2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[CoreUtils]{Utility functions on @Core@ syntax}
9 mkNote, mkInlineMe, mkSCC, mkCoerce,
10 bindNonRec, mkIfThenElse, mkAltExpr,
13 -- Taking expressions apart
16 -- Properties of expressions
17 exprType, coreAltsType,
18 exprIsBottom, exprIsDupable, exprIsTrivial, exprIsCheap,
19 exprIsValue,exprOkForSpeculation, exprIsBig,
20 exprIsConApp_maybe, exprIsAtom,
21 idAppIsBottom, idAppIsCheap,
24 -- Expr transformation
26 exprArity, exprEtaExpandArity,
35 cheapEqExpr, eqExpr, applyTypeToArgs
38 #include "HsVersions.h"
41 import GlaExts -- For `xori`
44 import CoreFVs ( exprFreeVars )
45 import PprCore ( pprCoreExpr )
46 import Var ( Var, isId, isTyVar )
49 import Name ( hashName )
50 import Literal ( hashLiteral, literalType, litIsDupable )
51 import DataCon ( DataCon, dataConRepArity )
52 import PrimOp ( primOpOkForSpeculation, primOpIsCheap,
54 import Id ( Id, idType, idFlavour, idStrictness, idLBVarInfo,
55 mkWildId, idArity, idName, idUnfolding, idInfo,
56 isDataConId_maybe, isPrimOpId_maybe, mkSysLocal, hasNoBinding
58 import IdInfo ( LBVarInfo(..),
61 import Demand ( appIsBottom )
62 import Type ( Type, mkFunTy, mkForAllTy, splitFunTy_maybe,
63 applyTys, isUnLiftedType, seqType, mkUTy, mkTyVarTy,
64 splitForAllTy_maybe, splitNewType_maybe
66 import TysWiredIn ( boolTy, trueDataCon, falseDataCon )
67 import CostCentre ( CostCentre )
68 import UniqSupply ( UniqSupply, splitUniqSupply, uniqFromSupply )
69 import Maybes ( maybeToBool )
71 import TysPrim ( alphaTy ) -- Debugging only
75 %************************************************************************
77 \subsection{Find the type of a Core atom/expression}
79 %************************************************************************
82 exprType :: CoreExpr -> Type
84 exprType (Var var) = idType var
85 exprType (Lit lit) = literalType lit
86 exprType (Let _ body) = exprType body
87 exprType (Case _ _ alts) = coreAltsType alts
88 exprType (Note (Coerce ty _) e) = ty -- **! should take usage from e
89 exprType (Note other_note e) = exprType e
90 exprType (Lam binder expr) = mkPiType binder (exprType expr)
92 = case collectArgs e of
93 (fun, args) -> applyTypeToArgs e (exprType fun) args
95 exprType other = pprTrace "exprType" (pprCoreExpr other) alphaTy
97 coreAltsType :: [CoreAlt] -> Type
98 coreAltsType ((_,_,rhs) : _) = exprType rhs
101 @mkPiType@ makes a (->) type or a forall type, depending on whether
102 it is given a type variable or a term variable. We cleverly use the
103 lbvarinfo field to figure out the right annotation for the arrove in
104 case of a term variable.
107 mkPiType :: Var -> Type -> Type -- The more polymorphic version doesn't work...
108 mkPiType v ty | isId v = (case idLBVarInfo v of
109 LBVarInfo u -> mkUTy u
111 mkFunTy (idType v) ty
112 | isTyVar v = mkForAllTy v ty
116 -- The first argument is just for debugging
117 applyTypeToArgs :: CoreExpr -> Type -> [CoreExpr] -> Type
118 applyTypeToArgs e op_ty [] = op_ty
120 applyTypeToArgs e op_ty (Type ty : args)
121 = -- Accumulate type arguments so we can instantiate all at once
122 applyTypeToArgs e (applyTys op_ty tys) rest_args
124 (tys, rest_args) = go [ty] args
125 go tys (Type ty : args) = go (ty:tys) args
126 go tys rest_args = (reverse tys, rest_args)
128 applyTypeToArgs e op_ty (other_arg : args)
129 = case (splitFunTy_maybe op_ty) of
130 Just (_, res_ty) -> applyTypeToArgs e res_ty args
131 Nothing -> pprPanic "applyTypeToArgs" (pprCoreExpr e)
136 %************************************************************************
138 \subsection{Attaching notes}
140 %************************************************************************
142 mkNote removes redundant coercions, and SCCs where possible
145 mkNote :: Note -> CoreExpr -> CoreExpr
146 mkNote (Coerce to_ty from_ty) expr = mkCoerce to_ty from_ty expr
147 mkNote (SCC cc) expr = mkSCC cc expr
148 mkNote InlineMe expr = mkInlineMe expr
149 mkNote note expr = Note note expr
151 -- Slide InlineCall in around the function
152 -- No longer necessary I think (SLPJ Apr 99)
153 -- mkNote InlineCall (App f a) = App (mkNote InlineCall f) a
154 -- mkNote InlineCall (Var v) = Note InlineCall (Var v)
155 -- mkNote InlineCall expr = expr
158 Drop trivial InlineMe's. This is somewhat important, because if we have an unfolding
159 that looks like (Note InlineMe (Var v)), the InlineMe doesn't go away because it may
160 not be *applied* to anything.
162 We don't use exprIsTrivial here, though, because we sometimes generate worker/wrapper
165 f = inline_me (coerce t fw)
166 As usual, the inline_me prevents the worker from getting inlined back into the wrapper.
167 We want the split, so that the coerces can cancel at the call site.
169 However, we can get left with tiresome type applications. Notably, consider
170 f = /\ a -> let t = e in (t, w)
171 Then lifting the let out of the big lambda gives
173 f = /\ a -> let t = inline_me (t' a) in (t, w)
174 The inline_me is to stop the simplifier inlining t' right back
175 into t's RHS. In the next phase we'll substitute for t (since
176 its rhs is trivial) and *then* we could get rid of the inline_me.
177 But it hardly seems worth it, so I don't bother.
180 mkInlineMe (Var v) = Var v
181 mkInlineMe e = Note InlineMe e
187 mkCoerce :: Type -> Type -> CoreExpr -> CoreExpr
189 mkCoerce to_ty from_ty (Note (Coerce to_ty2 from_ty2) expr)
190 = ASSERT( from_ty == to_ty2 )
191 mkCoerce to_ty from_ty2 expr
193 mkCoerce to_ty from_ty expr
194 | to_ty == from_ty = expr
195 | otherwise = ASSERT( from_ty == exprType expr )
196 Note (Coerce to_ty from_ty) expr
200 mkSCC :: CostCentre -> Expr b -> Expr b
201 -- Note: Nested SCC's *are* preserved for the benefit of
202 -- cost centre stack profiling (Durham)
204 mkSCC cc (Lit lit) = Lit lit
205 mkSCC cc (Lam x e) = Lam x (mkSCC cc e) -- Move _scc_ inside lambda
206 mkSCC cc expr = Note (SCC cc) expr
210 %************************************************************************
212 \subsection{Other expression construction}
214 %************************************************************************
217 bindNonRec :: Id -> CoreExpr -> CoreExpr -> CoreExpr
218 -- (bindNonRec x r b) produces either
221 -- case r of x { _DEFAULT_ -> b }
223 -- depending on whether x is unlifted or not
224 -- It's used by the desugarer to avoid building bindings
225 -- that give Core Lint a heart attack. Actually the simplifier
226 -- deals with them perfectly well.
227 bindNonRec bndr rhs body
228 | isUnLiftedType (idType bndr) = Case rhs bndr [(DEFAULT,[],body)]
229 | otherwise = Let (NonRec bndr rhs) body
233 mkAltExpr :: AltCon -> [CoreBndr] -> [Type] -> CoreExpr
234 -- This guy constructs the value that the scrutinee must have
235 -- when you are in one particular branch of a case
236 mkAltExpr (DataAlt con) args inst_tys
237 = mkConApp con (map Type inst_tys ++ map varToCoreExpr args)
238 mkAltExpr (LitAlt lit) [] []
241 mkIfThenElse :: CoreExpr -> CoreExpr -> CoreExpr -> CoreExpr
242 mkIfThenElse guard then_expr else_expr
243 = Case guard (mkWildId boolTy)
244 [ (DataAlt trueDataCon, [], then_expr),
245 (DataAlt falseDataCon, [], else_expr) ]
249 %************************************************************************
251 \subsection{Taking expressions apart}
253 %************************************************************************
257 findDefault :: [CoreAlt] -> ([CoreAlt], Maybe CoreExpr)
258 findDefault [] = ([], Nothing)
259 findDefault ((DEFAULT,args,rhs) : alts) = ASSERT( null alts && null args )
261 findDefault (alt : alts) = case findDefault alts of
262 (alts', deflt) -> (alt : alts', deflt)
264 findAlt :: AltCon -> [CoreAlt] -> CoreAlt
268 go [] = pprPanic "Missing alternative" (ppr con $$ vcat (map ppr alts))
269 go (alt : alts) | matches alt = alt
270 | otherwise = go alts
272 matches (DEFAULT, _, _) = True
273 matches (con1, _, _) = con == con1
277 %************************************************************************
279 \subsection{Figuring out things about expressions}
281 %************************************************************************
283 @exprIsTrivial@ is true of expressions we are unconditionally happy to
284 duplicate; simple variables and constants, and type
285 applications. Note that primop Ids aren't considered
288 @exprIsBottom@ is true of expressions that are guaranteed to diverge
292 exprIsTrivial (Var v)
293 | hasNoBinding v = idArity v == 0
294 -- WAS: | Just op <- isPrimOpId_maybe v = primOpIsDupable op
295 -- The idea here is that a constructor worker, like $wJust, is
296 -- really short for (\x -> $wJust x), becuase $wJust has no binding.
297 -- So it should be treated like a lambda.
298 -- Ditto unsaturated primops.
299 -- This came up when dealing with eta expansion/reduction for
301 -- Here we want to eta-expand. This looks like an optimisation,
302 -- but it's important (albeit tiresome) that CoreSat doesn't increase
305 exprIsTrivial (Type _) = True
306 exprIsTrivial (Lit lit) = True
307 exprIsTrivial (App e arg) = isTypeArg arg && exprIsTrivial e
308 exprIsTrivial (Note _ e) = exprIsTrivial e
309 exprIsTrivial (Lam b body) | isTyVar b = exprIsTrivial body
310 exprIsTrivial other = False
312 exprIsAtom :: CoreExpr -> Bool
313 -- Used to decide whether to let-binding an STG argument
314 -- when compiling to ILX => type applications are not allowed
315 exprIsAtom (Var v) = True -- primOpIsDupable?
316 exprIsAtom (Lit lit) = True
317 exprIsAtom (Type ty) = True
318 exprIsAtom (Note _ e) = exprIsAtom e
319 exprIsAtom other = False
323 @exprIsDupable@ is true of expressions that can be duplicated at a modest
324 cost in code size. This will only happen in different case
325 branches, so there's no issue about duplicating work.
327 That is, exprIsDupable returns True of (f x) even if
328 f is very very expensive to call.
330 Its only purpose is to avoid fruitless let-binding
331 and then inlining of case join points
335 exprIsDupable (Type _) = True
336 exprIsDupable (Var v) = True
337 exprIsDupable (Lit lit) = litIsDupable lit
338 exprIsDupable (Note _ e) = exprIsDupable e
342 go (Var v) n_args = True
343 go (App f a) n_args = n_args < dupAppSize
346 go other n_args = False
349 dupAppSize = 4 -- Size of application we are prepared to duplicate
352 @exprIsCheap@ looks at a Core expression and returns \tr{True} if
353 it is obviously in weak head normal form, or is cheap to get to WHNF.
354 [Note that that's not the same as exprIsDupable; an expression might be
355 big, and hence not dupable, but still cheap.]
357 By ``cheap'' we mean a computation we're willing to:
358 push inside a lambda, or
359 inline at more than one place
360 That might mean it gets evaluated more than once, instead of being
361 shared. The main examples of things which aren't WHNF but are
366 (where e, and all the ei are cheap)
369 (where e and b are cheap)
372 (where op is a cheap primitive operator)
375 (because we are happy to substitute it inside a lambda)
377 Notice that a variable is considered 'cheap': we can push it inside a lambda,
378 because sharing will make sure it is only evaluated once.
381 exprIsCheap :: CoreExpr -> Bool
382 exprIsCheap (Lit lit) = True
383 exprIsCheap (Type _) = True
384 exprIsCheap (Var _) = True
385 exprIsCheap (Note _ e) = exprIsCheap e
386 exprIsCheap (Lam x e) = if isId x then True else exprIsCheap e
387 exprIsCheap (Case e _ alts) = exprIsCheap e &&
388 and [exprIsCheap rhs | (_,_,rhs) <- alts]
389 -- Experimentally, treat (case x of ...) as cheap
390 -- (and case __coerce x etc.)
391 -- This improves arities of overloaded functions where
392 -- there is only dictionary selection (no construction) involved
393 exprIsCheap (Let (NonRec x _) e)
394 | isUnLiftedType (idType x) = exprIsCheap e
396 -- strict lets always have cheap right hand sides, and
399 exprIsCheap other_expr
400 = go other_expr 0 True
402 go (Var f) n_args args_cheap
403 = (idAppIsCheap f n_args && args_cheap)
404 -- A constructor, cheap primop, or partial application
406 || idAppIsBottom f n_args
407 -- Application of a function which
408 -- always gives bottom; we treat this as cheap
409 -- because it certainly doesn't need to be shared!
411 go (App f a) n_args args_cheap
412 | isTypeArg a = go f n_args args_cheap
413 | otherwise = go f (n_args + 1) (exprIsCheap a && args_cheap)
415 go other n_args args_cheap = False
417 idAppIsCheap :: Id -> Int -> Bool
418 idAppIsCheap id n_val_args
419 | n_val_args == 0 = True -- Just a type application of
420 -- a variable (f t1 t2 t3)
422 | otherwise = case idFlavour id of
424 RecordSelId _ -> True -- I'm experimenting with making record selection
425 -- look cheap, so we will substitute it inside a
426 -- lambda. Particularly for dictionary field selection
428 PrimOpId op -> primOpIsCheap op -- In principle we should worry about primops
429 -- that return a type variable, since the result
430 -- might be applied to something, but I'm not going
431 -- to bother to check the number of args
432 other -> n_val_args < idArity id
435 exprOkForSpeculation returns True of an expression that it is
437 * safe to evaluate even if normal order eval might not
438 evaluate the expression at all, or
440 * safe *not* to evaluate even if normal order would do so
444 the expression guarantees to terminate,
446 without raising an exception,
447 without causing a side effect (e.g. writing a mutable variable)
450 let x = case y# +# 1# of { r# -> I# r# }
453 case y# +# 1# of { r# ->
458 We can only do this if the (y+1) is ok for speculation: it has no
459 side effects, and can't diverge or raise an exception.
462 exprOkForSpeculation :: CoreExpr -> Bool
463 exprOkForSpeculation (Lit _) = True
464 exprOkForSpeculation (Var v) = isUnLiftedType (idType v)
465 exprOkForSpeculation (Note _ e) = exprOkForSpeculation e
466 exprOkForSpeculation other_expr
467 = go other_expr 0 True
469 go (Var f) n_args args_ok
470 = case idFlavour f of
471 DataConId _ -> True -- The strictness of the constructor has already
472 -- been expressed by its "wrapper", so we don't need
473 -- to take the arguments into account
475 PrimOpId op -> primOpOkForSpeculation op && args_ok
476 -- A bit conservative: we don't really need
477 -- to care about lazy arguments, but this is easy
481 go (App f a) n_args args_ok
482 | isTypeArg a = go f n_args args_ok
483 | otherwise = go f (n_args + 1) (exprOkForSpeculation a && args_ok)
485 go other n_args args_ok = False
490 exprIsBottom :: CoreExpr -> Bool -- True => definitely bottom
491 exprIsBottom e = go 0 e
493 -- n is the number of args
494 go n (Note _ e) = go n e
495 go n (Let _ e) = go n e
496 go n (Case e _ _) = go 0 e -- Just check the scrut
497 go n (App e _) = go (n+1) e
498 go n (Var v) = idAppIsBottom v n
500 go n (Lam _ _) = False
502 idAppIsBottom :: Id -> Int -> Bool
503 idAppIsBottom id n_val_args = appIsBottom (idStrictness id) n_val_args
506 @exprIsValue@ returns true for expressions that are certainly *already*
507 evaluated to WHNF. This is used to decide wether it's ok to change
508 case x of _ -> e ===> e
510 and to decide whether it's safe to discard a `seq`
512 So, it does *not* treat variables as evaluated, unless they say they are
515 exprIsValue :: CoreExpr -> Bool -- True => Value-lambda, constructor, PAP
516 exprIsValue (Type ty) = True -- Types are honorary Values; we don't mind
518 exprIsValue (Lit l) = True
519 exprIsValue (Lam b e) = isId b || exprIsValue e
520 exprIsValue (Note _ e) = exprIsValue e
521 exprIsValue other_expr
524 go (Var f) n_args = idAppIsValue f n_args
527 | isTypeArg a = go f n_args
528 | otherwise = go f (n_args + 1)
530 go (Note _ f) n_args = go f n_args
532 go other n_args = False
534 idAppIsValue :: Id -> Int -> Bool
535 idAppIsValue id n_val_args
536 = case idFlavour id of
538 PrimOpId _ -> n_val_args < idArity id
539 other | n_val_args == 0 -> isEvaldUnfolding (idUnfolding id)
540 | otherwise -> n_val_args < idArity id
541 -- A worry: what if an Id's unfolding is just itself:
542 -- then we could get an infinite loop...
546 exprIsConApp_maybe :: CoreExpr -> Maybe (DataCon, [CoreExpr])
547 exprIsConApp_maybe expr
548 = analyse (collectArgs expr)
550 analyse (Var fun, args)
551 | maybeToBool maybe_con_app = maybe_con_app
553 maybe_con_app = case isDataConId_maybe fun of
554 Just con | length args >= dataConRepArity con
555 -- Might be > because the arity excludes type args
559 analyse (Var fun, [])
560 = case maybeUnfoldingTemplate (idUnfolding fun) of
562 Just unf -> exprIsConApp_maybe unf
564 analyse other = Nothing
567 The arity of an expression (in the code-generator sense, i.e. the
568 number of lambdas at the beginning).
571 exprArity :: CoreExpr -> Int
573 | isTyVar x = exprArity e
574 | otherwise = 1 + exprArity e
576 -- Ignore coercions. Top level sccs are removed by the final
577 -- profiling pass, so we ignore those too.
583 %************************************************************************
585 \subsection{Eta reduction and expansion}
587 %************************************************************************
589 @etaReduce@ trys an eta reduction at the top level of a Core Expr.
591 e.g. \ x y -> f x y ===> f
593 But we only do this if it gets rid of a whole lambda, not part.
594 The idea is that lambdas are often quite helpful: they indicate
595 head normal forms, so we don't want to chuck them away lightly.
598 etaReduce :: CoreExpr -> CoreExpr
599 -- ToDo: we should really check that we don't turn a non-bottom
600 -- lambda into a bottom variable. Sigh
602 etaReduce expr@(Lam bndr body)
603 = check (reverse binders) body
605 (binders, body) = collectBinders expr
608 | not (any (`elemVarSet` body_fvs) binders)
611 body_fvs = exprFreeVars body
613 check (b : bs) (App fun arg)
614 | (varToCoreExpr b `cheapEqExpr` arg)
617 check _ _ = expr -- Bale out
619 etaReduce expr = expr -- The common case
624 exprEtaExpandArity :: CoreExpr -> (Int, Bool)
625 -- The Int is number of value args the thing can be
626 -- applied to without doing much work
627 -- The Bool is True iff there are enough explicit value lambdas
628 -- at the top to make this arity apparent
629 -- (but ignore it when arity==0)
631 -- This is used when eta expanding
632 -- e ==> \xy -> e x y
634 -- It returns 1 (or more) to:
635 -- case x of p -> \s -> ...
636 -- because for I/O ish things we really want to get that \s to the top.
637 -- We are prepared to evaluate x each time round the loop in order to get that
638 -- Hence "generous" arity
643 go ar (Lam x e) | isId x = go (ar+1) e
644 | otherwise = go ar e
645 go ar (Note n e) | ok_note n = go ar e
646 go ar other = (ar + ar', ar' == 0)
648 ar' = go1 other `max` 0
650 go1 (Var v) = idArity v
651 go1 (Lam x e) | isId x = go1 e + 1
653 go1 (Note n e) | ok_note n = go1 e
654 go1 (App f (Type _)) = go1 f
655 go1 (App f a) | exprIsCheap a = go1 f - 1
656 go1 (Case scrut _ alts)
657 | exprIsCheap scrut = min_zero [go1 rhs | (_,_,rhs) <- alts]
659 | all exprIsCheap (rhssOfBind b) = go1 e
663 ok_note (Coerce _ _) = True
664 ok_note InlineCall = True
665 ok_note other = False
666 -- Notice that we do not look through __inline_me__
667 -- This one is a bit more surprising, but consider
668 -- f = _inline_me (\x -> e)
669 -- We DO NOT want to eta expand this to
670 -- f = \x -> (_inline_me (\x -> e)) x
671 -- because the _inline_me gets dropped now it is applied,
676 min_zero :: [Int] -> Int -- Find the minimum, but zero is the smallest
677 min_zero (x:xs) = go x xs
679 go 0 xs = 0 -- Nothing beats zero
681 go min (x:xs) | x < min = go x xs
682 | otherwise = go min xs
688 etaExpand :: Int -- Add this number of value args
690 -> CoreExpr -> Type -- Expression and its type
692 -- (etaExpand n us e ty) returns an expression with
693 -- the same meaning as 'e', but with arity 'n'.
695 -- Given e' = etaExpand n us e ty
697 -- ty = exprType e = exprType e'
699 -- etaExpand deals with for-alls and coerces. For example:
701 -- where E :: forall a. T
702 -- newtype T = MkT (A -> B)
705 -- (/\b. coerce T (\y::A -> (coerce (A->B) (E b) y)
707 -- (case x of { I# x -> /\ a -> coerce T E)
709 etaExpand n us expr ty
710 | n == 0 -- Saturated, so nothing to do
713 | otherwise -- An unsaturated constructor or primop; eta expand it
714 = case splitForAllTy_maybe ty of {
715 Just (tv,ty') -> Lam tv (etaExpand n us (App expr (Type (mkTyVarTy tv))) ty')
719 case splitFunTy_maybe ty of {
720 Just (arg_ty, res_ty) -> Lam arg1 (etaExpand (n-1) us2 (App expr (Var arg1)) res_ty)
722 arg1 = mkSysLocal SLIT("eta") uniq arg_ty
723 (us1, us2) = splitUniqSupply us
724 uniq = uniqFromSupply us1
728 case splitNewType_maybe ty of {
729 Just ty' -> mkCoerce ty ty' (etaExpand n us (mkCoerce ty' ty expr) ty') ;
731 Nothing -> pprTrace "Bad eta expand" (ppr expr $$ ppr ty) expr
736 %************************************************************************
738 \subsection{Equality}
740 %************************************************************************
742 @cheapEqExpr@ is a cheap equality test which bales out fast!
743 True => definitely equal
744 False => may or may not be equal
747 cheapEqExpr :: Expr b -> Expr b -> Bool
749 cheapEqExpr (Var v1) (Var v2) = v1==v2
750 cheapEqExpr (Lit lit1) (Lit lit2) = lit1 == lit2
751 cheapEqExpr (Type t1) (Type t2) = t1 == t2
753 cheapEqExpr (App f1 a1) (App f2 a2)
754 = f1 `cheapEqExpr` f2 && a1 `cheapEqExpr` a2
756 cheapEqExpr _ _ = False
758 exprIsBig :: Expr b -> Bool
759 -- Returns True of expressions that are too big to be compared by cheapEqExpr
760 exprIsBig (Lit _) = False
761 exprIsBig (Var v) = False
762 exprIsBig (Type t) = False
763 exprIsBig (App f a) = exprIsBig f || exprIsBig a
764 exprIsBig other = True
769 eqExpr :: CoreExpr -> CoreExpr -> Bool
770 -- Works ok at more general type, but only needed at CoreExpr
772 = eq emptyVarEnv e1 e2
774 -- The "env" maps variables in e1 to variables in ty2
775 -- So when comparing lambdas etc,
776 -- we in effect substitute v2 for v1 in e1 before continuing
777 eq env (Var v1) (Var v2) = case lookupVarEnv env v1 of
778 Just v1' -> v1' == v2
781 eq env (Lit lit1) (Lit lit2) = lit1 == lit2
782 eq env (App f1 a1) (App f2 a2) = eq env f1 f2 && eq env a1 a2
783 eq env (Lam v1 e1) (Lam v2 e2) = eq (extendVarEnv env v1 v2) e1 e2
784 eq env (Let (NonRec v1 r1) e1)
785 (Let (NonRec v2 r2) e2) = eq env r1 r2 && eq (extendVarEnv env v1 v2) e1 e2
786 eq env (Let (Rec ps1) e1)
787 (Let (Rec ps2) e2) = length ps1 == length ps2 &&
788 and (zipWith eq_rhs ps1 ps2) &&
791 env' = extendVarEnvList env [(v1,v2) | ((v1,_),(v2,_)) <- zip ps1 ps2]
792 eq_rhs (_,r1) (_,r2) = eq env' r1 r2
793 eq env (Case e1 v1 a1)
794 (Case e2 v2 a2) = eq env e1 e2 &&
795 length a1 == length a2 &&
796 and (zipWith (eq_alt env') a1 a2)
798 env' = extendVarEnv env v1 v2
800 eq env (Note n1 e1) (Note n2 e2) = eq_note env n1 n2 && eq env e1 e2
801 eq env (Type t1) (Type t2) = t1 == t2
804 eq_list env [] [] = True
805 eq_list env (e1:es1) (e2:es2) = eq env e1 e2 && eq_list env es1 es2
806 eq_list env es1 es2 = False
808 eq_alt env (c1,vs1,r1) (c2,vs2,r2) = c1==c2 &&
809 eq (extendVarEnvList env (vs1 `zip` vs2)) r1 r2
811 eq_note env (SCC cc1) (SCC cc2) = cc1 == cc2
812 eq_note env (Coerce t1 f1) (Coerce t2 f2) = t1==t2 && f1==f2
813 eq_note env InlineCall InlineCall = True
814 eq_note env other1 other2 = False
818 %************************************************************************
820 \subsection{The size of an expression}
822 %************************************************************************
825 coreBindsSize :: [CoreBind] -> Int
826 coreBindsSize bs = foldr ((+) . bindSize) 0 bs
828 exprSize :: CoreExpr -> Int
829 -- A measure of the size of the expressions
830 -- It also forces the expression pretty drastically as a side effect
831 exprSize (Var v) = varSize v
832 exprSize (Lit lit) = lit `seq` 1
833 exprSize (App f a) = exprSize f + exprSize a
834 exprSize (Lam b e) = varSize b + exprSize e
835 exprSize (Let b e) = bindSize b + exprSize e
836 exprSize (Case e b as) = exprSize e + varSize b + foldr ((+) . altSize) 0 as
837 exprSize (Note n e) = noteSize n + exprSize e
838 exprSize (Type t) = seqType t `seq` 1
840 noteSize (SCC cc) = cc `seq` 1
841 noteSize (Coerce t1 t2) = seqType t1 `seq` seqType t2 `seq` 1
842 noteSize InlineCall = 1
843 noteSize InlineMe = 1
845 varSize :: Var -> Int
846 varSize b | isTyVar b = 1
847 | otherwise = seqType (idType b) `seq`
848 megaSeqIdInfo (idInfo b) `seq`
851 varsSize = foldr ((+) . varSize) 0
853 bindSize (NonRec b e) = varSize b + exprSize e
854 bindSize (Rec prs) = foldr ((+) . pairSize) 0 prs
856 pairSize (b,e) = varSize b + exprSize e
858 altSize (c,bs,e) = c `seq` varsSize bs + exprSize e
862 %************************************************************************
866 %************************************************************************
869 hashExpr :: CoreExpr -> Int
870 hashExpr e | hash < 0 = 77 -- Just in case we hit -maxInt
873 hash = abs (hash_expr e) -- Negative numbers kill UniqFM
875 hash_expr (Note _ e) = hash_expr e
876 hash_expr (Let (NonRec b r) e) = hashId b
877 hash_expr (Let (Rec ((b,r):_)) e) = hashId b
878 hash_expr (Case _ b _) = hashId b
879 hash_expr (App f e) = hash_expr f * fast_hash_expr e
880 hash_expr (Var v) = hashId v
881 hash_expr (Lit lit) = hashLiteral lit
882 hash_expr (Lam b _) = hashId b
883 hash_expr (Type t) = trace "hash_expr: type" 1 -- Shouldn't happen
885 fast_hash_expr (Var v) = hashId v
886 fast_hash_expr (Lit lit) = hashLiteral lit
887 fast_hash_expr (App f (Type _)) = fast_hash_expr f
888 fast_hash_expr (App f a) = fast_hash_expr a
889 fast_hash_expr (Lam b _) = hashId b
890 fast_hash_expr other = 1
893 hashId id = hashName (idName id)