2 % (c) The GRASP/AQUA Project, Glasgow University, 1993-1998
10 module DmdAnal ( dmdAnalPgm ) where
12 #include "HsVersions.h"
14 import CmdLineOpts ( DynFlags, DynFlag(..) )
15 import NewDemand -- All of it
17 import CoreUtils ( exprIsValue, exprArity )
18 import DataCon ( dataConTyCon )
19 import TyCon ( isProductTyCon, isRecursiveTyCon )
20 import Id ( Id, idType, idInfo, idArity, idStrictness, idCprInfo, idDemandInfo,
21 modifyIdInfo, isDataConId, isImplicitId, isGlobalId )
22 import IdInfo ( newStrictnessInfo, setNewStrictnessInfo, mkNewStrictnessInfo,
23 newDemandInfo, setNewDemandInfo, newDemand
27 import UniqFM ( plusUFM_C, addToUFM_Directly, lookupUFM_Directly,
28 keysUFM, minusUFM, ufmToList, filterUFM )
29 import Type ( isUnLiftedType )
30 import CoreLint ( showPass, endPass )
31 import ErrUtils ( dumpIfSet_dyn )
32 import Util ( mapAndUnzip, mapAccumL, mapAccumR, zipWithEqual )
33 import BasicTypes ( Arity, TopLevelFlag(..), isTopLevel )
34 import Maybes ( orElse, expectJust )
39 ToDo: set a noinline pragma on bottoming Ids
41 instance Outputable TopLevelFlag where
45 %************************************************************************
47 \subsection{Top level stuff}
49 %************************************************************************
52 dmdAnalPgm :: DynFlags -> [CoreBind] -> IO [CoreBind]
55 dmdAnalPgm dflags binds = return binds
59 dmdAnalPgm dflags binds
61 showPass dflags "Demand analysis" ;
62 let { binds_plus_dmds = do_prog binds ;
63 dmd_changes = get_changes binds_plus_dmds } ;
64 endPass dflags "Demand analysis"
65 Opt_D_dump_stranal binds_plus_dmds ;
66 printDump (text "Changes in demands" $$ dmd_changes) ;
67 return binds_plus_dmds
70 do_prog :: [CoreBind] -> [CoreBind]
71 do_prog binds = snd $ mapAccumL dmdAnalTopBind emptySigEnv binds
73 dmdAnalTopBind :: SigEnv
76 dmdAnalTopBind sigs (NonRec id rhs)
77 | isImplicitId id -- Don't touch the info on constructors, selectors etc
78 = (sigs, NonRec id rhs) -- It's pre-computed in MkId.lhs
81 (sigs', _, (id', rhs')) = downRhs TopLevel sigs (id, rhs)
83 (sigs', NonRec id' rhs')
85 dmdAnalTopBind sigs (Rec pairs)
87 (sigs', _, pairs') = dmdFix TopLevel sigs pairs
93 %************************************************************************
95 \subsection{The analyser itself}
97 %************************************************************************
100 dmdAnal :: SigEnv -> Demand -> CoreExpr -> (DmdType, CoreExpr)
102 dmdAnal sigs Abs e = (topDmdType, e)
104 dmdAnal sigs Lazy e = let
105 (res_ty, e') = dmdAnal sigs Eval e
107 (deferType res_ty, e')
108 -- It's important not to analyse e with a lazy demand because
109 -- a) When we encounter case s of (a,b) ->
110 -- we demand s with U(d1d2)... but if the overall demand is lazy
111 -- that is wrong, and we'd need to reduce the demand on s,
112 -- which is inconvenient
113 -- b) More important, consider
114 -- f (let x = R in x+x), where f is lazy
115 -- We still want to mark x as demanded, because it will be when we
116 -- enter the let. If we analyse f's arg with a Lazy demand, we'll
117 -- just mark x as Lazy
120 dmdAnal sigs dmd (Lit lit)
121 = (topDmdType, Lit lit)
123 dmdAnal sigs dmd (Var var)
124 = (dmdTransform sigs var dmd, Var var)
126 dmdAnal sigs dmd (Note n e)
127 = (dmd_ty, Note n e')
129 (dmd_ty, e') = dmdAnal sigs dmd e
131 dmdAnal sigs dmd (App fun (Type ty))
132 = (fun_ty, App fun' (Type ty))
134 (fun_ty, fun') = dmdAnal sigs dmd fun
136 dmdAnal sigs dmd (App fun arg) -- Non-type arguments
137 = let -- [Type arg handled above]
138 (fun_ty, fun') = dmdAnal sigs (Call dmd) fun
139 (arg_ty, arg') = dmdAnal sigs arg_dmd arg
140 (arg_dmd, res_ty) = splitDmdTy fun_ty
142 (res_ty `bothType` arg_ty, App fun' arg')
144 dmdAnal sigs dmd (Lam var body)
147 (body_ty, body') = dmdAnal sigs dmd body
149 (body_ty, Lam var body')
151 | Call body_dmd <- dmd -- A call demand: good!
153 (body_ty, body') = dmdAnal sigs body_dmd body
154 (lam_ty, var') = annotateLamIdBndr body_ty var
156 (lam_ty, Lam var' body')
158 | otherwise -- Not enough demand on the lambda; but do the body
159 = let -- anyway to annotate it and gather free var info
160 (body_ty, body') = dmdAnal sigs Eval body
161 (lam_ty, var') = annotateLamIdBndr body_ty var
163 (deferType lam_ty, Lam var' body')
165 dmdAnal sigs dmd (Case scrut case_bndr [alt@(DataAlt dc,bndrs,rhs)])
166 | let tycon = dataConTyCon dc,
167 isProductTyCon tycon,
168 not (isRecursiveTyCon tycon)
170 bndr_ids = filter isId bndrs
171 (alt_ty, alt') = dmdAnalAlt sigs dmd alt
172 (alt_ty1, case_bndr') = annotateBndr alt_ty case_bndr
173 (_, bndrs', _) = alt'
174 scrut_dmd = Seq Drop Now [idNewDemandInfo b | b <- bndrs', isId b]
175 (scrut_ty, scrut') = dmdAnal sigs scrut_dmd scrut
177 (alt_ty1 `bothType` scrut_ty, Case scrut' case_bndr' [alt'])
179 dmdAnal sigs dmd (Case scrut case_bndr alts)
181 (alt_tys, alts') = mapAndUnzip (dmdAnalAlt sigs dmd) alts
182 (scrut_ty, scrut') = dmdAnal sigs Eval scrut
183 (alt_ty, case_bndr') = annotateBndr (foldr1 lubType alt_tys) case_bndr
185 -- pprTrace "dmdAnal:Case" (ppr alts $$ ppr alt_tys)
186 (alt_ty `bothType` scrut_ty, Case scrut' case_bndr' alts')
188 dmdAnal sigs dmd (Let (NonRec id rhs) body)
190 (sigs', lazy_fv, (id1, rhs')) = downRhs NotTopLevel sigs (id, rhs)
191 (body_ty, body') = dmdAnal sigs' dmd body
192 (body_ty1, id2) = annotateBndr body_ty id1
193 body_ty2 = addLazyFVs body_ty1 lazy_fv
195 -- pprTrace "dmdLet" (ppr id <+> ppr (sig,rhs_env))
196 (body_ty2, Let (NonRec id2 rhs') body')
198 dmdAnal sigs dmd (Let (Rec pairs) body)
200 bndrs = map fst pairs
201 (sigs', lazy_fv, pairs') = dmdFix NotTopLevel sigs pairs
202 (body_ty, body') = dmdAnal sigs' dmd body
203 body_ty1 = addLazyFVs body_ty lazy_fv
205 sigs' `seq` body_ty `seq`
207 (body_ty2, _) = annotateBndrs body_ty1 bndrs
208 -- Don't bother to add demand info to recursive
209 -- binders as annotateBndr does;
210 -- being recursive, we can't treat them strictly.
211 -- But we do need to remove the binders from the result demand env
213 (body_ty2, Let (Rec pairs') body')
216 dmdAnalAlt sigs dmd (con,bndrs,rhs)
218 (rhs_ty, rhs') = dmdAnal sigs dmd rhs
219 (alt_ty, bndrs') = annotateBndrs rhs_ty bndrs
221 (alt_ty, (con, bndrs', rhs'))
224 %************************************************************************
226 \subsection{Bindings}
228 %************************************************************************
231 dmdFix :: TopLevelFlag
232 -> SigEnv -- Does not include bindings for this binding
235 [(Id,CoreExpr)]) -- Binders annotated with stricness info
237 dmdFix top_lvl sigs pairs
238 = loop 1 initial_sigs pairs
240 bndrs = map fst pairs
241 initial_sigs = extendSigEnvList sigs [(id, (initial_sig id, top_lvl)) | id <- bndrs]
244 -> SigEnv -- Already contains the current sigs
246 -> (SigEnv, DmdEnv, [(Id,CoreExpr)])
248 | all (same_sig sigs sigs') bndrs = (sigs', lazy_fv, pairs')
249 -- Note: use pairs', not pairs. pairs' is the result of
250 -- processing the RHSs with sigs (= sigs'), whereas pairs
251 -- is the result of processing the RHSs with the *previous*
252 -- iteration of sigs.
253 | n >= 5 = pprTrace "dmdFix" (ppr n <+> ppr pairs) (loop (n+1) sigs' pairs')
254 | otherwise = {- pprTrace "dmdFixLoop" (ppr id_sigs) -} (loop (n+1) sigs' pairs')
256 -- Use the new signature to do the next pair
257 -- The occurrence analyser has arranged them in a good order
258 -- so this can significantly reduce the number of iterations needed
259 ((sigs',lazy_fv), pairs') = mapAccumL (my_downRhs top_lvl) (sigs, emptyDmdEnv) pairs
261 my_downRhs top_lvl (sigs,lazy_fv) (id,rhs)
262 = -- pprTrace "downRhs {" (ppr id <+> (ppr old_sig))
264 -- pprTrace "downRhsEnd" (ppr id <+> ppr new_sig <+> char '}' )
265 ((sigs', lazy_fv'), pair')
268 (sigs', lazy_fv1, pair') = downRhs top_lvl sigs (id,rhs)
269 lazy_fv' = plusUFM_C both lazy_fv lazy_fv1
270 old_sig = lookup sigs id
271 new_sig = lookup sigs' id
273 -- Get an initial strictness signature from the Id
274 -- itself. That way we make use of earlier iterations
275 -- of the fixpoint algorithm. (Cunning plan.)
276 -- Note that the cunning plan extends to the DmdEnv too,
277 -- since it is part of the strictness signature
278 initial_sig id = idNewStrictness_maybe id `orElse` botSig
280 same_sig sigs sigs' var = lookup sigs var == lookup sigs' var
281 lookup sigs var = case lookupVarEnv sigs var of
284 downRhs :: TopLevelFlag
285 -> SigEnv -> (Id, CoreExpr)
286 -> (SigEnv, DmdEnv, (Id, CoreExpr))
287 -- Process the RHS of the binding, add the strictness signature
288 -- to the Id, and augment the environment with the signature as well.
290 downRhs top_lvl sigs (id, rhs)
291 = (sigs', lazy_fv, (id', rhs'))
293 arity = exprArity rhs -- The idArity may not be up to date
294 (rhs_ty, rhs') = dmdAnal sigs (vanillaCall arity) rhs
295 (lazy_fv, sig_ty) = mkSigTy rhs rhs_ty
296 sig = mkStrictSig id arity sig_ty
297 id' = id `setIdNewStrictness` sig
298 sigs' = extendSigEnv top_lvl sigs id sig
300 mkSigTy rhs (DmdType fv dmds res)
301 = (lazy_fv, DmdType strict_fv lazified_dmds res')
303 lazy_fv = filterUFM (not . isStrictDmd) fv
304 strict_fv = filterUFM isStrictDmd fv
305 -- We put the strict FVs in the DmdType of the Id, so
306 -- that at its call sites we unleash demands on its strict fvs.
307 -- An example is 'roll' in imaginary/wheel-sieve2
308 -- Something like this:
310 -- go y = if ... then roll (x-1) else x+1
313 -- We want to see that roll is strict in x, which is because
314 -- go is called. So we put the DmdEnv for x in go's DmdType.
317 -- f :: Int -> Int -> Int
318 -- f x y = let t = x+1
319 -- h z = if z==0 then t else
320 -- if z==1 then x+1 else
324 -- Calling h does indeed evaluate x, but we can only see
325 -- that if we unleash a demand on x at the call site for t.
327 -- Incidentally, here's a place where lambda-lifting h would
328 -- lose the cigar --- we couldn't see the joint strictness in t/x
331 -- We don't want to put *all* the fv's from the RHS into the
332 -- DmdType, because that makes fixpointing very slow --- the
333 -- DmdType gets full of lazy demands that are slow to converge.
335 lazified_dmds = map lazify dmds
336 -- Get rid of defers in the arguments
338 res' = case (dmds, res) of
339 ([], RetCPR) | not (exprIsValue rhs) -> TopRes
341 -- If the rhs is a thunk, we forget the CPR info, because
342 -- it is presumably shared (else it would have been inlined, and
343 -- so we'd lose sharing if w/w'd it into a function.
345 -- DONE IN OLD CPR ANALYSER, BUT NOT YET HERE
346 -- Also, if the strictness analyser has figured out that it's strict,
347 -- the let-to-case transformation will happen, so again it's good.
348 -- (CPR analysis runs before the simplifier has had a chance to do
349 -- the let-to-case transform.)
350 -- This made a big difference to PrelBase.modInt, which had something like
351 -- modInt = \ x -> let r = ... -> I# v in
352 -- ...body strict in r...
353 -- r's RHS isn't a value yet; but modInt returns r in various branches, so
354 -- if r doesn't have the CPR property then neither does modInt
358 %************************************************************************
360 \subsection{Strictness signatures and types}
362 %************************************************************************
365 unitVarDmd var dmd = DmdType (unitVarEnv var dmd) [] TopRes
367 addVarDmd top_lvl dmd_ty@(DmdType fv ds res) var dmd
368 | isTopLevel top_lvl = dmd_ty -- Don't record top level things
369 | otherwise = DmdType (extendVarEnv fv var dmd) ds res
371 addLazyFVs (DmdType fv ds res) lazy_fvs
372 = DmdType (plusUFM_C both fv lazy_fvs) ds res
374 annotateBndr :: DmdType -> Var -> (DmdType, Var)
375 -- The returned env has the var deleted
376 -- The returned var is annotated with demand info
377 -- No effect on the argument demands
378 annotateBndr dmd_ty@(DmdType fv ds res) var
379 | isTyVar var = (dmd_ty, var)
380 | otherwise = (DmdType fv' ds res, setIdNewDemandInfo var dmd)
382 (fv', dmd) = removeFV fv var res
384 annotateBndrs = mapAccumR annotateBndr
386 annotateLamIdBndr dmd_ty@(DmdType fv ds res) id
387 -- For lambdas we add the demand to the argument demands
388 -- Only called for Ids
390 (DmdType fv' (dmd:ds) res, setIdNewDemandInfo id dmd)
392 (fv', dmd) = removeFV fv id res
394 removeFV fv var res = (fv', dmd)
396 fv' = fv `delVarEnv` var
397 dmd = lookupVarEnv fv var `orElse` deflt
398 deflt | isBotRes res = Bot
402 %************************************************************************
404 \subsection{Demand types}
406 %************************************************************************
409 splitDmdTy :: DmdType -> (Demand, DmdType)
410 -- Split off one function argument
411 splitDmdTy (DmdType fv (dmd:dmds) res_ty) = (dmd, DmdType fv dmds res_ty)
412 splitDmdTy ty@(DmdType fv [] TopRes) = (topDmd, ty)
413 splitDmdTy ty@(DmdType fv [] BotRes) = (Abs, ty)
414 -- We already have a suitable demand on all
415 -- free vars, so no need to add more!
416 splitDmdTy (DmdType fv [] RetCPR) = panic "splitDmdTy"
418 -------------------------
419 dmdTypeRes :: DmdType -> DmdResult
420 dmdTypeRes (DmdType _ _ res_ty) = res_ty
424 %************************************************************************
426 \subsection{Strictness signatures}
428 %************************************************************************
431 type SigEnv = VarEnv (StrictSig, TopLevelFlag)
432 -- We use the SigEnv to tell us whether to
433 -- record info about a variable in the DmdEnv
434 -- We do so if it's a LocalId, but not top-level
436 -- The DmdEnv gives the demand on the free vars of the function
437 -- when it is given enough args to satisfy the strictness signature
439 emptySigEnv = emptyVarEnv
441 extendSigEnv :: TopLevelFlag -> SigEnv -> Id -> StrictSig -> SigEnv
442 extendSigEnv top_lvl env var sig = extendVarEnv env var (sig, top_lvl)
444 extendSigEnvList = extendVarEnvList
446 dmdTransform :: SigEnv -- The strictness environment
447 -> Id -- The function
448 -> Demand -- The demand on the function
449 -> DmdType -- The demand type of the function in this context
450 -- Returned DmdEnv includes the demand on
451 -- this function plus demand on its free variables
453 dmdTransform sigs var dmd
455 ------ DATA CONSTRUCTOR
456 | isDataConId var, -- Data constructor
457 Seq k Now ds <- res_dmd, -- and the demand looks inside its fields
458 let StrictSig arity dmd_ty = idNewStrictness var -- It must have a strictness sig
459 = if arity == length ds then -- Saturated, so unleash the demand
460 -- ds can be empty, when we are just seq'ing the thing
461 mkDmdType emptyDmdEnv ds (dmdTypeRes dmd_ty)
462 -- Need to extract whether it's a product
466 ------ IMPORTED FUNCTION
467 | isGlobalId var, -- Imported function
468 let StrictSig arity dmd_ty = getNewStrictness var
469 = if arity <= depth then -- Saturated, so unleash the demand
474 ------ LOCAL LET/REC BOUND THING
475 | Just (StrictSig arity dmd_ty, top_lvl) <- lookupVarEnv sigs var
477 fn_ty | arity <= depth = dmd_ty
478 | otherwise = deferType dmd_ty
479 -- NB: it's important to use deferType, and not just return topDmdType
480 -- Consider let { f x y = p + x } in f 1
481 -- The application isn't saturated, but we must nevertheless propagate
482 -- a lazy demand for p!
484 addVarDmd top_lvl fn_ty var dmd
486 ------ LOCAL NON-LET/REC BOUND THING
487 | otherwise -- Default case
491 (depth, res_dmd) = splitCallDmd dmd
495 squashDmdEnv (StrictSig a (DmdType fv ds res)) = StrictSig a (DmdType emptyDmdEnv ds res)
497 betterStrict :: StrictSig -> StrictSig -> Bool
498 betterStrict (StrictSig ar1 t1) (StrictSig ar2 t2)
499 = (ar1 >= ar2) && (t1 `betterDmdType` t2)
501 betterDmdType t1 t2 = (t1 `lubType` t2) == t2
505 %************************************************************************
509 %************************************************************************
512 splitCallDmd :: Demand -> (Int, Demand)
513 splitCallDmd (Call d) = case splitCallDmd d of
515 splitCallDmd d = (0, d)
517 vanillaCall :: Arity -> Demand
519 vanillaCall n = Call (vanillaCall (n-1))
521 deferType :: DmdType -> DmdType
522 deferType (DmdType fv _ _) = DmdType (mapVarEnv defer fv) [] TopRes
523 -- Notice that we throw away info about both arguments and results
524 -- For example, f = let ... in \x -> x
525 -- We don't want to get a stricness type V->T for f.
527 defer :: Demand -> Demand
530 defer (Seq k _ ds) = Seq k Defer ds
533 isStrictDmd :: Demand -> Bool
534 isStrictDmd Bot = True
535 isStrictDmd Err = True
536 isStrictDmd (Seq _ Now _) = True
537 isStrictDmd Eval = True
538 isStrictDmd (Call _) = True
539 isStrictDmd other = False
541 lazify :: Demand -> Demand
542 -- The 'Defer' demands are just Lazy at function boundaries
543 lazify (Seq k Defer ds) = Lazy
544 lazify (Seq k Now ds) = Seq k Now (map lazify ds)
545 lazify Bot = Abs -- Don't pass args that are consumed by bottom
548 betterDemand :: Demand -> Demand -> Bool
549 -- If d1 `better` d2, and d2 `better` d2, then d1==d2
550 betterDemand d1 d2 = (d1 `lub` d2) == d2
554 %************************************************************************
556 \subsection{LUB and BOTH}
558 %************************************************************************
561 lub :: Demand -> Demand -> Demand
573 lub Abs (Seq k _ ds) = Seq k Defer ds -- Very important ('radicals' example)
578 lub Eval (Seq k Now ds) = Seq Keep Now ds
581 lub (Call d1) (Call d2) = Call (lub d1 d2)
583 lub (Seq k1 l1 ds1) (Seq k2 l2 ds2) = Seq (k1 `vee` k2) (l1 `or_defer` l2)
584 (zipWithEqual "lub" lub ds1 ds2)
586 -- The last clauses deal with the remaining cases for Call and Seq
587 lub d1@(Call _) d2@(Seq _ _ _) = pprPanic "lub" (ppr d1 $$ ppr d2)
588 lub d1 d2 = lub d2 d1
590 or_defer Now Now = Now
593 -------------------------
594 -- Consider (if x then y else []) with demand V
595 -- Then the first branch gives {y->V} and the second
596 -- *implicitly* has {y->A}. So we must put {y->(V `lub` A)}
597 -- in the result env.
598 lubType (DmdType fv1 ds1 r1) (DmdType fv2 ds2 r2)
599 = DmdType lub_fv2 (zipWith lub ds1 ds2) (r1 `lubRes` r2)
601 lub_fv = plusUFM_C lub fv1 fv2
602 lub_fv1 = modifyEnv (not (isBotRes r1)) (Abs `lub`) fv2 fv1 lub_fv
603 lub_fv2 = modifyEnv (not (isBotRes r2)) (Abs `lub`) fv1 fv2 lub_fv1
604 -- lub is the identity for Bot
606 -------------------------
609 lubRes RetCPR RetCPR = RetCPR
610 lubRes r1 r2 = TopRes
612 -----------------------------------
613 vee :: Keepity -> Keepity -> Keepity
617 -----------------------------------
618 both :: Demand -> Demand -> Demand
623 -- The experimental one
639 both Lazy (Seq k Now ds) = Seq Keep Now ds
642 -- Part of the Bot like Err experiment
643 -- both Eval Bot = Bot
644 both Eval (Seq k l ds) = Seq Keep Now ds
645 both Eval (Call d) = Call d
648 both (Seq k1 Defer ds1) (Seq k2 Defer ds2) = Seq (k1 `vee` k2) Defer
649 (zipWithEqual "both" both ds1 ds2)
650 both (Seq k1 l1 ds1) (Seq k2 l2 ds2) = Seq (k1 `vee` k2) Now
651 (zipWithEqual "both" both ds1' ds2')
653 ds1' = case l1 of { Now -> ds1; Defer -> map defer ds1 }
654 ds2' = case l2 of { Now -> ds2; Defer -> map defer ds2 }
656 both (Call d1) (Call d2) = Call (d1 `both` d2)
658 -- The last clauses deal with the remaining cases for Call and Seq
659 both d1@(Call _) d2@(Seq _ _ _) = pprPanic "both" (ppr d1 $$ ppr d2)
660 both d1 d2 = both d2 d1
662 -----------------------------------
663 bothRes :: DmdResult -> DmdResult -> DmdResult
664 -- Left-biased for CPR info
665 bothRes BotRes _ = BotRes
666 bothRes _ BotRes = BotRes
669 -----------------------------------
670 -- (t1 `bothType` t2) takes the argument/result info from t1,
671 -- using t2 just for its free-var info
672 bothType (DmdType fv1 ds1 r1) (DmdType fv2 ds2 r2)
673 = DmdType both_fv2 ds1 r1
675 both_fv = plusUFM_C both fv1 fv2
676 both_fv1 = modifyEnv (isBotRes r1) (`both` Bot) fv2 fv1 both_fv
677 both_fv2 = modifyEnv (isBotRes r2) (`both` Bot) fv1 fv2 both_fv1
678 -- both is the identity for Abs
682 modifyEnv :: Bool -- No-op if False
683 -> (Demand -> Demand) -- The zapper
684 -> DmdEnv -> DmdEnv -- Env1 and Env2
685 -> DmdEnv -> DmdEnv -- Transform this env
686 -- Zap anything in Env1 but not in Env2
687 -- Assume: dom(env) includes dom(Env1) and dom(Env2)
689 modifyEnv need_to_modify zapper env1 env2 env
690 | need_to_modify = foldr zap env (keysUFM (env1 `minusUFM` env2))
693 zap uniq env = addToUFM_Directly env uniq (zapper current_val)
695 current_val = expectJust "modifyEnv" (lookupUFM_Directly env uniq)
699 %************************************************************************
701 \subsection{Miscellaneous
703 %************************************************************************
707 -- Move these to Id.lhs
708 idNewStrictness_maybe :: Id -> Maybe StrictSig
709 idNewStrictness :: Id -> StrictSig
711 idNewStrictness_maybe id = newStrictnessInfo (idInfo id)
712 idNewStrictness id = idNewStrictness_maybe id `orElse` topSig
714 getNewStrictness :: Id -> StrictSig
715 -- First tries the "new-strictness" field, and then
716 -- reverts to the old one. This is just until we have
717 -- cross-module info for new strictness
718 getNewStrictness id = idNewStrictness_maybe id `orElse` newStrictnessFromOld id
720 newStrictnessFromOld :: Id -> StrictSig
721 newStrictnessFromOld id = mkNewStrictnessInfo id (idArity id) (idStrictness id) (idCprInfo id)
723 setIdNewStrictness :: Id -> StrictSig -> Id
724 setIdNewStrictness id sig = modifyIdInfo (`setNewStrictnessInfo` sig) id
726 idNewDemandInfo :: Id -> Demand
727 idNewDemandInfo id = newDemandInfo (idInfo id)
729 setIdNewDemandInfo :: Id -> Demand -> Id
730 setIdNewDemandInfo id dmd = modifyIdInfo (`setNewDemandInfo` dmd) id
734 get_changes binds = vcat (map get_changes_bind binds)
736 get_changes_bind (Rec pairs) = vcat (map get_changes_pr pairs)
737 get_changes_bind (NonRec id rhs) = get_changes_pr (id,rhs)
739 get_changes_pr (id,rhs)
740 | isImplicitId id = empty -- We don't look inside these
741 | otherwise = get_changes_var id $$ get_changes_expr rhs
744 | isId var = get_changes_str var $$ get_changes_dmd var
747 get_changes_expr (Type t) = empty
748 get_changes_expr (Var v) = empty
749 get_changes_expr (Lit l) = empty
750 get_changes_expr (Note n e) = get_changes_expr e
751 get_changes_expr (App e1 e2) = get_changes_expr e1 $$ get_changes_expr e2
752 get_changes_expr (Lam b e) = {- get_changes_var b $$ -} get_changes_expr e
753 get_changes_expr (Let b e) = get_changes_bind b $$ get_changes_expr e
754 get_changes_expr (Case e b a) = get_changes_expr e $$ get_changes_var b $$ vcat (map get_changes_alt a)
756 get_changes_alt (con,bs,rhs) = {- vcat (map get_changes_var bs) $$ -} get_changes_expr rhs
759 | new_better && old_better = empty
760 | new_better = message "BETTER"
761 | old_better = message "WORSE"
762 | otherwise = message "INCOMPARABLE"
764 message word = text word <+> text "strictness for" <+> ppr id <+> info
765 info = (text "Old" <+> ppr old) $$ (text "New" <+> ppr new)
766 new = squashDmdEnv (idNewStrictness id) -- Don't report diffs in the env
767 old = newStrictnessFromOld id
768 old_better = old `betterStrict` new
769 new_better = new `betterStrict` old
772 | isUnLiftedType (idType id) = empty -- Not useful
773 | new_better && old_better = empty
774 | new_better = message "BETTER"
775 | old_better = message "WORSE"
776 | otherwise = message "INCOMPARABLE"
778 message word = text word <+> text "demand for" <+> ppr id <+> info
779 info = (text "Old" <+> ppr old) $$ (text "New" <+> ppr new)
780 new = lazify (idNewDemandInfo id) -- Lazify to avoid spurious improvements
781 old = newDemand (idDemandInfo id)
782 new_better = new `betterDemand` old
783 old_better = old `betterDemand` new