2 % (c) The GRASP/AQUA Project, Glasgow University, 1993-1995
4 \section[Specialise]{Stamping out overloading, and (optionally) polymorphism}
7 #include "HsVersions.h"
22 import Outputable -- ToDo: these may be removable...
25 import AbsPrel ( liftDataCon, PrimOp(..), PrimKind -- for CCallOp
26 IF_ATTACK_PRAGMAS(COMMA tagOf_PrimOp)
27 IF_ATTACK_PRAGMAS(COMMA pprPrimOp)
31 import CmdLineOpts ( GlobalSwitch(..) )
32 import CoreLift ( mkLiftedId, liftExpr, bindUnlift, applyBindUnlifts )
36 import IdInfo -- All of it
37 import InstEnv ( lookupClassInstAtSimpleType )
38 import Maybes ( catMaybes, firstJust, maybeToBool, Maybe(..) )
39 import TyVarEnv -- ( growTyVarEnvList, nullTyVarEnv, TyVarEnv, TypeEnv(..) )
40 import UniqSet -- All of it
47 %************************************************************************
49 \subsection[notes-Specialise]{Implementation notes [SLPJ, Aug 18 1993]}
51 %************************************************************************
53 These notes describe how we implement specialisation to eliminate
54 overloading, and optionally to eliminate unboxed polymorphism, and
57 The specialisation pass is a partial evaluator which works on Core
58 syntax, complete with all the explicit dictionary application,
59 abstraction and construction as added by the type checker. The
60 existing type checker remains largely as it is.
62 One important thought: the {\em types} passed to an overloaded
63 function, and the {\em dictionaries} passed are mutually redundant.
64 If the same function is applied to the same type(s) then it is sure to
65 be applied to the same dictionary(s)---or rather to the same {\em
66 values}. (The arguments might look different but they will evaluate
69 Second important thought: we know that we can make progress by
70 treating dictionary arguments as static and worth specialising on. So
71 we can do without binding-time analysis, and instead specialise on
72 dictionary arguments and no others.
81 and suppose f is overloaded.
83 STEP 1: CALL-INSTANCE COLLECTION
85 We traverse <body>, accumulating all applications of f to types and
88 (Might there be partial applications, to just some of its types and
89 dictionaries? In principle yes, but in practice the type checker only
90 builds applications of f to all its types and dictionaries, so partial
91 applications could only arise as a result of transformation, and even
92 then I think it's unlikely. In any case, we simply don't accumulate such
93 partial applications.)
95 There's a choice of whether to collect details of all *polymorphic* functions
96 or simply all *overloaded* ones. How to sort this out?
97 Pass in a predicate on the function to say if it is "interesting"?
98 This is dependent on the user flags: SpecialiseOverloaded
104 So now we have a collection of calls to f:
108 Notice that f may take several type arguments. To avoid ambiguity, we
109 say that f is called at type t1/t2 and t3/t4.
111 We take equivalence classes using equality of the *types* (ignoring
112 the dictionary args, which as mentioned previously are redundant).
114 STEP 3: SPECIALISATION
116 For each equivalence class, choose a representative (f t1 t2 d1 d2),
117 and create a local instance of f, defined thus:
119 f@t1/t2 = <f_rhs> t1 t2 d1 d2
121 (f_rhs presumably has some big lambdas and dictionary lambdas, so lots
122 of simplification will now result.) Then we should recursively do
125 The new id has its own unique, but its print-name (if exported) has
126 an explicit representation of the instance types t1/t2.
128 Add this new id to f's IdInfo, to record that f has a specialised version.
130 Before doing any of this, check that f's IdInfo doesn't already
131 tell us about an existing instance of f at the required type/s.
132 (This might happen if specialisation was applied more than once, or
133 it might arise from user SPECIALIZE pragmas.)
137 Wait a minute! What if f is recursive? Then we can't just plug in
138 its right-hand side, can we?
140 But it's ok. The type checker *always* creates non-recursive definitions
141 for overloaded recursive functions. For example:
143 f x = f (x+x) -- Yes I know its silly
147 f a (d::Num a) = let p = +.sel a d
149 letrec fl (y::a) = fl (p y y)
153 We still have recusion for non-overloadd functions which we
154 speciailise, but the recursive call should get speciailised to the
155 same recursive version.
161 All this is crystal clear when the function is applied to *constant
162 types*; that is, types which have no type variables inside. But what if
163 it is applied to non-constant types? Suppose we find a call of f at type
164 t1/t2. There are two possibilities:
166 (a) The free type variables of t1, t2 are in scope at the definition point
167 of f. In this case there's no problem, we proceed just as before. A common
168 example is as follows. Here's the Haskell:
173 After typechecking we have
175 g a (d::Num a) (y::a) = let f b (d'::Num b) (x::b) = +.sel b d' x x
176 in +.sel a d (f a d y) (f a d y)
178 Notice that the call to f is at type type "a"; a non-constant type.
179 Both calls to f are at the same type, so we can specialise to give:
181 g a (d::Num a) (y::a) = let f@a (x::a) = +.sel a d x x
182 in +.sel a d (f@a y) (f@a y)
185 (b) The other case is when the type variables in the instance types
186 are *not* in scope at the definition point of f. The example we are
187 working with above is a good case. There are two instances of (+.sel a d),
188 but "a" is not in scope at the definition of +.sel. Can we do anything?
189 Yes, we can "common them up", a sort of limited common sub-expression deal.
192 g a (d::Num a) (y::a) = let +.sel@a = +.sel a d
193 f@a (x::a) = +.sel@a x x
194 in +.sel@a (f@a y) (f@a y)
196 This can save work, and can't be spotted by the type checker, because
197 the two instances of +.sel weren't originally at the same type.
201 * There are quite a few variations here. For example, the defn of
202 +.sel could be floated ouside the \y, to attempt to gain laziness.
203 It certainly mustn't be floated outside the \d because the d has to
206 * We don't want to inline f_rhs in this case, because
207 that will duplicate code. Just commoning up the call is the point.
209 * Nothing gets added to +.sel's IdInfo.
211 * Don't bother unless the equivalence class has more than one item!
213 Not clear whether this is all worth it. It is of course OK to
214 simply discard call-instances when passing a big lambda.
216 Polymorphism 2 -- Overloading
218 Consider a function whose most general type is
220 f :: forall a b. Ord a => [a] -> b -> b
222 There is really no point in making a version of g at Int/Int and another
223 at Int/Bool, because it's only instancing the type variable "a" which
224 buys us any efficiency. Since g is completely polymorphic in b there
225 ain't much point in making separate versions of g for the different
228 That suggests that we should identify which of g's type variables
229 are constrained (like "a") and which are unconstrained (like "b").
230 Then when taking equivalence classes in STEP 2, we ignore the type args
231 corresponding to unconstrained type variable. In STEP 3 we make
232 polymorphic versions. Thus:
234 f@t1/ = /\b -> <f_rhs> t1 b d1 d2
236 This seems pretty simple, and a Good Thing.
238 Polymorphism 3 -- Unboxed
241 If we are speciailising at unboxed types we must speciailise
242 regardless of the overloading constraint. In the exaple above it is
243 worth speciailising at types Int/Int#, Int/Bool# and a/Int#, Int#/Int#
246 Note that specialising an overloaded type at an uboxed type requires
247 an unboxed instance -- we cannot default to an unspecialised version!
254 f x = let g p q = p==q
260 Before specialisation, leaving out type abstractions we have
262 f df x = let g :: Eq a => a -> a -> Bool
264 h :: Num a => a -> a -> (a, Bool)
265 h dh r s = let deq = eqFromNum dh
266 in (+ dh r s, g deq r s)
270 After specialising h we get a specialised version of h, like this:
272 h' r s = let deq = eqFromNum df
273 in (+ df r s, g deq r s)
275 But we can't naively make an instance for g from this, because deq is not in scope
276 at the defn of g. Instead, we have to float out the (new) defn of deq
277 to widen its scope. Notice that this floating can't be done in advance -- it only
278 shows up when specialisation is done.
280 DELICATE MATTER: the way we tell a dictionary binding is by looking to
281 see if it has a Dict type. If the type has been "undictify'd", so that
282 it looks like a tuple, then the dictionary binding won't be floated, and
283 an opportunity to specialise might be lost.
285 User SPECIALIZE pragmas
286 ~~~~~~~~~~~~~~~~~~~~~~~
287 Specialisation pragmas can be digested by the type checker, and implemented
288 by adding extra definitions along with that of f, in the same way as before
290 f@t1/t2 = <f_rhs> t1 t2 d1 d2
292 Indeed the pragmas *have* to be dealt with by the type checker, because
293 only it knows how to build the dictionaries d1 and d2! For example
295 g :: Ord a => [a] -> [a]
296 {-# SPECIALIZE f :: [Tree Int] -> [Tree Int] #-}
298 Here, the specialised version of g is an application of g's rhs to the
299 Ord dictionary for (Tree Int), which only the type checker can conjure
300 up. There might not even *be* one, if (Tree Int) is not an instance of
301 Ord! (All the other specialision has suitable dictionaries to hand
304 Problem. The type checker doesn't have to hand a convenient <f_rhs>, because
305 it is buried in a complex (as-yet-un-desugared) binding group.
308 f@t1/t2 = f* t1 t2 d1 d2
310 where f* is the Id f with an IdInfo which says "inline me regardless!".
311 Indeed all the specialisation could be done in this way.
312 That in turn means that the simplifier has to be prepared to inline absolutely
313 any in-scope let-bound thing.
316 Again, the pragma should permit polymorphism in unconstrained variables:
318 h :: Ord a => [a] -> b -> b
319 {-# SPECIALIZE h :: [Int] -> b -> b #-}
321 We *insist* that all overloaded type variables are specialised to ground types,
322 (and hence there can be no context inside a SPECIALIZE pragma).
323 We *permit* unconstrained type variables to be specialised to
325 - or left as a polymorphic type variable
326 but nothing in between. So
328 {-# SPECIALIZE h :: [Int] -> [c] -> [c] #-}
330 is *illegal*. (It can be handled, but it adds complication, and gains the
334 SPECIALISING INSTANCE DECLARATIONS
335 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
338 instance Foo a => Foo [a] where
340 {-# SPECIALIZE instance Foo [Int] #-}
342 The original instance decl creates a dictionary-function
345 dfun.Foo.List :: forall a. Foo a -> Foo [a]
347 The SPECIALIZE pragma just makes a specialised copy, just as for
348 ordinary function definitions:
350 dfun.Foo.List@Int :: Foo [Int]
351 dfun.Foo.List@Int = dfun.Foo.List Int dFooInt
353 The information about what instance of the dfun exist gets added to
354 the dfun's IdInfo in the same way as a user-defined function too.
356 In fact, matters are a little bit more complicated than this.
357 When we make one of these specialised instances, we are defining
358 a constant dictionary, and so we want immediate access to its constant
359 methods and superclasses. Indeed, these constant methods and superclasses
360 must be in the IdInfo for the class selectors! We need help from the
361 typechecker to sort this out, perhaps by generating a separate IdInfo
364 Automatic instance decl specialisation?
365 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
366 Can instance decls be specialised automatically? It's tricky.
367 We could collect call-instance information for each dfun, but
368 then when we specialised their bodies we'd get new call-instances
369 for ordinary functions; and when we specialised their bodies, we might get
370 new call-instances of the dfuns, and so on. This all arises because of
371 the unrestricted mutual recursion between instance decls and value decls.
373 Furthermore, instance decls are usually exported and used non-locally,
374 so we'll want to compile enough to get those specialisations done.
376 Lastly, there's no such thing as a local instance decl, so we can
377 survive solely by spitting out *usage* information, and then reading that
378 back in as a pragma when next compiling the file. So for now,
379 we only specialise instance decls in response to pragmas.
381 That means that even if an instance decl ain't otherwise exported it
382 needs to be spat out as with a SPECIALIZE pragma. Furthermore, it needs
383 something to say which module defined the instance, so the usage info
384 can be fed into the right reqts info file. Blegh.
387 SPECIAILISING DATA DECLARATIONS
388 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
390 With unboxed specialisation (or full specialisation) we also require
391 data types (and their constructors) to be speciailised on unboxed
394 In addition to normal call instances we gather TyCon call instances at
395 unboxed types, determine equivalence classes for the locally defined
396 TyCons and build speciailised data constructor Ids for each TyCon and
397 substitute these in the CoCon calls.
399 We need the list of local TyCons to partition the TyCon instance info.
400 We pass out a FiniteMap from local TyCons to Specialised Instances to
401 give to the interface and code genertors.
403 N.B. The specialised data constructors reference the original data
404 constructor and type constructor which do not have the updated
405 specialisation info attached. Any specialisation info must be
406 extracted from the TyCon map returned.
409 SPITTING OUT USAGE INFORMATION
410 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
412 To spit out usage information we need to traverse the code collecting
413 call-instance information for all imported (non-prelude?) functions
414 and data types. Then we equivalence-class it and spit it out.
416 This is done at the top-level when all the call instances which escape
417 must be for imported functions and data types.
420 Partial specialisation by pragmas
421 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
422 What about partial specialisation:
424 k :: (Ord a, Eq b) => [a] -> b -> b -> [a]
425 {-# SPECIALIZE k :: Eq b => [Int] -> b -> b -> [a] #-}
429 {-# SPECIALIZE k :: Eq b => [Int] -> [b] -> [b] -> [a] #-}
431 Seems quite reasonable. Similar things could be done with instance decls:
433 instance (Foo a, Foo b) => Foo (a,b) where
435 {-# SPECIALIZE instance Foo a => Foo (a,Int) #-}
436 {-# SPECIALIZE instance Foo b => Foo (Int,b) #-}
438 Ho hum. Things are complex enough without this. I pass.
441 Requirements for the simplifer
442 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
443 The simplifier has to be able to take advantage of the specialisation.
445 * When the simplifier finds an application of a polymorphic f, it looks in
446 f's IdInfo in case there is a suitable instance to call instead. This converts
448 f t1 t2 d1 d2 ===> f_t1_t2
450 Note that the dictionaries get eaten up too!
452 * Dictionary selection operations on constant dictionaries must be
455 +.sel Int d ===> +Int
457 The obvious way to do this is in the same way as other specialised
458 calls: +.sel has inside it some IdInfo which tells that if it's applied
459 to the type Int then it should eat a dictionary and transform to +Int.
461 In short, dictionary selectors need IdInfo inside them for constant
464 * Exactly the same applies if a superclass dictionary is being
467 Eq.sel Int d ===> dEqInt
469 * Something similar applies to dictionary construction too. Suppose
470 dfun.Eq.List is the function taking a dictionary for (Eq a) to
471 one for (Eq [a]). Then we want
473 dfun.Eq.List Int d ===> dEq.List_Int
475 Where does the Eq [Int] dictionary come from? It is built in
476 response to a SPECIALIZE pragma on the Eq [a] instance decl.
478 In short, dfun Ids need IdInfo with a specialisation for each
479 constant instance of their instance declaration.
482 What does the specialisation IdInfo look like?
483 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
486 [Maybe UniType] -- Instance types
487 Int -- No of dicts to eat
488 Id -- Specialised version
490 For example, if f has this SpecInfo:
492 SpecInfo [Just t1, Nothing, Just t3] 2 f'
496 f t1 t2 t3 d1 d2 ===> f t2
498 The "Nothings" identify type arguments in which the specialised
499 version is polymorphic.
501 What can't be done this way?
502 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
503 There is no way, post-typechecker, to get a dictionary for (say)
504 Eq a from a dictionary for Eq [a]. So if we find
508 we can't transform to
513 eqList :: (a->a->Bool) -> [a] -> [a] -> Bool
515 Of course, we currently have no way to automatically derive
516 eqList, nor to connect it to the Eq [a] instance decl, but you
517 can imagine that it might somehow be possible. Taking advantage
518 of this is permanently ruled out.
520 Still, this is no great hardship, because we intend to eliminate
521 overloading altogether anyway!
526 What about types/classes mentioned in SPECIALIZE pragmas spat out,
527 but not otherwise exported. Even if they are exported, what about
528 their original names.
530 Suggestion: use qualified names in pragmas, omitting module for
531 prelude and "this module".
538 f a (d::Num a) = let g = ...
540 ...(let d1::Ord a = Num.Ord.sel a d in g a d1)...
542 Here, g is only called at one type, but the dictionary isn't in scope at the
543 definition point for g. Usually the type checker would build a
544 definition for d1 which enclosed g, but the transformation system
545 might have moved d1's defn inward.
551 What should we do when a value is specialised to a *strict* unboxed value?
553 map_*_* f (x:xs) = let h = f x
557 Could convert let to case:
559 map_*_Int# f (x:xs) = case f x of h# ->
563 This may be undesirable since it forces evaluation here, but the value
564 may not be used in all branches of the body. In the general case this
565 transformation is impossible since the mutual recursion in a letrec
566 cannot be expressed as a case.
568 There is also a problem with top-level unboxed values, since our
569 implementation cannot handle unboxed values at the top level.
571 Solution: Lift the binding of the unboxed value and extract it when it
574 map_*_Int# f (x:xs) = let h = case (f x) of h# -> _Lift h#
579 Now give it to the simplifier and the _Lifting will be optimised away.
581 The benfit is that we have given the specialised "unboxed" values a
582 very simple lifted semantics and then leave it up to the simplifier to
583 optimise it --- knowing that the overheads will be removed in nearly
586 In particular, the value will only be evaluted in the branches of the
587 program which use it, rather than being forced at the point where the
588 value is bound. For example:
590 filtermap_*_* p f (x:xs)
597 filtermap_*_Int# p f (x:xs)
598 = let h = case (f x) of h# -> _Lift h#
601 True -> case h of _Lift h#
605 The binding for h can still be inlined in the one branch and the
609 Question: When won't the _Lifting be eliminated?
611 Answer: When they at the top-level (where it is necessary) or when
612 inlining would duplicate work (or possibly code depending on
613 options). However, the _Lifting will still be eliminated if the
614 strictness analyser deems the lifted binding strict.
618 %************************************************************************
620 \subsubsection[CallInstances]{@CallInstances@ data type}
622 %************************************************************************
625 type FreeVarsSet = UniqSet Id
626 type FreeTyVarsSet = UniqSet TyVar
630 Id -- This Id; *new* ie *cloned* id
631 [Maybe UniType] -- Specialised at these types (*new*, cloned)
632 -- Nothing => no specialisation on this type arg
633 -- is required (flag dependent).
634 [PlainCoreArg] -- And these dictionaries; all ValArgs
635 FreeVarsSet -- Free vars of the dict-args in terms of *new* ids
636 (Maybe SpecInfo) -- For specialisation with explicit SpecId
640 pprCI :: CallInstance -> Pretty
641 pprCI (CallInstance id spec_tys dicts _ maybe_specinfo)
642 = ppHang (ppCat [ppStr "Call inst for", ppr PprDebug id])
643 4 (ppAboves [ppCat (ppStr "types" : [pprMaybeTy PprDebug ty | ty <- spec_tys]),
644 case maybe_specinfo of
645 Nothing -> ppCat (ppStr "dicts" : [ppr PprDebug dict | dict <- dicts])
646 Just (SpecInfo _ _ spec_id)
647 -> ppCat [ppStr "Explicit SpecId", ppr PprDebug spec_id]
650 isUnboxedCI :: CallInstance -> Bool
651 isUnboxedCI (CallInstance _ spec_tys _ _ _)
652 = any isUnboxedDataType (catMaybes spec_tys)
654 isExplicitCI :: CallInstance -> Bool
655 isExplicitCI (CallInstance _ _ _ _ (Just _))
657 isExplicitCI (CallInstance _ _ _ _ Nothing)
661 Comparisons are based on the {\em types}, ignoring the dictionary args:
665 cmpCI :: CallInstance -> CallInstance -> TAG_
666 cmpCI (CallInstance id1 tys1 _ _ _) (CallInstance id2 tys2 _ _ _)
667 = case cmpId id1 id2 of { EQ_ -> cmpUniTypeMaybeList tys1 tys2; other -> other }
669 cmpCI_tys :: CallInstance -> CallInstance -> TAG_
670 cmpCI_tys (CallInstance _ tys1 _ _ _) (CallInstance _ tys2 _ _ _)
671 = cmpUniTypeMaybeList tys1 tys2
673 eqCI_tys :: CallInstance -> CallInstance -> Bool
675 = case cmpCI_tys c1 c2 of { EQ_ -> True; other -> False }
677 isCIofTheseIds :: [Id] -> CallInstance -> Bool
678 isCIofTheseIds ids (CallInstance ci_id _ _ _ _)
679 = any (eqId ci_id) ids
681 singleCI :: Id -> [Maybe UniType] -> [PlainCoreArg] -> UsageDetails
682 singleCI id tys dicts
683 = UsageDetails (unitBag (CallInstance id tys dicts fv_set Nothing))
684 emptyBag [] emptyUniqSet 0 0
686 fv_set = mkUniqSet (id : [dict | ValArg (CoVarAtom dict) <- dicts])
688 explicitCI :: Id -> [Maybe UniType] -> SpecInfo -> UsageDetails
689 explicitCI id tys specinfo
690 = UsageDetails (unitBag call_inst) emptyBag [] emptyUniqSet 0 0
692 call_inst = CallInstance id tys dicts fv_set (Just specinfo)
693 dicts = panic "Specialise:explicitCI:dicts"
694 fv_set = singletonUniqSet id
696 -- We do not process the CIs for top-level dfuns or defms
697 -- Instead we require an explicit SPEC inst pragma for dfuns
698 -- and an explict method within any instances for the defms
700 getCIids :: Bool -> [Id] -> [Id]
701 getCIids True ids = filter not_dict_or_defm ids
705 = not (isDictTy (getIdUniType id) || maybeToBool (isDefaultMethodId_maybe id))
707 getCIs :: Bool -> [Id] -> UsageDetails -> ([CallInstance], UsageDetails)
708 getCIs top_lev ids (UsageDetails cis tycon_cis dbs fvs c i)
710 (cis_here, cis_not_here) = partitionBag (isCIofTheseIds (getCIids top_lev ids)) cis
711 cis_here_list = bagToList cis_here
713 -- pprTrace "getCIs:"
714 -- (ppHang (ppBesides [ppStr "{", ppr PprDebug ids, ppStr "}"])
715 -- 4 (ppAboves (map pprCI cis_here_list)))
716 (cis_here_list, UsageDetails cis_not_here tycon_cis dbs fvs c i)
718 dumpCIs :: Bag CallInstance -- The call instances
719 -> Bool -- True <=> top level bound Ids
720 -> Bool -- True <=> dict bindings to be floated (specBind only)
721 -> [CallInstance] -- Call insts for bound ids (instBind only)
722 -> [Id] -- Bound ids *new*
723 -> [Id] -- Full bound ids: includes dumped dicts
724 -> Bag CallInstance -- Kept call instances
726 -- CIs are dumped if:
727 -- 1) they are a CI for one of the bound ids, or
728 -- 2) they mention any of the dicts in a local unfloated binding
730 -- For top-level bindings we allow the call instances to
731 -- float past a dict bind and place all the top-level binds
732 -- in a *global* CoRec.
733 -- We leave it to the simplifier will sort it all out ...
735 dumpCIs cis top_lev floating inst_cis bound_ids full_ids
736 = (if not (isEmptyBag cis_of_bound_id) &&
737 not (isEmptyBag cis_of_bound_id_without_inst_cis)
739 pprTrace ("dumpCIs: dumping CI which was not instantiated ... \n" ++
740 " (may be a non-HM recursive call)\n")
741 (ppHang (ppBesides [ppStr "{", ppr PprDebug bound_ids, ppStr "}"])
742 4 (ppAboves [ppStr "Dumping CIs:",
743 ppAboves (map pprCI (bagToList cis_of_bound_id)),
744 ppStr "Instantiating CIs:",
745 ppAboves (map pprCI inst_cis)]))
747 if top_lev || floating then
750 (if not (isEmptyBag cis_dump_unboxed)
751 then pprTrace "dumpCIs: bound dictionary arg ... WITH UNBOXED TYPES!\n"
752 (ppHang (ppBesides [ppStr "{", ppr PprDebug full_ids, ppStr "}"])
753 4 (ppAboves (map pprCI (bagToList cis_dump))))
755 cis_keep_not_bound_id
758 (cis_of_bound_id, cis_not_bound_id)
759 = partitionBag (isCIofTheseIds (getCIids top_lev bound_ids)) cis
761 (cis_dump, cis_keep_not_bound_id)
762 = partitionBag ok_to_dump_ci cis_not_bound_id
764 ok_to_dump_ci (CallInstance _ _ _ fv_set _)
765 = or [i `elementOfUniqSet` fv_set | i <- full_ids]
767 (_, cis_of_bound_id_without_inst_cis) = partitionBag have_inst_ci cis_of_bound_id
768 have_inst_ci ci = any (eqCI_tys ci) inst_cis
770 (cis_dump_unboxed, _) = partitionBag isUnboxedCI cis_dump
774 Any call instances of a bound_id can be safely dumped, because any
775 recursive calls should be at the same instance as the parent instance.
777 letrec f = /\a -> \x::a -> ...(f t x')...
779 Here, the type, t, at which f is used in its own RHS should be
780 just "a"; that is, the recursive call is at the same type as
781 the original call. That means that when specialising f at some
782 type, say Int#, we shouldn't find any *new* instances of f
783 arising from specialising f's RHS. The only instance we'll find
784 is another call of (f Int#).
786 We check this in dumpCIs by passing in all the instantiated call
787 instances (inst_cis) and reporting any dumped cis (cis_of_bound_id)
788 for which there is no such instance.
790 We also report CIs dumped due to a bound dictionary arg if they
791 contain unboxed types.
793 %************************************************************************
795 \subsubsection[TyConInstances]{@TyConInstances@ data type}
797 %************************************************************************
801 = TyConInstance TyCon -- Type Constructor
802 [Maybe UniType] -- Applied to these specialising types
804 cmpTyConI :: TyConInstance -> TyConInstance -> TAG_
805 cmpTyConI (TyConInstance tc1 tys1) (TyConInstance tc2 tys2)
806 = case cmpTyCon tc1 tc2 of { EQ_ -> cmpUniTypeMaybeList tys1 tys2; other -> other }
808 cmpTyConI_tys :: TyConInstance -> TyConInstance -> TAG_
809 cmpTyConI_tys (TyConInstance _ tys1) (TyConInstance _ tys2)
810 = cmpUniTypeMaybeList tys1 tys2
812 singleTyConI :: TyCon -> [Maybe UniType] -> UsageDetails
813 singleTyConI ty_con spec_tys
814 = UsageDetails emptyBag (unitBag (TyConInstance ty_con spec_tys)) [] emptyUniqSet 0 0
816 isTyConIofThisTyCon :: TyCon -> TyConInstance -> Bool
817 isTyConIofThisTyCon ty_con (TyConInstance inst_ty_con _) = eqTyCon ty_con inst_ty_con
819 isLocalSpecTyConI :: Bool -> TyConInstance -> Bool
820 isLocalSpecTyConI comp_prel (TyConInstance inst_ty_con _) = isLocalSpecTyCon comp_prel inst_ty_con
822 getLocalSpecTyConIs :: Bool -> UsageDetails -> ([TyConInstance], UsageDetails)
823 getLocalSpecTyConIs comp_prel (UsageDetails cis tycon_cis dbs fvs c i)
825 (tycon_cis_local, tycon_cis_global)
826 = partitionBag (isLocalSpecTyConI comp_prel) tycon_cis
827 tycon_cis_local_list = bagToList tycon_cis_local
829 (tycon_cis_local_list, UsageDetails cis tycon_cis_global dbs fvs c i)
833 %************************************************************************
835 \subsubsection[UsageDetails]{@UsageDetails@ data type}
837 %************************************************************************
842 (Bag CallInstance) -- The collection of call-instances
843 (Bag TyConInstance) -- Constructor call-instances
844 [DictBindDetails] -- Dictionary bindings in data-dependence order!
845 FreeVarsSet -- Free variables (excl imported ones, incl top level) (cloned)
846 Int -- no. of spec calls
847 Int -- no. of spec insts
850 The DictBindDetails are fully processed; their call-instance information is
851 incorporated in the call-instances of the
852 UsageDetails which includes the DictBindDetails. The free vars in a usage details
853 will *include* the binders of the DictBind details.
855 A @DictBindDetails@ contains bindings for dictionaries *only*.
860 [Id] -- Main binders, originally visible in scope of binding (cloned)
861 PlainCoreBinding -- Fully processed
862 FreeVarsSet -- Free in binding group (cloned)
863 FreeTyVarsSet -- Free in binding group
867 emptyUDs :: UsageDetails
868 unionUDs :: UsageDetails -> UsageDetails -> UsageDetails
869 unionUDList :: [UsageDetails] -> UsageDetails
871 tickSpecCall :: Bool -> UsageDetails -> UsageDetails
872 tickSpecInsts :: UsageDetails -> UsageDetails
874 tickSpecCall found (UsageDetails cis ty_cis dbs fvs c i)
875 = UsageDetails cis ty_cis dbs fvs (c + (if found then 1 else 0)) i
877 tickSpecInsts (UsageDetails cis ty_cis dbs fvs c i)
878 = UsageDetails cis ty_cis dbs fvs c (i+1)
880 emptyUDs = UsageDetails emptyBag emptyBag [] emptyUniqSet 0 0
882 unionUDs (UsageDetails cis1 tycon_cis1 dbs1 fvs1 c1 i1) (UsageDetails cis2 tycon_cis2 dbs2 fvs2 c2 i2)
883 = UsageDetails (unionBags cis1 cis2) (unionBags tycon_cis1 tycon_cis2)
884 (dbs1 ++ dbs2) (fvs1 `unionUniqSets` fvs2) (c1+c2) (i1+i2)
885 -- The append here is really redundant, since the bindings don't
886 -- scope over each other. ToDo.
888 unionUDList = foldr unionUDs emptyUDs
890 singleFvUDs (CoVarAtom v) | not (isImportedId v)
891 = UsageDetails emptyBag emptyBag [] (singletonUniqSet v) 0 0
895 singleConUDs con = UsageDetails emptyBag emptyBag [] (singletonUniqSet con) 0 0
897 dumpDBs :: [DictBindDetails]
898 -> Bool -- True <=> top level bound Ids
899 -> [TyVar] -- TyVars being bound (cloned)
900 -> [Id] -- Ids being bound (cloned)
901 -> FreeVarsSet -- Fvs of body
902 -> ([PlainCoreBinding], -- These ones have to go here
903 [DictBindDetails], -- These can float further
904 [Id], -- Incoming list + names of dicts bound here
905 FreeVarsSet -- Incoming fvs + fvs of dicts bound here
908 -- It is just to complex to try to float top-level
909 -- dict bindings with constant methods, inst methods,
910 -- auxillary derived instance defns and user instance
911 -- defns all getting in the way.
912 -- So we dump all dbinds as soon as we get to the top
913 -- level and place them in a *global* CoRec.
914 -- We leave it to the simplifier will sort it all out ...
916 dumpDBs [] top_lev bound_tyvars bound_ids fvs
917 = ([], [], bound_ids, fvs)
919 dumpDBs ((db@(DictBindDetails dbinders dbind db_fvs db_ftv)):dbs)
920 top_lev bound_tyvars bound_ids fvs
922 || or [i `elementOfUniqSet` db_fvs | i <- bound_ids]
923 || or [tv `elementOfUniqSet` db_ftv | tv <- bound_tyvars]
924 = let -- Ha! Dump it!
925 (dbinds_here, dbs_outer, full_bound_ids, full_fvs)
926 = dumpDBs dbs top_lev bound_tyvars (dbinders ++ bound_ids) (db_fvs `unionUniqSets` fvs)
928 (dbind : dbinds_here, dbs_outer, full_bound_ids, full_fvs)
930 | otherwise -- This one can float out further
932 (dbinds_here, dbs_outer, full_bound_ids, full_fvs)
933 = dumpDBs dbs top_lev bound_tyvars bound_ids fvs
935 (dbinds_here, db : dbs_outer, full_bound_ids, full_fvs)
939 dumpUDs :: UsageDetails
940 -> Bool -- True <=> top level bound Ids
941 -> Bool -- True <=> dict bindings to be floated (specBind only)
942 -> [CallInstance] -- Call insts for bound Ids (instBind only)
943 -> [Id] -- Ids which are just being bound; *new*
944 -> [TyVar] -- TyVars which are just being bound
945 -> ([PlainCoreBinding], -- Bindings from UsageDetails which mention the ids
946 UsageDetails) -- The above bindings removed, and
947 -- any call-instances which mention the ids dumped too
949 dumpUDs (UsageDetails cis tycon_cis dbs fvs c i) top_lev floating inst_cis bound_ids tvs
951 (dict_binds_here, dbs_outer, full_bound_ids, full_fvs)
952 = dumpDBs dbs top_lev tvs bound_ids fvs
953 cis_outer = dumpCIs cis top_lev floating inst_cis bound_ids full_bound_ids
954 fvs_outer = full_fvs `minusUniqSet` (mkUniqSet full_bound_ids)
956 (dict_binds_here, UsageDetails cis_outer tycon_cis dbs_outer fvs_outer c i)
960 addDictBinds :: [Id] -> PlainCoreBinding -> UsageDetails -- Dict binding and RHS usage
961 -> UsageDetails -- The usage to augment
963 addDictBinds dbinders dbind (UsageDetails db_cis db_tycon_cis db_dbs db_fvs db_c db_i)
964 (UsageDetails cis tycon_cis dbs fvs c i)
965 = UsageDetails (db_cis `unionBags` cis)
966 (db_tycon_cis `unionBags` tycon_cis)
967 (db_dbs ++ [DictBindDetails dbinders dbind db_fvs db_ftvs] ++ dbs)
969 -- NB: We ignore counts from dictbinds since it is not user code
971 -- The free tyvars of the dictionary bindings should really be
972 -- gotten from the RHSs, but I'm pretty sure it's good enough just
973 -- to look at the type of the dictionary itself.
974 -- Doing the proper job would entail keeping track of free tyvars as
975 -- well as free vars, which would be a bore.
976 db_ftvs = mkUniqSet (extractTyVarsFromTys (map getIdUniType dbinders))
979 %************************************************************************
981 \subsection[cloning-binders]{The Specialising IdEnv and CloneInfo}
983 %************************************************************************
985 @SpecIdEnv@ maps old Ids to their new "clone". There are three cases:
987 1) (NoLift CoLitAtom l) : an Id which is bound to a literal
989 2) (NoLift CoLitAtom l) : an Id bound to a "new" Id
990 The new Id is a possibly-type-specialised clone of the original
992 3) Lifted lifted_id unlifted_id :
994 This indicates that the original Id has been specialised to an
995 unboxed value which must be lifted (see "Unboxed bindings" above)
996 @unlifted_id@ is the unboxed clone of the original Id
997 @lifted_id@ is a *lifted* version of the original Id
999 When you lookup Ids which are Lifted, you have to insert a case
1000 expression to un-lift the value (done with @bindUnlift@)
1002 You also have to insert a case to lift the value in the binding
1003 (done with @liftExpr@)
1007 type SpecIdEnv = IdEnv CloneInfo
1010 = NoLift PlainCoreAtom -- refers to cloned id or literal
1012 | Lifted Id -- lifted, cloned id
1013 Id -- unlifted, cloned id
1017 %************************************************************************
1019 \subsection[specialise-data]{Data returned by specialiser}
1021 %************************************************************************
1026 -- True <=> Specialisation performed
1028 -- False <=> Specialisation completed with errors
1031 -- Local tycons declared in this module
1034 -- Those in-scope data types for which we want to
1035 -- generate code for their constructors.
1036 -- Namely: data types declared in this module +
1037 -- any big tuples used in this module
1038 -- The initial (and default) value is the local tycons
1040 (FiniteMap TyCon [(Bool, [Maybe UniType])])
1041 -- TyCon specialisations to be generated
1042 -- We generate specialialised code (Bool=True) for data types
1043 -- defined in this module and any tuples used in this module
1044 -- The initial (and default) value is the specialisations
1045 -- requested by source-level SPECIALIZE data pragmas (Bool=True)
1046 -- and _SPECIALISE_ pragmas (Bool=False) in the interface files
1048 (Bag (Id,[Maybe UniType]))
1049 -- Imported specialisation errors
1050 (Bag (Id,[Maybe UniType]))
1051 -- Imported specialisation warnings
1052 (Bag (TyCon,[Maybe UniType]))
1053 -- Imported TyCon specialisation errors
1055 initSpecData local_tycons tycon_specs
1056 = SpecData False True local_tycons local_tycons tycon_specs emptyBag emptyBag emptyBag
1059 ToDo[sansom]: Transformation data to process specialisation requests.
1061 %************************************************************************
1063 \subsection[specProgram]{Specialising a core program}
1065 %************************************************************************
1068 specProgram :: (GlobalSwitch -> Bool)
1070 -> [PlainCoreBinding] -- input ...
1072 -> ([PlainCoreBinding], -- main result
1073 SpecialiseData) -- result specialise data
1075 specProgram sw_chker uniqs binds
1076 (SpecData False _ local_tycons _ init_specs init_errs init_warn init_tyerrs)
1077 = case (initSM (specTyConsAndScope (specTopBinds binds)) sw_chker uniqs) of
1078 (final_binds, tycon_specs_list,
1079 UsageDetails import_cis import_tycis _ fvs spec_calls spec_insts)
1081 used_conids = filter isDataCon (uniqSetToList fvs)
1082 used_tycons = map getDataConTyCon used_conids
1083 used_gen = filter isLocalGenTyCon used_tycons
1084 gen_tycons = setToList (mkSet local_tycons `union` mkSet used_gen)
1086 result_specs = addListToFM_C (++) init_specs tycon_specs_list
1088 uniq_cis = map head (equivClasses cmpCI (bagToList import_cis))
1089 cis_list = [(id, tys) | CallInstance id tys _ _ _ <- uniq_cis]
1090 (cis_unboxed, cis_other) = partition (isUnboxedSpecialisation . snd) cis_list
1091 cis_warn = init_warn `unionBags` listToBag cis_other
1092 cis_errs = init_errs `unionBags` listToBag cis_unboxed
1094 uniq_tycis = map head (equivClasses cmpTyConI (bagToList import_tycis))
1095 tycis_unboxed = [(con, tys) | TyConInstance con tys <- uniq_tycis]
1096 tycis_errs = init_tyerrs `unionBags` listToBag tycis_unboxed
1098 no_errs = isEmptyBag cis_errs && isEmptyBag tycis_errs
1099 && (not (sw_chker SpecialiseImports) || isEmptyBag cis_warn)
1101 (if sw_chker D_simplifier_stats then
1102 pprTrace "\nSpecialiser Stats:\n" (ppAboves [
1103 ppBesides [ppStr "SpecCalls ", ppInt spec_calls],
1104 ppBesides [ppStr "SpecInsts ", ppInt spec_insts],
1109 SpecData True no_errs local_tycons gen_tycons result_specs
1110 cis_errs cis_warn tycis_errs)
1112 specProgram sw_chker uniqs binds (SpecData True _ _ _ _ _ _ _)
1113 = panic "Specialise:specProgram: specialiser called more than once"
1115 -- It may be possible safely to call the specialiser more than once,
1116 -- but I am not sure there is any benefit in doing so (Patrick)
1118 -- ToDo: What about unfoldings performed after specialisation ???
1121 %************************************************************************
1123 \subsection[specTyConsAndScope]{Specialising data constructors within tycons}
1125 %************************************************************************
1127 In the specialiser we just collect up the specialisations which will
1128 be required. We don't create the specialised constructors in
1129 Core. These are only introduced when we convert to StgSyn.
1131 ToDo: Perhaps this collection should be done in CoreToStg to ensure no inconsistencies!
1134 specTyConsAndScope :: SpecM ([PlainCoreBinding], UsageDetails)
1135 -> SpecM ([PlainCoreBinding], [(TyCon,[(Bool,[Maybe UniType])])], UsageDetails)
1137 specTyConsAndScope scopeM
1138 = scopeM `thenSM` \ (binds, scope_uds) ->
1139 getSwitchCheckerSM `thenSM` \ sw_chkr ->
1141 (tycons_cis, gotci_scope_uds)
1142 = getLocalSpecTyConIs (sw_chkr CompilingPrelude) scope_uds
1144 tycon_specs_list = collectTyConSpecs tycons_cis
1146 (if sw_chkr SpecialiseTrace && not (null tycon_specs_list) then
1147 pprTrace "Specialising TyCons:\n"
1148 (ppAboves [ if not (null specs) then
1149 ppHang (ppCat [(ppr PprDebug tycon), ppStr "at types"])
1150 4 (ppAboves (map pp_specs specs))
1152 | (tycon, specs) <- tycon_specs_list])
1154 returnSM (binds, tycon_specs_list, gotci_scope_uds)
1157 collectTyConSpecs []
1159 collectTyConSpecs tycons_cis@(TyConInstance tycon _ : _)
1160 = (tycon, tycon_specs) : collectTyConSpecs other_tycons_cis
1162 (tycon_cis, other_tycons_cis) = partition (isTyConIofThisTyCon tycon) tycons_cis
1163 uniq_cis = map head (equivClasses cmpTyConI_tys tycon_cis)
1164 tycon_specs = [(False, spec_tys) | TyConInstance _ spec_tys <- uniq_cis]
1166 pp_specs (False, spec_tys) = ppInterleave ppNil [pprMaybeTy PprDebug spec_ty | spec_ty <- spec_tys]
1170 %************************************************************************
1172 \subsection[specTopBinds]{Specialising top-level bindings}
1174 %************************************************************************
1177 specTopBinds :: [PlainCoreBinding]
1178 -> SpecM ([PlainCoreBinding], UsageDetails)
1181 = spec_top_binds binds `thenSM` \ (binds, UsageDetails cis tycis dbind_details fvs c i) ->
1183 -- Add bindings for floated dbinds and collect fvs
1184 -- In actual fact many of these bindings are dead code since dict
1185 -- arguments are dropped when a specialised call is created
1186 -- The simplifier should be able to cope ...
1188 (dbinders_s, dbinds, dfvs_s)
1189 = unzip3 [(dbinders, dbind, dfvs) | DictBindDetails dbinders dbind dfvs _ <- dbind_details]
1191 full_fvs = fvs `unionUniqSets` unionManyUniqSets dfvs_s
1192 fvs_outer = full_fvs `minusUniqSet` (mkUniqSet (concat dbinders_s))
1194 -- It is just to complex to try to sort out top-level dependencies
1195 -- So we just place all the top-level binds in a *global* CoRec and
1196 -- leave it to the simplifier to sort it all out ...
1199 returnSM ([CoRec (pairsFromCoreBinds binds)], UsageDetails cis tycis [] fvs_outer c i)
1202 spec_top_binds (first_bind:rest_binds)
1203 = specBindAndScope True first_bind (
1204 spec_top_binds rest_binds `thenSM` \ (rest_binds, rest_uds) ->
1205 returnSM (ItsABinds rest_binds, rest_uds)
1206 ) `thenSM` \ (first_binds, ItsABinds rest_binds, all_uds) ->
1207 returnSM (first_binds ++ rest_binds, all_uds)
1210 = returnSM ([], emptyUDs)
1213 %************************************************************************
1215 \subsection[specExpr]{Specialising expressions}
1217 %************************************************************************
1220 specExpr :: PlainCoreExpr
1221 -> [PlainCoreArg] -- The arguments:
1222 -- TypeArgs are speced
1223 -- ValArgs are unprocessed
1224 -> SpecM (PlainCoreExpr, -- Result expression with specialised versions installed
1225 UsageDetails) -- Details of usage of enclosing binders in the result
1228 specExpr (CoVar v) args
1229 = lookupId v `thenSM` \ vlookup ->
1232 -> -- Binding has been lifted, need to extract un-lifted value
1233 -- NB: a function binding will never be lifted => args always null
1234 -- i.e. no call instance required or call to be constructed
1236 returnSM (bindUnlift vl vu (CoVar vu), singleFvUDs (CoVarAtom vl))
1238 NoLift vatom@(CoVarAtom new_v)
1239 -> mapSM specArg args `thenSM` \ arg_info ->
1240 mkCallInstance v new_v arg_info `thenSM` \ call_uds ->
1241 mkCall new_v arg_info `thenSM` \ ~(speced, call) ->
1243 uds = unionUDList [call_uds,
1245 unionUDList [uds | (_,uds,_) <- arg_info]
1248 returnSM (call, tickSpecCall speced uds)
1250 specExpr expr@(CoLit _) null_args
1251 = ASSERT (null null_args)
1252 returnSM (expr, emptyUDs)
1254 specExpr (CoCon con tys args) null_args
1255 = ASSERT (null null_args)
1256 mapSM specTy tys `thenSM` \ tys ->
1257 mapAndUnzip3SM specAtom args `thenSM` \ (args, args_uds_s, unlifts) ->
1258 mkTyConInstance con tys `thenSM` \ con_uds ->
1259 returnSM (applyBindUnlifts unlifts (CoCon con tys args),
1260 unionUDList args_uds_s `unionUDs` con_uds)
1262 specExpr (CoPrim op@(CCallOp str is_asm may_gc arg_tys res_ty) tys args) null_args
1263 = ASSERT (null null_args)
1265 mapSM specTy arg_tys `thenSM` \ arg_tys ->
1266 specTy res_ty `thenSM` \ res_ty ->
1267 mapAndUnzip3SM specAtom args `thenSM` \ (args, args_uds_s, unlifts) ->
1268 returnSM (applyBindUnlifts unlifts (CoPrim (CCallOp str is_asm may_gc arg_tys res_ty) tys args),
1269 unionUDList args_uds_s)
1271 specExpr (CoPrim prim tys args) null_args
1272 = ASSERT (null null_args)
1273 mapSM specTy tys `thenSM` \ tys ->
1274 mapAndUnzip3SM specAtom args `thenSM` \ (args, args_uds_s, unlifts) ->
1275 -- specPrimOp prim tys `thenSM` \ (prim, tys, prim_uds) ->
1276 returnSM (applyBindUnlifts unlifts (CoPrim prim tys args),
1277 unionUDList args_uds_s {-`unionUDs` prim_uds-} )
1281 specPrimOp :: PrimOp
1287 -- Checks that PrimOp can handle (possibly unboxed) tys passed
1288 -- and/or chooses PrimOp specialised to any unboxed tys
1289 -- Errors are dealt with by returning a PrimOp call instance
1290 -- which will result in a cis_errs message
1292 -- ToDo: Deal with checkSpecTyApp for CoPrim in CoreLint
1296 specExpr (CoApp fun arg) args
1297 = -- Arg is passed on unprocessed
1298 specExpr fun (ValArg arg : args) `thenSM` \ (expr,uds) ->
1299 returnSM (expr, uds)
1301 specExpr (CoTyApp fun ty) args
1302 = -- Spec the tyarg and pass it on
1303 specTy ty `thenSM` \ ty ->
1304 specExpr fun (TypeArg ty : args)
1306 specExpr (CoLam bound_ids body) args
1307 = specLam bound_ids body args
1309 specExpr (CoTyLam tyvar body) (TypeArg ty : args)
1310 = -- Type lambda with argument; argument already spec'd
1311 bindTyVar tyvar ty (
1315 specExpr (CoTyLam tyvar body) []
1317 cloneTyVarSM tyvar `thenSM` \ new_tyvar ->
1318 bindTyVar tyvar (mkTyVarTy new_tyvar) (
1319 specExpr body [] `thenSM` \ (body, body_uds) ->
1321 (binds_here, final_uds) = dumpUDs body_uds False False [] [] [new_tyvar]
1323 returnSM (CoTyLam new_tyvar (mkCoLetsNoUnboxed binds_here body), final_uds)
1326 specExpr (CoCase scrutinee alts) args
1327 = specExpr scrutinee [] `thenSM` \ (scrutinee, scrut_uds) ->
1328 specAlts alts scrutinee_type args `thenSM` \ (alts, alts_uds) ->
1329 returnSM (CoCase scrutinee alts, scrut_uds `unionUDs` alts_uds)
1331 scrutinee_type = typeOfCoreExpr scrutinee
1334 specExpr (CoLet bind body) args
1335 = specBindAndScope False bind (
1336 specExpr body args `thenSM` \ (body, body_uds) ->
1337 returnSM (ItsAnExpr body, body_uds)
1338 ) `thenSM` \ (binds, ItsAnExpr body, all_uds) ->
1339 returnSM (mkCoLetsUnboxedToCase binds body, all_uds)
1341 specExpr (CoSCC cc expr) args
1342 = specExpr expr [] `thenSM` \ (expr, expr_uds) ->
1343 mapAndUnzip3SM specArg args `thenSM` \ (args, args_uds_s, unlifts) ->
1346 = if squashableDictishCcExpr cc expr -- can toss the _scc_
1350 returnSM (applyBindUnlifts unlifts (applyToArgs scc_expr args),
1351 unionUDList args_uds_s `unionUDs` expr_uds)
1353 -- ToDo: This may leave some unspeced dictionaries !!
1355 -- ToDo: DPH: add stuff here!
1358 %************************************************************************
1360 \subsubsection{Specialising a lambda}
1362 %************************************************************************
1365 specLam :: [Id] -> PlainCoreExpr -> [PlainCoreArg]
1366 -> SpecM (PlainCoreExpr, UsageDetails)
1368 specLam [] body args
1369 = -- All lambdas saturated
1372 specLam (binder:binders) body (ValArg arg : args)
1373 = -- Lambda with an unprocessed argument
1374 lookup_arg arg `thenSM` \ arg ->
1376 specLam binders body args
1379 lookup_arg (CoLitAtom l) = returnSM (NoLift (CoLitAtom l))
1380 lookup_arg (CoVarAtom v) = lookupId v
1382 specLam bound_ids body []
1383 = -- Lambda with no arguments
1384 specLambdaOrCaseBody bound_ids body [] `thenSM` \ (bound_ids, body, uds) ->
1385 returnSM (CoLam bound_ids body, uds)
1389 specLambdaOrCaseBody :: [Id] -- The binders
1390 -> PlainCoreExpr -- The body
1391 -> [PlainCoreArg] -- Its args
1392 -> SpecM ([Id], -- New binders
1393 PlainCoreExpr, -- New body
1396 specLambdaOrCaseBody bound_ids body args
1397 = cloneLambdaOrCaseBinders bound_ids `thenSM` \ (new_ids, clone_infos) ->
1398 bindIds bound_ids clone_infos (
1400 specExpr body args `thenSM` \ (body, body_uds) ->
1403 -- Dump any dictionary bindings (and call instances)
1404 -- from the scope which mention things bound here
1405 (binds_here, final_uds) = dumpUDs body_uds False False [] new_ids []
1407 returnSM (new_ids, mkCoLetsNoUnboxed binds_here body, final_uds)
1410 -- ToDo: Opportunity here to common-up dictionaries with same type,
1411 -- thus avoiding recomputation.
1414 A variable bound in a lambda or case is normally monomorphic so no
1415 specialised versions will be required. This is just as well since we
1416 do not know what code to specialise!
1418 Unfortunately this is not always the case. For example a class Foo
1419 with polymorphic methods gives rise to a dictionary with polymorphic
1420 components as follows:
1427 instance Foo Int where
1435 d.Foo.Int :: ( \/b . Int -> b -> Int, \/c . Int -> c -> Int )
1436 d.Foo.Int = (op1_Int, op2_Int)
1438 op1 = /\ a b -> \ dFoo -> case dFoo of (meth1, _) -> meth1 b
1440 ... op1 {Int Int#} d.Foo.Int 1 3# ...
1443 N.B. The type of the dictionary is not Hindley Milner!
1445 Now we must specialise op1 at {* Int#} which requires a version of
1446 meth1 at {Int#}. But since meth1 was extracted from a dictionary we do
1447 not have access to its code to create the specialised version.
1450 If we specialise on overloaded types as well we specialise op1 at
1451 {Int Int#} d.Foo.Int:
1453 op1_Int_Int# = case d.Foo.Int of (meth1, _) -> meth1 {Int#}
1455 Though this is still invalid, after further simplification we get:
1457 op1_Int_Int# = opInt1 {Int#}
1459 Another round of specialisation will result in the specialised
1460 version of op1Int being called directly.
1462 For now we PANIC if a polymorphic lambda/case bound variable is found
1463 in a call instance with an unboxed type. Other call instances, arising
1464 from overloaded type arguments, are discarded since the unspecialised
1465 version extracted from the method can be called as normal.
1467 ToDo: Implement and test second round of specialisation.
1470 %************************************************************************
1472 \subsubsection{Specialising case alternatives}
1474 %************************************************************************
1478 specAlts (CoAlgAlts alts deflt) scrutinee_ty args
1479 = mapSM specTy ty_args `thenSM` \ ty_args ->
1480 mapAndUnzipSM (specAlgAlt ty_args) alts `thenSM` \ (alts, alts_uds_s) ->
1481 specDeflt deflt args `thenSM` \ (deflt, deflt_uds) ->
1482 returnSM (CoAlgAlts alts deflt,
1483 unionUDList alts_uds_s `unionUDs` deflt_uds)
1486 -- We use ty_args of scrutinee type to identify specialisation of alternatives
1487 (_, ty_args, _) = getUniDataTyCon scrutinee_ty
1489 specAlgAlt ty_args (con,binders,rhs)
1490 = specLambdaOrCaseBody binders rhs args `thenSM` \ (binders, rhs, rhs_uds) ->
1491 mkTyConInstance con ty_args `thenSM` \ con_uds ->
1492 returnSM ((con,binders,rhs), rhs_uds `unionUDs` con_uds)
1494 specAlts (CoPrimAlts alts deflt) scrutinee_ty args
1495 = mapAndUnzipSM specPrimAlt alts `thenSM` \ (alts, alts_uds_s) ->
1496 specDeflt deflt args `thenSM` \ (deflt, deflt_uds) ->
1497 returnSM (CoPrimAlts alts deflt,
1498 unionUDList alts_uds_s `unionUDs` deflt_uds)
1500 specPrimAlt (lit,rhs) = specExpr rhs args `thenSM` \ (rhs, uds) ->
1501 returnSM ((lit,rhs), uds)
1504 specDeflt CoNoDefault args = returnSM (CoNoDefault, emptyUDs)
1505 specDeflt (CoBindDefault binder rhs) args
1506 = specLambdaOrCaseBody [binder] rhs args `thenSM` \ ([binder], rhs, uds) ->
1507 returnSM (CoBindDefault binder rhs, uds)
1511 %************************************************************************
1513 \subsubsection{Specialising an atom}
1515 %************************************************************************
1518 specAtom :: PlainCoreAtom -> SpecM (PlainCoreAtom, UsageDetails,
1519 PlainCoreExpr -> PlainCoreExpr)
1521 specAtom (CoLitAtom lit)
1522 = returnSM (CoLitAtom lit, emptyUDs, id)
1524 specAtom (CoVarAtom v)
1525 = lookupId v `thenSM` \ vlookup ->
1528 -> returnSM (CoVarAtom vu, singleFvUDs (CoVarAtom vl), bindUnlift vl vu)
1531 -> returnSM (vatom, singleFvUDs vatom, id)
1534 specArg :: PlainCoreArg -> SpecM (PlainCoreArg, UsageDetails,
1535 PlainCoreExpr -> PlainCoreExpr)
1537 specArg (ValArg arg) -- unprocessed; spec the atom
1538 = specAtom arg `thenSM` \ (arg, uds, unlift) ->
1539 returnSM (ValArg arg, uds, unlift)
1541 specArg (TypeArg ty) -- already speced; no action
1542 = returnSM (TypeArg ty, emptyUDs, id)
1546 %************************************************************************
1548 \subsubsection{Specialising bindings}
1550 %************************************************************************
1552 A classic case of when having a polymorphic recursive function would help!
1555 data BindsOrExpr = ItsABinds [PlainCoreBinding]
1556 | ItsAnExpr PlainCoreExpr
1561 :: Bool -- True <=> a top level group
1562 -> PlainCoreBinding -- As yet unprocessed
1563 -> SpecM (BindsOrExpr, UsageDetails) -- Something to do the scope of the bindings
1564 -> SpecM ([PlainCoreBinding], -- Processed
1565 BindsOrExpr, -- Combined result
1566 UsageDetails) -- Usage details of the whole lot
1568 specBindAndScope top_lev bind scopeM
1569 = cloneLetBinders top_lev (is_rec bind) binders
1570 `thenSM` \ (new_binders, clone_infos) ->
1572 -- Two cases now: either this is a bunch of local dictionaries,
1573 -- in which case we float them; or its a bunch of other values,
1574 -- in which case we see if they correspond to any call-instances
1575 -- we have from processing the scope
1577 if not top_lev && all (isDictTy . getIdUniType) binders
1579 -- Ha! A group of local dictionary bindings
1581 bindIds binders clone_infos (
1583 -- Process the dictionary bindings themselves
1584 specBind False True new_binders [] bind `thenSM` \ (bind, rhs_uds) ->
1586 -- Process their scope
1587 scopeM `thenSM` \ (thing, scope_uds) ->
1589 -- Add the bindings to the current stuff
1590 final_uds = addDictBinds new_binders bind rhs_uds scope_uds
1592 returnSM ([], thing, final_uds)
1595 -- Ho! A group of bindings
1597 fixSM (\ ~(_, _, _, rec_spec_infos) ->
1599 bindSpecIds binders clone_infos rec_spec_infos (
1600 -- It's ok to have new binders in scope in
1601 -- non-recursive decls too, cos name shadowing is gone by now
1603 -- Do the scope of the bindings
1604 scopeM `thenSM` \ (thing, scope_uds) ->
1606 (call_insts, gotci_scope_uds) = getCIs top_lev new_binders scope_uds
1608 equiv_ciss = equivClasses cmpCI_tys call_insts
1609 inst_cis = map head equiv_ciss
1612 -- Do the bindings themselves
1613 specBind top_lev False new_binders inst_cis bind
1614 `thenSM` \ (spec_bind, spec_uds) ->
1616 -- Create any necessary instances
1617 instBind top_lev new_binders bind equiv_ciss inst_cis
1618 `thenSM` \ (inst_binds, inst_uds, spec_infos) ->
1621 -- NB: dumpUDs only worries about new_binders since the free var
1622 -- stuff only records free new_binders
1623 -- The spec_ids only appear in SpecInfos and final speced calls
1625 -- Build final binding group and usage details
1626 (final_binds, final_uds)
1628 -- For a top-level binding we have to dumpUDs from
1629 -- spec_uds and inst_uds and scope_uds creating
1630 -- *global* dict bindings
1632 (scope_dict_binds, final_scope_uds)
1633 = dumpUDs gotci_scope_uds True False [] new_binders []
1634 (spec_dict_binds, final_spec_uds)
1635 = dumpUDs spec_uds True False inst_cis new_binders []
1636 (inst_dict_binds, final_inst_uds)
1637 = dumpUDs inst_uds True False inst_cis new_binders []
1639 ([spec_bind] ++ inst_binds ++ scope_dict_binds
1640 ++ spec_dict_binds ++ inst_dict_binds,
1641 final_spec_uds `unionUDs` final_scope_uds `unionUDs` final_inst_uds)
1643 -- For a local binding we only have to dumpUDs from
1644 -- scope_uds since the UDs from spec_uds and inst_uds
1645 -- have already been dumped by specBind and instBind
1647 (scope_dict_binds, final_scope_uds)
1648 = dumpUDs gotci_scope_uds False False [] new_binders []
1650 ([spec_bind] ++ inst_binds ++ scope_dict_binds,
1651 spec_uds `unionUDs` final_scope_uds `unionUDs` inst_uds)
1653 -- inst_uds comes last, because there may be dict bindings
1654 -- floating outward in scope_uds which are mentioned
1655 -- in the call-instances, and hence in spec_uds.
1656 -- This ordering makes sure that the precedence order
1657 -- among the dict bindings finally floated out is maintained.
1659 returnSM (final_binds, thing, final_uds, spec_infos)
1661 ) `thenSM` \ (binds, thing, final_uds, spec_infos) ->
1662 returnSM (binds, thing, final_uds)
1664 binders = bindersOf bind
1666 is_rec (CoNonRec _ _) = False
1671 specBind :: Bool -> Bool -> [Id] -> [CallInstance]
1673 -> SpecM (PlainCoreBinding, UsageDetails)
1674 -- The UsageDetails returned has already had stuff to do with this group
1675 -- of binders deleted; that's why new_binders is passed in.
1676 specBind top_lev floating new_binders inst_cis (CoNonRec binder rhs)
1677 = specOneBinding top_lev floating new_binders inst_cis (binder,rhs)
1678 `thenSM` \ ((binder,rhs), rhs_uds) ->
1679 returnSM (CoNonRec binder rhs, rhs_uds)
1681 specBind top_lev floating new_binders inst_cis (CoRec pairs)
1682 = mapAndUnzipSM (specOneBinding top_lev floating new_binders inst_cis) pairs
1683 `thenSM` \ (pairs, rhs_uds_s) ->
1684 returnSM (CoRec pairs, unionUDList rhs_uds_s)
1687 specOneBinding :: Bool -> Bool -> [Id] -> [CallInstance]
1688 -> (Id,PlainCoreExpr)
1689 -> SpecM ((Id,PlainCoreExpr), UsageDetails)
1691 specOneBinding top_lev floating new_binders inst_cis (binder, rhs)
1692 = lookupId binder `thenSM` \ blookup ->
1693 specExpr rhs [] `thenSM` \ (rhs, rhs_uds) ->
1695 specid_maybe_maybe = isSpecPragmaId_maybe binder
1696 is_specid = maybeToBool specid_maybe_maybe
1697 Just specinfo_maybe = specid_maybe_maybe
1698 specid_with_info = maybeToBool specinfo_maybe
1699 Just spec_info = specinfo_maybe
1701 -- If we have a SpecInfo stored in a SpecPragmaId binder
1702 -- it will contain a SpecInfo with an explicit SpecId
1703 -- We add the explicit ci to the usage details
1704 -- Any ordinary cis for orig_id (there should only be one)
1705 -- will be ignored later
1708 = if is_specid && specid_with_info then
1710 (SpecInfo spec_tys _ spec_id) = spec_info
1711 Just (orig_id, _) = isSpecId_maybe spec_id
1713 ASSERT(toplevelishId orig_id) -- must not be cloned!
1714 explicitCI orig_id spec_tys spec_info
1718 -- For a local binding we dump the usage details, creating
1719 -- any local dict bindings required
1720 -- At the top-level the uds will be dumped in specBindAndScope
1721 -- and the dict bindings made *global*
1723 (local_dict_binds, final_uds)
1724 = if not top_lev then
1725 dumpUDs rhs_uds False floating inst_cis new_binders []
1730 Lifted lift_binder unlift_binder
1731 -> -- We may need to record an unboxed instance of
1732 -- the _Lift data type in the usage details
1733 mkTyConInstance liftDataCon [getIdUniType unlift_binder]
1734 `thenSM` \ lift_uds ->
1735 returnSM ((lift_binder,
1736 mkCoLetsNoUnboxed local_dict_binds (liftExpr unlift_binder rhs)),
1737 final_uds `unionUDs` pragma_uds `unionUDs` lift_uds)
1739 NoLift (CoVarAtom binder)
1740 -> returnSM ((binder, mkCoLetsNoUnboxed local_dict_binds rhs),
1741 final_uds `unionUDs` pragma_uds)
1745 %************************************************************************
1747 \subsection{@instBind@}
1749 %************************************************************************
1752 instBind top_lev new_ids@(first_binder:other_binders) bind equiv_ciss inst_cis
1754 = returnSM ([], emptyUDs, [])
1756 | all same_overloading other_binders
1757 = -- For each call_inst, build an instance
1758 mapAndUnzip3SM do_this_class equiv_ciss
1759 `thenSM` \ (inst_binds, inst_uds_s, spec_infos) ->
1761 -- Add in the remaining UDs
1762 returnSM (catMaybes inst_binds,
1763 unionUDList inst_uds_s,
1767 | otherwise -- Incompatible overloadings; see below by same_overloading
1768 = (if not (null (filter isUnboxedCI (concat equiv_ciss)))
1769 then pprTrace "dumpCIs: not same overloading ... WITH UNBOXED TYPES!\n"
1771 then pprTrace "dumpCIs: not same overloading ... top level \n"
1773 ) (ppHang (ppBesides [ppStr "{", ppr PprDebug new_ids, ppStr "}"])
1774 4 (ppAboves [ppAboves (map (pprUniType PprDebug . getIdUniType) new_ids),
1775 ppAboves (map pprCI (concat equiv_ciss))]))
1776 (returnSM ([], emptyUDs, []))
1779 (tyvar_tmpls, class_tyvar_pairs) = getIdOverloading first_binder
1780 tyvar_tmpl_tys = map mkTyVarTemplateTy tyvar_tmpls
1782 no_of_tyvars = length tyvar_tmpls
1783 no_of_dicts = length class_tyvar_pairs
1785 do_this_class equiv_cis
1786 = mkOneInst do_cis explicit_cis no_of_dicts top_lev inst_cis new_ids bind
1788 (explicit_cis, normal_cis) = partition isExplicitCI equiv_cis
1789 do_cis = head (normal_cis ++ explicit_cis)
1790 -- must choose a normal_cis in preference since dict_args will
1791 -- not be defined for an explicit_cis
1793 -- same_overloading tests whether the types of all the binders
1794 -- are "compatible"; ie have the same type and dictionary abstractions
1795 -- Almost always this is the case, because a recursive group is abstracted
1796 -- all together. But, it can happen that it ain't the case, because of
1797 -- code generated from instance decls:
1800 -- dfun.Foo.Int :: (forall a. a -> Int, Int)
1801 -- dfun.Foo.Int = (const.op1.Int, const.op2.Int)
1803 -- const.op1.Int :: forall a. a -> Int
1804 -- const.op1.Int a = defm.Foo.op1 Int a dfun.Foo.Int
1806 -- const.op2.Int :: Int
1807 -- const.op2.Int = 3
1809 -- Note that the first two defns have different polymorphism, but they are
1810 -- mutually recursive!
1812 same_overloading :: Id -> Bool
1814 = no_of_tyvars == length this_id_tyvars -- Same no of tyvars
1816 no_of_dicts == length this_id_class_tyvar_pairs -- Same no of vdicts
1818 and (zipWith same_ov class_tyvar_pairs this_id_class_tyvar_pairs) -- Same overloading
1820 (this_id_tyvars, this_id_class_tyvar_pairs) = getIdOverloading id
1821 tyvar_pairs = this_id_tyvars `zip` tyvar_tmpls
1823 same_ov (clas1,tyvar1) (clas2,tyvar2)
1825 tyvar1 == assoc "same_overloading" tyvar_pairs tyvar2
1829 - a call instance eg f [t1,t2,t3] [d1,d2]
1830 - the rhs of the function eg orig_rhs
1831 - a constraint vector, saying which of eg [T,F,T]
1832 the functions type args are constrained
1835 We return a new definition
1837 f@t1//t3 = /\a -> orig_rhs t1 a t3 d1 d2
1839 The SpecInfo for f will be (the "2" indicates 2 dictionaries to eat)
1841 SpecInfo [Just t1, Nothing, Just t3] 2 f@t1//t3
1843 Based on this SpecInfo, a call instance of f
1845 ...(f t1 t2 t3 d1 d2)...
1847 should get replaced by
1851 (But that is the business of @mkCall@.)
1854 mkOneInst :: CallInstance
1855 -> [CallInstance] -- Any explicit cis for this inst
1856 -> Int -- No of dicts to specialise
1857 -> Bool -- Top level binders?
1858 -> [CallInstance] -- Instantiated call insts for binders
1859 -> [Id] -- New binders
1860 -> PlainCoreBinding -- Unprocessed
1861 -> SpecM (Maybe PlainCoreBinding, -- Instantiated version of input
1863 [Maybe SpecInfo] -- One for each id in the original binding
1866 mkOneInst do_cis@(CallInstance _ spec_tys dict_args _ _) explicit_cis
1867 no_of_dicts_to_specialise top_lev inst_cis new_ids orig_bind
1868 = getSwitchCheckerSM `thenSM` \ sw_chkr ->
1869 newSpecIds new_ids spec_tys no_of_dicts_to_specialise
1870 `thenSM` \ spec_ids ->
1871 newTyVars (length [() | Nothing <- spec_tys]) `thenSM` \ poly_tyvars ->
1873 -- arg_tys is spec_tys with tyvars instead of the Nothing spec_tys
1874 -- which correspond to unspeciailsed args
1875 arg_tys :: [UniType]
1876 (_,arg_tys) = mapAccumL do_the_wotsit poly_tyvars spec_tys
1878 args :: [PlainCoreArg]
1879 args = map TypeArg arg_tys ++ dict_args
1881 (new_id:_) = new_ids
1882 (spec_id:_) = spec_ids
1884 do_bind (CoNonRec orig_id rhs)
1885 = do_one_rhs (spec_id, new_id, (orig_id,rhs))
1886 `thenSM` \ (maybe_spec, rhs_uds, spec_info) ->
1888 Just (spec_id, rhs) -> returnSM (Just (CoNonRec spec_id rhs), rhs_uds, [spec_info])
1889 Nothing -> returnSM (Nothing, rhs_uds, [spec_info])
1891 do_bind (CoRec pairs)
1892 = mapAndUnzip3SM do_one_rhs (zip3 spec_ids new_ids pairs)
1893 `thenSM` \ (maybe_pairs, rhss_uds_s, spec_infos) ->
1894 returnSM (Just (CoRec (catMaybes maybe_pairs)),
1895 unionUDList rhss_uds_s, spec_infos)
1897 do_one_rhs (spec_id, new_id, (orig_id, orig_rhs))
1899 -- Avoid duplicating a spec which has already been created ...
1900 -- This can arise in a CoRec involving a dfun for which a
1901 -- a specialised instance has been created but specialisation
1902 -- "required" by one of the other Ids in the CoRec
1903 | top_lev && maybeToBool lookup_orig_spec
1904 = (if sw_chkr SpecialiseTrace
1905 then trace_nospec " Exists: " exists_id
1908 returnSM (Nothing, emptyUDs, Nothing)
1911 -- Check for a (single) explicit call instance for this id
1912 | not (null explicit_cis_for_this_id)
1913 = ASSERT (length explicit_cis_for_this_id == 1)
1914 (if sw_chkr SpecialiseTrace
1915 then trace_nospec " Explicit: " explicit_id
1918 returnSM (Nothing, tickSpecInsts emptyUDs, Just explicit_spec_info)
1921 -- Apply the specialiser to (orig_rhs t1 a t3 d1 d2)
1923 = ASSERT (no_of_dicts_to_specialise == length dict_args)
1924 specExpr orig_rhs args `thenSM` \ (inst_rhs, inst_uds) ->
1926 -- For a local binding we dump the usage details, creating
1927 -- any local dict bindings required
1928 -- At the top-level the uds will be dumped in specBindAndScope
1929 -- and the dict bindings made *global*
1931 (local_dict_binds, final_uds)
1932 = if not top_lev then
1933 dumpUDs inst_uds False False inst_cis new_ids []
1937 spec_info = Just (SpecInfo spec_tys no_of_dicts_to_specialise spec_id)
1939 if isUnboxedDataType (getIdUniType spec_id) then
1940 ASSERT (null poly_tyvars)
1941 liftId spec_id `thenSM` \ (lift_spec_id, unlift_spec_id) ->
1942 mkTyConInstance liftDataCon [getIdUniType unlift_spec_id]
1943 `thenSM` \ lift_uds ->
1944 returnSM (Just (lift_spec_id,
1945 mkCoLetsNoUnboxed local_dict_binds (liftExpr unlift_spec_id inst_rhs)),
1946 tickSpecInsts (final_uds `unionUDs` lift_uds), spec_info)
1948 returnSM (Just (spec_id,
1949 mkCoLetsNoUnboxed local_dict_binds (mkCoTyLam poly_tyvars inst_rhs)),
1950 tickSpecInsts final_uds, spec_info)
1952 lookup_orig_spec = lookupSpecEnv (getIdSpecialisation orig_id) arg_tys
1953 Just (exists_id, _, _) = lookup_orig_spec
1955 explicit_cis_for_this_id = filter (isCIofTheseIds [new_id]) explicit_cis
1956 [CallInstance _ _ _ _ (Just explicit_spec_info)] = explicit_cis_for_this_id
1957 SpecInfo _ _ explicit_id = explicit_spec_info
1959 trace_nospec str spec_id
1961 (ppCat [ppr PprDebug new_id, ppInterleave ppNil (map pp_ty arg_tys),
1962 ppStr "==>", ppr PprDebug spec_id])
1964 (if sw_chkr SpecialiseTrace then
1965 pprTrace "Specialising:"
1966 (ppHang (ppBesides [ppStr "{", ppr PprDebug new_ids, ppStr "}"])
1968 ppBesides [ppStr "types: ", ppInterleave ppNil (map pp_ty arg_tys)],
1969 if isExplicitCI do_cis then ppNil else
1970 ppBesides [ppStr "dicts: ", ppInterleave ppNil (map pp_dict dict_args)],
1971 ppBesides [ppStr "specs: ", ppr PprDebug spec_ids]]))
1974 do_bind orig_bind `thenSM` \ (maybe_inst_bind, inst_uds, spec_infos) ->
1976 returnSM (maybe_inst_bind, inst_uds, spec_infos)
1979 pp_dict (ValArg d) = ppr PprDebug d
1980 pp_ty t = pprParendUniType PprDebug t
1982 do_the_wotsit (tyvar:tyvars) Nothing = (tyvars, mkTyVarTy tyvar)
1983 do_the_wotsit tyvars (Just ty) = (tyvars, ty)
1987 %************************************************************************
1989 \subsection[Misc]{Miscellaneous junk}
1991 %************************************************************************
1994 mkCallInstance :: Id
1996 -> [(PlainCoreArg, UsageDetails, PlainCoreExpr -> PlainCoreExpr)]
1997 -> SpecM UsageDetails
1999 mkCallInstance id new_id []
2002 mkCallInstance id new_id args
2004 -- No specialised versions for "error" and friends are req'd.
2005 -- This is a special case in core lint etc.
2010 -- No call instances for SuperDictSelIds
2011 -- These are a special case in mkCall
2013 | maybeToBool (isSuperDictSelId_maybe id)
2016 -- There are also no call instances for ClassOpIds
2017 -- However, we need to process it to get any second-level call
2018 -- instances for a ConstMethodId extracted from its SpecEnv
2021 = getSwitchCheckerSM `thenSM` \ sw_chkr ->
2023 spec_overloading = sw_chkr SpecialiseOverloaded
2024 spec_unboxed = sw_chkr SpecialiseUnboxed
2025 spec_all = sw_chkr SpecialiseAll
2027 (tyvars, class_tyvar_pairs) = getIdOverloading id
2029 arg_res = take_type_args tyvars class_tyvar_pairs args
2030 enough_args = maybeToBool arg_res
2032 (Just (tys, dicts, rest_args)) = arg_res
2035 = (record, lookup, spec_tys)
2037 spec_tys = specialiseCallTys spec_all spec_unboxed spec_overloading
2038 (mkConstraintVector id) tys
2040 record = any (not . isTyVarTy) (catMaybes spec_tys)
2042 lookup = lookupSpecEnv (getIdSpecialisation id) tys
2044 if (not enough_args) then
2045 pprPanic "Specialise:recordCallInst: Unsaturated Type & Dict Application:\n\t"
2046 (ppCat [ppr PprDebug id, ppr PprDebug [arg | (arg,_,_) <- args] ])
2048 case record_spec id tys of
2050 -> -- pprTrace "CallInst:NotReqd\n"
2051 -- (ppCat [ppr PprDebug id, ppCat (map (ppr PprDebug) args)])
2054 (True, Nothing, spec_tys)
2055 -> if isClassOpId id then -- No CIs for class ops, dfun will give SPEC inst
2058 -- pprTrace "CallInst:Reqd\n"
2059 -- (ppAboves [ppCat [ppr PprDebug id, ppCat (map (ppr PprDebug) args)],
2060 -- ppCat [ppStr "CI", ppCat (map (pprMaybeTy PprDebug) spec_tys),
2061 -- ppCat (map (ppr PprDebug) dicts)]])
2062 (returnSM (singleCI new_id spec_tys dicts))
2064 (True, Just (spec_id, tys_left, toss), _)
2065 -> if maybeToBool (isConstMethodId_maybe spec_id) then
2066 -- If we got a const method spec_id see if further spec required
2067 -- NB: const method is top-level so spec_id will not be cloned
2068 case record_spec spec_id tys_left of
2070 -> -- pprTrace "CallInst:Exists\n"
2071 -- (ppAboves [ppCat [ppr PprDebug id, ppCat (map (ppr PprDebug) args)],
2072 -- ppCat [ppStr "->", ppr PprDebug spec_id,
2073 -- ppr PprDebug (tys_left ++ drop toss dicts)]])
2076 (True, Nothing, spec_tys)
2077 -> -- pprTrace "CallInst:Exists:Reqd\n"
2078 -- (ppAboves [ppCat [ppr PprDebug id, ppCat (map (ppr PprDebug) args)],
2079 -- ppCat [ppStr "->", ppr PprDebug spec_id,
2080 -- ppr PprDebug (tys_left ++ drop toss dicts)],
2081 -- ppCat [ppStr "CI", ppCat (map (pprMaybeTy PprDebug) spec_tys),
2082 -- ppCat (map (ppr PprDebug) (drop toss dicts))]])
2083 (returnSM (singleCI spec_id spec_tys (drop toss dicts)))
2085 (True, Just (spec_spec_id, tys_left_left, toss_toss), _)
2086 -> -- pprTrace "CallInst:Exists:Exists\n"
2087 -- (ppAboves [ppCat [ppr PprDebug id, ppCat (map (ppr PprDebug) args)],
2088 -- ppCat [ppStr "->", ppr PprDebug spec_id,
2089 -- ppr PprDebug (tys_left ++ drop toss dicts)],
2090 -- ppCat [ppStr "->", ppr PprDebug spec_spec_id,
2091 -- ppr PprDebug (tys_left_left ++ drop (toss + toss_toss) dicts)]])
2095 -- pprTrace "CallInst:Exists\n"
2096 -- (ppAboves [ppCat [ppr PprDebug id, ppCat (map (ppr PprDebug) args)],
2097 -- ppCat [ppStr "->", ppr PprDebug spec_id,
2098 -- ppr PprDebug (tys_left ++ drop toss dicts)]])
2102 take_type_args (_:tyvars) class_tyvar_pairs ((TypeArg ty,_,_):args)
2103 = case take_type_args tyvars class_tyvar_pairs args of
2105 Just (tys, dicts, others) -> Just (ty:tys, dicts, others)
2106 take_type_args (_:tyvars) class_tyvar_pairs []
2108 take_type_args [] class_tyvar_pairs args
2109 = case take_dict_args class_tyvar_pairs args of
2111 Just (dicts, others) -> Just ([], dicts, others)
2113 take_dict_args (_:class_tyvar_pairs) ((dict@(ValArg _),_,_):args)
2114 = case take_dict_args class_tyvar_pairs args of
2116 Just (dicts, others) -> Just (dict:dicts, others)
2117 take_dict_args (_:class_tyvar_pairs) []
2119 take_dict_args [] args
2125 -> [(PlainCoreArg, UsageDetails, PlainCoreExpr -> PlainCoreExpr)]
2126 -> SpecM (Bool, PlainCoreExpr)
2129 | maybeToBool (isSuperDictSelId_maybe new_id)
2130 && any isUnboxedDataType ty_args
2131 -- No specialisations for super-dict selectors
2132 -- Specialise unboxed calls to SuperDictSelIds by extracting
2133 -- the super class dictionary directly form the super class
2134 -- NB: This should be dead code since all uses of this dictionary should
2135 -- have been specialised. We only do this to keep core-lint happy.
2137 Just (_, super_class) = isSuperDictSelId_maybe new_id
2138 super_dict_id = case lookupClassInstAtSimpleType super_class (head ty_args) of
2139 Nothing -> panic "Specialise:mkCall:SuperDictId"
2142 returnSM (False, CoVar super_dict_id)
2145 = case lookupSpecEnv (getIdSpecialisation new_id) ty_args of
2146 Nothing -> checkUnspecOK new_id ty_args (
2147 returnSM (False, unspec_call)
2150 Just spec_1_details@(spec_id_1, tys_left_1, dicts_to_toss_1)
2152 -- It may be necessary to specialsie a constant method spec_id again
2153 (spec_id, tys_left, dicts_to_toss) =
2154 case (maybeToBool (isConstMethodId_maybe spec_id_1),
2155 lookupSpecEnv (getIdSpecialisation spec_id_1) tys_left_1) of
2156 (False, _ ) -> spec_1_details
2157 (True, Nothing) -> spec_1_details
2158 (True, Just (spec_id_2, tys_left_2, dicts_to_toss_2))
2159 -> (spec_id_2, tys_left_2, dicts_to_toss_1 + dicts_to_toss_2)
2161 args_left = toss_dicts dicts_to_toss val_args
2163 checkSpecOK new_id ty_args spec_id tys_left (
2165 -- The resulting spec_id may be a top-level unboxed value
2166 -- This can arise for:
2167 -- 1) constant method values
2168 -- eq: class Num a where pi :: a
2169 -- instance Num Double# where pi = 3.141#
2170 -- 2) specilised overloaded values
2171 -- eq: i1 :: Num a => a
2172 -- i1 Int# d.Num.Int# ==> i1.Int#
2173 -- These top level defns should have been lifted.
2174 -- We must add code to unlift such a spec_id.
2176 if isUnboxedDataType (getIdUniType spec_id) then
2177 ASSERT (null tys_left && null args_left)
2178 if toplevelishId spec_id then
2179 liftId spec_id `thenSM` \ (lift_spec_id, unlift_spec_id) ->
2180 returnSM (True, bindUnlift lift_spec_id unlift_spec_id
2181 (CoVar unlift_spec_id))
2183 pprPanic "Specialise:mkCall: unboxed spec_id not top-level ...\n"
2184 (ppCat [ppr PprDebug new_id,
2185 ppInterleave ppNil (map (pprParendUniType PprDebug) ty_args),
2187 ppr PprDebug spec_id])
2190 (vals_left, _, unlifts_left) = unzip3 args_left
2191 applied_tys = mkCoTyApps (CoVar spec_id) tys_left
2192 applied_vals = applyToArgs applied_tys vals_left
2194 returnSM (True, applyBindUnlifts unlifts_left applied_vals)
2197 (tys_and_vals, _, unlifts) = unzip3 args
2198 unspec_call = applyBindUnlifts unlifts (applyToArgs (CoVar new_id) tys_and_vals)
2201 -- ty_args is the types at the front of the arg list
2202 -- val_args is the rest of the arg-list
2204 (ty_args, val_args) = get args
2206 get ((TypeArg ty,_,_) : args) = (ty : tys, rest) where (tys,rest) = get args
2207 get args = ([], args)
2210 -- toss_dicts chucks away dict args, checking that they ain't types!
2211 toss_dicts 0 args = args
2212 toss_dicts n ((ValArg _,_,_) : args) = toss_dicts (n-1) args
2217 checkUnspecOK :: Id -> [UniType] -> a -> a
2218 checkUnspecOK check_id tys
2219 = if isLocallyDefined check_id && any isUnboxedDataType tys
2220 then pprPanic "Specialise:checkUnspecOK: unboxed instance for local id not found\n"
2221 (ppCat [ppr PprDebug check_id,
2222 ppInterleave ppNil (map (pprParendUniType PprDebug) tys)])
2225 checkSpecOK :: Id -> [UniType] -> Id -> [UniType] -> a -> a
2226 checkSpecOK check_id tys spec_id tys_left
2227 = if any isUnboxedDataType tys_left
2228 then pprPanic "Specialise:checkSpecOK: unboxed type args in specialised application\n"
2229 (ppAboves [ppCat [ppr PprDebug check_id,
2230 ppInterleave ppNil (map (pprParendUniType PprDebug) tys)],
2231 ppCat [ppr PprDebug spec_id,
2232 ppInterleave ppNil (map (pprParendUniType PprDebug) tys_left)]])
2237 mkTyConInstance :: Id
2239 -> SpecM UsageDetails
2240 mkTyConInstance con tys
2241 = recordTyConInst con tys `thenSM` \ record_inst ->
2243 Nothing -- No TyCon instance
2244 -> -- pprTrace "NoTyConInst:"
2245 -- (ppCat [ppr PprDebug tycon, ppStr "at",
2246 -- ppr PprDebug con, ppCat (map (ppr PprDebug) tys)])
2247 (returnSM (singleConUDs con))
2249 Just spec_tys -- Record TyCon instance
2250 -> -- pprTrace "TyConInst:"
2251 -- (ppCat [ppr PprDebug tycon, ppStr "at",
2252 -- ppr PprDebug con, ppCat (map (ppr PprDebug) tys),
2253 -- ppBesides [ppStr "(",
2254 -- ppCat [pprMaybeTy PprDebug ty | ty <- spec_tys],
2256 (returnSM (singleTyConI tycon spec_tys `unionUDs` singleConUDs con))
2258 tycon = getDataConTyCon con
2262 recordTyConInst :: Id
2264 -> SpecM (Maybe [Maybe UniType])
2266 recordTyConInst con tys
2268 spec_tys = specialiseConstrTys tys
2270 do_tycon_spec = maybeToBool (firstJust spec_tys)
2272 spec_exists = maybeToBool (lookupSpecEnv
2273 (getIdSpecialisation con)
2276 -- pprTrace "ConSpecExists?: "
2277 -- (ppAboves [ppStr (if spec_exists then "True" else "False"),
2278 -- ppr PprShowAll con, ppCat (map (ppr PprDebug) tys)])
2279 (if (not spec_exists && do_tycon_spec)
2280 then returnSM (Just spec_tys)
2281 else returnSM Nothing)
2284 %************************************************************************
2286 \subsection[monad-Specialise]{Monad used in specialisation}
2288 %************************************************************************
2292 inherited: control flags and
2293 recordInst functions with flags cached
2295 environment mapping tyvars to types
2296 environment mapping Ids to Atoms
2298 threaded in and out: unique supply
2302 = (GlobalSwitch -> Bool)
2308 initSM m sw_chker uniqs
2309 = m sw_chker nullTyVarEnv nullIdEnv uniqs
2311 returnSM :: a -> SpecM a
2312 thenSM :: SpecM a -> (a -> SpecM b) -> SpecM b
2313 fixSM :: (a -> SpecM a) -> SpecM a
2315 thenSM m k sw_chkr tvenv idenv us
2316 = case splitUniqSupply us of { (s1, s2) ->
2317 case (m sw_chkr tvenv idenv s1) of { r ->
2318 k r sw_chkr tvenv idenv s2 }}
2320 returnSM r sw_chkr tvenv idenv us = r
2322 fixSM k sw_chkr tvenv idenv us
2325 r = k r sw_chkr tvenv idenv us -- Recursive in r!
2329 getSwitchCheckerSM sw_chkr tvenv idenv us = sw_chkr
2332 The only interesting bit is figuring out the type of the SpecId!
2335 newSpecIds :: [Id] -- The id of which to make a specialised version
2336 -> [Maybe UniType] -- Specialise to these types
2337 -> Int -- No of dicts to specialise
2340 newSpecIds new_ids maybe_tys dicts_to_ignore sw_chkr tvenv idenv us
2341 = [ mkSpecId uniq id maybe_tys (spec_id_ty id) (selectIdInfoForSpecId id)
2342 | (id,uniq) <- new_ids `zip` uniqs ]
2344 uniqs = getSUniques (length new_ids) us
2345 spec_id_ty id = specialiseTy (getIdUniType id) maybe_tys dicts_to_ignore
2347 newTyVars :: Int -> SpecM [TyVar]
2348 newTyVars n sw_chkr tvenv idenv us
2349 = map mkPolySysTyVar uniqs
2351 uniqs = getSUniques n us
2354 @cloneLambdaOrCaseBinders@ and @cloneLetBinders@ take a bunch of
2355 binders, and build ``clones'' for them. The clones differ from the
2356 originals in three ways:
2358 (a) they have a fresh unique
2359 (b) they have the current type environment applied to their type
2360 (c) for Let binders which have been specialised to unboxed values
2361 the clone will have a lifted type
2363 As well as returning the list of cloned @Id@s they also return a list of
2364 @CloneInfo@s which the original binders should be bound to.
2367 cloneLambdaOrCaseBinders :: [Id] -- Old binders
2368 -> SpecM ([Id], [CloneInfo]) -- New ones
2370 cloneLambdaOrCaseBinders old_ids sw_chkr tvenv idenv us
2372 uniqs = getSUniques (length old_ids) us
2374 unzip (zipWith clone_it old_ids uniqs)
2376 clone_it old_id uniq
2377 = (new_id, NoLift (CoVarAtom new_id))
2379 new_id = applyTypeEnvToId tvenv (mkIdWithNewUniq old_id uniq)
2381 cloneLetBinders :: Bool -- Top level ?
2382 -> Bool -- Recursice
2383 -> [Id] -- Old binders
2384 -> SpecM ([Id], [CloneInfo]) -- New ones
2386 cloneLetBinders top_lev is_rec old_ids sw_chkr tvenv idenv us
2388 uniqs = getSUniques (2 * length old_ids) us
2390 unzip (clone_them old_ids uniqs)
2392 clone_them [] [] = []
2394 clone_them (old_id:olds) (u1:u2:uniqs)
2397 NoLift (CoVarAtom old_id)) : clone_rest
2399 -- Don't clone if it is a top-level thing. Why not?
2400 -- (a) we don't want to change the uniques
2401 -- on such things (see TopLevId in Id.lhs)
2402 -- (b) we don't have to be paranoid about name capture
2403 -- (c) the thing is polymorphic so no need to subst
2406 = if (is_rec && isUnboxedDataType new_ty && not (isUnboxedDataType old_ty))
2408 Lifted lifted_id unlifted_id) : clone_rest
2410 NoLift (CoVarAtom new_id)) : clone_rest
2413 clone_rest = clone_them olds uniqs
2415 new_id = applyTypeEnvToId tvenv (mkIdWithNewUniq old_id u1)
2416 new_ty = getIdUniType new_id
2417 old_ty = getIdUniType old_id
2419 (lifted_id, unlifted_id) = mkLiftedId new_id u2
2422 cloneTyVarSM :: TyVar -> SpecM TyVar
2424 cloneTyVarSM old_tyvar sw_chkr tvenv idenv us
2426 uniq = getSUnique us
2428 cloneTyVar old_tyvar uniq -- new_tyvar
2430 bindId :: Id -> CloneInfo -> SpecM thing -> SpecM thing
2432 bindId id val specm sw_chkr tvenv idenv us
2433 = specm sw_chkr tvenv (addOneToIdEnv idenv id val) us
2435 bindIds :: [Id] -> [CloneInfo] -> SpecM thing -> SpecM thing
2437 bindIds olds news specm sw_chkr tvenv idenv us
2438 = specm sw_chkr tvenv (growIdEnvList idenv (zip olds news)) us
2440 bindSpecIds :: [Id] -- Old
2441 -> [(CloneInfo)] -- New
2442 -> [[Maybe SpecInfo]] -- Corresponding specialisations
2443 -- Each sub-list corresponds to a different type,
2444 -- and contains one Maybe spec_info for each id
2448 bindSpecIds olds clones spec_infos specm sw_chkr tvenv idenv us
2449 = specm sw_chkr tvenv (growIdEnvList idenv old_to_clone) us
2451 old_to_clone = mk_old_to_clone olds clones spec_infos
2453 -- The important thing here is that we are *lazy* in spec_infos
2454 mk_old_to_clone [] [] _ = []
2455 mk_old_to_clone (old:rest_olds) (clone:rest_clones) spec_infos
2456 = (old, add_spec_info clone) :
2457 mk_old_to_clone rest_olds rest_clones spec_infos_rest
2459 add_spec_info (NoLift (CoVarAtom new))
2460 = NoLift (CoVarAtom (new `addIdSpecialisation`
2461 (mkSpecEnv spec_infos_this_id)))
2462 add_spec_info lifted
2463 = lifted -- no specialised instances for unboxed lifted values
2465 spec_infos_this_id = catMaybes (map head spec_infos)
2466 spec_infos_rest = map tail spec_infos
2469 bindTyVar :: TyVar -> UniType -> SpecM thing -> SpecM thing
2471 bindTyVar tyvar ty specm sw_chkr tvenv idenv us
2472 = specm sw_chkr (growTyVarEnvList tvenv [(tyvar,ty)]) idenv us
2476 lookupId :: Id -> SpecM CloneInfo
2478 lookupId id sw_chkr tvenv idenv us
2479 = case lookupIdEnv idenv id of
2480 Nothing -> NoLift (CoVarAtom id)
2485 specTy :: UniType -> SpecM UniType -- Apply the current type envt to the type
2487 specTy ty sw_chkr tvenv idenv us
2488 = applyTypeEnvToTy tvenv ty
2492 liftId :: Id -> SpecM (Id, Id)
2493 liftId id sw_chkr tvenv idenv us
2495 uniq = getSUnique us
2500 In other monads these @mapSM@ things are usually called @listM@.
2501 I think @mapSM@ is a much better name. The `2' and `3' variants are
2502 when you want to return two or three results, and get at them
2503 separately. It saves you having to do an (unzip stuff) right after.
2506 mapSM :: (a -> SpecM b) -> [a] -> SpecM [b]
2507 mapAndUnzipSM :: (a -> SpecM (b1, b2)) -> [a] -> SpecM ([b1],[b2])
2508 mapAndUnzip3SM :: (a -> SpecM (b1, b2, b3)) -> [a] -> SpecM ([b1],[b2],[b3])
2509 mapAndUnzip4SM :: (a -> SpecM (b1, b2, b3, b4)) -> [a] -> SpecM ([b1],[b2],[b3],[b4])
2511 mapSM f [] = returnSM []
2512 mapSM f (x:xs) = f x `thenSM` \ r ->
2513 mapSM f xs `thenSM` \ rs ->
2516 mapAndUnzipSM f [] = returnSM ([],[])
2517 mapAndUnzipSM f (x:xs) = f x `thenSM` \ (r1, r2) ->
2518 mapAndUnzipSM f xs `thenSM` \ (rs1,rs2) ->
2519 returnSM ((r1:rs1),(r2:rs2))
2521 mapAndUnzip3SM f [] = returnSM ([],[],[])
2522 mapAndUnzip3SM f (x:xs) = f x `thenSM` \ (r1,r2,r3) ->
2523 mapAndUnzip3SM f xs `thenSM` \ (rs1,rs2,rs3) ->
2524 returnSM ((r1:rs1),(r2:rs2),(r3:rs3))
2526 mapAndUnzip4SM f [] = returnSM ([],[],[],[])
2527 mapAndUnzip4SM f (x:xs) = f x `thenSM` \ (r1,r2,r3,r4) ->
2528 mapAndUnzip4SM f xs `thenSM` \ (rs1,rs2,rs3,rs4) ->
2529 returnSM ((r1:rs1),(r2:rs2),(r3:rs3),(r4:rs4))