2 % (c) The GRASP/AQUA Project, Glasgow University, 1993-1996
4 \section[Specialise]{Stamping out overloading, and (optionally) polymorphism}
7 #include "HsVersions.h"
17 IMPORT_1_3(List(partition))
19 import Bag ( emptyBag, unitBag, isEmptyBag, unionBags,
20 partitionBag, listToBag, bagToList, Bag
22 import Class ( GenClass{-instance Eq-}, SYN_IE(Class) )
23 import CmdLineOpts ( opt_SpecialiseImports, opt_D_simplifier_stats,
24 opt_CompilingGhcInternals, opt_SpecialiseTrace
26 import CoreLift ( mkLiftedId, liftExpr, bindUnlift, applyBindUnlifts )
28 import CoreUtils ( coreExprType, squashableDictishCcExpr )
29 import FiniteMap ( addListToFM_C, FiniteMap )
30 import Kind ( mkBoxedTypeKind, isBoxedTypeKind )
31 import Id ( idType, isDefaultMethodId_maybe, toplevelishId,
32 isSuperDictSelId_maybe, isBottomingId,
34 isImportedId, mkIdWithNewUniq,
35 dataConTyCon, applyTypeEnvToId,
36 nullIdEnv, addOneToIdEnv, growIdEnvList,
37 lookupIdEnv, SYN_IE(IdEnv),
38 emptyIdSet, mkIdSet, unitIdSet,
39 elementOfIdSet, minusIdSet,
40 unionIdSets, unionManyIdSets, SYN_IE(IdSet),
41 GenId{-instance Eq-}, SYN_IE(Id)
43 import Literal ( Literal{-instance Outputable-} )
44 import Maybes ( catMaybes, firstJust, maybeToBool )
45 import Name ( isLocallyDefined )
46 import Outputable ( PprStyle(..), interppSP, Outputable(..){-instance * []-} )
47 import PprType ( pprGenType, pprParendGenType, pprMaybeTy,
48 GenType{-instance Outputable-}, GenTyVar{-ditto-},
51 import Pretty ( hang, hsep, text, vcat, hcat, ptext, char,
52 int, space, empty, Doc
54 import PrimOp ( PrimOp(..) )
56 import Type ( mkTyVarTy, mkTyVarTys, isTyVarTy, getAppDataTyConExpandingDicts,
57 tyVarsOfTypes, applyTypeEnvToTy, isUnboxedType, isDictTy,
60 import TyCon ( TyCon{-instance Eq-} )
61 import TyVar ( cloneTyVar, mkSysTyVar,
62 elementOfTyVarSet, SYN_IE(TyVarSet),
63 nullTyVarEnv, growTyVarEnvList, SYN_IE(TyVarEnv),
64 GenTyVar{-instance Eq-}
66 import TysWiredIn ( liftDataCon )
67 import Unique ( Unique{-instance Eq-} )
68 import UniqSet ( mkUniqSet, unionUniqSets, uniqSetToList )
69 import UniqSupply ( splitUniqSupply, getUniques, getUnique )
70 import Util ( equivClasses, mapAccumL, assoc, zipEqual, zipWithEqual,
71 thenCmp, panic, pprTrace, pprPanic, assertPanic
76 specProgram = panic "SpecProgram"
79 data SpecInfo = SpecInfo [Maybe Type] Int Id
83 lookupSpecEnv = panic "Specialise.lookupSpecEnv (ToDo)"
84 addIdSpecialisation = panic "Specialise.addIdSpecialisation (ToDo)"
85 cmpUniTypeMaybeList = panic "Specialise.cmpUniTypeMaybeList (ToDo)"
86 getIdSpecialisation = panic "Specialise.getIdSpecialisation (ToDo)"
87 isClassOpId = panic "Specialise.isClassOpId (ToDo)"
88 isLocalGenTyCon = panic "Specialise.isLocalGenTyCon (ToDo)"
89 isLocalSpecTyCon = panic "Specialise.isLocalSpecTyCon (ToDo)"
90 isSpecId_maybe = panic "Specialise.isSpecId_maybe (ToDo)"
91 isSpecPragmaId_maybe = panic "Specialise.isSpecPragmaId_maybe (ToDo)"
92 lookupClassInstAtSimpleType = panic "Specialise.lookupClassInstAtSimpleType (ToDo)"
93 mkSpecEnv = panic "Specialise.mkSpecEnv (ToDo)"
94 mkSpecId = panic "Specialise.mkSpecId (ToDo)"
95 selectIdInfoForSpecId = panic "Specialise.selectIdInfoForSpecId (ToDo)"
96 specialiseTy = panic "Specialise.specialiseTy (ToDo)"
99 %************************************************************************
101 \subsection[notes-Specialise]{Implementation notes [SLPJ, Aug 18 1993]}
103 %************************************************************************
105 These notes describe how we implement specialisation to eliminate
106 overloading, and optionally to eliminate unboxed polymorphism, and
109 The specialisation pass is a partial evaluator which works on Core
110 syntax, complete with all the explicit dictionary application,
111 abstraction and construction as added by the type checker. The
112 existing type checker remains largely as it is.
114 One important thought: the {\em types} passed to an overloaded
115 function, and the {\em dictionaries} passed are mutually redundant.
116 If the same function is applied to the same type(s) then it is sure to
117 be applied to the same dictionary(s)---or rather to the same {\em
118 values}. (The arguments might look different but they will evaluate
121 Second important thought: we know that we can make progress by
122 treating dictionary arguments as static and worth specialising on. So
123 we can do without binding-time analysis, and instead specialise on
124 dictionary arguments and no others.
133 and suppose f is overloaded.
135 STEP 1: CALL-INSTANCE COLLECTION
137 We traverse <body>, accumulating all applications of f to types and
140 (Might there be partial applications, to just some of its types and
141 dictionaries? In principle yes, but in practice the type checker only
142 builds applications of f to all its types and dictionaries, so partial
143 applications could only arise as a result of transformation, and even
144 then I think it's unlikely. In any case, we simply don't accumulate such
145 partial applications.)
147 There's a choice of whether to collect details of all *polymorphic* functions
148 or simply all *overloaded* ones. How to sort this out?
149 Pass in a predicate on the function to say if it is "interesting"?
150 This is dependent on the user flags: SpecialiseOverloaded
156 So now we have a collection of calls to f:
160 Notice that f may take several type arguments. To avoid ambiguity, we
161 say that f is called at type t1/t2 and t3/t4.
163 We take equivalence classes using equality of the *types* (ignoring
164 the dictionary args, which as mentioned previously are redundant).
166 STEP 3: SPECIALISATION
168 For each equivalence class, choose a representative (f t1 t2 d1 d2),
169 and create a local instance of f, defined thus:
171 f@t1/t2 = <f_rhs> t1 t2 d1 d2
173 (f_rhs presumably has some big lambdas and dictionary lambdas, so lots
174 of simplification will now result.) Then we should recursively do
177 The new id has its own unique, but its print-name (if exported) has
178 an explicit representation of the instance types t1/t2.
180 Add this new id to f's IdInfo, to record that f has a specialised version.
182 Before doing any of this, check that f's IdInfo doesn't already
183 tell us about an existing instance of f at the required type/s.
184 (This might happen if specialisation was applied more than once, or
185 it might arise from user SPECIALIZE pragmas.)
189 Wait a minute! What if f is recursive? Then we can't just plug in
190 its right-hand side, can we?
192 But it's ok. The type checker *always* creates non-recursive definitions
193 for overloaded recursive functions. For example:
195 f x = f (x+x) -- Yes I know its silly
199 f a (d::Num a) = let p = +.sel a d
201 letrec fl (y::a) = fl (p y y)
205 We still have recusion for non-overloadd functions which we
206 speciailise, but the recursive call should get speciailised to the
207 same recursive version.
213 All this is crystal clear when the function is applied to *constant
214 types*; that is, types which have no type variables inside. But what if
215 it is applied to non-constant types? Suppose we find a call of f at type
216 t1/t2. There are two possibilities:
218 (a) The free type variables of t1, t2 are in scope at the definition point
219 of f. In this case there's no problem, we proceed just as before. A common
220 example is as follows. Here's the Haskell:
225 After typechecking we have
227 g a (d::Num a) (y::a) = let f b (d'::Num b) (x::b) = +.sel b d' x x
228 in +.sel a d (f a d y) (f a d y)
230 Notice that the call to f is at type type "a"; a non-constant type.
231 Both calls to f are at the same type, so we can specialise to give:
233 g a (d::Num a) (y::a) = let f@a (x::a) = +.sel a d x x
234 in +.sel a d (f@a y) (f@a y)
237 (b) The other case is when the type variables in the instance types
238 are *not* in scope at the definition point of f. The example we are
239 working with above is a good case. There are two instances of (+.sel a d),
240 but "a" is not in scope at the definition of +.sel. Can we do anything?
241 Yes, we can "common them up", a sort of limited common sub-expression deal.
244 g a (d::Num a) (y::a) = let +.sel@a = +.sel a d
245 f@a (x::a) = +.sel@a x x
246 in +.sel@a (f@a y) (f@a y)
248 This can save work, and can't be spotted by the type checker, because
249 the two instances of +.sel weren't originally at the same type.
253 * There are quite a few variations here. For example, the defn of
254 +.sel could be floated ouside the \y, to attempt to gain laziness.
255 It certainly mustn't be floated outside the \d because the d has to
258 * We don't want to inline f_rhs in this case, because
259 that will duplicate code. Just commoning up the call is the point.
261 * Nothing gets added to +.sel's IdInfo.
263 * Don't bother unless the equivalence class has more than one item!
265 Not clear whether this is all worth it. It is of course OK to
266 simply discard call-instances when passing a big lambda.
268 Polymorphism 2 -- Overloading
270 Consider a function whose most general type is
272 f :: forall a b. Ord a => [a] -> b -> b
274 There is really no point in making a version of g at Int/Int and another
275 at Int/Bool, because it's only instancing the type variable "a" which
276 buys us any efficiency. Since g is completely polymorphic in b there
277 ain't much point in making separate versions of g for the different
280 That suggests that we should identify which of g's type variables
281 are constrained (like "a") and which are unconstrained (like "b").
282 Then when taking equivalence classes in STEP 2, we ignore the type args
283 corresponding to unconstrained type variable. In STEP 3 we make
284 polymorphic versions. Thus:
286 f@t1/ = /\b -> <f_rhs> t1 b d1 d2
288 This seems pretty simple, and a Good Thing.
290 Polymorphism 3 -- Unboxed
293 If we are speciailising at unboxed types we must speciailise
294 regardless of the overloading constraint. In the exaple above it is
295 worth speciailising at types Int/Int#, Int/Bool# and a/Int#, Int#/Int#
298 Note that specialising an overloaded type at an uboxed type requires
299 an unboxed instance -- we cannot default to an unspecialised version!
306 f x = let g p q = p==q
312 Before specialisation, leaving out type abstractions we have
314 f df x = let g :: Eq a => a -> a -> Bool
316 h :: Num a => a -> a -> (a, Bool)
317 h dh r s = let deq = eqFromNum dh
318 in (+ dh r s, g deq r s)
322 After specialising h we get a specialised version of h, like this:
324 h' r s = let deq = eqFromNum df
325 in (+ df r s, g deq r s)
327 But we can't naively make an instance for g from this, because deq is not in scope
328 at the defn of g. Instead, we have to float out the (new) defn of deq
329 to widen its scope. Notice that this floating can't be done in advance -- it only
330 shows up when specialisation is done.
332 DELICATE MATTER: the way we tell a dictionary binding is by looking to
333 see if it has a Dict type. If the type has been "undictify'd", so that
334 it looks like a tuple, then the dictionary binding won't be floated, and
335 an opportunity to specialise might be lost.
337 User SPECIALIZE pragmas
338 ~~~~~~~~~~~~~~~~~~~~~~~
339 Specialisation pragmas can be digested by the type checker, and implemented
340 by adding extra definitions along with that of f, in the same way as before
342 f@t1/t2 = <f_rhs> t1 t2 d1 d2
344 Indeed the pragmas *have* to be dealt with by the type checker, because
345 only it knows how to build the dictionaries d1 and d2! For example
347 g :: Ord a => [a] -> [a]
348 {-# SPECIALIZE f :: [Tree Int] -> [Tree Int] #-}
350 Here, the specialised version of g is an application of g's rhs to the
351 Ord dictionary for (Tree Int), which only the type checker can conjure
352 up. There might not even *be* one, if (Tree Int) is not an instance of
353 Ord! (All the other specialision has suitable dictionaries to hand
356 Problem. The type checker doesn't have to hand a convenient <f_rhs>, because
357 it is buried in a complex (as-yet-un-desugared) binding group.
360 f@t1/t2 = f* t1 t2 d1 d2
362 where f* is the Id f with an IdInfo which says "inline me regardless!".
363 Indeed all the specialisation could be done in this way.
364 That in turn means that the simplifier has to be prepared to inline absolutely
365 any in-scope let-bound thing.
368 Again, the pragma should permit polymorphism in unconstrained variables:
370 h :: Ord a => [a] -> b -> b
371 {-# SPECIALIZE h :: [Int] -> b -> b #-}
373 We *insist* that all overloaded type variables are specialised to ground types,
374 (and hence there can be no context inside a SPECIALIZE pragma).
375 We *permit* unconstrained type variables to be specialised to
377 - or left as a polymorphic type variable
378 but nothing in between. So
380 {-# SPECIALIZE h :: [Int] -> [c] -> [c] #-}
382 is *illegal*. (It can be handled, but it adds complication, and gains the
386 SPECIALISING INSTANCE DECLARATIONS
387 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
390 instance Foo a => Foo [a] where
392 {-# SPECIALIZE instance Foo [Int] #-}
394 The original instance decl creates a dictionary-function
397 dfun.Foo.List :: forall a. Foo a -> Foo [a]
399 The SPECIALIZE pragma just makes a specialised copy, just as for
400 ordinary function definitions:
402 dfun.Foo.List@Int :: Foo [Int]
403 dfun.Foo.List@Int = dfun.Foo.List Int dFooInt
405 The information about what instance of the dfun exist gets added to
406 the dfun's IdInfo in the same way as a user-defined function too.
408 In fact, matters are a little bit more complicated than this.
409 When we make one of these specialised instances, we are defining
410 a constant dictionary, and so we want immediate access to its constant
411 methods and superclasses. Indeed, these constant methods and superclasses
412 must be in the IdInfo for the class selectors! We need help from the
413 typechecker to sort this out, perhaps by generating a separate IdInfo
416 Automatic instance decl specialisation?
417 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
418 Can instance decls be specialised automatically? It's tricky.
419 We could collect call-instance information for each dfun, but
420 then when we specialised their bodies we'd get new call-instances
421 for ordinary functions; and when we specialised their bodies, we might get
422 new call-instances of the dfuns, and so on. This all arises because of
423 the unrestricted mutual recursion between instance decls and value decls.
425 Furthermore, instance decls are usually exported and used non-locally,
426 so we'll want to compile enough to get those specialisations done.
428 Lastly, there's no such thing as a local instance decl, so we can
429 survive solely by spitting out *usage* information, and then reading that
430 back in as a pragma when next compiling the file. So for now,
431 we only specialise instance decls in response to pragmas.
433 That means that even if an instance decl ain't otherwise exported it
434 needs to be spat out as with a SPECIALIZE pragma. Furthermore, it needs
435 something to say which module defined the instance, so the usage info
436 can be fed into the right reqts info file. Blegh.
439 SPECIAILISING DATA DECLARATIONS
440 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
442 With unboxed specialisation (or full specialisation) we also require
443 data types (and their constructors) to be speciailised on unboxed
446 In addition to normal call instances we gather TyCon call instances at
447 unboxed types, determine equivalence classes for the locally defined
448 TyCons and build speciailised data constructor Ids for each TyCon and
449 substitute these in the Con calls.
451 We need the list of local TyCons to partition the TyCon instance info.
452 We pass out a FiniteMap from local TyCons to Specialised Instances to
453 give to the interface and code genertors.
455 N.B. The specialised data constructors reference the original data
456 constructor and type constructor which do not have the updated
457 specialisation info attached. Any specialisation info must be
458 extracted from the TyCon map returned.
461 SPITTING OUT USAGE INFORMATION
462 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
464 To spit out usage information we need to traverse the code collecting
465 call-instance information for all imported (non-prelude?) functions
466 and data types. Then we equivalence-class it and spit it out.
468 This is done at the top-level when all the call instances which escape
469 must be for imported functions and data types.
472 Partial specialisation by pragmas
473 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
474 What about partial specialisation:
476 k :: (Ord a, Eq b) => [a] -> b -> b -> [a]
477 {-# SPECIALIZE k :: Eq b => [Int] -> b -> b -> [a] #-}
481 {-# SPECIALIZE k :: Eq b => [Int] -> [b] -> [b] -> [a] #-}
483 Seems quite reasonable. Similar things could be done with instance decls:
485 instance (Foo a, Foo b) => Foo (a,b) where
487 {-# SPECIALIZE instance Foo a => Foo (a,Int) #-}
488 {-# SPECIALIZE instance Foo b => Foo (Int,b) #-}
490 Ho hum. Things are complex enough without this. I pass.
493 Requirements for the simplifer
494 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
495 The simplifier has to be able to take advantage of the specialisation.
497 * When the simplifier finds an application of a polymorphic f, it looks in
498 f's IdInfo in case there is a suitable instance to call instead. This converts
500 f t1 t2 d1 d2 ===> f_t1_t2
502 Note that the dictionaries get eaten up too!
504 * Dictionary selection operations on constant dictionaries must be
507 +.sel Int d ===> +Int
509 The obvious way to do this is in the same way as other specialised
510 calls: +.sel has inside it some IdInfo which tells that if it's applied
511 to the type Int then it should eat a dictionary and transform to +Int.
513 In short, dictionary selectors need IdInfo inside them for constant
516 * Exactly the same applies if a superclass dictionary is being
519 Eq.sel Int d ===> dEqInt
521 * Something similar applies to dictionary construction too. Suppose
522 dfun.Eq.List is the function taking a dictionary for (Eq a) to
523 one for (Eq [a]). Then we want
525 dfun.Eq.List Int d ===> dEq.List_Int
527 Where does the Eq [Int] dictionary come from? It is built in
528 response to a SPECIALIZE pragma on the Eq [a] instance decl.
530 In short, dfun Ids need IdInfo with a specialisation for each
531 constant instance of their instance declaration.
534 What does the specialisation IdInfo look like?
535 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
538 [Maybe Type] -- Instance types
539 Int -- No of dicts to eat
540 Id -- Specialised version
542 For example, if f has this SpecInfo:
544 SpecInfo [Just t1, Nothing, Just t3] 2 f'
548 f t1 t2 t3 d1 d2 ===> f t2
550 The "Nothings" identify type arguments in which the specialised
551 version is polymorphic.
553 What can't be done this way?
554 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
555 There is no way, post-typechecker, to get a dictionary for (say)
556 Eq a from a dictionary for Eq [a]. So if we find
560 we can't transform to
565 eqList :: (a->a->Bool) -> [a] -> [a] -> Bool
567 Of course, we currently have no way to automatically derive
568 eqList, nor to connect it to the Eq [a] instance decl, but you
569 can imagine that it might somehow be possible. Taking advantage
570 of this is permanently ruled out.
572 Still, this is no great hardship, because we intend to eliminate
573 overloading altogether anyway!
578 What about types/classes mentioned in SPECIALIZE pragmas spat out,
579 but not otherwise exported. Even if they are exported, what about
580 their original names.
582 Suggestion: use qualified names in pragmas, omitting module for
583 prelude and "this module".
590 f a (d::Num a) = let g = ...
592 ...(let d1::Ord a = Num.Ord.sel a d in g a d1)...
594 Here, g is only called at one type, but the dictionary isn't in scope at the
595 definition point for g. Usually the type checker would build a
596 definition for d1 which enclosed g, but the transformation system
597 might have moved d1's defn inward.
603 What should we do when a value is specialised to a *strict* unboxed value?
605 map_*_* f (x:xs) = let h = f x
609 Could convert let to case:
611 map_*_Int# f (x:xs) = case f x of h# ->
615 This may be undesirable since it forces evaluation here, but the value
616 may not be used in all branches of the body. In the general case this
617 transformation is impossible since the mutual recursion in a letrec
618 cannot be expressed as a case.
620 There is also a problem with top-level unboxed values, since our
621 implementation cannot handle unboxed values at the top level.
623 Solution: Lift the binding of the unboxed value and extract it when it
626 map_*_Int# f (x:xs) = let h = case (f x) of h# -> _Lift h#
631 Now give it to the simplifier and the _Lifting will be optimised away.
633 The benfit is that we have given the specialised "unboxed" values a
634 very simple lifted semantics and then leave it up to the simplifier to
635 optimise it --- knowing that the overheads will be removed in nearly
638 In particular, the value will only be evaluted in the branches of the
639 program which use it, rather than being forced at the point where the
640 value is bound. For example:
642 filtermap_*_* p f (x:xs)
649 filtermap_*_Int# p f (x:xs)
650 = let h = case (f x) of h# -> _Lift h#
653 True -> case h of _Lift h#
657 The binding for h can still be inlined in the one branch and the
661 Question: When won't the _Lifting be eliminated?
663 Answer: When they at the top-level (where it is necessary) or when
664 inlining would duplicate work (or possibly code depending on
665 options). However, the _Lifting will still be eliminated if the
666 strictness analyser deems the lifted binding strict.
669 A note about non-tyvar dictionaries
670 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
671 Some Ids have types like
673 forall a,b,c. Eq a -> Ord [a] -> tau
675 This seems curious at first, because we usually only have dictionary
676 args whose types are of the form (C a) where a is a type variable.
677 But this doesn't hold for the functions arising from instance decls,
678 which sometimes get arguements with types of form (C (T a)) for some
681 Should we specialise wrt this compound-type dictionary? We used to say
683 "This is a heuristic judgement, as indeed is the fact that we
684 specialise wrt only dictionaries. We choose *not* to specialise
685 wrt compound dictionaries because at the moment the only place
686 they show up is in instance decls, where they are simply plugged
687 into a returned dictionary. So nothing is gained by specialising
690 But it is simpler and more uniform to specialise wrt these dicts too;
691 and in future GHC is likely to support full fledged type signatures
693 f ;: Eq [(a,b)] => ...
696 %************************************************************************
698 \subsubsection[CallInstances]{@CallInstances@ data type}
700 %************************************************************************
703 type FreeVarsSet = IdSet
704 type FreeTyVarsSet = TyVarSet
708 Id -- This Id; *new* ie *cloned* id
709 [Maybe Type] -- Specialised at these types (*new*, cloned)
710 -- Nothing => no specialisation on this type arg
711 -- is required (flag dependent).
712 [CoreArg] -- And these dictionaries; all ValArgs
713 FreeVarsSet -- Free vars of the dict-args in terms of *new* ids
714 (Maybe SpecInfo) -- For specialisation with explicit SpecId
718 pprCI :: CallInstance -> Doc
719 pprCI (CallInstance id spec_tys dicts _ maybe_specinfo)
720 = hang (hsep [ptext SLIT("Call inst for"), ppr PprDebug id])
721 4 (vcat [hsep (text "types" : [pprMaybeTy PprDebug ty | ty <- spec_tys]),
722 case maybe_specinfo of
723 Nothing -> hsep (text "dicts" : [ppr_arg PprDebug dict | dict <- dicts])
724 Just (SpecInfo _ _ spec_id)
725 -> hsep [ptext SLIT("Explicit SpecId"), ppr PprDebug spec_id]
728 -- ToDo: instance Outputable CoreArg?
729 ppr_arg sty (TyArg t) = ppr sty t
730 ppr_arg sty (LitArg i) = ppr sty i
731 ppr_arg sty (VarArg v) = ppr sty v
733 isUnboxedCI :: CallInstance -> Bool
734 isUnboxedCI (CallInstance _ spec_tys _ _ _)
735 = any isUnboxedType (catMaybes spec_tys)
737 isExplicitCI :: CallInstance -> Bool
738 isExplicitCI (CallInstance _ _ _ _ (Just _))
740 isExplicitCI (CallInstance _ _ _ _ Nothing)
744 Comparisons are based on the {\em types}, ignoring the dictionary args:
748 cmpCI :: CallInstance -> CallInstance -> TAG_
749 cmpCI (CallInstance id1 tys1 _ _ _) (CallInstance id2 tys2 _ _ _)
750 = cmp id1 id2 `thenCmp` cmpUniTypeMaybeList tys1 tys2
752 cmpCI_tys :: CallInstance -> CallInstance -> TAG_
753 cmpCI_tys (CallInstance _ tys1 _ _ _) (CallInstance _ tys2 _ _ _)
754 = cmpUniTypeMaybeList tys1 tys2
756 eqCI_tys :: CallInstance -> CallInstance -> Bool
758 = case cmpCI_tys c1 c2 of { EQ_ -> True; other -> False }
760 isCIofTheseIds :: [Id] -> CallInstance -> Bool
761 isCIofTheseIds ids (CallInstance ci_id _ _ _ _)
762 = any ((==) ci_id) ids
764 singleCI :: Id -> [Maybe Type] -> [CoreArg] -> UsageDetails
765 singleCI id tys dicts
766 = UsageDetails (unitBag (CallInstance id tys dicts fv_set Nothing))
767 emptyBag [] emptyIdSet 0 0
769 fv_set = mkIdSet (id : [dict | (VarArg dict) <- dicts])
771 explicitCI :: Id -> [Maybe Type] -> SpecInfo -> UsageDetails
772 explicitCI id tys specinfo
773 = UsageDetails (unitBag call_inst) emptyBag [] emptyIdSet 0 0
775 call_inst = CallInstance id tys dicts fv_set (Just specinfo)
776 dicts = panic "Specialise:explicitCI:dicts"
777 fv_set = unitIdSet id
779 -- We do not process the CIs for top-level dfuns or defms
780 -- Instead we require an explicit SPEC inst pragma for dfuns
781 -- and an explict method within any instances for the defms
783 getCIids :: Bool -> [Id] -> [Id]
784 getCIids True ids = filter not_dict_or_defm ids
788 = not (isDictTy (idType id) || maybeToBool (isDefaultMethodId_maybe id))
790 getCIs :: Bool -> [Id] -> UsageDetails -> ([CallInstance], UsageDetails)
791 getCIs top_lev ids (UsageDetails cis tycon_cis dbs fvs c i)
793 (cis_here, cis_not_here) = partitionBag (isCIofTheseIds (getCIids top_lev ids)) cis
794 cis_here_list = bagToList cis_here
796 -- pprTrace "getCIs:"
797 -- (hang (hcat [char '{',
798 -- interppSP PprDebug ids,
800 -- 4 (vcat (map pprCI cis_here_list)))
801 (cis_here_list, UsageDetails cis_not_here tycon_cis dbs fvs c i)
803 dumpCIs :: Bag CallInstance -- The call instances
804 -> Bool -- True <=> top level bound Ids
805 -> Bool -- True <=> dict bindings to be floated (specBind only)
806 -> [CallInstance] -- Call insts for bound ids (instBind only)
807 -> [Id] -- Bound ids *new*
808 -> [Id] -- Full bound ids: includes dumped dicts
809 -> Bag CallInstance -- Kept call instances
811 -- CIs are dumped if:
812 -- 1) they are a CI for one of the bound ids, or
813 -- 2) they mention any of the dicts in a local unfloated binding
815 -- For top-level bindings we allow the call instances to
816 -- float past a dict bind and place all the top-level binds
817 -- in a *global* Rec.
818 -- We leave it to the simplifier will sort it all out ...
820 dumpCIs cis top_lev floating inst_cis bound_ids full_ids
821 = (if not (isEmptyBag cis_of_bound_id) &&
822 not (isEmptyBag cis_of_bound_id_without_inst_cis)
824 pprTrace ("dumpCIs: dumping CI which was not instantiated ... \n" ++
825 " (may be a non-HM recursive call)\n")
826 (hang (hcat [char '{',
827 interppSP PprDebug bound_ids,
829 4 (vcat [ptext SLIT("Dumping CIs:"),
830 vcat (map pprCI (bagToList cis_of_bound_id)),
831 ptext SLIT("Instantiating CIs:"),
832 vcat (map pprCI inst_cis)]))
834 if top_lev || floating then
837 (if not (isEmptyBag cis_dump_unboxed)
838 then pprTrace "dumpCIs: bound dictionary arg ... WITH UNBOXED TYPES!\n"
839 (hang (hcat [char '{',
840 interppSP PprDebug full_ids,
842 4 (vcat (map pprCI (bagToList cis_dump))))
844 cis_keep_not_bound_id
847 (cis_of_bound_id, cis_not_bound_id)
848 = partitionBag (isCIofTheseIds (getCIids top_lev bound_ids)) cis
850 (cis_dump, cis_keep_not_bound_id)
851 = partitionBag ok_to_dump_ci cis_not_bound_id
853 ok_to_dump_ci (CallInstance _ _ _ fv_set _)
854 = any (\ i -> i `elementOfIdSet` fv_set) full_ids
856 (_, cis_of_bound_id_without_inst_cis) = partitionBag have_inst_ci cis_of_bound_id
857 have_inst_ci ci = any (eqCI_tys ci) inst_cis
859 (cis_dump_unboxed, _) = partitionBag isUnboxedCI cis_dump
863 Any call instances of a bound_id can be safely dumped, because any
864 recursive calls should be at the same instance as the parent instance.
866 letrec f = /\a -> \x::a -> ...(f t x')...
868 Here, the type, t, at which f is used in its own RHS should be
869 just "a"; that is, the recursive call is at the same type as
870 the original call. That means that when specialising f at some
871 type, say Int#, we shouldn't find any *new* instances of f
872 arising from specialising f's RHS. The only instance we'll find
873 is another call of (f Int#).
875 We check this in dumpCIs by passing in all the instantiated call
876 instances (inst_cis) and reporting any dumped cis (cis_of_bound_id)
877 for which there is no such instance.
879 We also report CIs dumped due to a bound dictionary arg if they
880 contain unboxed types.
882 %************************************************************************
884 \subsubsection[TyConInstances]{@TyConInstances@ data type}
886 %************************************************************************
890 = TyConInstance TyCon -- Type Constructor
891 [Maybe Type] -- Applied to these specialising types
893 cmpTyConI :: TyConInstance -> TyConInstance -> TAG_
894 cmpTyConI (TyConInstance tc1 tys1) (TyConInstance tc2 tys2)
895 = cmp tc1 tc2 `thenCmp` cmpUniTypeMaybeList tys1 tys2
897 cmpTyConI_tys :: TyConInstance -> TyConInstance -> TAG_
898 cmpTyConI_tys (TyConInstance _ tys1) (TyConInstance _ tys2)
899 = cmpUniTypeMaybeList tys1 tys2
901 singleTyConI :: TyCon -> [Maybe Type] -> UsageDetails
902 singleTyConI ty_con spec_tys
903 = UsageDetails emptyBag (unitBag (TyConInstance ty_con spec_tys)) [] emptyIdSet 0 0
905 isTyConIofThisTyCon :: TyCon -> TyConInstance -> Bool
906 isTyConIofThisTyCon ty_con (TyConInstance inst_ty_con _) = ty_con == inst_ty_con
908 isLocalSpecTyConI :: Bool -> TyConInstance -> Bool
909 isLocalSpecTyConI comp_prel (TyConInstance inst_ty_con _) = isLocalSpecTyCon comp_prel inst_ty_con
911 getLocalSpecTyConIs :: Bool -> UsageDetails -> ([TyConInstance], UsageDetails)
912 getLocalSpecTyConIs comp_prel (UsageDetails cis tycon_cis dbs fvs c i)
914 (tycon_cis_local, tycon_cis_global)
915 = partitionBag (isLocalSpecTyConI comp_prel) tycon_cis
916 tycon_cis_local_list = bagToList tycon_cis_local
918 (tycon_cis_local_list, UsageDetails cis tycon_cis_global dbs fvs c i)
922 %************************************************************************
924 \subsubsection[UsageDetails]{@UsageDetails@ data type}
926 %************************************************************************
931 (Bag CallInstance) -- The collection of call-instances
932 (Bag TyConInstance) -- Constructor call-instances
933 [DictBindDetails] -- Dictionary bindings in data-dependence order!
934 FreeVarsSet -- Free variables (excl imported ones, incl top level) (cloned)
935 Int -- no. of spec calls
936 Int -- no. of spec insts
939 The DictBindDetails are fully processed; their call-instance
940 information is incorporated in the call-instances of the UsageDetails
941 which includes the DictBindDetails. The free vars in a usage details
942 will *include* the binders of the DictBind details.
944 A @DictBindDetails@ contains bindings for dictionaries *only*.
949 [Id] -- Main binders, originally visible in scope of binding (cloned)
950 CoreBinding -- Fully processed
951 FreeVarsSet -- Free in binding group (cloned)
952 FreeTyVarsSet -- Free in binding group
956 emptyUDs :: UsageDetails
957 unionUDs :: UsageDetails -> UsageDetails -> UsageDetails
958 unionUDList :: [UsageDetails] -> UsageDetails
960 -- tickSpecCall :: Bool -> UsageDetails -> UsageDetails
961 tickSpecInsts :: UsageDetails -> UsageDetails
963 -- tickSpecCall found (UsageDetails cis ty_cis dbs fvs c i)
964 -- = UsageDetails cis ty_cis dbs fvs (c + (if found then 1 else 0)) i
966 tickSpecInsts (UsageDetails cis ty_cis dbs fvs c i)
967 = UsageDetails cis ty_cis dbs fvs c (i+1)
969 emptyUDs = UsageDetails emptyBag emptyBag [] emptyIdSet 0 0
971 unionUDs (UsageDetails cis1 tycon_cis1 dbs1 fvs1 c1 i1) (UsageDetails cis2 tycon_cis2 dbs2 fvs2 c2 i2)
972 = UsageDetails (unionBags cis1 cis2) (unionBags tycon_cis1 tycon_cis2)
973 (dbs1 ++ dbs2) (fvs1 `unionIdSets` fvs2) (c1+c2) (i1+i2)
974 -- The append here is really redundant, since the bindings don't
975 -- scope over each other. ToDo.
977 unionUDList = foldr unionUDs emptyUDs
979 singleFvUDs (VarArg v) | not (isImportedId v)
980 = UsageDetails emptyBag emptyBag [] (unitIdSet v) 0 0
984 singleConUDs con = UsageDetails emptyBag emptyBag [] (unitIdSet con) 0 0
986 dumpDBs :: [DictBindDetails]
987 -> Bool -- True <=> top level bound Ids
988 -> [TyVar] -- TyVars being bound (cloned)
989 -> [Id] -- Ids being bound (cloned)
990 -> FreeVarsSet -- Fvs of body
991 -> ([CoreBinding], -- These ones have to go here
992 [DictBindDetails], -- These can float further
993 [Id], -- Incoming list + names of dicts bound here
994 FreeVarsSet -- Incoming fvs + fvs of dicts bound here
997 -- It is just to complex to try to float top-level
998 -- dict bindings with constant methods, inst methods,
999 -- auxillary derived instance defns and user instance
1000 -- defns all getting in the way.
1001 -- So we dump all dbinds as soon as we get to the top
1002 -- level and place them in a *global* Rec.
1003 -- We leave it to the simplifier will sort it all out ...
1005 dumpDBs [] top_lev bound_tyvars bound_ids fvs
1006 = ([], [], bound_ids, fvs)
1008 dumpDBs ((db@(DictBindDetails dbinders dbind db_fvs db_ftv)):dbs)
1009 top_lev bound_tyvars bound_ids fvs
1011 || any (\ i -> i `elementOfIdSet` db_fvs) bound_ids
1012 || any (\ t -> t `elementOfTyVarSet` db_ftv) bound_tyvars
1013 = let -- Ha! Dump it!
1014 (dbinds_here, dbs_outer, full_bound_ids, full_fvs)
1015 = dumpDBs dbs top_lev bound_tyvars (dbinders ++ bound_ids) (db_fvs `unionIdSets` fvs)
1017 (dbind : dbinds_here, dbs_outer, full_bound_ids, full_fvs)
1019 | otherwise -- This one can float out further
1021 (dbinds_here, dbs_outer, full_bound_ids, full_fvs)
1022 = dumpDBs dbs top_lev bound_tyvars bound_ids fvs
1024 (dbinds_here, db : dbs_outer, full_bound_ids, full_fvs)
1028 dumpUDs :: UsageDetails
1029 -> Bool -- True <=> top level bound Ids
1030 -> Bool -- True <=> dict bindings to be floated (specBind only)
1031 -> [CallInstance] -- Call insts for bound Ids (instBind only)
1032 -> [Id] -- Ids which are just being bound; *new*
1033 -> [TyVar] -- TyVars which are just being bound
1034 -> ([CoreBinding], -- Bindings from UsageDetails which mention the ids
1035 UsageDetails) -- The above bindings removed, and
1036 -- any call-instances which mention the ids dumped too
1038 dumpUDs (UsageDetails cis tycon_cis dbs fvs c i) top_lev floating inst_cis bound_ids tvs
1040 (dict_binds_here, dbs_outer, full_bound_ids, full_fvs)
1041 = dumpDBs dbs top_lev tvs bound_ids fvs
1042 cis_outer = dumpCIs cis top_lev floating inst_cis bound_ids full_bound_ids
1043 fvs_outer = full_fvs `minusIdSet` (mkIdSet full_bound_ids)
1045 (dict_binds_here, UsageDetails cis_outer tycon_cis dbs_outer fvs_outer c i)
1049 addDictBinds :: [Id] -> CoreBinding -> UsageDetails -- Dict binding and RHS usage
1050 -> UsageDetails -- The usage to augment
1052 addDictBinds dbinders dbind (UsageDetails db_cis db_tycon_cis db_dbs db_fvs db_c db_i)
1053 (UsageDetails cis tycon_cis dbs fvs c i)
1054 = UsageDetails (db_cis `unionBags` cis)
1055 (db_tycon_cis `unionBags` tycon_cis)
1056 (db_dbs ++ [DictBindDetails dbinders dbind db_fvs db_ftvs] ++ dbs)
1058 -- NB: We ignore counts from dictbinds since it is not user code
1060 -- The free tyvars of the dictionary bindings should really be
1061 -- gotten from the RHSs, but I'm pretty sure it's good enough just
1062 -- to look at the type of the dictionary itself.
1063 -- Doing the proper job would entail keeping track of free tyvars as
1064 -- well as free vars, which would be a bore.
1065 db_ftvs = tyVarsOfTypes (map idType dbinders)
1068 %************************************************************************
1070 \subsection[cloning-binders]{The Specialising IdEnv and CloneInfo}
1072 %************************************************************************
1074 @SpecIdEnv@ maps old Ids to their new "clone". There are three cases:
1076 1) (NoLift LitArg l) : an Id which is bound to a literal
1078 2) (NoLift LitArg l) : an Id bound to a "new" Id
1079 The new Id is a possibly-type-specialised clone of the original
1081 3) Lifted lifted_id unlifted_id :
1083 This indicates that the original Id has been specialised to an
1084 unboxed value which must be lifted (see "Unboxed bindings" above)
1085 @unlifted_id@ is the unboxed clone of the original Id
1086 @lifted_id@ is a *lifted* version of the original Id
1088 When you lookup Ids which are Lifted, you have to insert a case
1089 expression to un-lift the value (done with @bindUnlift@)
1091 You also have to insert a case to lift the value in the binding
1092 (done with @liftExpr@)
1096 type SpecIdEnv = IdEnv CloneInfo
1099 = NoLift CoreArg -- refers to cloned id or literal
1101 | Lifted Id -- lifted, cloned id
1102 Id -- unlifted, cloned id
1106 %************************************************************************
1108 \subsection[specialise-data]{Data returned by specialiser}
1110 %************************************************************************
1117 -- True <=> Specialisation performed
1119 -- False <=> Specialisation completed with errors
1122 -- Local tycons declared in this module
1125 -- Those in-scope data types for which we want to
1126 -- generate code for their constructors.
1127 -- Namely: data types declared in this module +
1128 -- any big tuples used in this module
1129 -- The initial (and default) value is the local tycons
1131 (FiniteMap TyCon [(Bool, [Maybe Type])])
1132 -- TyCon specialisations to be generated
1133 -- We generate specialialised code (Bool=True) for data types
1134 -- defined in this module and any tuples used in this module
1135 -- The initial (and default) value is the specialisations
1136 -- requested by source-level SPECIALIZE data pragmas (Bool=True)
1137 -- and _SPECIALISE_ pragmas (Bool=False) in the interface files
1139 (Bag (Id,[Maybe Type]))
1140 -- Imported specialisation errors
1141 (Bag (Id,[Maybe Type]))
1142 -- Imported specialisation warnings
1143 (Bag (TyCon,[Maybe Type]))
1144 -- Imported TyCon specialisation errors
1146 initSpecData local_tycons tycon_specs
1147 = SpecData False True local_tycons local_tycons tycon_specs emptyBag emptyBag emptyBag
1152 ToDo[sansom]: Transformation data to process specialisation requests.
1154 %************************************************************************
1156 \subsection[specProgram]{Specialising a core program}
1158 %************************************************************************
1161 specProgram :: UniqSupply
1162 -> [CoreBinding] -- input ...
1164 -> ([CoreBinding], -- main result
1165 SpecialiseData) -- result specialise data
1167 specProgram uniqs binds
1168 (SpecData False _ local_tycons _ init_specs init_errs init_warn init_tyerrs)
1169 = case (initSM (specTyConsAndScope (specTopBinds binds)) uniqs) of
1170 (final_binds, tycon_specs_list,
1171 UsageDetails import_cis import_tycis _ fvs spec_calls spec_insts)
1173 used_conids = filter isDataCon (uniqSetToList fvs)
1174 used_tycons = map dataConTyCon used_conids
1175 used_gen = filter isLocalGenTyCon used_tycons
1176 gen_tycons = uniqSetToList (mkUniqSet local_tycons `unionUniqSets` mkUniqSet used_gen)
1178 result_specs = addListToFM_C (++) init_specs tycon_specs_list
1180 uniq_cis = map head (equivClasses cmpCI (bagToList import_cis))
1181 cis_list = [(id, tys) | CallInstance id tys _ _ _ <- uniq_cis]
1182 (cis_unboxed, cis_other) = partition (isUnboxedSpecialisation . snd) cis_list
1183 cis_warn = init_warn `unionBags` listToBag cis_other
1184 cis_errs = init_errs `unionBags` listToBag cis_unboxed
1186 uniq_tycis = map head (equivClasses cmpTyConI (bagToList import_tycis))
1187 tycis_unboxed = [(con, tys) | TyConInstance con tys <- uniq_tycis]
1188 tycis_errs = init_tyerrs `unionBags` listToBag tycis_unboxed
1190 no_errs = isEmptyBag cis_errs && isEmptyBag tycis_errs
1191 && (not opt_SpecialiseImports || isEmptyBag cis_warn)
1193 (if opt_D_simplifier_stats then
1194 pprTrace "\nSpecialiser Stats:\n" (vcat [
1195 hcat [ptext SLIT("SpecCalls "), int spec_calls],
1196 hcat [ptext SLIT("SpecInsts "), int spec_insts],
1201 SpecData True no_errs local_tycons gen_tycons result_specs
1202 cis_errs cis_warn tycis_errs)
1204 specProgram uniqs binds (SpecData True _ _ _ _ _ _ _)
1205 = panic "Specialise:specProgram: specialiser called more than once"
1207 -- It may be possible safely to call the specialiser more than once,
1208 -- but I am not sure there is any benefit in doing so (Patrick)
1210 -- ToDo: What about unfoldings performed after specialisation ???
1213 %************************************************************************
1215 \subsection[specTyConsAndScope]{Specialising data constructors within tycons}
1217 %************************************************************************
1219 In the specialiser we just collect up the specialisations which will
1220 be required. We don't create the specialised constructors in
1221 Core. These are only introduced when we convert to StgSyn.
1223 ToDo: Perhaps this collection should be done in CoreToStg to ensure no inconsistencies!
1226 specTyConsAndScope :: SpecM ([CoreBinding], UsageDetails)
1227 -> SpecM ([CoreBinding], [(TyCon,[(Bool,[Maybe Type])])], UsageDetails)
1229 specTyConsAndScope scopeM
1230 = scopeM `thenSM` \ (binds, scope_uds) ->
1232 (tycons_cis, gotci_scope_uds)
1233 = getLocalSpecTyConIs opt_CompilingGhcInternals scope_uds
1235 tycon_specs_list = collectTyConSpecs tycons_cis
1237 (if opt_SpecialiseTrace && not (null tycon_specs_list) then
1238 pprTrace "Specialising TyCons:\n"
1239 (vcat [ if not (null specs) then
1240 hang (hsep [(ppr PprDebug tycon), ptext SLIT("at types")])
1241 4 (vcat (map pp_specs specs))
1243 | (tycon, specs) <- tycon_specs_list])
1245 returnSM (binds, tycon_specs_list, gotci_scope_uds)
1248 collectTyConSpecs []
1250 collectTyConSpecs tycons_cis@(TyConInstance tycon _ : _)
1251 = (tycon, tycon_specs) : collectTyConSpecs other_tycons_cis
1253 (tycon_cis, other_tycons_cis) = partition (isTyConIofThisTyCon tycon) tycons_cis
1254 uniq_cis = map head (equivClasses cmpTyConI_tys tycon_cis)
1255 tycon_specs = [(False, spec_tys) | TyConInstance _ spec_tys <- uniq_cis]
1257 pp_specs (False, spec_tys) = hsep [pprMaybeTy PprDebug spec_ty | spec_ty <- spec_tys]
1261 %************************************************************************
1263 \subsection[specTopBinds]{Specialising top-level bindings}
1265 %************************************************************************
1268 specTopBinds :: [CoreBinding]
1269 -> SpecM ([CoreBinding], UsageDetails)
1272 = spec_top_binds binds `thenSM` \ (binds, UsageDetails cis tycis dbind_details fvs c i) ->
1274 -- Add bindings for floated dbinds and collect fvs
1275 -- In actual fact many of these bindings are dead code since dict
1276 -- arguments are dropped when a specialised call is created
1277 -- The simplifier should be able to cope ...
1279 (dbinders_s, dbinds, dfvs_s)
1280 = unzip3 [(dbinders, dbind, dfvs) | DictBindDetails dbinders dbind dfvs _ <- dbind_details]
1282 full_fvs = fvs `unionIdSets` unionManyIdSets dfvs_s
1283 fvs_outer = full_fvs `minusIdSet` (mkIdSet (concat dbinders_s))
1285 -- It is just to complex to try to sort out top-level dependencies
1286 -- So we just place all the top-level binds in a *global* Rec and
1287 -- leave it to the simplifier to sort it all out ...
1290 returnSM ([Rec (pairsFromCoreBinds binds)], UsageDetails cis tycis [] fvs_outer c i)
1293 spec_top_binds (first_bind:rest_binds)
1294 = specBindAndScope True first_bind (
1295 spec_top_binds rest_binds `thenSM` \ (rest_binds, rest_uds) ->
1296 returnSM (ItsABinds rest_binds, rest_uds)
1297 ) `thenSM` \ (first_binds, ItsABinds rest_binds, all_uds) ->
1298 returnSM (first_binds ++ rest_binds, all_uds)
1301 = returnSM ([], emptyUDs)
1304 %************************************************************************
1306 \subsection[specExpr]{Specialising expressions}
1308 %************************************************************************
1311 specExpr :: CoreExpr
1312 -> [CoreArg] -- The arguments:
1313 -- TypeArgs are speced
1314 -- ValArgs are unprocessed
1315 -> SpecM (CoreExpr, -- Result expression with specialised versions installed
1316 UsageDetails)-- Details of usage of enclosing binders in the result
1319 specExpr (Var v) args
1320 = specId v $ \ v_arg ->
1322 LitArg lit -> ASSERT( null args )
1323 returnSM (Lit lit, emptyUDs)
1325 VarArg new_v -> mkCallInstance v new_v args `thenSM` \ uds ->
1326 returnSM (mkGenApp (Var new_v) args, uds)
1328 specExpr expr@(Lit _) null_args
1329 = ASSERT (null null_args)
1330 returnSM (expr, emptyUDs)
1332 specExpr (Con con args) null_args
1333 = ASSERT (null null_args)
1334 specArgs args $ \ args' ->
1335 mkTyConInstance con args' `thenSM` \ con_uds ->
1336 returnSM (Con con args', con_uds)
1338 specExpr (Prim op@(CCallOp str is_asm may_gc arg_tys res_ty) args) null_args
1339 = ASSERT (null null_args)
1340 specArgs args $ \ args' ->
1341 mapSM specTy arg_tys `thenSM` \ arg_tys' ->
1342 specTy res_ty `thenSM` \ res_ty' ->
1343 returnSM (Prim (CCallOp str is_asm may_gc arg_tys' res_ty') args', emptuUDs)
1345 specExpr (Prim prim args) null_args
1346 = ASSERT (null null_args)
1347 specArgs args $ \ args' ->
1348 -- specPrimOp prim tys `thenSM` \ (prim, tys, prim_uds) ->
1349 returnSM (Prim prim args', emptyUDs {-`unionUDs` prim_uds-} )
1353 specPrimOp :: PrimOp
1359 -- Checks that PrimOp can handle (possibly unboxed) tys passed
1360 -- and/or chooses PrimOp specialised to any unboxed tys
1361 -- Errors are dealt with by returning a PrimOp call instance
1362 -- which will result in a cis_errs message
1364 -- ToDo: Deal with checkSpecTyApp for Prim in CoreLint
1368 specExpr (App fun arg) args
1369 = specArg arg `thenSM` \ new_arg ->
1370 specExpr fun (new_arg : args) `thenSM` \ (expr,uds) ->
1371 returnSM (expr, uds)
1373 specExpr (Lam (ValBinder binder) body) (arg : args) | isValArg arg
1374 = lookup_arg arg `thenSM` \ arg ->
1375 bindId binder arg (specExpr body args)
1377 lookup_arg (LitArg l) = returnSM (NoLift (LitArg l))
1378 lookup_arg (VarArg v) = lookupId v
1380 specExpr (Lam (ValBinder binder) body) []
1381 = specLambdaOrCaseBody [binder] body [] `thenSM` \ ([binder], body, uds) ->
1382 returnSM (Lam (ValBinder binder) body, uds)
1384 specExpr (Lam (TyBinder tyvar) body) (TyArg ty : args)
1385 = -- Type lambda with argument; argument already spec'd
1386 bindTyVar tyvar ty ( specExpr body args )
1388 specExpr (Lam (TyBinder tyvar) body) []
1390 cloneTyVarSM tyvar `thenSM` \ new_tyvar ->
1391 bindTyVar tyvar (mkTyVarTy new_tyvar) (
1392 specExpr body [] `thenSM` \ (body, body_uds) ->
1394 (binds_here, final_uds) = dumpUDs body_uds False False [] [] [new_tyvar]
1396 returnSM (Lam (TyBinder new_tyvar)
1397 (mkCoLetsNoUnboxed binds_here body),
1401 specExpr (Case scrutinee alts) args
1402 = specExpr scrutinee [] `thenSM` \ (scrutinee, scrut_uds) ->
1403 specAlts alts scrutinee_type args `thenSM` \ (alts, alts_uds) ->
1404 returnSM (Case scrutinee alts, scrut_uds `unionUDs` alts_uds)
1406 scrutinee_type = coreExprType scrutinee
1408 specExpr (Let bind body) args
1409 = specBindAndScope False bind (
1410 specExpr body args `thenSM` \ (body, body_uds) ->
1411 returnSM (ItsAnExpr body, body_uds)
1412 ) `thenSM` \ (binds, ItsAnExpr body, all_uds) ->
1413 returnSM (mkCoLetsUnboxedToCase binds body, all_uds)
1415 specExpr (SCC cc expr) args
1416 = specExpr expr [] `thenSM` \ (expr, expr_uds) ->
1417 mapAndUnzip3SM specOutArg args `thenSM` \ (args, args_uds_s, unlifts) ->
1420 = if squashableDictishCcExpr cc expr -- can toss the _scc_
1424 returnSM (applyBindUnlifts unlifts (mkGenApp scc_expr args),
1425 unionUDList args_uds_s `unionUDs` expr_uds)
1427 specExpr (Coerce _ _ _) args = panic "Specialise.specExpr:Coerce"
1429 -- ToDo: This may leave some unspec'd dictionaries!!
1432 %************************************************************************
1434 \subsubsection{Specialising a lambda}
1436 %************************************************************************
1439 specLambdaOrCaseBody :: [Id] -- The binders
1440 -> CoreExpr -- The body
1441 -> [CoreArg] -- Its args
1442 -> SpecM ([Id], -- New binders
1443 CoreExpr, -- New body
1446 specLambdaOrCaseBody bound_ids body args
1447 = cloneLambdaOrCaseBinders bound_ids `thenSM` \ (new_ids, clone_infos) ->
1448 bindIds bound_ids clone_infos (
1450 specExpr body args `thenSM` \ (body, body_uds) ->
1453 -- Dump any dictionary bindings (and call instances)
1454 -- from the scope which mention things bound here
1455 (binds_here, final_uds) = dumpUDs body_uds False False [] new_ids []
1457 returnSM (new_ids, mkCoLetsNoUnboxed binds_here body, final_uds)
1460 -- ToDo: Opportunity here to common-up dictionaries with same type,
1461 -- thus avoiding recomputation.
1464 A variable bound in a lambda or case is normally monomorphic so no
1465 specialised versions will be required. This is just as well since we
1466 do not know what code to specialise!
1468 Unfortunately this is not always the case. For example a class Foo
1469 with polymorphic methods gives rise to a dictionary with polymorphic
1470 components as follows:
1477 instance Foo Int where
1485 d.Foo.Int :: ( \/b . Int -> b -> Int, \/c . Int -> c -> Int )
1486 d.Foo.Int = (op1_Int, op2_Int)
1488 op1 = /\ a b -> \ dFoo -> case dFoo of (meth1, _) -> meth1 b
1490 ... op1 {Int Int#} d.Foo.Int 1 3# ...
1493 N.B. The type of the dictionary is not Hindley Milner!
1495 Now we must specialise op1 at {* Int#} which requires a version of
1496 meth1 at {Int#}. But since meth1 was extracted from a dictionary we do
1497 not have access to its code to create the specialised version.
1499 If we specialise on overloaded types as well we specialise op1 at
1500 {Int Int#} d.Foo.Int:
1502 op1_Int_Int# = case d.Foo.Int of (meth1, _) -> meth1 {Int#}
1504 Though this is still invalid, after further simplification we get:
1506 op1_Int_Int# = opInt1 {Int#}
1508 Another round of specialisation will result in the specialised
1509 version of op1Int being called directly.
1511 For now we PANIC if a polymorphic lambda/case bound variable is found
1512 in a call instance with an unboxed type. Other call instances, arising
1513 from overloaded type arguments, are discarded since the unspecialised
1514 version extracted from the method can be called as normal.
1516 ToDo: Implement and test second round of specialisation.
1519 %************************************************************************
1521 \subsubsection{Specialising case alternatives}
1523 %************************************************************************
1527 specAlts (AlgAlts alts deflt) scrutinee_ty args
1528 = mapSM specTy ty_args `thenSM` \ ty_args ->
1529 mapAndUnzipSM (specAlgAlt ty_args) alts `thenSM` \ (alts, alts_uds_s) ->
1530 specDeflt deflt args `thenSM` \ (deflt, deflt_uds) ->
1531 returnSM (AlgAlts alts deflt,
1532 unionUDList alts_uds_s `unionUDs` deflt_uds)
1534 -- We use ty_args of scrutinee type to identify specialisation of
1537 (_, ty_args, _) = --trace "Specialise.specAlts:getAppData..." $
1538 getAppDataTyConExpandingDicts scrutinee_ty
1540 specAlgAlt ty_args (con,binders,rhs)
1541 = specLambdaOrCaseBody binders rhs args `thenSM` \ (binders, rhs, rhs_uds) ->
1542 mkTyConInstance con ty_args `thenSM` \ con_uds ->
1543 returnSM ((con,binders,rhs), rhs_uds `unionUDs` con_uds)
1545 specAlts (PrimAlts alts deflt) scrutinee_ty args
1546 = mapAndUnzipSM specPrimAlt alts `thenSM` \ (alts, alts_uds_s) ->
1547 specDeflt deflt args `thenSM` \ (deflt, deflt_uds) ->
1548 returnSM (PrimAlts alts deflt,
1549 unionUDList alts_uds_s `unionUDs` deflt_uds)
1551 specPrimAlt (lit,rhs) = specExpr rhs args `thenSM` \ (rhs, uds) ->
1552 returnSM ((lit,rhs), uds)
1555 specDeflt NoDefault args = returnSM (NoDefault, emptyUDs)
1556 specDeflt (BindDefault binder rhs) args
1557 = specLambdaOrCaseBody [binder] rhs args `thenSM` \ ([binder], rhs, uds) ->
1558 returnSM (BindDefault binder rhs, uds)
1562 %************************************************************************
1564 \subsubsection{Specialising an atom}
1566 %************************************************************************
1569 partition_args :: [CoreArg] -> ([CoreArg], [CoreArg])
1571 = span is_ty_arg args
1573 is_ty_arg (TyArg _) = True
1578 -> (CoreArg -> SpecM (CoreExpr, UsageDetails))
1579 -> SpecM (CoreExpr, UsageDetails)
1581 = lookupId v `thenSM` \ vlookup ->
1585 -> thing_inside (VarArg vu) `thenSM` \ (expr, uds) ->
1586 returnSM (bindUnlift vl vu expr, singleFvUDs (VarArg vl) `unionUDs` uds)
1589 -> thing_inside vatom `thenSM` \ (expr, uds) ->
1590 returnSM (expr, singleFvUDs vatom `unionUDs` uds)
1593 -> (CoreArg -> SpecM (CoreExpr, UsageDetails))
1594 -> SpecM (CoreExpr, UsageDetails))
1596 specArg (TyArg ty) thing_inside
1597 = specTy ty `thenSM` \ new_ty ->
1598 thing_inside (TyArg new_ty)
1600 specArg (LitArg lit)
1601 = thing_inside (LitArg lit)
1606 specArgs [] thing_inside
1609 specArgs (arg:args) thing_inside
1610 = specArg arg $ \ arg' ->
1611 specArgs args $ \ args' ->
1612 thing_inside (arg' : args')
1616 %************************************************************************
1618 \subsubsection{Specialising bindings}
1620 %************************************************************************
1622 A classic case of when having a polymorphic recursive function would help!
1625 data BindsOrExpr = ItsABinds [CoreBinding]
1626 | ItsAnExpr CoreExpr
1631 :: Bool -- True <=> a top level group
1632 -> CoreBinding -- As yet unprocessed
1633 -> SpecM (BindsOrExpr, UsageDetails) -- Something to do the scope of the bindings
1634 -> SpecM ([CoreBinding], -- Processed
1635 BindsOrExpr, -- Combined result
1636 UsageDetails) -- Usage details of the whole lot
1638 specBindAndScope top_lev bind scopeM
1639 = cloneLetBinders top_lev (is_rec bind) binders
1640 `thenSM` \ (new_binders, clone_infos) ->
1642 -- Two cases now: either this is a bunch of local dictionaries,
1643 -- in which case we float them; or its a bunch of other values,
1644 -- in which case we see if they correspond to any call-instances
1645 -- we have from processing the scope
1647 if not top_lev && all (isDictTy . idType) binders
1649 -- Ha! A group of local dictionary bindings
1651 bindIds binders clone_infos (
1653 -- Process the dictionary bindings themselves
1654 specBind False True new_binders [] bind `thenSM` \ (bind, rhs_uds) ->
1656 -- Process their scope
1657 scopeM `thenSM` \ (thing, scope_uds) ->
1659 -- Add the bindings to the current stuff
1660 final_uds = addDictBinds new_binders bind rhs_uds scope_uds
1662 returnSM ([], thing, final_uds)
1665 -- Ho! A group of bindings
1667 fixSM (\ ~(_, _, _, rec_spec_infos) ->
1669 bindSpecIds binders clone_infos rec_spec_infos (
1670 -- It's ok to have new binders in scope in
1671 -- non-recursive decls too, cos name shadowing is gone by now
1673 -- Do the scope of the bindings
1674 scopeM `thenSM` \ (thing, scope_uds) ->
1676 (call_insts, gotci_scope_uds) = getCIs top_lev new_binders scope_uds
1678 equiv_ciss = equivClasses cmpCI_tys call_insts
1679 inst_cis = map head equiv_ciss
1682 -- Do the bindings themselves
1683 specBind top_lev False new_binders inst_cis bind
1684 `thenSM` \ (spec_bind, spec_uds) ->
1686 -- Create any necessary instances
1687 instBind top_lev new_binders bind equiv_ciss inst_cis
1688 `thenSM` \ (inst_binds, inst_uds, spec_infos) ->
1691 -- NB: dumpUDs only worries about new_binders since the free var
1692 -- stuff only records free new_binders
1693 -- The spec_ids only appear in SpecInfos and final speced calls
1695 -- Build final binding group and usage details
1696 (final_binds, final_uds)
1698 -- For a top-level binding we have to dumpUDs from
1699 -- spec_uds and inst_uds and scope_uds creating
1700 -- *global* dict bindings
1702 (scope_dict_binds, final_scope_uds)
1703 = dumpUDs gotci_scope_uds True False [] new_binders []
1704 (spec_dict_binds, final_spec_uds)
1705 = dumpUDs spec_uds True False inst_cis new_binders []
1706 (inst_dict_binds, final_inst_uds)
1707 = dumpUDs inst_uds True False inst_cis new_binders []
1709 ([spec_bind] ++ inst_binds ++ scope_dict_binds
1710 ++ spec_dict_binds ++ inst_dict_binds,
1711 final_spec_uds `unionUDs` final_scope_uds `unionUDs` final_inst_uds)
1713 -- For a local binding we only have to dumpUDs from
1714 -- scope_uds since the UDs from spec_uds and inst_uds
1715 -- have already been dumped by specBind and instBind
1717 (scope_dict_binds, final_scope_uds)
1718 = dumpUDs gotci_scope_uds False False [] new_binders []
1720 ([spec_bind] ++ inst_binds ++ scope_dict_binds,
1721 spec_uds `unionUDs` final_scope_uds `unionUDs` inst_uds)
1723 -- inst_uds comes last, because there may be dict bindings
1724 -- floating outward in scope_uds which are mentioned
1725 -- in the call-instances, and hence in spec_uds.
1726 -- This ordering makes sure that the precedence order
1727 -- among the dict bindings finally floated out is maintained.
1729 returnSM (final_binds, thing, final_uds, spec_infos)
1731 ) `thenSM` \ (binds, thing, final_uds, spec_infos) ->
1732 returnSM (binds, thing, final_uds)
1734 binders = bindersOf bind
1736 is_rec (NonRec _ _) = False
1741 specBind :: Bool -> Bool -> [Id] -> [CallInstance]
1743 -> SpecM (CoreBinding, UsageDetails)
1744 -- The UsageDetails returned has already had stuff to do with this group
1745 -- of binders deleted; that's why new_binders is passed in.
1746 specBind top_lev floating new_binders inst_cis (NonRec binder rhs)
1747 = specOneBinding top_lev floating new_binders inst_cis (binder,rhs)
1748 `thenSM` \ ((binder,rhs), rhs_uds) ->
1749 returnSM (NonRec binder rhs, rhs_uds)
1751 specBind top_lev floating new_binders inst_cis (Rec pairs)
1752 = mapAndUnzipSM (specOneBinding top_lev floating new_binders inst_cis) pairs
1753 `thenSM` \ (pairs, rhs_uds_s) ->
1754 returnSM (Rec pairs, unionUDList rhs_uds_s)
1757 specOneBinding :: Bool -> Bool -> [Id] -> [CallInstance]
1759 -> SpecM ((Id,CoreExpr), UsageDetails)
1761 specOneBinding top_lev floating new_binders inst_cis (binder, rhs)
1762 = lookupId binder `thenSM` \ blookup ->
1763 specExpr rhs [] `thenSM` \ (rhs, rhs_uds) ->
1765 specid_maybe_maybe = isSpecPragmaId_maybe binder
1766 is_specid = maybeToBool specid_maybe_maybe
1767 Just specinfo_maybe = specid_maybe_maybe
1768 specid_with_info = maybeToBool specinfo_maybe
1769 Just spec_info = specinfo_maybe
1771 -- If we have a SpecInfo stored in a SpecPragmaId binder
1772 -- it will contain a SpecInfo with an explicit SpecId
1773 -- We add the explicit ci to the usage details
1774 -- Any ordinary cis for orig_id (there should only be one)
1775 -- will be ignored later
1778 = if is_specid && specid_with_info then
1780 (SpecInfo spec_tys _ spec_id) = spec_info
1781 Just (orig_id, _) = isSpecId_maybe spec_id
1783 ASSERT(toplevelishId orig_id) -- must not be cloned!
1784 explicitCI orig_id spec_tys spec_info
1788 -- For a local binding we dump the usage details, creating
1789 -- any local dict bindings required
1790 -- At the top-level the uds will be dumped in specBindAndScope
1791 -- and the dict bindings made *global*
1793 (local_dict_binds, final_uds)
1794 = if not top_lev then
1795 dumpUDs rhs_uds False floating inst_cis new_binders []
1800 Lifted lift_binder unlift_binder
1801 -> -- We may need to record an unboxed instance of
1802 -- the _Lift data type in the usage details
1803 mkTyConInstance liftDataCon [idType unlift_binder]
1804 `thenSM` \ lift_uds ->
1805 returnSM ((lift_binder,
1806 mkCoLetsNoUnboxed local_dict_binds (liftExpr unlift_binder rhs)),
1807 final_uds `unionUDs` pragma_uds `unionUDs` lift_uds)
1809 NoLift (VarArg binder)
1810 -> returnSM ((binder, mkCoLetsNoUnboxed local_dict_binds rhs),
1811 final_uds `unionUDs` pragma_uds)
1815 %************************************************************************
1817 \subsection{@instBind@}
1819 %************************************************************************
1822 instBind top_lev new_ids@(first_binder:other_binders) bind equiv_ciss inst_cis
1824 = returnSM ([], emptyUDs, [])
1826 | all same_overloading other_binders
1827 = -- For each call_inst, build an instance
1828 mapAndUnzip3SM do_this_class equiv_ciss
1829 `thenSM` \ (inst_binds, inst_uds_s, spec_infos) ->
1831 -- Add in the remaining UDs
1832 returnSM (catMaybes inst_binds,
1833 unionUDList inst_uds_s,
1837 | otherwise -- Incompatible overloadings; see below by same_overloading
1838 = (if not (null (filter isUnboxedCI (concat equiv_ciss)))
1839 then pprTrace "dumpCIs: not same overloading ... WITH UNBOXED TYPES!\n"
1841 then pprTrace "dumpCIs: not same overloading ... top level \n"
1843 ) (hang (hcat [ptext SLIT("{"),
1844 interppSP PprDebug new_ids,
1846 4 (vcat [vcat (map (pprGenType PprDebug . idType) new_ids),
1847 vcat (map pprCI (concat equiv_ciss))]))
1848 (returnSM ([], emptyUDs, []))
1851 (tyvar_tmpls, class_tyvar_pairs) = getIdOverloading first_binder
1852 tyvar_tmpl_tys = mkTyVarTys tyvar_tmpls
1854 no_of_tyvars = length tyvar_tmpls
1855 no_of_dicts = length class_tyvar_pairs
1857 do_this_class equiv_cis
1858 = mkOneInst do_cis explicit_cis no_of_dicts top_lev inst_cis new_ids bind
1860 (explicit_cis, normal_cis) = partition isExplicitCI equiv_cis
1861 do_cis = head (normal_cis ++ explicit_cis)
1862 -- must choose a normal_cis in preference since dict_args will
1863 -- not be defined for an explicit_cis
1865 -- same_overloading tests whether the types of all the binders
1866 -- are "compatible"; ie have the same type and dictionary abstractions
1867 -- Almost always this is the case, because a recursive group is abstracted
1868 -- all together. But, it can happen that it ain't the case, because of
1869 -- code generated from instance decls:
1872 -- dfun.Foo.Int :: (forall a. a -> Int, Int)
1873 -- dfun.Foo.Int = (const.op1.Int, const.op2.Int)
1875 -- const.op1.Int :: forall a. a -> Int
1876 -- const.op1.Int a = defm.Foo.op1 Int a dfun.Foo.Int
1878 -- const.op2.Int :: Int
1879 -- const.op2.Int = 3
1881 -- Note that the first two defns have different polymorphism, but they are
1882 -- mutually recursive!
1884 same_overloading :: Id -> Bool
1886 = no_of_tyvars == length this_id_tyvars
1887 -- Same no of tyvars
1888 && no_of_dicts == length this_id_class_tyvar_pairs
1889 -- Same no of vdicts
1890 && and (zipWith same_ov class_tyvar_pairs this_id_class_tyvar_pairs)
1891 && length class_tyvar_pairs == length this_id_class_tyvar_pairs
1894 (this_id_tyvars, this_id_class_tyvar_pairs) = getIdOverloading id
1895 tyvar_pairs = this_id_tyvars `zip` tyvar_tmpls
1897 same_ov (clas1,tyvar1) (clas2,tyvar2)
1899 tyvar1 == assoc "same_overloading" tyvar_pairs tyvar2
1903 - a call instance eg f [t1,t2,t3] [d1,d2]
1904 - the rhs of the function eg orig_rhs
1905 - a constraint vector, saying which of eg [T,F,T]
1906 the functions type args are constrained
1909 We return a new definition
1911 $f1 = /\a -> orig_rhs t1 a t3 d1 d2
1913 The SpecInfo for f will be:
1915 SpecInfo [t1, a, t3] (\d1 d2 -> $f1 a)
1917 Based on this SpecInfo, a call instance of f
1921 should get replaced by
1923 ...(\d1 d2 -> $f1 t2)...
1925 (But that is the business of the simplifier.)
1928 mkOneInst :: CallInstance
1929 -> [CallInstance] -- Any explicit cis for this inst
1930 -> Int -- No of dicts to specialise
1931 -> Bool -- Top level binders?
1932 -> [CallInstance] -- Instantiated call insts for binders
1933 -> [Id] -- New binders
1934 -> CoreBinding -- Unprocessed
1935 -> SpecM (Maybe CoreBinding, -- Instantiated version of input
1937 [Maybe SpecInfo] -- One for each id in the original binding
1940 mkOneInst do_cis@(CallInstance _ spec_tys dict_args _ _) explicit_cis
1941 no_of_dicts_to_specialise top_lev inst_cis new_ids orig_bind
1942 = newSpecIds new_ids spec_tys no_of_dicts_to_specialise
1943 `thenSM` \ spec_ids ->
1944 newTyVars (length [() | Nothing <- spec_tys]) `thenSM` \ poly_tyvars ->
1946 -- arg_tys is spec_tys with tyvars instead of the Nothing spec_tys
1947 -- which correspond to unspecialised args
1949 (_,arg_tys) = mapAccumL do_the_wotsit poly_tyvars spec_tys
1952 args = map TyArg arg_tys ++ dict_args
1954 (new_id:_) = new_ids
1955 (spec_id:_) = spec_ids
1957 do_bind (NonRec orig_id rhs)
1958 = do_one_rhs (spec_id, new_id, (orig_id,rhs))
1959 `thenSM` \ (maybe_spec, rhs_uds, spec_info) ->
1961 Just (spec_id, rhs) -> returnSM (Just (NonRec spec_id rhs), rhs_uds, [spec_info])
1962 Nothing -> returnSM (Nothing, rhs_uds, [spec_info])
1965 = mapAndUnzip3SM do_one_rhs (zip3 spec_ids new_ids pairs)
1966 `thenSM` \ (maybe_pairs, rhss_uds_s, spec_infos) ->
1967 returnSM (Just (Rec (catMaybes maybe_pairs)),
1968 unionUDList rhss_uds_s, spec_infos)
1970 do_one_rhs (spec_id, new_id, (orig_id, orig_rhs))
1972 -- Avoid duplicating a spec which has already been created ...
1973 -- This can arise in a Rec involving a dfun for which a
1974 -- a specialised instance has been created but specialisation
1975 -- "required" by one of the other Ids in the Rec
1976 | top_lev && maybeToBool lookup_orig_spec
1977 = (if opt_SpecialiseTrace
1978 then trace_nospec " Exists: " orig_id
1981 returnSM (Nothing, emptyUDs, Nothing)
1984 -- Check for a (single) explicit call instance for this id
1985 | not (null explicit_cis_for_this_id)
1986 = ASSERT (length explicit_cis_for_this_id == 1)
1987 (if opt_SpecialiseTrace
1988 then trace_nospec " Explicit: " explicit_id
1991 returnSM (Nothing, tickSpecInsts emptyUDs, Just explicit_spec_info)
1994 -- Apply the specialiser to (orig_rhs t1 a t3 d1 d2)
1996 = ASSERT (no_of_dicts_to_specialise == length dict_args)
1997 specExpr orig_rhs args `thenSM` \ (inst_rhs, inst_uds) ->
1999 -- For a local binding we dump the usage details, creating
2000 -- any local dict bindings required
2001 -- At the top-level the uds will be dumped in specBindAndScope
2002 -- and the dict bindings made *global*
2004 (local_dict_binds, final_uds)
2005 = if not top_lev then
2006 dumpUDs inst_uds False False inst_cis new_ids []
2010 spec_info = Just (SpecInfo spec_tys no_of_dicts_to_specialise spec_id)
2012 if isUnboxedType (idType spec_id) then
2013 ASSERT (null poly_tyvars)
2014 liftId spec_id `thenSM` \ (lift_spec_id, unlift_spec_id) ->
2015 mkTyConInstance liftDataCon [idType unlift_spec_id]
2016 `thenSM` \ lift_uds ->
2017 returnSM (Just (lift_spec_id,
2018 mkCoLetsNoUnboxed local_dict_binds (liftExpr unlift_spec_id inst_rhs)),
2019 tickSpecInsts (final_uds `unionUDs` lift_uds), spec_info)
2021 returnSM (Just (spec_id,
2022 mkCoLetsNoUnboxed local_dict_binds (mkTyLam poly_tyvars inst_rhs)),
2023 tickSpecInsts final_uds, spec_info)
2025 lookup_orig_spec = lookupSpecEnv (getIdSpecialisation orig_id) arg_tys
2027 explicit_cis_for_this_id = filter (isCIofTheseIds [new_id]) explicit_cis
2028 [CallInstance _ _ _ _ (Just explicit_spec_info)] = explicit_cis_for_this_id
2029 SpecInfo _ _ explicit_id = explicit_spec_info
2031 trace_nospec :: String -> Id -> a -> a
2032 trace_nospec str spec_id
2034 (hsep [ppr PprDebug new_id, hsep (map pp_ty arg_tys),
2035 ptext SLIT("==>"), ppr PprDebug spec_id])
2037 (if opt_SpecialiseTrace then
2038 pprTrace "Specialising:"
2039 (hang (hcat [char '{',
2040 interppSP PprDebug new_ids,
2043 hcat [ptext SLIT("types: "), hsep (map pp_ty arg_tys)],
2044 if isExplicitCI do_cis then empty else
2045 hcat [ptext SLIT("dicts: "), hsep (map pp_dict dict_args)],
2046 hcat [ptext SLIT("specs: "), ppr PprDebug spec_ids]]))
2049 do_bind orig_bind `thenSM` \ (maybe_inst_bind, inst_uds, spec_infos) ->
2051 returnSM (maybe_inst_bind, inst_uds, spec_infos)
2054 pp_dict d = ppr_arg PprDebug d
2055 pp_ty t = pprParendGenType PprDebug t
2057 do_the_wotsit (tyvar:tyvars) Nothing = (tyvars, mkTyVarTy tyvar)
2058 do_the_wotsit tyvars (Just ty) = (tyvars, ty)
2062 %************************************************************************
2064 \subsection[Misc]{Miscellaneous junk}
2066 %************************************************************************
2069 mkCallInstance :: Id
2072 -> SpecM UsageDetails
2074 mkCallInstance id new_id args
2075 | null args || -- No args at all
2076 idWantsToBeINLINEd id || -- It's going to be inlined anyway
2077 not enough_args || -- Not enough type and dict args
2078 not interesting_overloading -- Overloaded types are just tyvars
2082 = returnSM (singleCI new_id spec_tys dicts)
2085 (tyvars, theta, _) = splitSigmaTy (idType id)
2086 constrained_tyvars = tyvarsOfTypes (map snd class_tyvar_pairs)
2088 arg_res = take_type_args tyvars class_tyvar_pairs args
2089 enough_args = maybeToBool arg_res
2090 (Just (tys, dicts, rest_args)) = arg_res
2092 interesting_overloading = not (null (catMaybes spec_tys))
2093 spec_tys = zipWithEqual "spec_ty" spec_ty tyvars tys
2095 ---------------------------------------------------------------
2096 -- Should we specialise on this type argument?
2097 spec_ty tyvar ty | isTyVarTy ty = Nothing
2099 spec_ty tyvar ty | opt_SpecialiseAll
2100 || (opt_SpecialiseUnboxed
2102 && isBoxedTypeKind (tyVarKind tyvar))
2103 || (opt_SpecialiseOverloaded
2104 && tyvar `elemTyVarSet` constrained_tyvars)
2107 | otherwise = Nothing
2109 ----------------- Rather a gruesome help-function ---------------
2110 take_type_args (_:tyvars) (TyArg ty : args)
2111 = case (take_type_args tyvars args) of
2113 Just (tys, dicts, others) -> Just (ty:tys, dicts, others)
2115 take_type_args (_:tyvars) [] = Nothing
2117 take_type_args [] args
2118 = case (take_dict_args class_tyvar_pairs args) of
2120 Just (dicts, others) -> Just ([], dicts, others)
2122 take_dict_args (_:class_tyvar_pairs) (dict : args) | isValArg dict
2123 = case (take_dict_args class_tyvar_pairs args) of
2125 Just (dicts, others) -> Just (dict:dicts, others)
2127 take_dict_args (_:class_tyvar_pairs) args = Nothing
2129 take_dict_args [] args = Just ([], args)
2134 mkTyConInstance :: Id
2136 -> SpecM UsageDetails
2137 mkTyConInstance con tys
2138 = recordTyConInst con tys `thenSM` \ record_inst ->
2140 Nothing -- No TyCon instance
2141 -> -- pprTrace "NoTyConInst:"
2142 -- (hsep [ppr PprDebug tycon, ptext SLIT("at"),
2143 -- ppr PprDebug con, hsep (map (ppr PprDebug) tys)])
2144 (returnSM (singleConUDs con))
2146 Just spec_tys -- Record TyCon instance
2147 -> -- pprTrace "TyConInst:"
2148 -- (hsep [ppr PprDebug tycon, ptext SLIT("at"),
2149 -- ppr PprDebug con, hsep (map (ppr PprDebug) tys),
2151 -- hsep [pprMaybeTy PprDebug ty | ty <- spec_tys],
2153 (returnSM (singleTyConI tycon spec_tys `unionUDs` singleConUDs con))
2155 tycon = dataConTyCon con
2159 recordTyConInst :: Id
2161 -> SpecM (Maybe [Maybe Type])
2163 recordTyConInst con tys
2165 spec_tys = specialiseConstrTys tys
2167 do_tycon_spec = maybeToBool (firstJust spec_tys)
2169 spec_exists = maybeToBool (lookupSpecEnv
2170 (getIdSpecialisation con)
2173 -- pprTrace "ConSpecExists?: "
2174 -- (vcat [ptext (if spec_exists then SLIT("True") else SLIT("False")),
2175 -- ppr PprShowAll con, hsep (map (ppr PprDebug) tys)])
2176 (if (not spec_exists && do_tycon_spec)
2177 then returnSM (Just spec_tys)
2178 else returnSM Nothing)
2181 %************************************************************************
2183 \subsection[monad-Specialise]{Monad used in specialisation}
2185 %************************************************************************
2189 inherited: control flags and
2190 recordInst functions with flags cached
2192 environment mapping tyvars to types
2193 environment mapping Ids to Atoms
2195 threaded in and out: unique supply
2198 type TypeEnv = TyVarEnv Type
2206 initSM m uniqs = m nullTyVarEnv nullIdEnv uniqs
2208 returnSM :: a -> SpecM a
2209 thenSM :: SpecM a -> (a -> SpecM b) -> SpecM b
2210 fixSM :: (a -> SpecM a) -> SpecM a
2212 thenSM m k tvenv idenv us
2213 = case splitUniqSupply us of { (s1, s2) ->
2214 case (m tvenv idenv s1) of { r ->
2215 k r tvenv idenv s2 }}
2217 returnSM r tvenv idenv us = r
2219 fixSM k tvenv idenv us
2222 r = k r tvenv idenv us -- Recursive in r!
2225 The only interesting bit is figuring out the type of the SpecId!
2228 newSpecIds :: [Id] -- The id of which to make a specialised version
2229 -> [Maybe Type] -- Specialise to these types
2230 -> Int -- No of dicts to specialise
2233 newSpecIds new_ids maybe_tys dicts_to_ignore tvenv idenv us
2234 = [ mkSpecId uniq id maybe_tys (spec_id_ty id) (selectIdInfoForSpecId id)
2235 | (id,uniq) <- zipEqual "newSpecIds" new_ids uniqs ]
2237 uniqs = getUniques (length new_ids) us
2238 spec_id_ty id = specialiseTy (idType id) maybe_tys dicts_to_ignore
2240 newTyVars :: Int -> SpecM [TyVar]
2241 newTyVars n tvenv idenv us
2242 = [mkSysTyVar uniq mkBoxedTypeKind | uniq <- getUniques n us]
2245 @cloneLambdaOrCaseBinders@ and @cloneLetBinders@ take a bunch of
2246 binders, and build ``clones'' for them. The clones differ from the
2247 originals in three ways:
2249 (a) they have a fresh unique
2250 (b) they have the current type environment applied to their type
2251 (c) for Let binders which have been specialised to unboxed values
2252 the clone will have a lifted type
2254 As well as returning the list of cloned @Id@s they also return a list of
2255 @CloneInfo@s which the original binders should be bound to.
2258 cloneLambdaOrCaseBinders :: [Id] -- Old binders
2259 -> SpecM ([Id], [CloneInfo]) -- New ones
2261 cloneLambdaOrCaseBinders old_ids tvenv idenv us
2263 uniqs = getUniques (length old_ids) us
2265 unzip (zipWithEqual "cloneLambdaOrCaseBinders" clone_it old_ids uniqs)
2267 clone_it old_id uniq
2268 = (new_id, NoLift (VarArg new_id))
2270 new_id = applyTypeEnvToId tvenv (mkIdWithNewUniq old_id uniq)
2272 cloneLetBinders :: Bool -- Top level ?
2273 -> Bool -- Recursice
2274 -> [Id] -- Old binders
2275 -> SpecM ([Id], [CloneInfo]) -- New ones
2277 cloneLetBinders top_lev is_rec old_ids tvenv idenv us
2279 uniqs = getUniques (2 * length old_ids) us
2281 unzip (clone_them old_ids uniqs)
2283 clone_them [] [] = []
2285 clone_them (old_id:olds) (u1:u2:uniqs)
2288 NoLift (VarArg old_id)) : clone_rest
2290 -- Don't clone if it is a top-level thing. Why not?
2291 -- (a) we don't want to change the uniques
2293 -- (b) we don't have to be paranoid about name capture
2294 -- (c) the thing is polymorphic so no need to subst
2297 = if (is_rec && isUnboxedType new_ty && not (isUnboxedType old_ty))
2299 Lifted lifted_id unlifted_id) : clone_rest
2301 NoLift (VarArg new_id)) : clone_rest
2304 clone_rest = clone_them olds uniqs
2306 new_id = applyTypeEnvToId tvenv (mkIdWithNewUniq old_id u1)
2307 new_ty = idType new_id
2308 old_ty = idType old_id
2310 (lifted_id, unlifted_id) = mkLiftedId new_id u2
2313 cloneTyVarSM :: TyVar -> SpecM TyVar
2315 cloneTyVarSM old_tyvar tvenv idenv us
2319 cloneTyVar old_tyvar uniq -- new_tyvar
2321 bindId :: Id -> CloneInfo -> SpecM thing -> SpecM thing
2323 bindId id val specm tvenv idenv us
2324 = specm tvenv (addOneToIdEnv idenv id val) us
2326 bindIds :: [Id] -> [CloneInfo] -> SpecM thing -> SpecM thing
2328 bindIds olds news specm tvenv idenv us
2329 = specm tvenv (growIdEnvList idenv (zip olds news)) us
2331 bindSpecIds :: [Id] -- Old
2332 -> [(CloneInfo)] -- New
2333 -> [[Maybe SpecInfo]] -- Corresponding specialisations
2334 -- Each sub-list corresponds to a different type,
2335 -- and contains one Maybe spec_info for each id
2339 bindSpecIds olds clones spec_infos specm tvenv idenv us
2340 = specm tvenv (growIdEnvList idenv old_to_clone) us
2342 old_to_clone = mk_old_to_clone olds clones spec_infos
2344 -- The important thing here is that we are *lazy* in spec_infos
2345 mk_old_to_clone [] [] _ = []
2346 mk_old_to_clone (old:rest_olds) (clone:rest_clones) spec_infos
2347 = (old, add_spec_info clone) :
2348 mk_old_to_clone rest_olds rest_clones spec_infos_rest
2350 add_spec_info (NoLift (VarArg new))
2351 = NoLift (VarArg (new `addIdSpecialisation`
2352 (mkSpecEnv spec_infos_this_id)))
2353 add_spec_info lifted
2354 = lifted -- no specialised instances for unboxed lifted values
2356 spec_infos_this_id = catMaybes (map head spec_infos)
2357 spec_infos_rest = map tail spec_infos
2360 bindTyVar :: TyVar -> Type -> SpecM thing -> SpecM thing
2362 bindTyVar tyvar ty specm tvenv idenv us
2363 = specm (growTyVarEnvList tvenv [(tyvar,ty)]) idenv us
2367 lookupId :: Id -> SpecM CloneInfo
2369 lookupId id tvenv idenv us
2370 = case lookupIdEnv idenv id of
2371 Nothing -> NoLift (VarArg id)
2376 specTy :: Type -> SpecM Type -- Apply the current type envt to the type
2378 specTy ty tvenv idenv us
2379 = applyTypeEnvToTy tvenv ty
2383 liftId :: Id -> SpecM (Id, Id)
2384 liftId id tvenv idenv us
2391 In other monads these @mapSM@ things are usually called @listM@.
2392 I think @mapSM@ is a much better name. The `2' and `3' variants are
2393 when you want to return two or three results, and get at them
2394 separately. It saves you having to do an (unzip stuff) right after.
2397 mapSM :: (a -> SpecM b) -> [a] -> SpecM [b]
2398 mapAndUnzipSM :: (a -> SpecM (b1, b2)) -> [a] -> SpecM ([b1],[b2])
2399 mapAndUnzip3SM :: (a -> SpecM (b1, b2, b3)) -> [a] -> SpecM ([b1],[b2],[b3])
2400 mapAndUnzip4SM :: (a -> SpecM (b1, b2, b3, b4)) -> [a] -> SpecM ([b1],[b2],[b3],[b4])
2402 mapSM f [] = returnSM []
2403 mapSM f (x:xs) = f x `thenSM` \ r ->
2404 mapSM f xs `thenSM` \ rs ->
2407 mapAndUnzipSM f [] = returnSM ([],[])
2408 mapAndUnzipSM f (x:xs) = f x `thenSM` \ (r1, r2) ->
2409 mapAndUnzipSM f xs `thenSM` \ (rs1,rs2) ->
2410 returnSM ((r1:rs1),(r2:rs2))
2412 mapAndUnzip3SM f [] = returnSM ([],[],[])
2413 mapAndUnzip3SM f (x:xs) = f x `thenSM` \ (r1,r2,r3) ->
2414 mapAndUnzip3SM f xs `thenSM` \ (rs1,rs2,rs3) ->
2415 returnSM ((r1:rs1),(r2:rs2),(r3:rs3))
2417 mapAndUnzip4SM f [] = returnSM ([],[],[],[])
2418 mapAndUnzip4SM f (x:xs) = f x `thenSM` \ (r1,r2,r3,r4) ->
2419 mapAndUnzip4SM f xs `thenSM` \ (rs1,rs2,rs3,rs4) ->
2420 returnSM ((r1:rs1),(r2:rs2),(r3:rs3),(r4:rs4))
2426 ===================== OLD CODE, scheduled for deletion =================
2431 -> [(CoreArg, UsageDetails, CoreExpr -> CoreExpr)]
2434 mkCall new_id arg_infos = returnSM (
2436 | maybeToBool (isSuperDictSelId_maybe new_id)
2437 && any isUnboxedType ty_args
2438 -- No specialisations for super-dict selectors
2439 -- Specialise unboxed calls to SuperDictSelIds by extracting
2440 -- the super class dictionary directly form the super class
2441 -- NB: This should be dead code since all uses of this dictionary should
2442 -- have been specialised. We only do this to keep core-lint happy.
2444 Just (_, super_class) = isSuperDictSelId_maybe new_id
2445 super_dict_id = case lookupClassInstAtSimpleType super_class (head ty_args) of
2446 Nothing -> panic "Specialise:mkCall:SuperDictId"
2449 returnSM (False, Var super_dict_id)
2452 = case lookupSpecEnv (getIdSpecialisation new_id) ty_args of
2453 Nothing -> checkUnspecOK new_id ty_args (
2454 returnSM (False, unspec_call)
2457 Just spec_1_details@(spec_id_1, tys_left_1, dicts_to_toss_1)
2459 -- It may be necessary to specialsie a constant method spec_id again
2460 (spec_id, tys_left, dicts_to_toss) =
2461 case (maybeToBool (isConstMethodId_maybe spec_id_1),
2462 lookupSpecEnv (getIdSpecialisation spec_id_1) tys_left_1) of
2463 (False, _ ) -> spec_1_details
2464 (True, Nothing) -> spec_1_details
2465 (True, Just (spec_id_2, tys_left_2, dicts_to_toss_2))
2466 -> (spec_id_2, tys_left_2, dicts_to_toss_1 + dicts_to_toss_2)
2468 args_left = toss_dicts dicts_to_toss val_args
2470 checkSpecOK new_id ty_args spec_id tys_left (
2472 -- The resulting spec_id may be a top-level unboxed value
2473 -- This can arise for:
2474 -- 1) constant method values
2475 -- eq: class Num a where pi :: a
2476 -- instance Num Double# where pi = 3.141#
2477 -- 2) specilised overloaded values
2478 -- eq: i1 :: Num a => a
2479 -- i1 Int# d.Num.Int# ==> i1.Int#
2480 -- These top level defns should have been lifted.
2481 -- We must add code to unlift such a spec_id.
2483 if isUnboxedType (idType spec_id) then
2484 ASSERT (null tys_left && null args_left)
2485 if toplevelishId spec_id then
2486 liftId spec_id `thenSM` \ (lift_spec_id, unlift_spec_id) ->
2487 returnSM (True, bindUnlift lift_spec_id unlift_spec_id
2488 (Var unlift_spec_id))
2490 pprPanic "Specialise:mkCall: unboxed spec_id not top-level ...\n"
2491 (hsep [ppr PprDebug new_id,
2492 hsep (map (pprParendGenType PprDebug) ty_args),
2494 ppr PprDebug spec_id])
2497 (vals_left, _, unlifts_left) = unzip3 args_left
2498 applied_tys = mkTyApp (Var spec_id) tys_left
2499 applied_vals = mkGenApp applied_tys vals_left
2501 returnSM (True, applyBindUnlifts unlifts_left applied_vals)
2504 (tys_and_vals, _, unlifts) = unzip3 args
2505 unspec_call = applyBindUnlifts unlifts (mkGenApp (Var new_id) tys_and_vals)
2508 -- ty_args is the types at the front of the arg list
2509 -- val_args is the rest of the arg-list
2511 (ty_args, val_args) = get args
2513 get ((TyArg ty,_,_) : args) = (ty : tys, rest) where (tys,rest) = get args
2514 get args = ([], args)
2517 -- toss_dicts chucks away dict args, checking that they ain't types!
2518 toss_dicts 0 args = args
2519 toss_dicts n ((a,_,_) : args)
2520 | isValArg a = toss_dicts (n-1) args
2525 checkUnspecOK :: Id -> [Type] -> a -> a
2526 checkUnspecOK check_id tys
2527 = if isLocallyDefined check_id && any isUnboxedType tys
2528 then pprPanic "Specialise:checkUnspecOK: unboxed instance for local id not found\n"
2529 (hsep [ppr PprDebug check_id,
2530 hsep (map (pprParendGenType PprDebug) tys)])
2533 checkSpecOK :: Id -> [Type] -> Id -> [Type] -> a -> a
2534 checkSpecOK check_id tys spec_id tys_left
2535 = if any isUnboxedType tys_left
2536 then pprPanic "Specialise:checkSpecOK: unboxed type args in specialised application\n"
2537 (vcat [hsep [ppr PprDebug check_id,
2538 hsep (map (pprParendGenType PprDebug) tys)],
2539 hsep [ppr PprDebug spec_id,
2540 hsep (map (pprParendGenType PprDebug) tys_left)]])