2 % (c) The AQUA Project, Glasgow University, 1993-1998
4 \section[SimplMonad]{The simplifier Monad}
8 InId, InBind, InExpr, InAlt, InArg, InType, InBinder,
9 OutId, OutBind, OutExpr, OutAlt, OutArg, OutType, OutBinder,
10 OutExprStuff, OutStuff,
12 -- The continuation type
13 SimplCont(..), DupFlag(..), contIsDupable, contResultType,
14 contIsInteresting, pushArgs, discardCont, countValArgs, countArgs,
15 contIsInline, discardInlineCont,
19 initSmpl, returnSmpl, thenSmpl, thenSmpl_,
20 mapSmpl, mapAndUnzipSmpl, mapAccumLSmpl,
22 -- The inlining black-list
26 getUniqueSmpl, getUniquesSmpl,
30 SimplCount, Tick(..), TickCounts,
32 getSimplCount, zeroSimplCount, pprSimplCount,
33 plusSimplCount, isZeroSimplCount,
36 SwitchChecker, getSwitchChecker, getSimplIntSwitch,
39 getEnclosingCC, setEnclosingCC,
43 getSubstEnv, extendSubst, extendSubstList,
44 getInScope, setInScope, extendInScope, extendInScopes, modifyInScope,
45 setSubstEnv, zapSubstEnv,
46 getSimplBinderStuff, setSimplBinderStuff,
50 #include "HsVersions.h"
52 import Const ( Con(DEFAULT) )
53 import Id ( Id, mkSysLocal, idMustBeINLINEd )
54 import IdInfo ( InlinePragInfo(..) )
55 import Demand ( Demand )
57 import PprCore () -- Instances
58 import Rules ( RuleBase )
59 import CostCentre ( CostCentreStack, subsumedCCS )
63 import qualified Subst
64 import Subst ( Subst, emptySubst, mkSubst,
66 InScopeSet, substInScope, isInScope, lookupInScope
68 import Type ( Type, TyVarSubst, applyTy )
69 import UniqSupply ( uniqsFromSupply, uniqFromSupply, splitUniqSupply,
73 import CmdLineOpts ( SimplifierSwitch(..), SwitchResult(..),
74 opt_PprStyle_Debug, opt_HistorySize,
77 import Unique ( Unique )
78 import Maybes ( expectJust )
79 import Util ( zipWithEqual )
82 infixr 9 `thenSmpl`, `thenSmpl_`
85 %************************************************************************
87 \subsection[Simplify-types]{Type declarations}
89 %************************************************************************
92 type InBinder = CoreBndr
93 type InId = Id -- Not yet cloned
94 type InType = Type -- Ditto
95 type InBind = CoreBind
96 type InExpr = CoreExpr
100 type OutBinder = CoreBndr
101 type OutId = Id -- Cloned
102 type OutType = Type -- Cloned
103 type OutBind = CoreBind
104 type OutExpr = CoreExpr
105 type OutAlt = CoreAlt
106 type OutArg = CoreArg
108 type SwitchChecker = SimplifierSwitch -> SwitchResult
112 %************************************************************************
114 \subsection{The continuation data type}
116 %************************************************************************
119 type OutExprStuff = OutStuff (InScopeSet, OutExpr)
120 type OutStuff a = ([OutBind], a)
121 -- We return something equivalent to (let b in e), but
122 -- in pieces to avoid the quadratic blowup when floating
123 -- incrementally. Comments just before simplExprB in Simplify.lhs
125 data SimplCont -- Strict contexts
126 = Stop OutType -- Type of the result
128 | CoerceIt OutType -- The To-type, simplified
131 | InlinePlease -- This continuation makes a function very
132 SimplCont -- keen to inline itelf
135 InExpr SubstEnv -- The argument, as yet unsimplified,
136 SimplCont -- and its subst-env
139 InId [InAlt] SubstEnv -- The case binder, alts, and subst-env
142 | ArgOf DupFlag -- An arbitrary strict context: the argument
143 -- of a strict function, or a primitive-arg fn
145 OutType -- The type of the expression being sought by the context
146 -- f (error "foo") ==> coerce t (error "foo")
148 -- We need to know the type t, to which to coerce.
149 (OutExpr -> SimplM OutExprStuff) -- What to do with the result
151 instance Outputable SimplCont where
152 ppr (Stop _) = ptext SLIT("Stop")
153 ppr (ApplyTo dup arg se cont) = (ptext SLIT("ApplyTo") <+> ppr dup <+> ppr arg) $$ ppr cont
154 ppr (ArgOf dup _ _) = ptext SLIT("ArgOf...") <+> ppr dup
155 ppr (Select dup bndr alts se cont) = (ptext SLIT("Select") <+> ppr dup <+> ppr bndr) $$
156 (nest 4 (ppr alts)) $$ ppr cont
157 ppr (CoerceIt ty cont) = (ptext SLIT("CoerceIt") <+> ppr ty) $$ ppr cont
158 ppr (InlinePlease cont) = ptext SLIT("InlinePlease") $$ ppr cont
160 data DupFlag = OkToDup | NoDup
162 instance Outputable DupFlag where
163 ppr OkToDup = ptext SLIT("ok")
164 ppr NoDup = ptext SLIT("nodup")
166 contIsDupable :: SimplCont -> Bool
167 contIsDupable (Stop _) = True
168 contIsDupable (ApplyTo OkToDup _ _ _) = True
169 contIsDupable (ArgOf OkToDup _ _) = True
170 contIsDupable (Select OkToDup _ _ _ _) = True
171 contIsDupable (CoerceIt _ cont) = contIsDupable cont
172 contIsDupable (InlinePlease cont) = contIsDupable cont
173 contIsDupable other = False
175 contIsInline :: SimplCont -> Bool
176 contIsInline (InlinePlease cont) = True
177 contIsInline other = False
179 discardInlineCont :: SimplCont -> SimplCont
180 discardInlineCont (InlinePlease cont) = cont
181 discardInlineCont cont = cont
185 Comment about contIsInteresting
186 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
187 We want to avoid inlining an expression where there can't possibly be
188 any gain, such as in an argument position. Hence, if the continuation
189 is interesting (eg. a case scrutinee, application etc.) then we
190 inline, otherwise we don't.
192 Previously some_benefit used to return True only if the variable was
193 applied to some value arguments. This didn't work:
195 let x = _coerce_ (T Int) Int (I# 3) in
196 case _coerce_ Int (T Int) x of
199 we want to inline x, but can't see that it's a constructor in a case
200 scrutinee position, and some_benefit is False.
204 dMonadST = _/\_ t -> :Monad (g1 _@_ t, g2 _@_ t, g3 _@_ t)
206 .... case dMonadST _@_ x0 of (a,b,c) -> ....
208 we'd really like to inline dMonadST here, but we *don't* want to
209 inline if the case expression is just
211 case x of y { DEFAULT -> ... }
213 since we can just eliminate this case instead (x is in WHNF). Similar
214 applies when x is bound to a lambda expression. Hence
215 contIsInteresting looks for case expressions with just a single
219 contIsInteresting :: SimplCont -> Bool
220 contIsInteresting (Select _ _ alts _ _) = not (just_default alts)
221 contIsInteresting (CoerceIt _ cont) = contIsInteresting cont
222 contIsInteresting (ApplyTo _ (Type _) _ cont) = contIsInteresting cont
223 contIsInteresting (ApplyTo _ _ _ _) = True
224 contIsInteresting (ArgOf _ _ _) = True
225 -- If this call is the arg of a strict function, the context
226 -- is a bit interesting. If we inline here, we may get useful
227 -- evaluation information to avoid repeated evals: e.g.
229 -- Here the contIsInteresting makes the '*' keener to inline,
230 -- which in turn exposes a constructor which makes the '+' inline.
231 -- Assuming that +,* aren't small enough to inline regardless.
232 contIsInteresting (InlinePlease _) = True
233 contIsInteresting other = False
235 just_default [(DEFAULT,_,_)] = True -- See notes below for why we look
236 just_default alts = False -- for this special case
241 pushArgs :: SubstEnv -> [InExpr] -> SimplCont -> SimplCont
242 pushArgs se [] cont = cont
243 pushArgs se (arg:args) cont = ApplyTo NoDup arg se (pushArgs se args cont)
245 discardCont :: SimplCont -- A continuation, expecting
246 -> SimplCont -- Replace the continuation with a suitable coerce
247 discardCont (Stop to_ty) = Stop to_ty
248 discardCont cont = CoerceIt to_ty (Stop to_ty)
250 to_ty = contResultType cont
252 contResultType :: SimplCont -> OutType
253 contResultType (Stop to_ty) = to_ty
254 contResultType (ArgOf _ to_ty _) = to_ty
255 contResultType (ApplyTo _ _ _ cont) = contResultType cont
256 contResultType (CoerceIt _ cont) = contResultType cont
257 contResultType (InlinePlease cont) = contResultType cont
258 contResultType (Select _ _ _ _ cont) = contResultType cont
260 countValArgs :: SimplCont -> Int
261 countValArgs (ApplyTo _ (Type ty) se cont) = countValArgs cont
262 countValArgs (ApplyTo _ val_arg se cont) = 1 + countValArgs cont
263 countValArgs other = 0
265 countArgs :: SimplCont -> Int
266 countArgs (ApplyTo _ arg se cont) = 1 + countArgs cont
271 %************************************************************************
273 \subsection{Monad plumbing}
275 %************************************************************************
277 For the simplifier monad, we want to {\em thread} a unique supply and a counter.
278 (Command-line switches move around through the explicitly-passed SimplEnv.)
281 type SimplM result -- We thread the unique supply because
282 = SimplEnv -- constantly splitting it is rather expensive
285 -> (result, UniqSupply, SimplCount)
289 seChkr :: SwitchChecker,
290 seCC :: CostCentreStack, -- The enclosing CCS (when profiling)
291 seBlackList :: Id -> Bool, -- True => don't inline this Id
292 seSubst :: Subst -- The current substitution
294 -- The range of the substitution is OutType and OutExpr resp
296 -- The substitution is idempotent
297 -- It *must* be applied; things in its domain simply aren't
298 -- bound in the result.
300 -- The substitution usually maps an Id to its clone,
301 -- but if the orig defn is a let-binding, and
302 -- the RHS of the let simplifies to an atom,
303 -- we just add the binding to the substitution and elide the let.
305 -- The in-scope part of Subst includes *all* in-scope TyVars and Ids
306 -- The elements of the set may have better IdInfo than the
307 -- occurrences of in-scope Ids, and (more important) they will
308 -- have a correctly-substituted type. So we use a lookup in this
309 -- set to replace occurrences
313 initSmpl :: SwitchChecker
314 -> UniqSupply -- No init count; set to 0
315 -> VarSet -- In scope (usually empty, but useful for nested calls)
316 -> (Id -> Bool) -- Black-list function
320 initSmpl chkr us in_scope black_list m
321 = case m (emptySimplEnv chkr in_scope black_list) us zeroSimplCount of
322 (result, _, count) -> (result, count)
325 {-# INLINE thenSmpl #-}
326 {-# INLINE thenSmpl_ #-}
327 {-# INLINE returnSmpl #-}
329 returnSmpl :: a -> SimplM a
330 returnSmpl e env us sc = (e, us, sc)
332 thenSmpl :: SimplM a -> (a -> SimplM b) -> SimplM b
333 thenSmpl_ :: SimplM a -> SimplM b -> SimplM b
335 thenSmpl m k env us0 sc0
336 = case (m env us0 sc0) of
337 (m_result, us1, sc1) -> k m_result env us1 sc1
339 thenSmpl_ m k env us0 sc0
340 = case (m env us0 sc0) of
341 (_, us1, sc1) -> k env us1 sc1
346 mapSmpl :: (a -> SimplM b) -> [a] -> SimplM [b]
347 mapAndUnzipSmpl :: (a -> SimplM (b, c)) -> [a] -> SimplM ([b],[c])
349 mapSmpl f [] = returnSmpl []
351 = f x `thenSmpl` \ x' ->
352 mapSmpl f xs `thenSmpl` \ xs' ->
355 mapAndUnzipSmpl f [] = returnSmpl ([],[])
356 mapAndUnzipSmpl f (x:xs)
357 = f x `thenSmpl` \ (r1, r2) ->
358 mapAndUnzipSmpl f xs `thenSmpl` \ (rs1, rs2) ->
359 returnSmpl (r1:rs1, r2:rs2)
361 mapAccumLSmpl f acc [] = returnSmpl (acc, [])
362 mapAccumLSmpl f acc (x:xs) = f acc x `thenSmpl` \ (acc', x') ->
363 mapAccumLSmpl f acc' xs `thenSmpl` \ (acc'', xs') ->
364 returnSmpl (acc'', x':xs')
368 %************************************************************************
370 \subsection{The unique supply}
372 %************************************************************************
375 getUniqueSmpl :: SimplM Unique
376 getUniqueSmpl env us sc = case splitUniqSupply us of
377 (us1, us2) -> (uniqFromSupply us1, us2, sc)
379 getUniquesSmpl :: Int -> SimplM [Unique]
380 getUniquesSmpl n env us sc = case splitUniqSupply us of
381 (us1, us2) -> (uniqsFromSupply n us1, us2, sc)
385 %************************************************************************
387 \subsection{Counting up what we've done}
389 %************************************************************************
392 getSimplCount :: SimplM SimplCount
393 getSimplCount env us sc = (sc, us, sc)
395 tick :: Tick -> SimplM ()
396 tick t env us sc = sc' `seq` ((), us, sc')
400 freeTick :: Tick -> SimplM ()
401 -- Record a tick, but don't add to the total tick count, which is
402 -- used to decide when nothing further has happened
403 freeTick t env us sc = sc' `seq` ((), us, sc')
405 sc' = doFreeTick t sc
409 verboseSimplStats = opt_PprStyle_Debug -- For now, anyway
411 -- Defined both with and without debugging
412 zeroSimplCount :: SimplCount
413 isZeroSimplCount :: SimplCount -> Bool
414 pprSimplCount :: SimplCount -> SDoc
415 doTick, doFreeTick :: Tick -> SimplCount -> SimplCount
416 plusSimplCount :: SimplCount -> SimplCount -> SimplCount
421 ----------------------------------------------------------
423 ----------------------------------------------------------
424 type SimplCount = Int
426 zeroSimplCount :: SimplCount
429 isZeroSimplCount n = n==0
431 doTick t n = n+1 -- Very basic when not debugging
432 doFreeTick t n = n -- Don't count leaf visits
434 pprSimplCount n = ptext SLIT("Total ticks:") <+> int n
436 plusSimplCount n m = n+m
439 ----------------------------------------------------------
441 ----------------------------------------------------------
443 data SimplCount = SimplCount {
444 ticks :: !Int, -- Total ticks
445 details :: !TickCounts, -- How many of each type
447 log1 :: [Tick], -- Last N events; <= opt_HistorySize
448 log2 :: [Tick] -- Last opt_HistorySize events before that
451 type TickCounts = FiniteMap Tick Int
453 zeroSimplCount = SimplCount {ticks = 0, details = emptyFM,
454 n_log = 0, log1 = [], log2 = []}
456 isZeroSimplCount sc = ticks sc == 0
458 doFreeTick tick sc@SimplCount { details = dts }
459 = dts' `seqFM` sc { details = dts' }
461 dts' = dts `addTick` tick
463 -- Gross hack to persuade GHC 3.03 to do this important seq
464 seqFM fm x | isEmptyFM fm = x
467 doTick tick sc@SimplCount { ticks = tks, details = dts, n_log = nl, log1 = l1, log2 = l2 }
468 | nl >= opt_HistorySize = sc1 { n_log = 1, log1 = [tick], log2 = l1 }
469 | otherwise = sc1 { n_log = nl+1, log1 = tick : l1 }
471 sc1 = sc { ticks = tks+1, details = dts `addTick` tick }
473 -- Don't use plusFM_C because that's lazy, and we want to
474 -- be pretty strict here!
475 addTick :: TickCounts -> Tick -> TickCounts
476 addTick fm tick = case lookupFM fm tick of
477 Nothing -> addToFM fm tick 1
478 Just n -> n1 `seq` addToFM fm tick n1
482 plusSimplCount sc1@(SimplCount { ticks = tks1, details = dts1 })
483 sc2@(SimplCount { ticks = tks2, details = dts2 })
484 = log_base { ticks = tks1 + tks2, details = plusFM_C (+) dts1 dts2 }
486 -- A hackish way of getting recent log info
487 log_base | null (log1 sc2) = sc1 -- Nothing at all in sc2
488 | null (log2 sc2) = sc2 { log2 = log1 sc1 }
492 pprSimplCount (SimplCount { ticks = tks, details = dts, log1 = l1, log2 = l2 })
493 = vcat [ptext SLIT("Total ticks: ") <+> int tks,
495 pprTickCounts (fmToList dts),
496 if verboseSimplStats then
498 ptext SLIT("Log (most recent first)"),
499 nest 4 (vcat (map ppr l1) $$ vcat (map ppr l2))]
503 pprTickCounts :: [(Tick,Int)] -> SDoc
504 pprTickCounts [] = empty
505 pprTickCounts ((tick1,n1):ticks)
506 = vcat [int tot_n <+> text (tickString tick1),
507 pprTCDetails real_these,
511 tick1_tag = tickToTag tick1
512 (these, others) = span same_tick ticks
513 real_these = (tick1,n1):these
514 same_tick (tick2,_) = tickToTag tick2 == tick1_tag
515 tot_n = sum [n | (_,n) <- real_these]
517 pprTCDetails ticks@((tick,_):_)
518 | verboseSimplStats || isRuleFired tick
519 = nest 4 (vcat [int n <+> pprTickCts tick | (tick,n) <- ticks])
525 %************************************************************************
529 %************************************************************************
533 = PreInlineUnconditionally Id
534 | PostInlineUnconditionally Id
537 | RuleFired FAST_STRING -- Rule name
539 | LetFloatFromLet Id -- Thing floated out
540 | EtaExpansion Id -- LHS binder
541 | EtaReduction Id -- Binder on outer lambda
542 | BetaReduction Id -- Lambda binder
545 | CaseOfCase Id -- Bndr on *inner* case
546 | KnownBranch Id -- Case binder
547 | CaseMerge Id -- Binder on outer case
548 | CaseElim Id -- Case binder
549 | CaseIdentity Id -- Case binder
550 | FillInCaseDefault Id -- Case binder
554 | SimplifierDone -- Ticked at each iteration of the simplifier
556 isRuleFired (RuleFired _) = True
557 isRuleFired other = False
559 instance Outputable Tick where
560 ppr tick = text (tickString tick) <+> pprTickCts tick
562 instance Eq Tick where
563 a == b = case a `cmpTick` b of { EQ -> True; other -> False }
565 instance Ord Tick where
568 tickToTag :: Tick -> Int
569 tickToTag (PreInlineUnconditionally _) = 0
570 tickToTag (PostInlineUnconditionally _) = 1
571 tickToTag (UnfoldingDone _) = 2
572 tickToTag (RuleFired _) = 3
573 tickToTag (LetFloatFromLet _) = 4
574 tickToTag (EtaExpansion _) = 5
575 tickToTag (EtaReduction _) = 6
576 tickToTag (BetaReduction _) = 7
577 tickToTag (CaseOfCase _) = 8
578 tickToTag (KnownBranch _) = 9
579 tickToTag (CaseMerge _) = 10
580 tickToTag (CaseElim _) = 11
581 tickToTag (CaseIdentity _) = 12
582 tickToTag (FillInCaseDefault _) = 13
583 tickToTag BottomFound = 14
584 tickToTag LeafVisit = 15
585 tickToTag SimplifierDone = 16
587 tickString :: Tick -> String
588 tickString (PreInlineUnconditionally _) = "PreInlineUnconditionally"
589 tickString (PostInlineUnconditionally _)= "PostInlineUnconditionally"
590 tickString (UnfoldingDone _) = "UnfoldingDone"
591 tickString (RuleFired _) = "RuleFired"
592 tickString (LetFloatFromLet _) = "LetFloatFromLet"
593 tickString (EtaExpansion _) = "EtaExpansion"
594 tickString (EtaReduction _) = "EtaReduction"
595 tickString (BetaReduction _) = "BetaReduction"
596 tickString (CaseOfCase _) = "CaseOfCase"
597 tickString (KnownBranch _) = "KnownBranch"
598 tickString (CaseMerge _) = "CaseMerge"
599 tickString (CaseElim _) = "CaseElim"
600 tickString (CaseIdentity _) = "CaseIdentity"
601 tickString (FillInCaseDefault _) = "FillInCaseDefault"
602 tickString BottomFound = "BottomFound"
603 tickString SimplifierDone = "SimplifierDone"
604 tickString LeafVisit = "LeafVisit"
606 pprTickCts :: Tick -> SDoc
607 pprTickCts (PreInlineUnconditionally v) = ppr v
608 pprTickCts (PostInlineUnconditionally v)= ppr v
609 pprTickCts (UnfoldingDone v) = ppr v
610 pprTickCts (RuleFired v) = ppr v
611 pprTickCts (LetFloatFromLet v) = ppr v
612 pprTickCts (EtaExpansion v) = ppr v
613 pprTickCts (EtaReduction v) = ppr v
614 pprTickCts (BetaReduction v) = ppr v
615 pprTickCts (CaseOfCase v) = ppr v
616 pprTickCts (KnownBranch v) = ppr v
617 pprTickCts (CaseMerge v) = ppr v
618 pprTickCts (CaseElim v) = ppr v
619 pprTickCts (CaseIdentity v) = ppr v
620 pprTickCts (FillInCaseDefault v) = ppr v
621 pprTickCts other = empty
623 cmpTick :: Tick -> Tick -> Ordering
624 cmpTick a b = case (tickToTag a `compare` tickToTag b) of
626 EQ | isRuleFired a || verboseSimplStats -> cmpEqTick a b
629 -- Always distinguish RuleFired, so that the stats
630 -- can report them even in non-verbose mode
632 cmpEqTick :: Tick -> Tick -> Ordering
633 cmpEqTick (PreInlineUnconditionally a) (PreInlineUnconditionally b) = a `compare` b
634 cmpEqTick (PostInlineUnconditionally a) (PostInlineUnconditionally b) = a `compare` b
635 cmpEqTick (UnfoldingDone a) (UnfoldingDone b) = a `compare` b
636 cmpEqTick (RuleFired a) (RuleFired b) = a `compare` b
637 cmpEqTick (LetFloatFromLet a) (LetFloatFromLet b) = a `compare` b
638 cmpEqTick (EtaExpansion a) (EtaExpansion b) = a `compare` b
639 cmpEqTick (EtaReduction a) (EtaReduction b) = a `compare` b
640 cmpEqTick (BetaReduction a) (BetaReduction b) = a `compare` b
641 cmpEqTick (CaseOfCase a) (CaseOfCase b) = a `compare` b
642 cmpEqTick (KnownBranch a) (KnownBranch b) = a `compare` b
643 cmpEqTick (CaseMerge a) (CaseMerge b) = a `compare` b
644 cmpEqTick (CaseElim a) (CaseElim b) = a `compare` b
645 cmpEqTick (CaseIdentity a) (CaseIdentity b) = a `compare` b
646 cmpEqTick (FillInCaseDefault a) (FillInCaseDefault b) = a `compare` b
647 cmpEqTick other1 other2 = EQ
651 %************************************************************************
653 \subsubsection{Command-line switches}
655 %************************************************************************
658 getSwitchChecker :: SimplM SwitchChecker
659 getSwitchChecker env us sc = (seChkr env, us, sc)
661 getSimplIntSwitch :: SwitchChecker -> (Int-> SimplifierSwitch) -> Int
662 getSimplIntSwitch chkr switch
663 = expectJust "getSimplIntSwitch" (intSwitchSet chkr switch)
667 @switchOffInlining@ is used to prepare the environment for simplifying
668 the RHS of an Id that's marked with an INLINE pragma. It is going to
669 be inlined wherever they are used, and then all the inlining will take
670 effect. Meanwhile, there isn't much point in doing anything to the
671 as-yet-un-INLINEd rhs. Furthremore, it's very important to switch off
673 (a) not doing so will inline a worker straight back into its wrapper!
675 and (b) Consider the following example
680 in ...g...g...g...g...g...
682 Now, if that's the ONLY occurrence of f, it will be inlined inside g,
683 and thence copied multiple times when g is inlined.
685 Andy disagrees! Example:
686 all xs = foldr (&&) True xs
687 any p = all . map p {-# INLINE any #-}
689 Problem: any won't get deforested, and so if it's exported and
690 the importer doesn't use the inlining, (eg passes it as an arg)
691 then we won't get deforestation at all.
692 We havn't solved this problem yet!
694 We prepare the envt by simply modifying the in_scope_env, which has all the
695 unfolding info. At one point we did it by modifying the chkr so that
696 it said "EssentialUnfoldingsOnly", but that prevented legitmate, and
697 important, simplifications happening in the body of the RHS.
701 We *don't* prevent inlining from happening for identifiers
702 that are marked as IMustBeINLINEd. An example of where
703 doing this is crucial is:
705 class Bar a => Foo a where
711 If `f' needs to peer inside Foo's superclass, Bar, it refers
712 to the appropriate super class selector, which is marked as
713 must-inlineable. We don't generate any code for a superclass
714 selector, so failing to inline it in the RHS of `f' will
715 leave a reference to a non-existent id, with bad consequences.
717 ALSO NOTE that we do all this by modifing the inline-pragma,
718 not by zapping the unfolding. The latter may still be useful for
719 knowing when something is evaluated.
721 June 98 update: I've gone back to dealing with this by adding
722 the EssentialUnfoldingsOnly switch. That doesn't stop essential
723 unfoldings, nor inlineUnconditionally stuff; and the thing's going
724 to be inlined at every call site anyway. Running over the whole
725 environment seems like wild overkill.
728 switchOffInlining :: SimplM a -> SimplM a
729 switchOffInlining m env us sc
730 = m (env { seBlackList = \v -> True }) us sc
734 %************************************************************************
736 \subsubsection{The ``enclosing cost-centre''}
738 %************************************************************************
741 getEnclosingCC :: SimplM CostCentreStack
742 getEnclosingCC env us sc = (seCC env, us, sc)
744 setEnclosingCC :: CostCentreStack -> SimplM a -> SimplM a
745 setEnclosingCC cc m env us sc = m (env { seCC = cc }) us sc
749 %************************************************************************
751 \subsubsection{The @SimplEnv@ type}
753 %************************************************************************
757 emptySimplEnv :: SwitchChecker -> InScopeSet -> (Id -> Bool) -> SimplEnv
759 emptySimplEnv sw_chkr in_scope black_list
760 = SimplEnv { seChkr = sw_chkr, seCC = subsumedCCS,
761 seBlackList = black_list,
762 seSubst = mkSubst in_scope emptySubstEnv }
763 -- The top level "enclosing CC" is "SUBSUMED".
765 getSubst :: SimplM Subst
766 getSubst env us sc = (seSubst env, us, sc)
768 getBlackList :: SimplM (Id -> Bool)
769 getBlackList env us sc = (seBlackList env, us, sc)
771 setSubst :: Subst -> SimplM a -> SimplM a
772 setSubst subst m env us sc = m (env {seSubst = subst}) us sc
774 getSubstEnv :: SimplM SubstEnv
775 getSubstEnv env us sc = (substEnv (seSubst env), us, sc)
777 extendInScope :: CoreBndr -> SimplM a -> SimplM a
778 extendInScope v m env@(SimplEnv {seSubst = subst}) us sc
779 = m (env {seSubst = Subst.extendInScope subst v}) us sc
781 extendInScopes :: [CoreBndr] -> SimplM a -> SimplM a
782 extendInScopes vs m env@(SimplEnv {seSubst = subst}) us sc
783 = m (env {seSubst = Subst.extendInScopes subst vs}) us sc
785 getInScope :: SimplM InScopeSet
786 getInScope env us sc = (substInScope (seSubst env), us, sc)
788 setInScope :: InScopeSet -> SimplM a -> SimplM a
789 setInScope in_scope m env@(SimplEnv {seSubst = subst}) us sc
790 = m (env {seSubst = Subst.setInScope subst in_scope}) us sc
792 modifyInScope :: CoreBndr -> SimplM a -> SimplM a
793 modifyInScope v m env us sc
795 | not (v `isInScope` seSubst env)
796 = pprTrace "modifyInScope: not in scope:" (ppr v)
800 = extendInScope v m env us sc
802 extendSubst :: CoreBndr -> SubstResult -> SimplM a -> SimplM a
803 extendSubst var res m env@(SimplEnv {seSubst = subst}) us sc
804 = m (env { seSubst = Subst.extendSubst subst var res }) us sc
806 extendSubstList :: [CoreBndr] -> [SubstResult] -> SimplM a -> SimplM a
807 extendSubstList vars ress m env@(SimplEnv {seSubst = subst}) us sc
808 = m (env { seSubst = Subst.extendSubstList subst vars ress }) us sc
810 setSubstEnv :: SubstEnv -> SimplM a -> SimplM a
811 setSubstEnv senv m env@(SimplEnv {seSubst = subst}) us sc
812 = m (env {seSubst = Subst.setSubstEnv subst senv}) us sc
814 zapSubstEnv :: SimplM a -> SimplM a
815 zapSubstEnv m env@(SimplEnv {seSubst = subst}) us sc
816 = m (env {seSubst = Subst.zapSubstEnv subst}) us sc
818 getSimplBinderStuff :: SimplM (Subst, UniqSupply)
819 getSimplBinderStuff (SimplEnv {seSubst = subst}) us sc
820 = ((subst, us), us, sc)
822 setSimplBinderStuff :: (Subst, UniqSupply) -> SimplM a -> SimplM a
823 setSimplBinderStuff (subst, us) m env _ sc
824 = m (env {seSubst = subst}) us sc
829 newId :: Type -> (Id -> SimplM a) -> SimplM a
830 -- Extends the in-scope-env too
831 newId ty m env@(SimplEnv {seSubst = subst}) us sc
832 = case splitUniqSupply us of
833 (us1, us2) -> m v (env {seSubst = Subst.extendInScope subst v}) us2 sc
835 v = mkSysLocal SLIT("s") (uniqFromSupply us1) ty
837 newIds :: [Type] -> ([Id] -> SimplM a) -> SimplM a
838 newIds tys m env@(SimplEnv {seSubst = subst}) us sc
839 = case splitUniqSupply us of
840 (us1, us2) -> m vs (env {seSubst = Subst.extendInScopes subst vs}) us2 sc
842 vs = zipWithEqual "newIds" (mkSysLocal SLIT("s"))
843 (uniqsFromSupply (length tys) us1) tys