2 % (c) The GRASP/AQUA Project, Glasgow University, 1998
4 \section[UsageSPUtils]{UsageSP Utilities}
6 This code is (based on) PhD work of Keith Wansbrough <kw217@cl.cam.ac.uk>,
7 September 1998 .. May 1999.
9 Keith Wansbrough 1998-09-04..1999-06-25
12 module UsageSPUtils ( AnnotM(AnnotM), initAnnotM,
14 MungeFlags(isSigma,isLocal,isExp,hasUsg,mfLoc),
16 doAnnotBinds, doUnAnnotBinds,
17 annotMany, annotManyN, unannotTy, freshannotTy,
20 UniqSMM, usToUniqSMM, uniqSMMToUs,
25 #include "HsVersions.h"
28 import Const ( Con(..), Literal(..) )
29 import Var ( IdOrTyVar, varName, varType, setVarType, mkUVar )
30 import Id ( idMustBeINLINEd, isExportedId )
31 import Name ( isLocallyDefined )
32 import Type ( Type(..), TyNote(..), UsageAnn(..), isUsgTy, splitFunTys )
33 import Subst ( substTy, mkTyVarSubst )
34 import TyCon ( isAlgTyCon, isPrimTyCon, isSynTyCon, isFunTyCon )
36 import PrimOp ( PrimOp, primOpUsg )
37 import Maybes ( expectJust )
38 import UniqSupply ( UniqSupply, UniqSM, initUs, getUniqueUs, thenUs, returnUs )
40 import PprCore ( ) -- instances only
43 ======================================================================
45 Walking over (and altering) types
46 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
48 We often need to fiddle with (i.e., add or remove) usage annotations
49 on a type. We define here a general framework to do this. Usage
50 annotations come from any monad with a function @getAnnM@ which yields
51 a new annotation. We use two mutually recursive functions, one for
52 sigma types and one for tau types.
55 genAnnotTy :: Monad m =>
56 (m UsageAnn) -- get new annotation
60 genAnnotTy getAnnM ty = do { u <- getAnnM
61 ; ty' <- genAnnotTyN getAnnM ty
62 ; return (NoteTy (UsgNote u) ty')
65 genAnnotTyN :: Monad m =>
71 (NoteTy (UsgNote _) ty) = panic "genAnnotTyN: unexpected UsgNote"
73 (NoteTy (SynNote sty) ty) = do { sty' <- genAnnotTyN getAnnM sty
74 -- is this right? shouldn't there be some
75 -- correlation between sty' and ty'?
76 -- But sty is a TyConApp; does this make it safer?
77 ; ty' <- genAnnotTyN getAnnM ty
78 ; return (NoteTy (SynNote sty') ty')
81 (NoteTy fvn@(FTVNote _) ty) = do { ty' <- genAnnotTyN getAnnM ty
82 ; return (NoteTy fvn ty')
86 ty0@(TyVarTy _) = do { return ty0 }
89 (AppTy ty1 ty2) = do { ty1' <- genAnnotTyN getAnnM ty1
90 ; ty2' <- genAnnotTyN getAnnM ty2
91 ; return (AppTy ty1' ty2')
95 (TyConApp tc tys) = ASSERT( isFunTyCon tc || isAlgTyCon tc || isPrimTyCon tc || isSynTyCon tc )
96 do { let gAT = if isFunTyCon tc
97 then genAnnotTy -- sigma for partial apps of (->)
98 else genAnnotTyN -- tau otherwise
99 ; tys' <- mapM (gAT getAnnM) tys
100 ; return (TyConApp tc tys')
104 (FunTy ty1 ty2) = do { ty1' <- genAnnotTy getAnnM ty1
105 ; ty2' <- genAnnotTy getAnnM ty2
106 ; return (FunTy ty1' ty2')
110 (ForAllTy v ty) = do { ty' <- genAnnotTyN getAnnM ty
111 ; return (ForAllTy v ty')
117 Walking over (and retyping) terms
118 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
120 We also often need to play with the types in a term. This is slightly
121 tricky because of redundancy: we want to change binder types, and keep
122 the bound types matching these; then there's a special case also with
123 non-locally-defined bound variables. We generalise over all this
126 The name `annot' is a bit of a misnomer, as the code is parameterised
127 over exactly what it does to the types (and certain terms). Notice
128 also that it is possible for this parameter to use
129 monadically-threaded state: here called `flexi'. For genuine
130 annotation, this state will be a UniqSupply.
132 We may add annotations to the outside of a (term, not type) lambda; a
133 function passed to @genAnnotBinds@ does this, taking the lambda and
134 returning the annotated lambda. It is inside the @AnnotM@ monad.
135 This term-munging function is applied when we see either a term lambda
136 or a usage annotation; *IMPORTANT:* it is applied *before* we recurse
137 down into the term, and it is expected to work only at the top level.
138 Recursion will subsequently be done by genAnnotBinds. It may
139 optionally remove a Note TermUsg, or optionally add one if it is not
140 already present, but it may perform NO OTHER MODIFICATIONS to the
141 structure of the term.
143 We do different things to types of variables bound locally and of
144 variables bound in other modules, in certain cases: the former get
145 uvars and the latter keep their existing annotations when we annotate,
146 for example. To control this, @MungeFlags@ describes what kind of a
147 type this is that we're about to munge.
150 data MungeFlags = MungeFlags { isSigma :: Bool, -- want annotated on top (sigma type)
151 isLocal :: Bool, -- is locally-defined type
152 hasUsg :: Bool, -- has fixed usage info, don't touch
153 isExp :: Bool, -- is exported (and must be pessimised)
154 mfLoc :: SDoc -- location info
157 tauTyMF loc = MungeFlags { isSigma = False, isLocal = True,
158 hasUsg = False, isExp = False, mfLoc = loc }
159 sigVarTyMF v = MungeFlags { isSigma = True, isLocal = hasLocalDef v,
160 hasUsg = hasUsgInfo v, isExp = isExportedId v,
161 mfLoc = ptext SLIT("type of binder") <+> ppr v }
164 The helper functions @tauTyMF@ and @sigVarTyMF@ create @MungeFlags@
165 for us. @sigVarTyMF@ checks the variable to see how to set the flags.
167 @hasLocalDef@ tells us if the given variable has an actual local
168 definition that we can play with. This is not quite the same as
169 @isLocallyDefined@, since @IMustBeINLINEd@ things (usually) don't have
170 a local definition - the simplifier will inline whatever their
171 unfolding is anyway. We treat these as if they were externally
172 defined, since we don't have access to their definition (at least not
173 easily). This doesn't hurt much, since after the simplifier has run
174 the unfolding will have been inlined and we can access the unfolding
177 @hasUsgInfo@, on the other hand, says if the variable already has
178 usage info in its type that must at all costs be preserved. This is
179 assumed true (exactly) of all imported ids.
182 hasLocalDef :: IdOrTyVar -> Bool
183 hasLocalDef var = isLocallyDefined var
184 && not (idMustBeINLINEd var)
186 hasUsgInfo :: IdOrTyVar -> Bool
187 hasUsgInfo var = (not . isLocallyDefined) var
190 Here's the walk itself.
193 genAnnotBinds :: (MungeFlags -> Type -> AnnotM flexi Type)
194 -> (CoreExpr -> AnnotM flexi CoreExpr) -- see caveats above
196 -> AnnotM flexi [CoreBind]
198 genAnnotBinds _ _ [] = return []
200 genAnnotBinds f g (b:bs) = do { (b',vs,vs') <- genAnnotBind f g b
201 ; bs' <- withAnnVars vs vs' $
206 genAnnotBind :: (MungeFlags -> Type -> AnnotM flexi Type) -- type-altering function
207 -> (CoreExpr -> AnnotM flexi CoreExpr) -- term-altering function
208 -> CoreBind -- original CoreBind
210 (CoreBind, -- annotated CoreBind
211 [IdOrTyVar], -- old variables, to be mapped to...
212 [IdOrTyVar]) -- ... new variables
214 genAnnotBind f g (NonRec v1 e1) = do { v1' <- genAnnotVar f v1
215 ; e1' <- genAnnotCE f g e1
216 ; return (NonRec v1' e1', [v1], [v1'])
219 genAnnotBind f g (Rec ves) = do { let (vs,es) = unzip ves
220 ; vs' <- mapM (genAnnotVar f) vs
221 ; es' <- withAnnVars vs vs' $
222 mapM (genAnnotCE f g) es
223 ; return (Rec (zip vs' es'), vs, vs')
226 genAnnotCE :: (MungeFlags -> Type -> AnnotM flexi Type) -- type-altering function
227 -> (CoreExpr -> AnnotM flexi CoreExpr) -- term-altering function
228 -> CoreExpr -- original expression
229 -> AnnotM flexi CoreExpr -- yields new expression
231 genAnnotCE mungeType mungeTerm = go
232 where go e0@(Var v) | isTyVar v = return e0 -- arises, e.g., as tyargs of Con
233 -- (no it doesn't: (Type (TyVar tyvar))
234 | otherwise = do { mv' <- lookupAnnVar v
236 Just var -> return var
237 Nothing -> fixedVar v
241 go (Con c args) = -- we know it's saturated
242 do { args' <- mapM go args
243 ; return (Con c args')
246 go (App e arg) = do { e' <- go e
248 ; return (App e' arg')
251 go e0@(Lam v0 _) = do { e1 <- (if isTyVar v0 then return else mungeTerm) e0
253 = case e1 of -- munge may have added note
254 Note tu@(TermUsg _) (Lam v e2)
256 Lam v e2 -> (v,e2,id)
257 ; v' <- genAnnotVar mungeType v
258 ; e' <- withAnnVar v v' $ go e2
259 ; return (wrap (Lam v' e'))
262 go (Let bind e) = do { (bind',vs,vs') <- genAnnotBind mungeType mungeTerm bind
263 ; e' <- withAnnVars vs vs' $ go e
264 ; return (Let bind' e')
267 go (Case e v alts) = do { e' <- go e
268 ; v' <- genAnnotVar mungeType v
269 ; alts' <- withAnnVar v v' $ mapM genAnnotAlt alts
270 ; return (Case e' v' alts')
273 go (Note scc@(SCC _) e) = do { e' <- go e
274 ; return (Note scc e')
276 go e0@(Note (Coerce ty1 ty0)
277 e) = do { ty1' <- mungeType
278 (tauTyMF (ptext SLIT("coercer of")
281 (tauTyMF (ptext SLIT("coercee of")
283 -- (Better to specify ty0'
284 -- identical to the type of e, including
285 -- annotations, right at the beginning, but
286 -- not possible at this point.)
288 ; return (Note (Coerce ty1' ty0') e')
290 go (Note InlineCall e) = do { e' <- go e
291 ; return (Note InlineCall e')
293 go (Note InlineMe e) = do { e' <- go e
294 ; return (Note InlineMe e')
296 go e0@(Note (TermUsg _) _) = do { e1 <- mungeTerm e0
297 ; case e1 of -- munge may have removed note
298 Note tu@(TermUsg _) e2 -> do { e3 <- go e2
299 ; return (Note tu e3)
304 go e0@(Type ty) = -- should only occur at toplevel of Arg,
306 do { ty' <- mungeType
307 (tauTyMF (ptext SLIT("tyarg")
312 fixedVar v = ASSERT2( not (hasLocalDef v), text "genAnnotCE: locally defined var" <+> ppr v <+> text "not in varenv" )
313 genAnnotVar mungeType v
315 genAnnotAlt (c,vs,e) = do { vs' <- mapM (genAnnotVar mungeType) vs
316 ; e' <- withAnnVars vs vs' $ go e
317 ; return (c, vs', e')
321 genAnnotVar :: (MungeFlags -> Type -> AnnotM flexi Type)
323 -> AnnotM flexi IdOrTyVar
325 genAnnotVar mungeType v | isTyVar v = return v
326 | otherwise = do { vty' <- mungeType (sigVarTyMF v) (varType v)
327 ; return (setVarType v vty')
331 pprTrace "genAnnotVar" (ppr (tyUsg vty') <+> ppr v) $
337 ======================================================================
339 Some specific things to do to types inside terms
340 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
342 @annotTyM@ annotates a type with fresh uvars everywhere the inference
343 is allowed to go, and leaves alone annotations where it may not go.
345 We assume there are no annotations already.
348 annotTyM :: MungeFlags -> Type -> AnnotM UniqSupply Type
350 annotTyM mf ty = uniqSMtoAnnotM . uniqSMMToUs $
351 case (hasUsg mf, isLocal mf, isSigma mf) of
352 (True ,_ ,_ ) -> ASSERT( isUsgTy ty )
354 (False,True ,True ) -> if isExp mf then
355 annotTyP (tag 'p') ty
358 (False,True ,False) -> annotTyN (tag 't') ty
359 (False,False,True ) -> return $ annotMany ty -- assume worst
360 (False,False,False) -> return $ annotManyN ty
361 where tag c = Right $ "annotTyM:" ++ [c] ++ ": " ++ showSDoc (ppr ty)
363 -- specific functions for annotating tau and sigma types
366 annotTy tag = genAnnotTy (newVarUSMM tag)
367 annotTyN tag = genAnnotTyN (newVarUSMM tag)
369 -- ...with uvars and pessimal Manys (for exported ids)
370 annotTyP tag ty = do { ty' <- annotTy tag ty ; return (pessimise True ty') }
373 annotMany, annotManyN :: Type -> Type
378 annotMany ty = unId (genAnnotTy (return UsMany) ty)
379 annotManyN ty = unId (genAnnotTyN (return UsMany) ty)
382 -- monad required for the above
383 newtype Id a = Id a ; unId (Id a) = a
384 instance Monad Id where { a >>= f = f (unId a) ; return a = Id a }
386 -- lambda-annotating function for use along with the above
387 annotLam e0@(Lam v e) = do { uv <- uniqSMtoAnnotM $ newVarUs (Left e0)
388 ; return (Note (TermUsg uv) (Lam v e))
390 annotLam (Note (TermUsg _) _) = panic "annotLam: unexpected term usage annot"
393 The above requires a `pessimising' translation. This is applied to
394 types of exported ids, and ensures that they have a fully general
395 type (since we don't know how they will be used in other modules).
398 pessimise :: Bool -> Type -> Type
401 pessimise co ty0@(NoteTy usg@(UsgNote u ) ty)
403 then case u of UsMany -> pty
404 UsVar _ -> pty -- force to UsMany
405 UsOnce -> pprPanic "pessimise:" (ppr ty0)
407 where pty = pessimiseN co ty
409 pessimise co ty0 = pessimiseN co ty0 -- assume UsMany
411 pessimise co ty0@(NoteTy usg@(UsgNote u ) ty)
413 then case u of UsMany -> NoteTy usg pty
414 UsVar _ -> NoteTy (UsgNote UsMany) pty
415 UsOnce -> pprPanic "pessimise:" (ppr ty0)
417 where pty = pessimiseN co ty
419 pessimise co ty0 = pprPanic "pessimise: missing usage note:" $
423 pessimiseN co ty0@(NoteTy usg@(UsgNote _ ) ty) = pprPanic "pessimiseN: unexpected usage note:" $
425 pessimiseN co (NoteTy (SynNote sty) ty) = NoteTy (SynNote (pessimiseN co sty))
427 pessimiseN co (NoteTy note@(FTVNote _ ) ty) = NoteTy note (pessimiseN co ty)
428 pessimiseN co ty0@(TyVarTy _) = ty0
429 pessimiseN co ty0@(AppTy _ _) = ty0
430 pessimiseN co ty0@(TyConApp tc tys) = ASSERT( not ((isFunTyCon tc) && (length tys > 1)) )
432 pessimiseN co (FunTy ty1 ty2) = FunTy (pessimise (not co) ty1)
434 pessimiseN co (ForAllTy tyv ty) = ForAllTy tyv (pessimiseN co ty)
438 @unAnnotTyM@ strips annotations (that the inference is allowed to
439 touch) from a term, and `fixes' those it isn't permitted to touch (by
440 putting @Many@ annotations where they are missing, but leaving
441 existing annotations in the type).
443 @unTermUsg@ removes from a term any term usage annotations it finds.
446 unAnnotTyM :: MungeFlags -> Type -> AnnotM a Type
448 unAnnotTyM mf ty = if hasUsg mf then
450 return (fixAnnotTy ty)
451 else return (unannotTy ty)
454 unTermUsg :: CoreExpr -> AnnotM a CoreExpr
455 -- strip all term annotations
456 unTermUsg e@(Lam _ _) = return e
457 unTermUsg (Note (TermUsg _) e) = return e
458 unTermUsg _ = panic "unTermUsg"
460 unannotTy :: Type -> Type
461 -- strip all annotations
462 unannotTy (NoteTy (UsgNote _ ) ty) = unannotTy ty
463 unannotTy (NoteTy (SynNote sty) ty) = NoteTy (SynNote (unannotTy sty)) (unannotTy ty)
464 unannotTy (NoteTy note@(FTVNote _ ) ty) = NoteTy note (unannotTy ty)
465 unannotTy ty@(TyVarTy _) = ty
466 unannotTy (AppTy ty1 ty2) = AppTy (unannotTy ty1) (unannotTy ty2)
467 unannotTy (TyConApp tc tys) = TyConApp tc (map unannotTy tys)
468 unannotTy (FunTy ty1 ty2) = FunTy (unannotTy ty1) (unannotTy ty2)
469 unannotTy (ForAllTy tyv ty) = ForAllTy tyv (unannotTy ty)
472 fixAnnotTy :: Type -> Type
473 -- put Manys where they are missing
477 fixAnnotTy (NoteTy note@(UsgNote _ ) ty) = NoteTy note (fixAnnotTyN ty)
478 fixAnnotTy ty0 = NoteTy (UsgNote UsMany) (fixAnnotTyN ty0)
480 fixAnnotTyN ty0@(NoteTy note@(UsgNote _ ) ty) = pprPanic "fixAnnotTyN: unexpected usage note:" $
482 fixAnnotTyN (NoteTy (SynNote sty) ty) = NoteTy (SynNote (fixAnnotTyN sty))
484 fixAnnotTyN (NoteTy note@(FTVNote _ ) ty) = NoteTy note (fixAnnotTyN ty)
485 fixAnnotTyN ty0@(TyVarTy _) = ty0
486 fixAnnotTyN (AppTy ty1 ty2) = AppTy (fixAnnotTyN ty1) (fixAnnotTyN ty2)
487 fixAnnotTyN (TyConApp tc tys) = ASSERT( isFunTyCon tc || isAlgTyCon tc || isPrimTyCon tc || isSynTyCon tc )
488 TyConApp tc (map (if isFunTyCon tc then
492 fixAnnotTyN (FunTy ty1 ty2) = FunTy (fixAnnotTy ty1) (fixAnnotTy ty2)
493 fixAnnotTyN (ForAllTy tyv ty) = ForAllTy tyv (fixAnnotTyN ty)
497 The composition (reannotating a type with fresh uvars but the same
498 structure) is useful elsewhere:
501 freshannotTy :: Type -> UniqSMM Type
502 freshannotTy = annotTy (Right "freshannotTy") . unannotTy
506 Wrappers apply these functions to sets of bindings.
509 doAnnotBinds :: UniqSupply
511 -> ([CoreBind],UniqSupply)
513 doAnnotBinds us binds = initAnnotM us (genAnnotBinds annotTyM annotLam binds)
516 doUnAnnotBinds :: [CoreBind]
519 doUnAnnotBinds binds = fst $ initAnnotM () $
520 genAnnotBinds unAnnotTyM unTermUsg binds
523 ======================================================================
528 The @UniqSM@ type is not an instance of @Monad@, and cannot be made so
529 since it is merely a synonym rather than a newtype. Here we define
530 @UniqSMM@, which *is* an instance of @Monad@.
533 newtype UniqSMM a = UsToUniqSMM (UniqSM a)
534 uniqSMMToUs (UsToUniqSMM us) = us
535 usToUniqSMM = UsToUniqSMM
537 instance Monad UniqSMM where
538 m >>= f = UsToUniqSMM $ uniqSMMToUs m `thenUs` \ a ->
540 return = UsToUniqSMM . returnUs
544 For annotation, the monad @AnnotM@, we need to carry around our
545 variable mapping, along with some general state.
548 newtype AnnotM flexi a = AnnotM ( flexi -- UniqSupply etc
549 -> VarEnv IdOrTyVar -- unannotated to annotated variables
550 -> (a,flexi,VarEnv IdOrTyVar))
551 unAnnotM (AnnotM f) = f
553 instance Monad (AnnotM flexi) where
554 a >>= f = AnnotM (\ us ve -> let (r,us',ve') = unAnnotM a us ve
555 in unAnnotM (f r) us' ve')
556 return a = AnnotM (\ us ve -> (a,us,ve))
558 initAnnotM :: fl -> AnnotM fl a -> (a,fl)
559 initAnnotM fl m = case (unAnnotM m) fl emptyVarEnv of { (r,fl',_) -> (r,fl') }
561 withAnnVar :: IdOrTyVar -> IdOrTyVar -> AnnotM fl a -> AnnotM fl a
562 withAnnVar v v' m = AnnotM (\ us ve -> let ve' = extendVarEnv ve v v'
563 (r,us',_) = (unAnnotM m) us ve'
566 withAnnVars :: [IdOrTyVar] -> [IdOrTyVar] -> AnnotM fl a -> AnnotM fl a
567 withAnnVars vs vs' m = AnnotM (\ us ve -> let ve' = plusVarEnv ve (zipVarEnv vs vs')
568 (r,us',_) = (unAnnotM m) us ve'
571 lookupAnnVar :: IdOrTyVar -> AnnotM fl (Maybe IdOrTyVar)
572 lookupAnnVar var = AnnotM (\ us ve -> (lookupVarEnv ve var,
577 A useful helper allows us to turn a computation in the unique supply
578 monad into one in the annotation monad parameterised by a unique
582 uniqSMtoAnnotM :: UniqSM a -> AnnotM UniqSupply a
584 uniqSMtoAnnotM m = AnnotM (\ us ve -> let (r,us') = initUs us m
588 @newVarUs@ and @newVarUSMM@ generate a new usage variable. They take
589 an argument which is used for debugging only, describing what the
590 variable is to annotate.
593 newVarUs :: (Either CoreExpr String) -> UniqSM UsageAnn
594 -- the first arg is for debugging use only
595 newVarUs e = getUniqueUs `thenUs` \ u ->
600 Left (Con (Literal _) _) -> "literal"
601 Left (Con _ _) -> "primop"
602 Left (Lam v e) -> "lambda: " ++ showSDoc (ppr v)
605 in pprTrace "newVarUs:" (ppr uv <+> text src) $
609 newVarUSMM :: (Either CoreExpr String) -> UniqSMM UsageAnn
610 newVarUSMM = usToUniqSMM . newVarUs
613 ======================================================================
615 PrimOps and usage information.
617 Analagously to @DataCon.dataConArgTys@, we determine the argtys and
618 result ty of a primop, *after* substition (which may reveal more args,
619 notably for @CCall@s).
622 primOpUsgTys :: PrimOp -- this primop
623 -> [Type] -- instantiated at these (tau) types
624 -> ([Type],Type) -- requires args of these (sigma) types,
625 -- and returns this (sigma) type
627 primOpUsgTys p tys = let (tyvs,ty0us,rtyu) = primOpUsg p
628 s = mkTyVarSubst tyvs tys
629 (ty1us,rty1u) = splitFunTys (substTy s rtyu)
630 -- substitution may reveal more args
631 in ((map (substTy s) ty0us) ++ ty1us,
635 ======================================================================