvlMFE strict_ctxt ctxt_lvl env (_, AnnType ty)
291 = returnLvl (Type ty)
293 lvlMFE strict_ctxt ctxt_lvl env ann_expr@(fvs, _)
294 | isUnLiftedType ty -- Can't let-bind it
295 || not good_destination
296 || exprIsTrivial expr -- Is trivial
297 || (strict_ctxt && exprIsBottom expr) -- Strict context and is bottom
298 = -- Don't float it out
299 lvlExpr ctxt_lvl env ann_expr
301 | otherwise -- Float it out!
302 = lvlFloatRhs abs_vars dest_lvl env ann_expr `thenLvl` \ expr' ->
303 newLvlVar "lvl" abs_vars ty `thenLvl` \ var ->
304 returnLvl (Let (NonRec (var,dest_lvl) expr')
305 (mkVarApps (Var var) abs_vars))
307 expr = deAnnotate ann_expr
309 dest_lvl = destLevel env fvs (isFunction ann_expr)
310 abs_vars = abstractVars dest_lvl env fvs
312 good_destination = dest_lvl `ltMajLvl` ctxt_lvl -- Escapes a value lambda
313 || (isTopLvl dest_lvl && not strict_ctxt) -- Goes to the top
314 -- A decision to float entails let-binding this thing, and we only do
315 -- that if we'll escape a value lambda, or will go to the top level.
317 -- concat = /\ a -> foldr ..a.. (++) []
318 -- was getting turned into
319 -- concat = /\ a -> lvl a
320 -- lvl = /\ a -> foldr ..a.. (++) []
321 -- which is pretty stupid. Hence the strict_ctxt test
325 %************************************************************************
327 \subsection{Bindings}
329 %************************************************************************
331 The binding stuff works for top level too.
334 lvlBind :: TopLevelFlag -- Used solely to decide whether to clone
335 -> Level -- Context level; might be Top even for bindings nested in the RHS
336 -- of a top level binding
339 -> LvlM (LevelledBind, LevelEnv)
341 lvlBind top_lvl ctxt_lvl env (AnnNonRec bndr rhs@(rhs_fvs,_))
343 = -- No type abstraction; clone existing binder
344 lvlExpr ctxt_lvl env rhs `thenLvl` \ rhs' ->
345 cloneVar top_lvl env bndr dest_lvl `thenLvl` \ (env', bndr') ->
346 returnLvl (NonRec (bndr', dest_lvl) rhs', env')
349 = -- Yes, type abstraction; create a new binder, extend substitution, etc
350 lvlFloatRhs abs_vars dest_lvl env rhs `thenLvl` \ rhs' ->
351 newPolyBndrs dest_lvl env abs_vars [bndr] `thenLvl` \ (env', [bndr']) ->
352 returnLvl (NonRec (bndr', dest_lvl) rhs', env')
355 bind_fvs = rhs_fvs `unionVarSet` idFreeVars bndr
356 abs_vars = abstractVars dest_lvl env bind_fvs
358 dest_lvl | isUnLiftedType (idType bndr) = destLevel env bind_fvs False `maxLvl` Level 1 0
359 | otherwise = destLevel env bind_fvs (isFunction rhs)
360 -- Hack alert! We do have some unlifted bindings, for cheap primops, and
361 -- it is ok to float them out; but not to the top level. If they would otherwise
362 -- go to the top level, we pin them inside the topmost lambda
367 lvlBind top_lvl ctxt_lvl env (AnnRec pairs)
369 = cloneVars top_lvl env bndrs dest_lvl `thenLvl` \ (new_env, new_bndrs) ->
370 mapLvl (lvlExpr ctxt_lvl new_env) rhss `thenLvl` \ new_rhss ->
371 returnLvl (Rec ((new_bndrs `zip` repeat dest_lvl) `zip` new_rhss), new_env)
373 | isSingleton pairs && count isId abs_vars > 1
374 = -- Special case for self recursion where there are
375 -- several variables carried around: build a local loop:
376 -- poly_f = \abs_vars. \lam_vars . letrec f = \lam_vars. rhs in f lam_vars
377 -- This just makes the closures a bit smaller. If we don't do
378 -- this, allocation rises significantly on some programs
380 -- We could elaborate it for the case where there are several
381 -- mutually functions, but it's quite a bit more complicated
383 -- This all seems a bit ad hoc -- sigh
385 (bndr,rhs) = head pairs
386 (rhs_lvl, abs_vars_w_lvls) = lvlLamBndrs dest_lvl abs_vars
387 rhs_env = extendLvlEnv env abs_vars_w_lvls
389 cloneVar NotTopLevel rhs_env bndr rhs_lvl `thenLvl` \ (rhs_env', new_bndr) ->
391 (lam_bndrs, rhs_body) = collect_binders rhs
392 (body_lvl, new_lam_bndrs) = lvlLamBndrs rhs_lvl lam_bndrs
393 body_env = extendLvlEnv rhs_env' new_lam_bndrs
395 lvlExpr body_lvl body_env rhs_body `thenLvl` \ new_rhs_body ->
396 newPolyBndrs dest_lvl env abs_vars [bndr] `thenLvl` \ (poly_env, [poly_bndr]) ->
397 returnLvl (Rec [((poly_bndr,dest_lvl), mkLams abs_vars_w_lvls $
398 glue_binders new_lam_bndrs rhs $
399 Let (Rec [((new_bndr,rhs_lvl), mkLams new_lam_bndrs new_rhs_body)])
400 (mkVarApps (Var new_bndr) lam_bndrs))],
404 = newPolyBndrs dest_lvl env abs_vars bndrs `thenLvl` \ (new_env, new_bndrs) ->
405 mapLvl (lvlFloatRhs abs_vars dest_lvl new_env) rhss `thenLvl` \ new_rhss ->
406 returnLvl (Rec ((new_bndrs `zip` repeat dest_lvl) `zip` new_rhss), new_env)
409 (bndrs,rhss) = unzip pairs
411 -- Finding the free vars of the binding group is annoying
412 bind_fvs = (unionVarSets [ idFreeVars bndr `unionVarSet` rhs_fvs
413 | (bndr, (rhs_fvs,_)) <- pairs])
417 dest_lvl = destLevel env bind_fvs (all isFunction rhss)
418 abs_vars = abstractVars dest_lvl env bind_fvs
420 ----------------------------------------------------
421 -- Three help functons for the type-abstraction case
423 lvlFloatRhs abs_vars dest_lvl env rhs
424 = lvlExpr rhs_lvl rhs_env rhs `thenLvl` \ rhs' ->
425 returnLvl (mkLams abs_vars_w_lvls rhs')
427 (rhs_lvl, abs_vars_w_lvls) = lvlLamBndrs dest_lvl abs_vars
428 rhs_env = extendLvlEnv env abs_vars_w_lvls
432 %************************************************************************
434 \subsection{Deciding floatability}
436 %************************************************************************
439 lvlLamBndrs :: Level -> [CoreBndr] -> (Level, [(CoreBndr, Level)])
440 -- Compute the levels for the binders of a lambda group
444 lvlLamBndrs lvl bndrs
445 = go (incMinorLvl lvl)
446 False -- Havn't bumped major level in this group
449 go old_lvl bumped_major rev_lvld_bndrs (bndr:bndrs)
450 | isId bndr && -- Go to the next major level if this is a value binder,
451 not bumped_major && -- and we havn't already gone to the next level (one jump per group)
452 not (isOneShotLambda bndr) -- and it isn't a one-shot lambda
453 = go new_lvl True ((bndr,new_lvl) : rev_lvld_bndrs) bndrs
456 = go old_lvl bumped_major ((bndr,old_lvl) : rev_lvld_bndrs) bndrs
459 new_lvl = incMajorLvl old_lvl
461 go old_lvl _ rev_lvld_bndrs []
462 = (old_lvl, reverse rev_lvld_bndrs)
463 -- a lambda like this (\x -> coerce t (\s -> ...))
464 -- This happens quite a bit in state-transformer programs
468 abstractVars :: Level -> LevelEnv -> VarSet -> [Var]
469 -- Find the variables in fvs, free vars of the target expresion,
470 -- whose level is less than than the supplied level
471 -- These are the ones we are going to abstract out
472 abstractVars dest_lvl env fvs
473 = uniq (sortLt lt [var | fv <- varSetElems fvs, var <- absVarsOf dest_lvl env fv])
475 -- Sort the variables so we don't get
476 -- mixed-up tyvars and Ids; it's just messy
477 v1 `lt` v2 = case (isId v1, isId v2) of
478 (True, False) -> False
479 (False, True) -> True
480 other -> v1 < v2 -- Same family
481 uniq :: [Var] -> [Var]
482 -- Remove adjacent duplicates; the sort will have brought them together
483 uniq (v1:v2:vs) | v1 == v2 = uniq (v2:vs)
484 | otherwise = v1 : uniq (v2:vs)
487 -- Destintion level is the max Id level of the expression
488 -- (We'll abstract the type variables, if any.)
489 destLevel :: LevelEnv -> VarSet -> Bool -> Level
490 destLevel env fvs is_function
492 && is_function = tOP_LEVEL -- Send functions to top level; see
493 -- the comments with isFunction
494 | otherwise = maxIdLevel env fvs
496 isFunction :: CoreExprWithFVs -> Bool
497 -- The idea here is that we want to float *functions* to
498 -- the top level. This saves no work, but
499 -- (a) it can make the host function body a lot smaller,
500 -- and hence inlinable.
501 -- (b) it can also save allocation when the function is recursive:
502 -- h = \x -> letrec f = \y -> ...f...y...x...
505 -- f = \x y -> ...(f x)...y...x...
507 -- No allocation for f now.
508 -- We may only want to do this if there are sufficiently few free
509 -- variables. We certainly only want to do it for values, and not for
510 -- constructors. So the simple thing is just to look for lambdas
511 isFunction (_, AnnLam b e) | isId b = True
512 | otherwise = isFunction e
513 isFunction (_, AnnNote n e) = isFunction e
514 isFunction other = False
518 %************************************************************************
520 \subsection{Free-To-Level Monad}
522 %************************************************************************
525 type LevelEnv = (Bool, -- True <=> Float lambdas too
526 VarEnv Level, -- Domain is *post-cloned* TyVars and Ids
527 SubstEnv, -- Domain is pre-cloned Ids
528 IdEnv ([Var], LevelledExpr)) -- Domain is pre-cloned Ids
529 -- We clone let-bound variables so that they are still
530 -- distinct when floated out; hence the SubstEnv/IdEnv.
531 -- We also use these envs when making a variable polymorphic
532 -- because we want to float it out past a big lambda.
534 -- The two Envs always implement the same mapping, but the
535 -- SubstEnv maps to CoreExpr and the IdEnv to LevelledExpr
536 -- Since the range is always a variable or type application,
537 -- there is never any difference between the two, but sadly
538 -- the types differ. The SubstEnv is used when substituting in
539 -- a variable's IdInfo; the IdEnv when we find a Var.
541 -- In addition the IdEnv records a list of tyvars free in the
542 -- type application, just so we don't have to call freeVars on
543 -- the type application repeatedly.
545 -- The domain of the both envs is *pre-cloned* Ids, though
547 -- The domain of the VarEnv Level is the *post-cloned* Ids
549 initialEnv :: Bool -> LevelEnv
550 initialEnv float_lams = (float_lams, emptyVarEnv, emptySubstEnv, emptyVarEnv)
552 floatLams :: LevelEnv -> Bool
553 floatLams (float_lams, _, _, _) = float_lams
555 extendLvlEnv :: LevelEnv -> [(Var,Level)] -> LevelEnv
556 -- Used when *not* cloning
557 extendLvlEnv (float_lams, lvl_env, subst_env, id_env) prs
558 = (float_lams, foldl add lvl_env prs, subst_env, id_env)
560 add env (v,l) = extendVarEnv env v l
562 -- extendCaseBndrLvlEnv adds the mapping case-bndr->scrut-var if it can
563 extendCaseBndrLvlEnv env scrut case_bndr lvl
565 Var v -> extendCloneLvlEnv lvl env [(case_bndr, v)]
566 other -> extendLvlEnv env [(case_bndr,lvl)]
568 extendPolyLvlEnv dest_lvl (float_lams, lvl_env, subst_env, id_env) abs_vars 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' dest_lvl
575 add_subst env (v,v') = extendSubstEnv env v (DoneEx (mkVarApps (Var v') abs_vars))
576 add_id env (v,v') = extendVarEnv env v ((v':abs_vars), mkVarApps (Var v') abs_vars)
578 extendCloneLvlEnv lvl (float_lams, lvl_env, subst_env, id_env) bndr_pairs
580 foldl add_lvl lvl_env bndr_pairs,
581 foldl add_subst subst_env bndr_pairs,
582 foldl add_id id_env bndr_pairs)
584 add_lvl env (v,v') = extendVarEnv env v' lvl
585 add_subst env (v,v') = extendSubstEnv env v (DoneEx (Var v'))
586 add_id env (v,v') = extendVarEnv env v ([v'], Var v')
589 maxIdLevel :: LevelEnv -> VarSet -> Level
590 maxIdLevel (_, lvl_env,_,id_env) var_set
591 = foldVarSet max_in tOP_LEVEL var_set
593 max_in in_var lvl = foldr max_out lvl (case lookupVarEnv id_env in_var of
594 Just (abs_vars, _) -> abs_vars
598 | isId out_var = case lookupVarEnv lvl_env out_var of
599 Just lvl' -> maxLvl lvl' lvl
601 | otherwise = lvl -- Ignore tyvars in *maxIdLevel*
603 lookupVar :: LevelEnv -> Id -> LevelledExpr
604 lookupVar (_, _, _, id_env) v = case lookupVarEnv id_env v of
605 Just (_, expr) -> expr
608 absVarsOf :: Level -> LevelEnv -> Var -> [Var]
609 -- If f is free in the exression, and f maps to poly_f a b c in the
610 -- current substitution, then we must report a b c as candidate type
612 absVarsOf dest_lvl (_, lvl_env, _, id_env) v
614 = [final_av | av <- lookup_avs v, abstract_me av, final_av <- add_tyvars av]
617 = if abstract_me v then [v] else []
620 abstract_me v = case lookupVarEnv lvl_env v of
621 Just lvl -> dest_lvl `ltLvl` lvl
624 lookup_avs v = case lookupVarEnv id_env v of
625 Just (abs_vars, _) -> abs_vars
628 -- We are going to lambda-abstract, so nuke any IdInfo,
629 -- and add the tyvars of the Id
630 add_tyvars v | isId v = zap v : varSetElems (idFreeTyVars v)
633 zap v = WARN( workerExists (idWorkerInfo v)
634 || not (isEmptyCoreRules (idSpecialisation v)),
635 text "absVarsOf: discarding info on" <+> ppr v )
636 setIdInfo v vanillaIdInfo
640 type LvlM result = UniqSM result
649 newPolyBndrs dest_lvl env abs_vars bndrs
650 = getUniquesUs (length bndrs) `thenLvl` \ uniqs ->
652 new_bndrs = zipWith mk_poly_bndr bndrs uniqs
654 returnLvl (extendPolyLvlEnv dest_lvl env abs_vars (bndrs `zip` new_bndrs), new_bndrs)
656 mk_poly_bndr bndr uniq = mkSysLocal (_PK_ str) uniq poly_ty
658 str = "poly_" ++ occNameUserString (getOccName bndr)
659 poly_ty = foldr mkPiType (idType bndr) abs_vars
663 -> [CoreBndr] -> Type -- Abstract wrt these bndrs
665 newLvlVar str vars body_ty
666 = getUniqueUs `thenLvl` \ uniq ->
667 returnUs (mkSysLocal (_PK_ str) uniq (foldr mkPiType body_ty vars))
669 -- The deeply tiresome thing is that we have to apply the substitution
670 -- to the rules inside each Id. Grr. But it matters.
672 cloneVar :: TopLevelFlag -> LevelEnv -> Id -> Level -> LvlM (LevelEnv, Id)
673 cloneVar TopLevel env v lvl
674 = returnUs (env, v) -- Don't clone top level things
675 cloneVar NotTopLevel env v lvl
676 = getUniqueUs `thenLvl` \ uniq ->
678 v' = setVarUnique v uniq
679 v'' = subst_id_info env v'
680 env' = extendCloneLvlEnv lvl env [(v,v'')]
684 cloneVars :: TopLevelFlag -> LevelEnv -> [Id] -> Level -> LvlM (LevelEnv, [Id])
685 cloneVars TopLevel env vs lvl
686 = returnUs (env, vs) -- Don't clone top level things
687 cloneVars NotTopLevel env vs lvl
688 = getUniquesUs (length vs) `thenLvl` \ uniqs ->
690 vs' = zipWith setVarUnique vs uniqs
691 vs'' = map (subst_id_info env') vs'
692 env' = extendCloneLvlEnv lvl env (vs `zip` vs'')
694 returnUs (env', vs'')
696 subst_id_info (_, _, subst_env, _) v
697 = modifyIdInfo (\info -> substIdInfo subst info info) v
699 subst = mkSubst emptyVarSet subst_env