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, deAnnotate, deAnnotate',
41 CoreRules(..), -- Representation needed by friends
42 CoreRule(..), -- CoreSubst, CoreTidy, CoreFVs, PprCore only
45 emptyCoreRules, isEmptyCoreRules, rulesRhsFreeVars, rulesRules,
49 #include "HsVersions.h"
51 import CostCentre ( CostCentre, noCostCentre )
52 import Var ( Var, Id, TyVar, isTyVar, isId )
53 import Type ( Type, mkTyVarTy, seqType )
54 import Literal ( Literal, mkMachInt )
55 import DataCon ( DataCon, dataConId )
60 %************************************************************************
62 \subsection{The main data types}
64 %************************************************************************
66 These data types are the heart of the compiler
69 infixl 8 `App` -- App brackets to the left
71 data Expr b -- "b" for the type of binders,
74 | App (Expr b) (Arg b)
76 | Let (Bind b) (Expr b)
77 | Case (Expr b) b [Alt b] -- Binder gets bound to value of scrutinee
78 -- DEFAULT case must be last, if it occurs at all
80 | Type Type -- This should only show up at the top
83 type Arg b = Expr b -- Can be a Type
85 type Alt b = (AltCon, [b], Expr b) -- (DEFAULT, [], rhs) is the default alternative
87 data AltCon = DataAlt DataCon
92 data Bind b = NonRec b (Expr b)
99 Type -- The to-type: type of whole coerce expression
100 Type -- The from-type: type of enclosed expression
102 | InlineCall -- Instructs simplifier to inline
105 | InlineMe -- Instructs simplifer to treat the enclosed expression
106 -- as very small, and inline it at its call sites
110 %************************************************************************
112 \subsection{Transformation rules}
114 %************************************************************************
116 The CoreRule type and its friends are dealt with mainly in CoreRules,
117 but CoreFVs, Subst, PprCore, CoreTidy also inspect the representation.
122 VarSet -- Locally-defined free vars of RHSs
124 emptyCoreRules :: CoreRules
125 emptyCoreRules = Rules [] emptyVarSet
127 isEmptyCoreRules :: CoreRules -> Bool
128 isEmptyCoreRules (Rules rs _) = null rs
130 rulesRhsFreeVars :: CoreRules -> VarSet
131 rulesRhsFreeVars (Rules _ fvs) = fvs
133 rulesRules :: CoreRules -> [CoreRule]
134 rulesRules (Rules rules _) = rules
138 type RuleName = FAST_STRING
139 type IdCoreRule = (Id,CoreRule) -- Rules don't have their leading Id inside them
143 [CoreBndr] -- Forall'd variables
144 [CoreExpr] -- LHS args
147 | BuiltinRule -- Built-in rules are used for constant folding
148 -- and suchlike. It has no free variables.
149 ([CoreExpr] -> Maybe (RuleName, CoreExpr))
151 isBuiltinRule (BuiltinRule _) = True
152 isBuiltinRule _ = False
156 %************************************************************************
158 \subsection{@Unfolding@ type}
160 %************************************************************************
162 The @Unfolding@ type is declared here to avoid numerous loops, but it
163 should be abstract everywhere except in CoreUnfold.lhs
169 | OtherCon [AltCon] -- It ain't one of these
170 -- (OtherCon xs) also indicates that something has been evaluated
171 -- and hence there's no point in re-evaluating it.
172 -- OtherCon [] is used even for non-data-type values
173 -- to indicated evaluated-ness. Notably:
174 -- data C = C !(Int -> Int)
175 -- case x of { C f -> ... }
176 -- Here, f gets an OtherCon [] unfolding.
178 | CompulsoryUnfolding CoreExpr -- There is no "original" definition,
179 -- so you'd better unfold.
181 | CoreUnfolding -- An unfolding with redundant cached information
182 CoreExpr -- Template; binder-info is correct
183 Bool -- True <=> top level binding
184 Bool -- exprIsValue template (cached); it is ok to discard a `seq` on
186 Bool -- True <=> doesn't waste (much) work to expand inside an inlining
187 -- Basically it's exprIsCheap
188 UnfoldingGuidance -- Tells about the *size* of the template.
191 data UnfoldingGuidance
193 | UnfoldIfGoodArgs Int -- and "n" value args
195 [Int] -- Discount if the argument is evaluated.
196 -- (i.e., a simplification will definitely
197 -- be possible). One elt of the list per *value* arg.
199 Int -- The "size" of the unfolding; to be elaborated
202 Int -- Scrutinee discount: the discount to substract if the thing is in
203 -- a context (case (thing args) of ...),
204 -- (where there are the right number of arguments.)
206 noUnfolding = NoUnfolding
207 mkOtherCon = OtherCon
209 seqUnfolding :: Unfolding -> ()
210 seqUnfolding (CoreUnfolding e top b1 b2 g)
211 = seqExpr e `seq` top `seq` b1 `seq` b2 `seq` seqGuidance g
212 seqUnfolding other = ()
214 seqGuidance (UnfoldIfGoodArgs n ns a b) = n `seq` sum ns `seq` a `seq` b `seq` ()
215 seqGuidance other = ()
219 unfoldingTemplate :: Unfolding -> CoreExpr
220 unfoldingTemplate (CoreUnfolding expr _ _ _ _) = expr
221 unfoldingTemplate (CompulsoryUnfolding expr) = expr
222 unfoldingTemplate other = panic "getUnfoldingTemplate"
224 maybeUnfoldingTemplate :: Unfolding -> Maybe CoreExpr
225 maybeUnfoldingTemplate (CoreUnfolding expr _ _ _ _) = Just expr
226 maybeUnfoldingTemplate (CompulsoryUnfolding expr) = Just expr
227 maybeUnfoldingTemplate other = Nothing
229 otherCons :: Unfolding -> [AltCon]
230 otherCons (OtherCon cons) = cons
233 isValueUnfolding :: Unfolding -> Bool
234 -- Returns False for OtherCon
235 isValueUnfolding (CoreUnfolding _ _ is_evald _ _) = is_evald
236 isValueUnfolding other = False
238 isEvaldUnfolding :: Unfolding -> Bool
239 -- Returns True for OtherCon
240 isEvaldUnfolding (OtherCon _) = True
241 isEvaldUnfolding (CoreUnfolding _ _ is_evald _ _) = is_evald
242 isEvaldUnfolding other = False
244 isCheapUnfolding :: Unfolding -> Bool
245 isCheapUnfolding (CoreUnfolding _ _ _ is_cheap _) = is_cheap
246 isCheapUnfolding other = False
248 isCompulsoryUnfolding :: Unfolding -> Bool
249 isCompulsoryUnfolding (CompulsoryUnfolding _) = True
250 isCompulsoryUnfolding other = False
252 hasUnfolding :: Unfolding -> Bool
253 hasUnfolding (CoreUnfolding _ _ _ _ _) = True
254 hasUnfolding (CompulsoryUnfolding _) = True
255 hasUnfolding other = False
257 hasSomeUnfolding :: Unfolding -> Bool
258 hasSomeUnfolding NoUnfolding = False
259 hasSomeUnfolding other = True
261 neverUnfold :: Unfolding -> Bool
262 neverUnfold NoUnfolding = True
263 neverUnfold (OtherCon _) = True
264 neverUnfold (CoreUnfolding _ _ _ _ UnfoldNever) = True
265 neverUnfold other = False
269 %************************************************************************
271 \subsection{The main data type}
273 %************************************************************************
276 -- The Ord is needed for the FiniteMap used in the lookForConstructor
277 -- in SimplEnv. If you declared that lookForConstructor *ignores*
278 -- constructor-applications with LitArg args, then you could get
281 instance Outputable AltCon where
282 ppr (DataAlt dc) = ppr dc
283 ppr (LitAlt lit) = ppr lit
284 ppr DEFAULT = ptext SLIT("__DEFAULT")
286 instance Show AltCon where
287 showsPrec p con = showsPrecSDoc p (ppr con)
291 %************************************************************************
293 \subsection{Useful synonyms}
295 %************************************************************************
301 type CoreExpr = Expr CoreBndr
302 type CoreArg = Arg CoreBndr
303 type CoreBind = Bind CoreBndr
304 type CoreAlt = Alt CoreBndr
307 Binders are ``tagged'' with a \tr{t}:
310 type Tagged t = (CoreBndr, t)
312 type TaggedBind t = Bind (Tagged t)
313 type TaggedExpr t = Expr (Tagged t)
314 type TaggedArg t = Arg (Tagged t)
315 type TaggedAlt t = Alt (Tagged t)
319 %************************************************************************
321 \subsection{Core-constructing functions with checking}
323 %************************************************************************
326 mkApps :: Expr b -> [Arg b] -> Expr b
327 mkTyApps :: Expr b -> [Type] -> Expr b
328 mkValApps :: Expr b -> [Expr b] -> Expr b
329 mkVarApps :: Expr b -> [Var] -> Expr b
331 mkApps f args = foldl App f args
332 mkTyApps f args = foldl (\ e a -> App e (Type a)) f args
333 mkValApps f args = foldl (\ e a -> App e a) f args
334 mkVarApps f vars = foldl (\ e a -> App e (varToCoreExpr a)) f vars
336 mkLit :: Literal -> Expr b
337 mkIntLit :: Integer -> Expr b
338 mkIntLitInt :: Int -> Expr b
339 mkConApp :: DataCon -> [Arg b] -> Expr b
340 mkLets :: [Bind b] -> Expr b -> Expr b
341 mkLams :: [b] -> Expr b -> Expr b
344 mkConApp con args = mkApps (Var (dataConId con)) args
346 mkLams binders body = foldr Lam body binders
347 mkLets binds body = foldr Let body binds
349 mkIntLit n = Lit (mkMachInt n)
350 mkIntLitInt n = Lit (mkMachInt (toInteger n))
352 varToCoreExpr :: CoreBndr -> Expr b
353 varToCoreExpr v | isId v = Var v
354 | otherwise = Type (mkTyVarTy v)
358 %************************************************************************
360 \subsection{Simple access functions}
362 %************************************************************************
365 bindersOf :: Bind b -> [b]
366 bindersOf (NonRec binder _) = [binder]
367 bindersOf (Rec pairs) = [binder | (binder, _) <- pairs]
369 bindersOfBinds :: [Bind b] -> [b]
370 bindersOfBinds binds = foldr ((++) . bindersOf) [] binds
372 rhssOfBind :: Bind b -> [Expr b]
373 rhssOfBind (NonRec _ rhs) = [rhs]
374 rhssOfBind (Rec pairs) = [rhs | (_,rhs) <- pairs]
376 rhssOfAlts :: [Alt b] -> [Expr b]
377 rhssOfAlts alts = [e | (_,_,e) <- alts]
379 flattenBinds :: [Bind b] -> [(b, Expr b)] -- Get all the lhs/rhs pairs
380 flattenBinds (NonRec b r : binds) = (b,r) : flattenBinds binds
381 flattenBinds (Rec prs1 : binds) = prs1 ++ flattenBinds binds
385 We often want to strip off leading lambdas before getting down to
386 business. @collectBinders@ is your friend.
388 We expect (by convention) type-, and value- lambdas in that
392 collectBinders :: Expr b -> ([b], Expr b)
393 collectBindersIgnoringNotes :: Expr b -> ([b], Expr b)
394 collectTyBinders :: CoreExpr -> ([TyVar], CoreExpr)
395 collectValBinders :: CoreExpr -> ([Id], CoreExpr)
396 collectTyAndValBinders :: CoreExpr -> ([TyVar], [Id], CoreExpr)
401 go bs (Lam b e) = go (b:bs) e
402 go bs e = (reverse bs, e)
404 -- This one ignores notes. It's used in CoreUnfold and StrAnal
405 -- when we aren't going to put the expression back together from
406 -- the pieces, so we don't mind losing the Notes
407 collectBindersIgnoringNotes expr
410 go bs (Lam b e) = go (b:bs) e
411 go bs (Note _ e) = go bs e
412 go bs e = (reverse bs, e)
414 collectTyAndValBinders expr
417 (tvs, body1) = collectTyBinders expr
418 (ids, body) = collectValBinders body1
420 collectTyBinders expr
423 go tvs (Lam b e) | isTyVar b = go (b:tvs) e
424 go tvs e = (reverse tvs, e)
426 collectValBinders expr
429 go ids (Lam b e) | isId b = go (b:ids) e
430 go ids body = (reverse ids, body)
434 @collectArgs@ takes an application expression, returning the function
435 and the arguments to which it is applied.
438 collectArgs :: Expr b -> (Expr b, [Arg b])
442 go (App f a) as = go f (a:as)
446 coreExprCc gets the cost centre enclosing an expression, if any.
447 It looks inside lambdas because (scc "foo" \x.e) = \x.scc "foo" e
450 coreExprCc :: Expr b -> CostCentre
451 coreExprCc (Note (SCC cc) e) = cc
452 coreExprCc (Note other_note e) = coreExprCc e
453 coreExprCc (Lam _ e) = coreExprCc e
454 coreExprCc other = noCostCentre
458 %************************************************************************
460 \subsection{Predicates}
462 %************************************************************************
465 isValArg (Type _) = False
466 isValArg other = True
468 isTypeArg (Type _) = True
469 isTypeArg other = False
471 valBndrCount :: [CoreBndr] -> Int
473 valBndrCount (b : bs) | isId b = 1 + valBndrCount bs
474 | otherwise = valBndrCount bs
476 valArgCount :: [Arg b] -> Int
478 valArgCount (Type _ : args) = valArgCount args
479 valArgCount (other : args) = 1 + valArgCount args
483 %************************************************************************
485 \subsection{Seq stuff}
487 %************************************************************************
490 seqExpr :: CoreExpr -> ()
491 seqExpr (Var v) = v `seq` ()
492 seqExpr (Lit lit) = lit `seq` ()
493 seqExpr (App f a) = seqExpr f `seq` seqExpr a
494 seqExpr (Lam b e) = seqBndr b `seq` seqExpr e
495 seqExpr (Let b e) = seqBind b `seq` seqExpr e
496 seqExpr (Case e b as) = seqExpr e `seq` seqBndr b `seq` seqAlts as
497 seqExpr (Note n e) = seqNote n `seq` seqExpr e
498 seqExpr (Type t) = seqType t
501 seqExprs (e:es) = seqExpr e `seq` seqExprs es
503 seqNote (Coerce t1 t2) = seqType t1 `seq` seqType t2
506 seqBndr b = b `seq` ()
509 seqBndrs (b:bs) = seqBndr b `seq` seqBndrs bs
511 seqBind (NonRec b e) = seqBndr b `seq` seqExpr e
512 seqBind (Rec prs) = seqPairs prs
515 seqPairs ((b,e):prs) = seqBndr b `seq` seqExpr e `seq` seqPairs prs
518 seqAlts ((c,bs,e):alts) = seqBndrs bs `seq` seqExpr e `seq` seqAlts alts
520 seqRules :: CoreRules -> ()
521 seqRules (Rules rules fvs) = seq_rules rules `seq` seqVarSet fvs
524 seq_rules (Rule fs bs es e : rules) = seqBndrs bs `seq` seqExprs (e:es) `seq` seq_rules rules
525 seq_rules (BuiltinRule _ : rules) = seq_rules rules
530 %************************************************************************
532 \subsection{Annotated core; annotation at every node in the tree}
534 %************************************************************************
537 type AnnExpr bndr annot = (annot, AnnExpr' bndr annot)
539 data AnnExpr' bndr annot
542 | AnnLam bndr (AnnExpr bndr annot)
543 | AnnApp (AnnExpr bndr annot) (AnnExpr bndr annot)
544 | AnnCase (AnnExpr bndr annot) bndr [AnnAlt bndr annot]
545 | AnnLet (AnnBind bndr annot) (AnnExpr bndr annot)
546 | AnnNote Note (AnnExpr bndr annot)
549 type AnnAlt bndr annot = (AltCon, [bndr], AnnExpr bndr annot)
551 data AnnBind bndr annot
552 = AnnNonRec bndr (AnnExpr bndr annot)
553 | AnnRec [(bndr, AnnExpr bndr annot)]
557 deAnnotate :: AnnExpr bndr annot -> Expr bndr
558 deAnnotate (_, e) = deAnnotate' e
560 deAnnotate' (AnnType t) = Type t
561 deAnnotate' (AnnVar v) = Var v
562 deAnnotate' (AnnLit lit) = Lit lit
563 deAnnotate' (AnnLam binder body) = Lam binder (deAnnotate body)
564 deAnnotate' (AnnApp fun arg) = App (deAnnotate fun) (deAnnotate arg)
565 deAnnotate' (AnnNote note body) = Note note (deAnnotate body)
567 deAnnotate' (AnnLet bind body)
568 = Let (deAnnBind bind) (deAnnotate body)
570 deAnnBind (AnnNonRec var rhs) = NonRec var (deAnnotate rhs)
571 deAnnBind (AnnRec pairs) = Rec [(v,deAnnotate rhs) | (v,rhs) <- pairs]
573 deAnnotate' (AnnCase scrut v alts)
574 = Case (deAnnotate scrut) v (map deAnnAlt alts)
576 deAnnAlt (con,args,rhs) = (con,args,deAnnotate rhs)