2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[CoreSyn]{A data type for the Haskell compiler midsection}
8 Expr(..), Alt, Bind(..), AltCon(..), Arg, Note(..),
9 CoreExpr, CoreAlt, CoreBind, CoreArg, CoreBndr,
10 TaggedExpr, TaggedAlt, TaggedBind, TaggedArg,
13 mkApps, mkTyApps, mkValApps, mkVarApps,
14 mkLit, mkIntLitInt, mkIntLit,
18 bindersOf, bindersOfBinds, rhssOfBind, rhssOfAlts, isTyVar, isId,
19 collectBinders, collectTyBinders, collectValBinders, collectTyAndValBinders,
20 collectArgs, collectBindersIgnoringNotes,
24 isValArg, isTypeArg, valArgCount, valBndrCount,
27 Unfolding(..), UnfoldingGuidance(..), -- Both abstract everywhere but in CoreUnfold.lhs
28 noUnfolding, mkOtherCon,
29 unfoldingTemplate, maybeUnfoldingTemplate, otherCons,
30 isValueUnfolding, isEvaldUnfolding, isCheapUnfolding, isCompulsoryUnfolding,
31 hasUnfolding, hasSomeUnfolding, neverUnfold,
34 seqRules, seqExpr, seqExprs, seqUnfolding,
36 -- Annotated expressions
37 AnnExpr, AnnExpr'(..), AnnBind(..), AnnAlt, deAnnotate, deAnnotate',
40 CoreRules(..), -- Representation needed by friends
41 CoreRule(..), -- CoreSubst, CoreTidy, CoreFVs, PprCore only
44 emptyCoreRules, isEmptyCoreRules, rulesRhsFreeVars, rulesRules,
48 #include "HsVersions.h"
50 import CostCentre ( CostCentre, noCostCentre )
51 import Var ( Var, Id, TyVar, isTyVar, isId )
52 import Type ( Type, mkTyVarTy, seqType )
53 import Literal ( Literal, mkMachInt )
54 import DataCon ( DataCon, dataConId )
59 %************************************************************************
61 \subsection{The main data types}
63 %************************************************************************
65 These data types are the heart of the compiler
68 infixl 8 `App` -- App brackets to the left
70 data Expr b -- "b" for the type of binders,
73 | App (Expr b) (Arg b)
75 | Let (Bind b) (Expr b)
76 | Case (Expr b) b [Alt b] -- Binder gets bound to value of scrutinee
77 -- DEFAULT case must be last, if it occurs at all
79 | Type Type -- This should only show up at the top
82 type Arg b = Expr b -- Can be a Type
84 type Alt b = (AltCon, [b], Expr b) -- (DEFAULT, [], rhs) is the default alternative
86 data AltCon = DataAlt DataCon
91 data Bind b = NonRec b (Expr b)
98 Type -- The to-type: type of whole coerce expression
99 Type -- The from-type: type of enclosed expression
101 | InlineCall -- Instructs simplifier to inline
104 | InlineMe -- Instructs simplifer to treat the enclosed expression
105 -- as very small, and inline it at its call sites
109 %************************************************************************
111 \subsection{Transformation rules}
113 %************************************************************************
115 The CoreRule type and its friends are dealt with mainly in CoreRules,
116 but CoreFVs, Subst, PprCore, CoreTidy also inspect the representation.
121 VarSet -- Locally-defined free vars of RHSs
123 emptyCoreRules :: CoreRules
124 emptyCoreRules = Rules [] emptyVarSet
126 isEmptyCoreRules :: CoreRules -> Bool
127 isEmptyCoreRules (Rules rs _) = null rs
129 rulesRhsFreeVars :: CoreRules -> VarSet
130 rulesRhsFreeVars (Rules _ fvs) = fvs
132 rulesRules :: CoreRules -> [CoreRule]
133 rulesRules (Rules rules _) = rules
137 type RuleName = FAST_STRING
138 type IdCoreRule = (Id,CoreRule) -- Rules don't have their leading Id inside them
142 [CoreBndr] -- Forall'd variables
143 [CoreExpr] -- LHS args
146 | BuiltinRule -- Built-in rules are used for constant folding
147 -- and suchlike. It has no free variables.
148 ([CoreExpr] -> Maybe (RuleName, CoreExpr))
150 isBuiltinRule (BuiltinRule _) = True
151 isBuiltinRule _ = False
155 %************************************************************************
157 \subsection{@Unfolding@ type}
159 %************************************************************************
161 The @Unfolding@ type is declared here to avoid numerous loops, but it
162 should be abstract everywhere except in CoreUnfold.lhs
168 | OtherCon [AltCon] -- It ain't one of these
169 -- (OtherCon xs) also indicates that something has been evaluated
170 -- and hence there's no point in re-evaluating it.
171 -- OtherCon [] is used even for non-data-type values
172 -- to indicated evaluated-ness. Notably:
173 -- data C = C !(Int -> Int)
174 -- case x of { C f -> ... }
175 -- Here, f gets an OtherCon [] unfolding.
177 | CompulsoryUnfolding CoreExpr -- There is no "original" definition,
178 -- so you'd better unfold.
180 | CoreUnfolding -- An unfolding with redundant cached information
181 CoreExpr -- Template; binder-info is correct
182 Bool -- True <=> top level binding
183 Bool -- exprIsValue template (cached); it is ok to discard a `seq` on
185 Bool -- True <=> doesn't waste (much) work to expand inside an inlining
186 -- Basically it's exprIsCheap
187 UnfoldingGuidance -- Tells about the *size* of the template.
190 data UnfoldingGuidance
192 | UnfoldIfGoodArgs Int -- and "n" value args
194 [Int] -- Discount if the argument is evaluated.
195 -- (i.e., a simplification will definitely
196 -- be possible). One elt of the list per *value* arg.
198 Int -- The "size" of the unfolding; to be elaborated
201 Int -- Scrutinee discount: the discount to substract if the thing is in
202 -- a context (case (thing args) of ...),
203 -- (where there are the right number of arguments.)
205 noUnfolding = NoUnfolding
206 mkOtherCon = OtherCon
208 seqUnfolding :: Unfolding -> ()
209 seqUnfolding (CoreUnfolding e top b1 b2 g)
210 = seqExpr e `seq` top `seq` b1 `seq` b2 `seq` seqGuidance g
211 seqUnfolding other = ()
213 seqGuidance (UnfoldIfGoodArgs n ns a b) = n `seq` sum ns `seq` a `seq` b `seq` ()
214 seqGuidance other = ()
218 unfoldingTemplate :: Unfolding -> CoreExpr
219 unfoldingTemplate (CoreUnfolding expr _ _ _ _) = expr
220 unfoldingTemplate (CompulsoryUnfolding expr) = expr
221 unfoldingTemplate other = panic "getUnfoldingTemplate"
223 maybeUnfoldingTemplate :: Unfolding -> Maybe CoreExpr
224 maybeUnfoldingTemplate (CoreUnfolding expr _ _ _ _) = Just expr
225 maybeUnfoldingTemplate (CompulsoryUnfolding expr) = Just expr
226 maybeUnfoldingTemplate other = Nothing
228 otherCons :: Unfolding -> [AltCon]
229 otherCons (OtherCon cons) = cons
232 isValueUnfolding :: Unfolding -> Bool
233 -- Returns False for OtherCon
234 isValueUnfolding (CoreUnfolding _ _ is_evald _ _) = is_evald
235 isValueUnfolding other = False
237 isEvaldUnfolding :: Unfolding -> Bool
238 -- Returns True for OtherCon
239 isEvaldUnfolding (OtherCon _) = True
240 isEvaldUnfolding (CoreUnfolding _ _ is_evald _ _) = is_evald
241 isEvaldUnfolding other = False
243 isCheapUnfolding :: Unfolding -> Bool
244 isCheapUnfolding (CoreUnfolding _ _ _ is_cheap _) = is_cheap
245 isCheapUnfolding other = False
247 isCompulsoryUnfolding :: Unfolding -> Bool
248 isCompulsoryUnfolding (CompulsoryUnfolding _) = True
249 isCompulsoryUnfolding other = False
251 hasUnfolding :: Unfolding -> Bool
252 hasUnfolding (CoreUnfolding _ _ _ _ _) = True
253 hasUnfolding (CompulsoryUnfolding _) = True
254 hasUnfolding other = False
256 hasSomeUnfolding :: Unfolding -> Bool
257 hasSomeUnfolding NoUnfolding = False
258 hasSomeUnfolding other = True
260 neverUnfold :: Unfolding -> Bool
261 neverUnfold NoUnfolding = True
262 neverUnfold (OtherCon _) = True
263 neverUnfold (CoreUnfolding _ _ _ _ UnfoldNever) = True
264 neverUnfold other = False
268 %************************************************************************
270 \subsection{The main data type}
272 %************************************************************************
275 -- The Ord is needed for the FiniteMap used in the lookForConstructor
276 -- in SimplEnv. If you declared that lookForConstructor *ignores*
277 -- constructor-applications with LitArg args, then you could get
280 instance Outputable AltCon where
281 ppr (DataAlt dc) = ppr dc
282 ppr (LitAlt lit) = ppr lit
283 ppr DEFAULT = ptext SLIT("__DEFAULT")
285 instance Show AltCon where
286 showsPrec p con = showsPrecSDoc p (ppr con)
290 %************************************************************************
292 \subsection{Useful synonyms}
294 %************************************************************************
300 type CoreExpr = Expr CoreBndr
301 type CoreArg = Arg CoreBndr
302 type CoreBind = Bind CoreBndr
303 type CoreAlt = Alt CoreBndr
306 Binders are ``tagged'' with a \tr{t}:
309 type Tagged t = (CoreBndr, t)
311 type TaggedBind t = Bind (Tagged t)
312 type TaggedExpr t = Expr (Tagged t)
313 type TaggedArg t = Arg (Tagged t)
314 type TaggedAlt t = Alt (Tagged t)
318 %************************************************************************
320 \subsection{Core-constructing functions with checking}
322 %************************************************************************
325 mkApps :: Expr b -> [Arg b] -> Expr b
326 mkTyApps :: Expr b -> [Type] -> Expr b
327 mkValApps :: Expr b -> [Expr b] -> Expr b
328 mkVarApps :: Expr b -> [Var] -> Expr b
330 mkApps f args = foldl App f args
331 mkTyApps f args = foldl (\ e a -> App e (Type a)) f args
332 mkValApps f args = foldl (\ e a -> App e a) f args
333 mkVarApps f vars = foldl (\ e a -> App e (varToCoreExpr a)) f vars
335 mkLit :: Literal -> Expr b
336 mkIntLit :: Integer -> Expr b
337 mkIntLitInt :: Int -> Expr b
338 mkConApp :: DataCon -> [Arg b] -> Expr b
339 mkLets :: [Bind b] -> Expr b -> Expr b
340 mkLams :: [b] -> Expr b -> Expr b
343 mkConApp con args = mkApps (Var (dataConId con)) args
345 mkLams binders body = foldr Lam body binders
346 mkLets binds body = foldr Let body binds
348 mkIntLit n = Lit (mkMachInt n)
349 mkIntLitInt n = Lit (mkMachInt (toInteger n))
351 varToCoreExpr :: CoreBndr -> Expr b
352 varToCoreExpr v | isId v = Var v
353 | otherwise = Type (mkTyVarTy v)
357 %************************************************************************
359 \subsection{Simple access functions}
361 %************************************************************************
364 bindersOf :: Bind b -> [b]
365 bindersOf (NonRec binder _) = [binder]
366 bindersOf (Rec pairs) = [binder | (binder, _) <- pairs]
368 bindersOfBinds :: [Bind b] -> [b]
369 bindersOfBinds binds = foldr ((++) . bindersOf) [] binds
371 rhssOfBind :: Bind b -> [Expr b]
372 rhssOfBind (NonRec _ rhs) = [rhs]
373 rhssOfBind (Rec pairs) = [rhs | (_,rhs) <- pairs]
375 rhssOfAlts :: [Alt b] -> [Expr b]
376 rhssOfAlts alts = [e | (_,_,e) <- alts]
378 flattenBinds :: [Bind b] -> [(b, Expr b)] -- Get all the lhs/rhs pairs
379 flattenBinds (NonRec b r : binds) = (b,r) : flattenBinds binds
380 flattenBinds (Rec prs1 : binds) = prs1 ++ flattenBinds binds
384 We often want to strip off leading lambdas before getting down to
385 business. @collectBinders@ is your friend.
387 We expect (by convention) type-, and value- lambdas in that
391 collectBinders :: Expr b -> ([b], Expr b)
392 collectBindersIgnoringNotes :: Expr b -> ([b], Expr b)
393 collectTyBinders :: CoreExpr -> ([TyVar], CoreExpr)
394 collectValBinders :: CoreExpr -> ([Id], CoreExpr)
395 collectTyAndValBinders :: CoreExpr -> ([TyVar], [Id], CoreExpr)
400 go bs (Lam b e) = go (b:bs) e
401 go bs e = (reverse bs, e)
403 -- This one ignores notes. It's used in CoreUnfold and StrAnal
404 -- when we aren't going to put the expression back together from
405 -- the pieces, so we don't mind losing the Notes
406 collectBindersIgnoringNotes expr
409 go bs (Lam b e) = go (b:bs) e
410 go bs (Note _ e) = go bs e
411 go bs e = (reverse bs, e)
413 collectTyAndValBinders expr
416 (tvs, body1) = collectTyBinders expr
417 (ids, body) = collectValBinders body1
419 collectTyBinders expr
422 go tvs (Lam b e) | isTyVar b = go (b:tvs) e
423 go tvs e = (reverse tvs, e)
425 collectValBinders expr
428 go ids (Lam b e) | isId b = go (b:ids) e
429 go ids body = (reverse ids, body)
433 @collectArgs@ takes an application expression, returning the function
434 and the arguments to which it is applied.
437 collectArgs :: Expr b -> (Expr b, [Arg b])
441 go (App f a) as = go f (a:as)
445 coreExprCc gets the cost centre enclosing an expression, if any.
446 It looks inside lambdas because (scc "foo" \x.e) = \x.scc "foo" e
449 coreExprCc :: Expr b -> CostCentre
450 coreExprCc (Note (SCC cc) e) = cc
451 coreExprCc (Note other_note e) = coreExprCc e
452 coreExprCc (Lam _ e) = coreExprCc e
453 coreExprCc other = noCostCentre
457 %************************************************************************
459 \subsection{Predicates}
461 %************************************************************************
464 isValArg (Type _) = False
465 isValArg other = True
467 isTypeArg (Type _) = True
468 isTypeArg other = False
470 valBndrCount :: [CoreBndr] -> Int
472 valBndrCount (b : bs) | isId b = 1 + valBndrCount bs
473 | otherwise = valBndrCount bs
475 valArgCount :: [Arg b] -> Int
477 valArgCount (Type _ : args) = valArgCount args
478 valArgCount (other : args) = 1 + valArgCount args
482 %************************************************************************
484 \subsection{Seq stuff}
486 %************************************************************************
489 seqExpr :: CoreExpr -> ()
490 seqExpr (Var v) = v `seq` ()
491 seqExpr (Lit lit) = lit `seq` ()
492 seqExpr (App f a) = seqExpr f `seq` seqExpr a
493 seqExpr (Lam b e) = seqBndr b `seq` seqExpr e
494 seqExpr (Let b e) = seqBind b `seq` seqExpr e
495 seqExpr (Case e b as) = seqExpr e `seq` seqBndr b `seq` seqAlts as
496 seqExpr (Note n e) = seqNote n `seq` seqExpr e
497 seqExpr (Type t) = seqType t
500 seqExprs (e:es) = seqExpr e `seq` seqExprs es
502 seqNote (Coerce t1 t2) = seqType t1 `seq` seqType t2
505 seqBndr b = b `seq` ()
508 seqBndrs (b:bs) = seqBndr b `seq` seqBndrs bs
510 seqBind (NonRec b e) = seqBndr b `seq` seqExpr e
511 seqBind (Rec prs) = seqPairs prs
514 seqPairs ((b,e):prs) = seqBndr b `seq` seqExpr e `seq` seqPairs prs
517 seqAlts ((c,bs,e):alts) = seqBndrs bs `seq` seqExpr e `seq` seqAlts alts
519 seqRules :: CoreRules -> ()
520 seqRules (Rules rules fvs) = seq_rules rules `seq` seqVarSet fvs
523 seq_rules (Rule fs bs es e : rules) = seqBndrs bs `seq` seqExprs (e:es) `seq` seq_rules rules
524 seq_rules (BuiltinRule _ : rules) = seq_rules rules
529 %************************************************************************
531 \subsection{Annotated core; annotation at every node in the tree}
533 %************************************************************************
536 type AnnExpr bndr annot = (annot, AnnExpr' bndr annot)
538 data AnnExpr' bndr annot
541 | AnnLam bndr (AnnExpr bndr annot)
542 | AnnApp (AnnExpr bndr annot) (AnnExpr bndr annot)
543 | AnnCase (AnnExpr bndr annot) bndr [AnnAlt bndr annot]
544 | AnnLet (AnnBind bndr annot) (AnnExpr bndr annot)
545 | AnnNote Note (AnnExpr bndr annot)
548 type AnnAlt bndr annot = (AltCon, [bndr], AnnExpr bndr annot)
550 data AnnBind bndr annot
551 = AnnNonRec bndr (AnnExpr bndr annot)
552 | AnnRec [(bndr, AnnExpr bndr annot)]
556 deAnnotate :: AnnExpr bndr annot -> Expr bndr
557 deAnnotate (_, e) = deAnnotate' e
559 deAnnotate' (AnnType t) = Type t
560 deAnnotate' (AnnVar v) = Var v
561 deAnnotate' (AnnLit lit) = Lit lit
562 deAnnotate' (AnnLam binder body) = Lam binder (deAnnotate body)
563 deAnnotate' (AnnApp fun arg) = App (deAnnotate fun) (deAnnotate arg)
564 deAnnotate' (AnnNote note body) = Note note (deAnnotate body)
566 deAnnotate' (AnnLet bind body)
567 = Let (deAnnBind bind) (deAnnotate body)
569 deAnnBind (AnnNonRec var rhs) = NonRec var (deAnnotate rhs)
570 deAnnBind (AnnRec pairs) = Rec [(v,deAnnotate rhs) | (v,rhs) <- pairs]
572 deAnnotate' (AnnCase scrut v alts)
573 = Case (deAnnotate scrut) v (map deAnnAlt alts)
575 deAnnAlt (con,args,rhs) = (con,args,deAnnotate rhs)