Automatic RTTI for ghci bindings
[ghc.git] / compiler / ghci / RtClosureInspect.hs
1 -----------------------------------------------------------------------------
2 --
3 -- GHC Interactive support for inspecting arbitrary closures at runtime
4 --
5 -- Pepe Iborra (supported by Google SoC) 2006
6 --
7 -----------------------------------------------------------------------------
8
9 module RtClosureInspect(
10
11 cvObtainTerm, -- :: HscEnv -> Bool -> Maybe Type -> HValue -> IO Term
12
13 Term(..),
14 pprTerm,
15 cPprTerm,
16 cPprTermBase,
17 termType,
18 foldTerm,
19 TermFold(..),
20 idTermFold,
21 idTermFoldM,
22 isFullyEvaluated,
23 isPointed,
24 isFullyEvaluatedTerm,
25 mapTermType,
26 termTyVars,
27 -- unsafeDeepSeq,
28 cvReconstructType,
29 computeRTTIsubst,
30 sigmaType
31 ) where
32
33 #include "HsVersions.h"
34
35 import ByteCodeItbls ( StgInfoTable )
36 import qualified ByteCodeItbls as BCI( StgInfoTable(..) )
37 import HscTypes ( HscEnv )
38 import Linker
39
40 import DataCon
41 import Type
42 import TcRnMonad ( TcM, initTc, initTcPrintErrors, ioToTcRn,
43 tryTcErrs)
44 import TcType
45 import TcMType
46 import TcUnify
47 import TcGadt
48 import TcEnv
49 import DriverPhases
50 import TyCon
51 import Name
52 import VarEnv
53 import Util
54 import VarSet
55
56 import TysPrim
57 import PrelNames
58 import TysWiredIn
59
60 import Constants
61 import Outputable
62 import Maybes
63 import Panic
64
65 import GHC.Arr ( Array(..) )
66 import GHC.Exts
67
68 import Control.Monad
69 import Data.Maybe
70 import Data.Array.Base
71 import Data.List ( partition )
72 import qualified Data.Sequence as Seq
73 import Foreign
74 import System.IO.Unsafe
75
76 ---------------------------------------------
77 -- * A representation of semi evaluated Terms
78 ---------------------------------------------
79 {-
80 A few examples in this representation:
81
82 > Just 10 = Term Data.Maybe Data.Maybe.Just (Just 10) [Term Int I# (10) "10"]
83
84 > (('a',_,_),_,('b',_,_)) =
85 Term ((Char,b,c),d,(Char,e,f)) (,,) (('a',_,_),_,('b',_,_))
86 [ Term (Char, b, c) (,,) ('a',_,_) [Term Char C# "a", Suspension, Suspension]
87 , Suspension
88 , Term (Char, e, f) (,,) ('b',_,_) [Term Char C# "b", Suspension, Suspension]]
89 -}
90
91 data Term = Term { ty :: Type
92 , dc :: Either String DataCon
93 -- The heap datacon. If ty is a newtype,
94 -- this is NOT the newtype datacon.
95 -- Empty if the datacon aint exported by the .hi
96 -- (private constructors in -O0 libraries)
97 , val :: HValue
98 , subTerms :: [Term] }
99
100 | Prim { ty :: Type
101 , value :: [Word] }
102
103 | Suspension { ctype :: ClosureType
104 , mb_ty :: Maybe Type
105 , val :: HValue
106 , bound_to :: Maybe Name -- Useful for printing
107 }
108
109 isTerm, isSuspension, isPrim :: Term -> Bool
110 isTerm Term{} = True
111 isTerm _ = False
112 isSuspension Suspension{} = True
113 isSuspension _ = False
114 isPrim Prim{} = True
115 isPrim _ = False
116
117 termType :: Term -> Maybe Type
118 termType t@(Suspension {}) = mb_ty t
119 termType t = Just$ ty t
120
121 isFullyEvaluatedTerm :: Term -> Bool
122 isFullyEvaluatedTerm Term {subTerms=tt} = all isFullyEvaluatedTerm tt
123 isFullyEvaluatedTerm Suspension {} = False
124 isFullyEvaluatedTerm Prim {} = True
125
126 instance Outputable (Term) where
127 ppr = head . cPprTerm cPprTermBase
128
129 -------------------------------------------------------------------------
130 -- Runtime Closure Datatype and functions for retrieving closure related stuff
131 -------------------------------------------------------------------------
132 data ClosureType = Constr
133 | Fun
134 | Thunk Int
135 | ThunkSelector
136 | Blackhole
137 | AP
138 | PAP
139 | Indirection Int
140 | Other Int
141 deriving (Show, Eq)
142
143 data Closure = Closure { tipe :: ClosureType
144 , infoPtr :: Ptr ()
145 , infoTable :: StgInfoTable
146 , ptrs :: Array Int HValue
147 , nonPtrs :: [Word]
148 }
149
150 instance Outputable ClosureType where
151 ppr = text . show
152
153 #include "../includes/ClosureTypes.h"
154
155 aP_CODE = AP
156 pAP_CODE = PAP
157 #undef AP
158 #undef PAP
159
160 getClosureData :: a -> IO Closure
161 getClosureData a =
162 case unpackClosure# a of
163 (# iptr, ptrs, nptrs #) -> do
164 itbl <- peek (Ptr iptr)
165 let tipe = readCType (BCI.tipe itbl)
166 elems = BCI.ptrs itbl
167 ptrsList = Array 0 ((fromIntegral elems) - 1) ptrs
168 nptrs_data = [W# (indexWordArray# nptrs i)
169 | I# i <- [0.. fromIntegral (BCI.nptrs itbl)] ]
170 ASSERT(fromIntegral elems >= 0) return ()
171 ptrsList `seq`
172 return (Closure tipe (Ptr iptr) itbl ptrsList nptrs_data)
173
174 readCType :: Integral a => a -> ClosureType
175 readCType i
176 | i >= CONSTR && i <= CONSTR_NOCAF_STATIC = Constr
177 | i >= FUN && i <= FUN_STATIC = Fun
178 | i >= THUNK && i < THUNK_SELECTOR = Thunk (fromIntegral i)
179 | i == THUNK_SELECTOR = ThunkSelector
180 | i == BLACKHOLE = Blackhole
181 | i >= IND && i <= IND_STATIC = Indirection (fromIntegral i)
182 | fromIntegral i == aP_CODE = AP
183 | i == AP_STACK = AP
184 | fromIntegral i == pAP_CODE = PAP
185 | otherwise = Other (fromIntegral i)
186
187 isConstr, isIndirection, isThunk :: ClosureType -> Bool
188 isConstr Constr = True
189 isConstr _ = False
190
191 isIndirection (Indirection _) = True
192 --isIndirection ThunkSelector = True
193 isIndirection _ = False
194
195 isThunk (Thunk _) = True
196 isThunk ThunkSelector = True
197 isThunk AP = True
198 isThunk _ = False
199
200 isFullyEvaluated :: a -> IO Bool
201 isFullyEvaluated a = do
202 closure <- getClosureData a
203 case tipe closure of
204 Constr -> do are_subs_evaluated <- amapM isFullyEvaluated (ptrs closure)
205 return$ and are_subs_evaluated
206 otherwise -> return False
207 where amapM f = sequence . amap' f
208
209 amap' f (Array i0 i arr#) = map (\(I# i#) -> case indexArray# arr# i# of
210 (# e #) -> f e)
211 [0 .. i - i0]
212
213 -- TODO: Fix it. Probably the otherwise case is failing, trace/debug it
214 {-
215 unsafeDeepSeq :: a -> b -> b
216 unsafeDeepSeq = unsafeDeepSeq1 2
217 where unsafeDeepSeq1 0 a b = seq a $! b
218 unsafeDeepSeq1 i a b -- 1st case avoids infinite loops for non reducible thunks
219 | not (isConstr tipe) = seq a $! unsafeDeepSeq1 (i-1) a b
220 -- | unsafePerformIO (isFullyEvaluated a) = b
221 | otherwise = case unsafePerformIO (getClosureData a) of
222 closure -> foldl' (flip unsafeDeepSeq) b (ptrs closure)
223 where tipe = unsafePerformIO (getClosureType a)
224 -}
225 isPointed :: Type -> Bool
226 isPointed t | Just (t, _) <- splitTyConApp_maybe t
227 = not$ isUnliftedTypeKind (tyConKind t)
228 isPointed _ = True
229
230 extractUnboxed :: [Type] -> Closure -> [[Word]]
231 extractUnboxed tt clos = go tt (nonPtrs clos)
232 where sizeofType t
233 | Just (tycon,_) <- splitTyConApp_maybe t
234 = ASSERT (isPrimTyCon tycon) sizeofTyCon tycon
235 | otherwise = pprPanic "Expected a TcTyCon" (ppr t)
236 go [] _ = []
237 go (t:tt) xx
238 | (x, rest) <- splitAt (sizeofType t `div` wORD_SIZE) xx
239 = x : go tt rest
240
241 sizeofTyCon = sizeofPrimRep . tyConPrimRep
242
243 -----------------------------------
244 -- * Traversals for Terms
245 -----------------------------------
246
247 data TermFold a = TermFold { fTerm :: Type -> Either String DataCon -> HValue -> [a] -> a
248 , fPrim :: Type -> [Word] -> a
249 , fSuspension :: ClosureType -> Maybe Type -> HValue
250 -> Maybe Name -> a
251 }
252
253 foldTerm :: TermFold a -> Term -> a
254 foldTerm tf (Term ty dc v tt) = fTerm tf ty dc v (map (foldTerm tf) tt)
255 foldTerm tf (Prim ty v ) = fPrim tf ty v
256 foldTerm tf (Suspension ct ty v b) = fSuspension tf ct ty v b
257
258 idTermFold :: TermFold Term
259 idTermFold = TermFold {
260 fTerm = Term,
261 fPrim = Prim,
262 fSuspension = Suspension
263 }
264 idTermFoldM :: Monad m => TermFold (m Term)
265 idTermFoldM = TermFold {
266 fTerm = \ty dc v tt -> sequence tt >>= return . Term ty dc v,
267 fPrim = (return.). Prim,
268 fSuspension = (((return.).).). Suspension
269 }
270
271 mapTermType :: (Type -> Type) -> Term -> Term
272 mapTermType f = foldTerm idTermFold {
273 fTerm = \ty dc hval tt -> Term (f ty) dc hval tt,
274 fSuspension = \ct mb_ty hval n ->
275 Suspension ct (fmap f mb_ty) hval n }
276
277 termTyVars :: Term -> TyVarSet
278 termTyVars = foldTerm TermFold {
279 fTerm = \ty _ _ tt ->
280 tyVarsOfType ty `plusVarEnv` concatVarEnv tt,
281 fSuspension = \_ mb_ty _ _ ->
282 maybe emptyVarEnv tyVarsOfType mb_ty,
283 fPrim = \ _ _ -> emptyVarEnv }
284 where concatVarEnv = foldr plusVarEnv emptyVarEnv
285 ----------------------------------
286 -- Pretty printing of terms
287 ----------------------------------
288
289 app_prec,cons_prec ::Int
290 app_prec = 10
291 cons_prec = 5 -- TODO Extract this info from GHC itself
292
293 pprTerm y p t | Just doc <- pprTermM y p t = doc
294
295 pprTermM :: Monad m => (Int -> Term -> m SDoc) -> Int -> Term -> m SDoc
296 pprTermM y p t@Term{dc=Left dc_tag, subTerms=tt, ty=ty} = do
297 tt_docs <- mapM (y app_prec) tt
298 return$ cparen (not(null tt) && p >= app_prec) (text dc_tag <+> sep tt_docs)
299
300 pprTermM y p t@Term{dc=Right dc, subTerms=tt, ty=ty}
301 {- | dataConIsInfix dc, (t1:t2:tt') <- tt --TODO fixity
302 = parens (pprTerm1 True t1 <+> ppr dc <+> pprTerm1 True ppr t2)
303 <+> hsep (map (pprTerm1 True) tt)
304 -} -- TODO Printing infix constructors properly
305 | null tt = return$ ppr dc
306 | Just (tc,_) <- splitNewTyConApp_maybe ty
307 , isNewTyCon tc
308 , Just new_dc <- maybeTyConSingleCon tc = do
309 real_value <- y 10 t{ty=repType ty}
310 return$ cparen (p >= app_prec) (ppr new_dc <+> real_value)
311 | otherwise = do
312 tt_docs <- mapM (y app_prec) tt
313 return$ cparen (p >= app_prec) (ppr dc <+> sep tt_docs)
314
315 pprTermM y _ t = pprTermM1 y t
316 pprTermM1 _ Prim{value=words, ty=ty} =
317 return$ text$ repPrim (tyConAppTyCon ty) words
318 pprTermM1 y t@Term{} = panic "pprTermM1 - unreachable"
319 pprTermM1 _ Suspension{bound_to=Nothing} = return$ char '_'
320 pprTermM1 _ Suspension{mb_ty=Just ty, bound_to=Just n}
321 | Just _ <- splitFunTy_maybe ty = return$ ptext SLIT("<function>")
322 | otherwise = return$ parens$ ppr n <> text "::" <> ppr ty
323
324 -- Takes a list of custom printers with a explicit recursion knot and a term,
325 -- and returns the output of the first succesful printer, or the default printer
326 cPprTerm :: forall m. Monad m =>
327 ((Int->Term->m SDoc)->[Int->Term->m (Maybe SDoc)]) -> Term -> m SDoc
328 cPprTerm custom = go 0 where
329 go prec t@Term{} = do
330 let default_ prec t = Just `liftM` pprTermM go prec t
331 mb_customDocs = [pp prec t | pp <- custom go ++ [default_]]
332 Just doc <- firstJustM mb_customDocs
333 return$ cparen (prec>app_prec+1) doc
334 go _ t = pprTermM1 go t
335 firstJustM (mb:mbs) = mb >>= maybe (firstJustM mbs) (return . Just)
336 firstJustM [] = return Nothing
337
338 -- Default set of custom printers. Note that the recursion knot is explicit
339 cPprTermBase :: Monad m => (Int->Term-> m SDoc)->[Int->Term->m (Maybe SDoc)]
340 cPprTermBase y =
341 [
342 ifTerm isTupleTy (\_ -> liftM (parens . hcat . punctuate comma)
343 . mapM (y (-1)) . subTerms)
344 , ifTerm (\t -> isTyCon listTyCon t && subTerms t `lengthIs` 2)
345 (\ p Term{subTerms=[h,t]} -> doList p h t)
346 , ifTerm (isTyCon intTyCon) (coerceShow$ \(a::Int)->a)
347 , ifTerm (isTyCon charTyCon) (coerceShow$ \(a::Char)->a)
348 -- , ifTerm (isTyCon wordTyCon) (coerceShow$ \(a::Word)->a)
349 , ifTerm (isTyCon floatTyCon) (coerceShow$ \(a::Float)->a)
350 , ifTerm (isTyCon doubleTyCon) (coerceShow$ \(a::Double)->a)
351 , ifTerm isIntegerTy (coerceShow$ \(a::Integer)->a)
352 ]
353 where ifTerm pred f p t@Term{} | pred t = liftM Just (f p t)
354 ifTerm _ _ _ _ = return Nothing
355 isIntegerTy Term{ty=ty} = fromMaybe False $ do
356 (tc,_) <- splitTyConApp_maybe ty
357 return (tyConName tc == integerTyConName)
358 isTupleTy Term{ty=ty} = fromMaybe False $ do
359 (tc,_) <- splitTyConApp_maybe ty
360 return (tc `elem` (fst.unzip.elems) boxedTupleArr)
361 isTyCon a_tc Term{ty=ty} = fromMaybe False $ do
362 (tc,_) <- splitTyConApp_maybe ty
363 return (a_tc == tc)
364 coerceShow f _ = return . text . show . f . unsafeCoerce# . val
365 --TODO pprinting of list terms is not lazy
366 doList p h t = do
367 let elems = h : getListTerms t
368 isConsLast = termType(last elems) /= termType h
369 print_elems <- mapM (y cons_prec) elems
370 return$ if isConsLast
371 then cparen (p >= cons_prec) . hsep . punctuate (space<>colon)
372 $ print_elems
373 else brackets (hcat$ punctuate comma print_elems)
374
375 where Just a /= Just b = not (a `coreEqType` b)
376 _ /= _ = True
377 getListTerms Term{subTerms=[h,t]} = h : getListTerms t
378 getListTerms t@Term{subTerms=[]} = []
379 getListTerms t@Suspension{} = [t]
380 getListTerms t = pprPanic "getListTerms" (ppr t)
381
382
383 repPrim :: TyCon -> [Word] -> String
384 repPrim t = rep where
385 rep x
386 | t == charPrimTyCon = show (build x :: Char)
387 | t == intPrimTyCon = show (build x :: Int)
388 | t == wordPrimTyCon = show (build x :: Word)
389 | t == floatPrimTyCon = show (build x :: Float)
390 | t == doublePrimTyCon = show (build x :: Double)
391 | t == int32PrimTyCon = show (build x :: Int32)
392 | t == word32PrimTyCon = show (build x :: Word32)
393 | t == int64PrimTyCon = show (build x :: Int64)
394 | t == word64PrimTyCon = show (build x :: Word64)
395 | t == addrPrimTyCon = show (nullPtr `plusPtr` build x)
396 | t == stablePtrPrimTyCon = "<stablePtr>"
397 | t == stableNamePrimTyCon = "<stableName>"
398 | t == statePrimTyCon = "<statethread>"
399 | t == realWorldTyCon = "<realworld>"
400 | t == threadIdPrimTyCon = "<ThreadId>"
401 | t == weakPrimTyCon = "<Weak>"
402 | t == arrayPrimTyCon = "<array>"
403 | t == byteArrayPrimTyCon = "<bytearray>"
404 | t == mutableArrayPrimTyCon = "<mutableArray>"
405 | t == mutableByteArrayPrimTyCon = "<mutableByteArray>"
406 | t == mutVarPrimTyCon= "<mutVar>"
407 | t == mVarPrimTyCon = "<mVar>"
408 | t == tVarPrimTyCon = "<tVar>"
409 | otherwise = showSDoc (char '<' <> ppr t <> char '>')
410 where build ww = unsafePerformIO $ withArray ww (peek . castPtr)
411 -- This ^^^ relies on the representation of Haskell heap values being
412 -- the same as in a C array.
413
414 -----------------------------------
415 -- Type Reconstruction
416 -----------------------------------
417 {-
418 Type Reconstruction is type inference done on heap closures.
419 The algorithm walks the heap generating a set of equations, which
420 are solved with syntactic unification.
421 A type reconstruction equation looks like:
422
423 <datacon reptype> = <actual heap contents>
424
425 The full equation set is generated by traversing all the subterms, starting
426 from a given term.
427
428 The only difficult part is that newtypes are only found in the lhs of equations.
429 Right hand sides are missing them. We can either (a) drop them from the lhs, or
430 (b) reconstruct them in the rhs when possible.
431
432 The function congruenceNewtypes takes a shot at (b)
433 -}
434
435 -- The Type Reconstruction monad
436 type TR a = TcM a
437
438 runTR :: HscEnv -> TR a -> IO a
439 runTR hsc_env c = do
440 mb_term <- runTR_maybe hsc_env c
441 case mb_term of
442 Nothing -> panic "Can't unify"
443 Just x -> return x
444
445 runTR_maybe :: HscEnv -> TR a -> IO (Maybe a)
446 runTR_maybe hsc_env = fmap snd . initTc hsc_env HsSrcFile False iNTERACTIVE
447
448 trIO :: IO a -> TR a
449 trIO = liftTcM . ioToTcRn
450
451 liftTcM :: TcM a -> TR a
452 liftTcM = id
453
454 newVar :: Kind -> TR TcType
455 newVar = liftTcM . fmap mkTyVarTy . newFlexiTyVar
456
457 -- | Returns the instantiated type scheme ty', and the substitution sigma
458 -- such that sigma(ty') = ty
459 instScheme :: Type -> TR (TcType, TvSubst)
460 instScheme ty | (tvs, rho) <- tcSplitForAllTys ty = liftTcM$ do
461 (tvs',theta,ty') <- tcInstType (mapM tcInstTyVar) ty
462 return (ty', zipTopTvSubst tvs' (mkTyVarTys tvs))
463
464 -- Adds a constraint of the form t1 == t2
465 -- t1 is expected to come from walking the heap
466 -- t2 is expected to come from a datacon signature
467 -- Before unification, congruenceNewtypes needs to
468 -- do its magic.
469 addConstraint :: TcType -> TcType -> TR ()
470 addConstraint t1 t2 = congruenceNewtypes t1 t2 >>= uncurry unifyType
471
472
473
474 -- Type & Term reconstruction
475 cvObtainTerm :: HscEnv -> Bool -> Maybe Type -> HValue -> IO Term
476 cvObtainTerm hsc_env force mb_ty hval = runTR hsc_env $ do
477 tv <- newVar argTypeKind
478 case mb_ty of
479 Nothing -> go tv tv hval >>= zonkTerm
480 Just ty | isMonomorphic ty -> go ty ty hval >>= zonkTerm
481 Just ty -> do
482 (ty',rev_subst) <- instScheme (sigmaType ty)
483 addConstraint tv ty'
484 term <- go tv tv hval >>= zonkTerm
485 --restore original Tyvars
486 return$ mapTermType (substTy rev_subst) term
487 where
488 go tv ty a = do
489 let monomorphic = not(isTyVarTy tv)
490 -- This ^^^ is a convention. The ancestor tests for
491 -- monomorphism and passes a type instead of a tv
492 clos <- trIO $ getClosureData a
493 case tipe clos of
494 -- Thunks we may want to force
495 -- NB. this won't attempt to force a BLACKHOLE. Even with :force, we never
496 -- force blackholes, because it would almost certainly result in deadlock,
497 -- and showing the '_' is more useful.
498 t | isThunk t && force -> seq a $ go tv ty a
499 -- We always follow indirections
500 Indirection _ -> go tv ty $! (ptrs clos ! 0)
501 -- The interesting case
502 Constr -> do
503 Right dcname <- dataConInfoPtrToName (infoPtr clos)
504 (_,mb_dc) <- tryTcErrs (tcLookupDataCon dcname)
505 case mb_dc of
506 Nothing -> do -- This can happen for private constructors compiled -O0
507 -- where the .hi descriptor does not export them
508 -- In such case, we return a best approximation:
509 -- ignore the unpointed args, and recover the pointeds
510 -- This preserves laziness, and should be safe.
511 let tag = showSDoc (ppr dcname)
512 vars <- replicateM (length$ elems$ ptrs clos)
513 (newVar (liftedTypeKind))
514 subTerms <- sequence [appArr (go tv tv) (ptrs clos) i
515 | (i, tv) <- zip [0..] vars]
516 return (Term tv (Left ('<' : tag ++ ">")) a subTerms)
517 Just dc -> do
518 let extra_args = length(dataConRepArgTys dc) -
519 length(dataConOrigArgTys dc)
520 subTtypes = matchSubTypes dc ty
521 (subTtypesP, subTtypesNP) = partition isPointed subTtypes
522 subTermTvs <- sequence
523 [ if isMonomorphic t then return t
524 else (newVar k)
525 | (t,k) <- zip subTtypesP (map typeKind subTtypesP)]
526 -- It is vital for newtype reconstruction that the unification step
527 -- is done right here, _before_ the subterms are RTTI reconstructed
528 when (not monomorphic) $ do
529 let myType = mkFunTys (reOrderTerms subTermTvs
530 subTtypesNP
531 subTtypes)
532 tv
533 (signatureType,_) <- instScheme(dataConRepType dc)
534 addConstraint myType signatureType
535 subTermsP <- sequence $ drop extra_args
536 -- ^^^ all extra arguments are pointed
537 [ appArr (go tv t) (ptrs clos) i
538 | (i,tv,t) <- zip3 [0..] subTermTvs subTtypesP]
539 let unboxeds = extractUnboxed subTtypesNP clos
540 subTermsNP = map (uncurry Prim) (zip subTtypesNP unboxeds)
541 subTerms = reOrderTerms subTermsP subTermsNP
542 (drop extra_args subTtypes)
543 return (Term tv (Right dc) a subTerms)
544 -- The otherwise case: can be a Thunk,AP,PAP,etc.
545 otherwise ->
546 return (Suspension (tipe clos) (Just tv) a Nothing)
547
548 matchSubTypes dc ty
549 | Just (_,ty_args) <- splitTyConApp_maybe (repType ty)
550 -- assumption: ^^^ looks through newtypes
551 , isVanillaDataCon dc --TODO non-vanilla case
552 = dataConInstArgTys dc ty_args
553 | otherwise = dataConRepArgTys dc
554
555 -- This is used to put together pointed and nonpointed subterms in the
556 -- correct order.
557 reOrderTerms _ _ [] = []
558 reOrderTerms pointed unpointed (ty:tys)
559 | isPointed ty = ASSERT2(not(null pointed)
560 , ptext SLIT("reOrderTerms") $$
561 (ppr pointed $$ ppr unpointed))
562 head pointed : reOrderTerms (tail pointed) unpointed tys
563 | otherwise = ASSERT2(not(null unpointed)
564 , ptext SLIT("reOrderTerms") $$
565 (ppr pointed $$ ppr unpointed))
566 head unpointed : reOrderTerms pointed (tail unpointed) tys
567
568
569
570 -- Fast, breadth-first Type reconstruction
571 max_depth = 10 :: Int
572 cvReconstructType :: HscEnv -> Bool -> Maybe Type -> HValue -> IO (Maybe Type)
573 cvReconstructType hsc_env force mb_ty hval = runTR_maybe hsc_env $ do
574 tv <- newVar argTypeKind
575 case mb_ty of
576 Nothing -> do search (isMonomorphic `fmap` zonkTcType tv)
577 (uncurry go)
578 [(tv, hval)]
579 max_depth
580 zonkTcType tv -- TODO untested!
581 Just ty | isMonomorphic ty -> return ty
582 Just ty -> do
583 (ty',rev_subst) <- instScheme (sigmaType ty)
584 addConstraint tv ty'
585 search (isMonomorphic `fmap` zonkTcType tv)
586 (\(ty,a) -> go ty a)
587 [(tv, hval)]
588 max_depth
589 substTy rev_subst `fmap` zonkTcType tv
590 where
591 -- search :: m Bool -> ([a] -> [a] -> [a]) -> [a] -> m ()
592 search stop expand [] depth = return ()
593 search stop expand x 0 = fail$ "Failed to reconstruct a type after " ++
594 show max_depth ++ " steps"
595 search stop expand (x:xx) d = unlessM stop $ do
596 new <- expand x
597 search stop expand (xx ++ new) $! (pred d)
598
599 -- returns unification tasks,since we are going to want a breadth-first search
600 go :: Type -> HValue -> TR [(Type, HValue)]
601 go tv a = do
602 clos <- trIO $ getClosureData a
603 case tipe clos of
604 Indirection _ -> go tv $! (ptrs clos ! 0)
605 Constr -> do
606 Right dcname <- dataConInfoPtrToName (infoPtr clos)
607 (_,mb_dc) <- tryTcErrs (tcLookupDataCon dcname)
608 case mb_dc of
609 Nothing-> do
610 -- TODO: Check this case
611 vars <- replicateM (length$ elems$ ptrs clos)
612 (newVar (liftedTypeKind))
613 subTerms <- sequence [ appArr (go tv) (ptrs clos) i
614 | (i, tv) <- zip [0..] vars]
615 forM [0..length (elems $ ptrs clos)] $ \i -> do
616 tv <- newVar liftedTypeKind
617 return$ appArr (\e->(tv,e)) (ptrs clos) i
618
619 Just dc -> do
620 let extra_args = length(dataConRepArgTys dc) -
621 length(dataConOrigArgTys dc)
622 subTtypes <- mapMif (not . isMonomorphic)
623 (\t -> newVar (typeKind t))
624 (dataConRepArgTys dc)
625 -- It is vital for newtype reconstruction that the unification step
626 -- is done right here, _before_ the subterms are RTTI reconstructed
627 let myType = mkFunTys subTtypes tv
628 (signatureType,_) <- instScheme(dataConRepType dc)
629 addConstraint myType signatureType
630 return $ [ appArr (\e->(t,e)) (ptrs clos) i
631 | (i,t) <- drop extra_args $ zip [0..] subTtypes]
632 otherwise -> return []
633
634 -- This helper computes the difference between a base type t and the
635 -- improved rtti_t computed by RTTI
636 -- The main difference between RTTI types and their normal counterparts
637 -- is that the former are _not_ polymorphic, thus polymorphism must
638 -- be stripped. Syntactically, forall's must be stripped
639 computeRTTIsubst ty rtti_ty =
640 -- In addition, we strip newtypes too, since the reconstructed type might
641 -- not have recovered them all
642 tcUnifyTys (const BindMe)
643 [repType' $ dropForAlls$ ty]
644 [repType' $ rtti_ty]
645 -- TODO stripping newtypes shouldn't be necessary, test
646
647
648 -- Dealing with newtypes
649 {-
650 A parallel fold over two Type values,
651 compensating for missing newtypes on both sides.
652 This is necessary because newtypes are not present
653 in runtime, but since sometimes there is evidence
654 available we do our best to reconstruct them.
655 Evidence can come from DataCon signatures or
656 from compile-time type inference.
657 I am using the words congruence and rewriting
658 because what we are doing here is an approximation
659 of unification modulo a set of equations, which would
660 come from newtype definitions. These should be the
661 equality coercions seen in System Fc. Rewriting
662 is performed, taking those equations as rules,
663 before launching unification.
664
665 It doesn't make sense to rewrite everywhere,
666 or we would end up with all newtypes. So we rewrite
667 only in presence of evidence.
668 The lhs comes from the heap structure of ptrs,nptrs.
669 The rhs comes from a DataCon type signature.
670 Rewriting in the rhs is restricted to the result type.
671
672 Note that it is very tricky to make this 'rewriting'
673 work with the unification implemented by TcM, where
674 substitutions are 'inlined'. The order in which
675 constraints are unified is vital for this (or I am
676 using TcM wrongly).
677 -}
678 congruenceNewtypes :: TcType -> TcType -> TcM (TcType,TcType)
679 congruenceNewtypes lhs rhs
680 -- TyVar lhs inductive case
681 | Just tv <- getTyVar_maybe lhs
682 = recoverTc (return (lhs,rhs)) $ do
683 Indirect ty_v <- readMetaTyVar tv
684 (lhs1, rhs1) <- congruenceNewtypes ty_v rhs
685 return (lhs, rhs1)
686 -- FunTy inductive case
687 | Just (l1,l2) <- splitFunTy_maybe lhs
688 , Just (r1,r2) <- splitFunTy_maybe rhs
689 = do (l2',r2') <- congruenceNewtypes l2 r2
690 (l1',r1') <- congruenceNewtypes l1 r1
691 return (mkFunTy l1' l2', mkFunTy r1' r2')
692 -- TyconApp Inductive case; this is the interesting bit.
693 | Just (tycon_l, args_l) <- splitNewTyConApp_maybe lhs
694 , Just (tycon_r, args_r) <- splitNewTyConApp_maybe rhs
695 , tycon_l /= tycon_r
696 = return (lhs, upgrade tycon_l rhs)
697
698 | otherwise = return (lhs,rhs)
699
700 where upgrade :: TyCon -> Type -> Type
701 upgrade new_tycon ty
702 | not (isNewTyCon new_tycon) = ty
703 | ty' <- mkTyConApp new_tycon (map mkTyVarTy $ tyConTyVars new_tycon)
704 , Just subst <- tcUnifyTys (const BindMe) [ty] [repType ty']
705 = substTy subst ty'
706 -- assumes that reptype doesn't touch tyconApp args ^^^
707
708
709 --------------------------------------------------------------------------------
710 -- Semantically different to recoverM in TcRnMonad
711 -- recoverM retains the errors in the first action,
712 -- whereas recoverTc here does not
713 recoverTc recover thing = do
714 (_,mb_res) <- tryTcErrs thing
715 case mb_res of
716 Nothing -> recover
717 Just res -> return res
718
719 isMonomorphic ty | (tvs, ty') <- splitForAllTys ty
720 = null tvs && (isEmptyVarSet . tyVarsOfType) ty'
721
722 mapMif :: Monad m => (a -> Bool) -> (a -> m a) -> [a] -> m [a]
723 mapMif pred f xx = sequence $ mapMif_ pred f xx
724 mapMif_ pred f [] = []
725 mapMif_ pred f (x:xx) = (if pred x then f x else return x) : mapMif_ pred f xx
726
727 unlessM condM acc = condM >>= \c -> unless c acc
728
729 -- Strict application of f at index i
730 appArr f a@(Array _ _ ptrs#) i@(I# i#) = ASSERT (i < length(elems a))
731 case indexArray# ptrs# i# of
732 (# e #) -> f e
733
734 zonkTerm :: Term -> TcM Term
735 zonkTerm = foldTerm idTermFoldM {
736 fTerm = \ty dc v tt -> sequence tt >>= \tt ->
737 zonkTcType ty >>= \ty' ->
738 return (Term ty' dc v tt)
739 ,fSuspension = \ct ty v b -> fmapMMaybe zonkTcType ty >>= \ty ->
740 return (Suspension ct ty v b)}
741
742
743 -- Is this defined elsewhere?
744 -- Generalize the type: find all free tyvars and wrap in the appropiate ForAll.
745 sigmaType ty = mkForAllTys (varSetElems$ tyVarsOfType (dropForAlls ty)) ty
746
747