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,
19 bindersOf, bindersOfBinds, rhssOfBind, rhssOfAlts,
20 collectBinders, collectTyBinders, collectValBinders, collectTyAndValBinders,
21 collectArgs, collectBindersIgnoringNotes,
25 isValArg, isTypeArg, valArgCount, valBndrCount,
28 Unfolding(..), UnfoldingGuidance(..), -- Both abstract everywhere but in CoreUnfold.lhs
29 noUnfolding, mkOtherCon,
30 unfoldingTemplate, maybeUnfoldingTemplate, otherCons,
31 isValueUnfolding, isEvaldUnfolding, isCheapUnfolding, isCompulsoryUnfolding,
32 hasUnfolding, hasSomeUnfolding, neverUnfold,
35 seqRules, seqExpr, seqExprs, seqUnfolding,
37 -- Annotated expressions
38 AnnExpr, AnnExpr'(..), AnnBind(..), AnnAlt,
39 deAnnotate, deAnnotate', deAnnAlt,
42 CoreRules(..), -- Representation needed by friends
43 CoreRule(..), -- CoreSubst, CoreTidy, CoreFVs, PprCore only
46 emptyCoreRules, isEmptyCoreRules, rulesRhsFreeVars, rulesRules,
50 #include "HsVersions.h"
52 import CostCentre ( CostCentre, noCostCentre )
53 import Var ( Var, Id, TyVar, isTyVar, isId )
54 import Type ( Type, mkTyVarTy, seqType )
55 import Literal ( Literal, mkMachInt )
56 import DataCon ( DataCon, dataConId )
61 %************************************************************************
63 \subsection{The main data types}
65 %************************************************************************
67 These data types are the heart of the compiler
70 infixl 8 `App` -- App brackets to the left
72 data Expr b -- "b" for the type of binders,
75 | App (Expr b) (Arg b)
77 | Let (Bind b) (Expr b)
78 | Case (Expr b) b [Alt b] -- Binder gets bound to value of scrutinee
79 -- DEFAULT case must be last, if it occurs at all
81 | Type Type -- This should only show up at the top
84 type Arg b = Expr b -- Can be a Type
86 type Alt b = (AltCon, [b], Expr b) -- (DEFAULT, [], rhs) is the default alternative
88 data AltCon = DataAlt DataCon
93 data Bind b = NonRec b (Expr b)
100 Type -- The to-type: type of whole coerce expression
101 Type -- The from-type: type of enclosed expression
103 | InlineCall -- Instructs simplifier to inline
106 | InlineMe -- Instructs simplifer to treat the enclosed expression
107 -- as very small, and inline it at its call sites
111 %************************************************************************
113 \subsection{Transformation rules}
115 %************************************************************************
117 The CoreRule type and its friends are dealt with mainly in CoreRules,
118 but CoreFVs, Subst, PprCore, CoreTidy also inspect the representation.
123 VarSet -- Locally-defined free vars of RHSs
125 emptyCoreRules :: CoreRules
126 emptyCoreRules = Rules [] emptyVarSet
128 isEmptyCoreRules :: CoreRules -> Bool
129 isEmptyCoreRules (Rules rs _) = null rs
131 rulesRhsFreeVars :: CoreRules -> VarSet
132 rulesRhsFreeVars (Rules _ fvs) = fvs
134 rulesRules :: CoreRules -> [CoreRule]
135 rulesRules (Rules rules _) = rules
139 type RuleName = FAST_STRING
140 type IdCoreRule = (Id,CoreRule) -- Rules don't have their leading Id inside them
144 [CoreBndr] -- Forall'd variables
145 [CoreExpr] -- LHS args
148 | BuiltinRule -- Built-in rules are used for constant folding
149 -- and suchlike. It has no free variables.
150 ([CoreExpr] -> Maybe (RuleName, CoreExpr))
152 isBuiltinRule (BuiltinRule _) = True
153 isBuiltinRule _ = False
157 %************************************************************************
159 \subsection{@Unfolding@ type}
161 %************************************************************************
163 The @Unfolding@ type is declared here to avoid numerous loops, but it
164 should be abstract everywhere except in CoreUnfold.lhs
170 | OtherCon [AltCon] -- It ain't one of these
171 -- (OtherCon xs) also indicates that something has been evaluated
172 -- and hence there's no point in re-evaluating it.
173 -- OtherCon [] is used even for non-data-type values
174 -- to indicated evaluated-ness. Notably:
175 -- data C = C !(Int -> Int)
176 -- case x of { C f -> ... }
177 -- Here, f gets an OtherCon [] unfolding.
179 | CompulsoryUnfolding CoreExpr -- There is no "original" definition,
180 -- so you'd better unfold.
182 | CoreUnfolding -- An unfolding with redundant cached information
183 CoreExpr -- Template; binder-info is correct
184 Bool -- True <=> top level binding
185 Bool -- exprIsValue template (cached); it is ok to discard a `seq` on
187 Bool -- True <=> doesn't waste (much) work to expand inside an inlining
188 -- Basically it's exprIsCheap
189 UnfoldingGuidance -- Tells about the *size* of the template.
192 data UnfoldingGuidance
194 | UnfoldIfGoodArgs Int -- and "n" value args
196 [Int] -- Discount if the argument is evaluated.
197 -- (i.e., a simplification will definitely
198 -- be possible). One elt of the list per *value* arg.
200 Int -- The "size" of the unfolding; to be elaborated
203 Int -- Scrutinee discount: the discount to substract if the thing is in
204 -- a context (case (thing args) of ...),
205 -- (where there are the right number of arguments.)
207 noUnfolding = NoUnfolding
208 mkOtherCon = OtherCon
210 seqUnfolding :: Unfolding -> ()
211 seqUnfolding (CoreUnfolding e top b1 b2 g)
212 = seqExpr e `seq` top `seq` b1 `seq` b2 `seq` seqGuidance g
213 seqUnfolding other = ()
215 seqGuidance (UnfoldIfGoodArgs n ns a b) = n `seq` sum ns `seq` a `seq` b `seq` ()
216 seqGuidance other = ()
220 unfoldingTemplate :: Unfolding -> CoreExpr
221 unfoldingTemplate (CoreUnfolding expr _ _ _ _) = expr
222 unfoldingTemplate (CompulsoryUnfolding expr) = expr
223 unfoldingTemplate other = panic "getUnfoldingTemplate"
225 maybeUnfoldingTemplate :: Unfolding -> Maybe CoreExpr
226 maybeUnfoldingTemplate (CoreUnfolding expr _ _ _ _) = Just expr
227 maybeUnfoldingTemplate (CompulsoryUnfolding expr) = Just expr
228 maybeUnfoldingTemplate other = Nothing
230 otherCons :: Unfolding -> [AltCon]
231 otherCons (OtherCon cons) = cons
234 isValueUnfolding :: Unfolding -> Bool
235 -- Returns False for OtherCon
236 isValueUnfolding (CoreUnfolding _ _ is_evald _ _) = is_evald
237 isValueUnfolding other = False
239 isEvaldUnfolding :: Unfolding -> Bool
240 -- Returns True for OtherCon
241 isEvaldUnfolding (OtherCon _) = True
242 isEvaldUnfolding (CoreUnfolding _ _ is_evald _ _) = is_evald
243 isEvaldUnfolding other = False
245 isCheapUnfolding :: Unfolding -> Bool
246 isCheapUnfolding (CoreUnfolding _ _ _ is_cheap _) = is_cheap
247 isCheapUnfolding other = False
249 isCompulsoryUnfolding :: Unfolding -> Bool
250 isCompulsoryUnfolding (CompulsoryUnfolding _) = True
251 isCompulsoryUnfolding other = False
253 hasUnfolding :: Unfolding -> Bool
254 hasUnfolding (CoreUnfolding _ _ _ _ _) = True
255 hasUnfolding (CompulsoryUnfolding _) = True
256 hasUnfolding other = False
258 hasSomeUnfolding :: Unfolding -> Bool
259 hasSomeUnfolding NoUnfolding = False
260 hasSomeUnfolding other = True
262 neverUnfold :: Unfolding -> Bool
263 neverUnfold NoUnfolding = True
264 neverUnfold (OtherCon _) = True
265 neverUnfold (CoreUnfolding _ _ _ _ UnfoldNever) = True
266 neverUnfold other = False
270 %************************************************************************
272 \subsection{The main data type}
274 %************************************************************************
277 -- The Ord is needed for the FiniteMap used in the lookForConstructor
278 -- in SimplEnv. If you declared that lookForConstructor *ignores*
279 -- constructor-applications with LitArg args, then you could get
282 instance Outputable AltCon where
283 ppr (DataAlt dc) = ppr dc
284 ppr (LitAlt lit) = ppr lit
285 ppr DEFAULT = ptext SLIT("__DEFAULT")
287 instance Show AltCon where
288 showsPrec p con = showsPrecSDoc p (ppr con)
292 %************************************************************************
294 \subsection{Useful synonyms}
296 %************************************************************************
302 type CoreExpr = Expr CoreBndr
303 type CoreArg = Arg CoreBndr
304 type CoreBind = Bind CoreBndr
305 type CoreAlt = Alt CoreBndr
308 Binders are ``tagged'' with a \tr{t}:
311 type Tagged t = (CoreBndr, t)
313 type TaggedBind t = Bind (Tagged t)
314 type TaggedExpr t = Expr (Tagged t)
315 type TaggedArg t = Arg (Tagged t)
316 type TaggedAlt t = Alt (Tagged t)
320 %************************************************************************
322 \subsection{Core-constructing functions with checking}
324 %************************************************************************
327 mkApps :: Expr b -> [Arg b] -> Expr b
328 mkTyApps :: Expr b -> [Type] -> Expr b
329 mkValApps :: Expr b -> [Expr b] -> Expr b
330 mkVarApps :: Expr b -> [Var] -> Expr b
332 mkApps f args = foldl App f args
333 mkTyApps f args = foldl (\ e a -> App e (Type a)) f args
334 mkValApps f args = foldl (\ e a -> App e a) f args
335 mkVarApps f vars = foldl (\ e a -> App e (varToCoreExpr a)) f vars
337 mkLit :: Literal -> Expr b
338 mkIntLit :: Integer -> Expr b
339 mkIntLitInt :: Int -> Expr b
340 mkConApp :: DataCon -> [Arg b] -> Expr b
341 mkLets :: [Bind b] -> Expr b -> Expr b
342 mkLams :: [b] -> Expr b -> Expr b
345 mkConApp con args = mkApps (Var (dataConId con)) args
347 mkLams binders body = foldr Lam body binders
348 mkLets binds body = foldr Let body binds
350 mkIntLit n = Lit (mkMachInt n)
351 mkIntLitInt n = Lit (mkMachInt (toInteger n))
353 varToCoreExpr :: CoreBndr -> Expr b
354 varToCoreExpr v | isId v = Var v
355 | otherwise = Type (mkTyVarTy v)
359 %************************************************************************
361 \subsection{Simple access functions}
363 %************************************************************************
366 bindersOf :: Bind b -> [b]
367 bindersOf (NonRec binder _) = [binder]
368 bindersOf (Rec pairs) = [binder | (binder, _) <- pairs]
370 bindersOfBinds :: [Bind b] -> [b]
371 bindersOfBinds binds = foldr ((++) . bindersOf) [] binds
373 rhssOfBind :: Bind b -> [Expr b]
374 rhssOfBind (NonRec _ rhs) = [rhs]
375 rhssOfBind (Rec pairs) = [rhs | (_,rhs) <- pairs]
377 rhssOfAlts :: [Alt b] -> [Expr b]
378 rhssOfAlts alts = [e | (_,_,e) <- alts]
380 flattenBinds :: [Bind b] -> [(b, Expr b)] -- Get all the lhs/rhs pairs
381 flattenBinds (NonRec b r : binds) = (b,r) : flattenBinds binds
382 flattenBinds (Rec prs1 : binds) = prs1 ++ flattenBinds binds
386 We often want to strip off leading lambdas before getting down to
387 business. @collectBinders@ is your friend.
389 We expect (by convention) type-, and value- lambdas in that
393 collectBinders :: Expr b -> ([b], Expr b)
394 collectBindersIgnoringNotes :: Expr b -> ([b], Expr b)
395 collectTyBinders :: CoreExpr -> ([TyVar], CoreExpr)
396 collectValBinders :: CoreExpr -> ([Id], CoreExpr)
397 collectTyAndValBinders :: CoreExpr -> ([TyVar], [Id], CoreExpr)
402 go bs (Lam b e) = go (b:bs) e
403 go bs e = (reverse bs, e)
405 -- This one ignores notes. It's used in CoreUnfold and StrAnal
406 -- when we aren't going to put the expression back together from
407 -- the pieces, so we don't mind losing the Notes
408 collectBindersIgnoringNotes expr
411 go bs (Lam b e) = go (b:bs) e
412 go bs (Note _ e) = go bs e
413 go bs e = (reverse bs, e)
415 collectTyAndValBinders expr
418 (tvs, body1) = collectTyBinders expr
419 (ids, body) = collectValBinders body1
421 collectTyBinders expr
424 go tvs (Lam b e) | isTyVar b = go (b:tvs) e
425 go tvs e = (reverse tvs, e)
427 collectValBinders expr
430 go ids (Lam b e) | isId b = go (b:ids) e
431 go ids body = (reverse ids, body)
435 @collectArgs@ takes an application expression, returning the function
436 and the arguments to which it is applied.
439 collectArgs :: Expr b -> (Expr b, [Arg b])
443 go (App f a) as = go f (a:as)
447 coreExprCc gets the cost centre enclosing an expression, if any.
448 It looks inside lambdas because (scc "foo" \x.e) = \x.scc "foo" e
451 coreExprCc :: Expr b -> CostCentre
452 coreExprCc (Note (SCC cc) e) = cc
453 coreExprCc (Note other_note e) = coreExprCc e
454 coreExprCc (Lam _ e) = coreExprCc e
455 coreExprCc other = noCostCentre
460 %************************************************************************
462 \subsection{Predicates}
464 %************************************************************************
467 isValArg (Type _) = False
468 isValArg other = True
470 isTypeArg (Type _) = True
471 isTypeArg other = False
473 valBndrCount :: [CoreBndr] -> Int
475 valBndrCount (b : bs) | isId b = 1 + valBndrCount bs
476 | otherwise = valBndrCount bs
478 valArgCount :: [Arg b] -> Int
480 valArgCount (Type _ : args) = valArgCount args
481 valArgCount (other : args) = 1 + valArgCount args
485 %************************************************************************
487 \subsection{Seq stuff}
489 %************************************************************************
492 seqExpr :: CoreExpr -> ()
493 seqExpr (Var v) = v `seq` ()
494 seqExpr (Lit lit) = lit `seq` ()
495 seqExpr (App f a) = seqExpr f `seq` seqExpr a
496 seqExpr (Lam b e) = seqBndr b `seq` seqExpr e
497 seqExpr (Let b e) = seqBind b `seq` seqExpr e
498 seqExpr (Case e b as) = seqExpr e `seq` seqBndr b `seq` seqAlts as
499 seqExpr (Note n e) = seqNote n `seq` seqExpr e
500 seqExpr (Type t) = seqType t
503 seqExprs (e:es) = seqExpr e `seq` seqExprs es
505 seqNote (Coerce t1 t2) = seqType t1 `seq` seqType t2
508 seqBndr b = b `seq` ()
511 seqBndrs (b:bs) = seqBndr b `seq` seqBndrs bs
513 seqBind (NonRec b e) = seqBndr b `seq` seqExpr e
514 seqBind (Rec prs) = seqPairs prs
517 seqPairs ((b,e):prs) = seqBndr b `seq` seqExpr e `seq` seqPairs prs
520 seqAlts ((c,bs,e):alts) = seqBndrs bs `seq` seqExpr e `seq` seqAlts alts
522 seqRules :: CoreRules -> ()
523 seqRules (Rules rules fvs) = seq_rules rules `seq` seqVarSet fvs
526 seq_rules (Rule fs bs es e : rules) = seqBndrs bs `seq` seqExprs (e:es) `seq` seq_rules rules
527 seq_rules (BuiltinRule _ : rules) = seq_rules rules
532 %************************************************************************
534 \subsection{Annotated core; annotation at every node in the tree}
536 %************************************************************************
539 type AnnExpr bndr annot = (annot, AnnExpr' bndr annot)
541 data AnnExpr' bndr annot
544 | AnnLam bndr (AnnExpr bndr annot)
545 | AnnApp (AnnExpr bndr annot) (AnnExpr bndr annot)
546 | AnnCase (AnnExpr bndr annot) bndr [AnnAlt bndr annot]
547 | AnnLet (AnnBind bndr annot) (AnnExpr bndr annot)
548 | AnnNote Note (AnnExpr bndr annot)
551 type AnnAlt bndr annot = (AltCon, [bndr], AnnExpr bndr annot)
553 data AnnBind bndr annot
554 = AnnNonRec bndr (AnnExpr bndr annot)
555 | AnnRec [(bndr, AnnExpr bndr annot)]
559 deAnnotate :: AnnExpr bndr annot -> Expr bndr
560 deAnnotate (_, e) = deAnnotate' e
562 deAnnotate' (AnnType t) = Type t
563 deAnnotate' (AnnVar v) = Var v
564 deAnnotate' (AnnLit lit) = Lit lit
565 deAnnotate' (AnnLam binder body) = Lam binder (deAnnotate body)
566 deAnnotate' (AnnApp fun arg) = App (deAnnotate fun) (deAnnotate arg)
567 deAnnotate' (AnnNote note body) = Note note (deAnnotate body)
569 deAnnotate' (AnnLet bind body)
570 = Let (deAnnBind bind) (deAnnotate body)
572 deAnnBind (AnnNonRec var rhs) = NonRec var (deAnnotate rhs)
573 deAnnBind (AnnRec pairs) = Rec [(v,deAnnotate rhs) | (v,rhs) <- pairs]
575 deAnnotate' (AnnCase scrut v alts)
576 = Case (deAnnotate scrut) v (map deAnnAlt alts)
578 deAnnAlt :: AnnAlt bndr annot -> Alt bndr
579 deAnnAlt (con,args,rhs) = (con,args,deAnnotate rhs)