X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FsimplCore%2FSimplUtils.lhs;h=a92ae3fac5fbd9b87545177b69dfd71a36e7805b;hb=9015d17020a8620c3fe15de4eab68573b07e7793;hp=e0ac4aac258b4f69c8c93a3cc36e29e35485ca42;hpb=e7d21ee4f8ac907665a7e170c71d59e13a01da09;p=ghc-hetmet.git diff --git a/ghc/compiler/simplCore/SimplUtils.lhs b/ghc/compiler/simplCore/SimplUtils.lhs index e0ac4aa..a92ae3f 100644 --- a/ghc/compiler/simplCore/SimplUtils.lhs +++ b/ghc/compiler/simplCore/SimplUtils.lhs @@ -1,5 +1,5 @@ % -% (c) The AQUA Project, Glasgow University, 1993-1995 +% (c) The AQUA Project, Glasgow University, 1993-1996 % \section[SimplUtils]{The simplifier utilities} @@ -9,47 +9,43 @@ module SimplUtils ( floatExposesHNF, - - mkCoTyLamTryingEta, mkCoLamTryingEta, + + etaCoreExpr, mkRhsTyLam, etaExpandCount, - + mkIdentityAlts, simplIdWantsToBeINLINEd, - type_ok_for_let_to_case + singleConstructorType, typeOkForCase ) where -IMPORT_Trace -- ToDo: rm (debugging) -import Pretty - -import TaggedCore -import PlainCore -import SimplEnv -import SimplMonad +IMP_Ubiq(){-uitous-} +IMPORT_DELOOPER(SmplLoop) -- paranoia checking import BinderInfo - -import AbsPrel ( primOpIsCheap, realWorldStateTy, buildId - IF_ATTACK_PRAGMAS(COMMA realWorldTy) - IF_ATTACK_PRAGMAS(COMMA tagOf_PrimOp) - IF_ATTACK_PRAGMAS(COMMA pprPrimOp) +import CmdLineOpts ( opt_DoEtaReduction, SimplifierSwitch(..) ) +import CoreSyn +import CoreUnfold ( SimpleUnfolding, mkFormSummary, exprIsTrivial, FormSummary(..) ) +import Id ( idType, isBottomingId, addInlinePragma, addIdDemandInfo, + idWantsToBeINLINEd, dataConArgTys, SYN_IE(Id), + getIdArity, GenId{-instance Eq-} ) -import AbsUniType ( extractTyVarsFromTy, getTyVarMaybe, isPrimType, - splitTypeWithDictsAsArgs, getUniDataTyCon_maybe, - applyTy, isFunType, TyVar, TyVarTemplate - IF_ATTACK_PRAGMAS(COMMA cmpTyVar COMMA cmpClass) - ) -import Id ( getInstantiatedDataConSig, isDataCon, getIdUniType, - getIdArity, isBottomingId, idWantsToBeINLINEd, - DataCon(..), Id +import IdInfo ( ArityInfo(..), DemandInfo ) +import Maybes ( maybeToBool ) +import PrelVals ( augmentId, buildId ) +import PrimOp ( primOpIsCheap ) +import SimplEnv +import SimplMonad +import Type ( tyVarsOfType, mkForAllTys, mkTyVarTys, isPrimType, + maybeAppDataTyConExpandingDicts, SYN_IE(Type) ) -import IdInfo -import CmdLineOpts ( SimplifierSwitch(..) ) -import Maybes ( maybeToBool, Maybe(..) ) -import Outputable -- isExported ... -import Util +import TysWiredIn ( realWorldStateTy ) +import TyVar ( elementOfTyVarSet, + GenTyVar{-instance Eq-} ) +import Util ( isIn, panic ) + \end{code} @@ -64,25 +60,31 @@ floatExposesHNF :: Bool -- Float let(rec)s out of rhs -> Bool -- Float cheap primops out of rhs -> Bool -- OK to duplicate code - -> CoreExpr bdr Id + -> GenCoreExpr bdr Id tyvar uvar -> Bool floatExposesHNF float_lets float_primops ok_to_dup rhs = try rhs where - try (CoCase (CoPrim _ _ _) (CoPrimAlts alts deflt) ) + try (Case (Prim _ _) (PrimAlts alts deflt) ) | float_primops && (null alts || ok_to_dup) = or (try_deflt deflt : map try_alt alts) - try (CoLet bind body) | float_lets = try body + try (Let bind body) | float_lets = try body -- `build g' -- is like a HNF, -- because it *will* become one. - try (CoApp (CoTyApp (CoVar bld) _) _) | bld == buildId = True + -- likewise for `augment g h' + -- + try (App (App (Var bld) _) _) | bld == buildId = True + try (App (App (App (Var aug) _) _) _) | aug == augmentId = True - try other = manifestlyWHNF other - {- but *not* necessarily "manifestlyBottom other"... + try other = case mkFormSummary other of + VarForm -> True + ValueForm -> True + other -> False + {- but *not* necessarily "BottomForm"... We may want to float a let out of a let to expose WHNFs, but to do that to expose a "bottom" is a Bad Idea: @@ -98,21 +100,119 @@ floatExposesHNF float_lets float_primops ok_to_dup rhs to allocate it eagerly as that's a waste. -} - try_alt (lit,rhs) = try rhs + try_alt (lit,rhs) = try rhs - try_deflt CoNoDefault = False - try_deflt (CoBindDefault _ rhs) = try rhs + try_deflt NoDefault = False + try_deflt (BindDefault _ rhs) = try rhs \end{code} -Eta reduction on ordinary lambdas -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -We have a go at doing +Local tyvar-lifting +~~~~~~~~~~~~~~~~~~~ +mkRhsTyLam tries this transformation, when the big lambda appears as +the RHS of a let(rec) binding: + + /\abc -> let(rec) x = e in b + ==> + let(rec) x' = /\abc -> let x = x' a b c in e + in + /\abc -> let x = x' a b c in b + +This is good because it can turn things like: + + let f = /\a -> letrec g = ... g ... in g +into + letrec g' = /\a -> ... g' a ... + in + let f = /\ a -> f a + +which is better. In effect, it means that big lambdas don't impede +let-floating. - \ x y -> f x y ===> f +This optimisation is CRUCIAL in eliminating the junk introduced by +desugaring mutually recursive definitions. Don't eliminate it lightly! + +So far as the implemtation is concerned: + + Invariant: go F e = /\tvs -> F e + + Equalities: + go F (Let x=e in b) + = Let x' = /\tvs -> F e + in + go G b + where + G = F . Let x = x' tvs + + go F (Letrec xi=ei in b) + = Letrec {xi' = /\tvs -> G ei} + in + go G b + where + G = F . Let {xi = xi' tvs} + +\begin{code} +mkRhsTyLam [] body = returnSmpl body + +mkRhsTyLam tyvars body + = go (\x -> x) body + where + tyvar_tys = mkTyVarTys tyvars + + go fn (Let bind@(NonRec var rhs) body) | exprIsTrivial rhs + = go (fn . Let bind) body + + go fn (Let bind@(NonRec var rhs) body) + = mk_poly var `thenSmpl` \ (var', rhs') -> + go (fn . Let (mk_silly_bind var rhs')) body `thenSmpl` \ body' -> + returnSmpl (Let (NonRec var' (mkTyLam tyvars (fn rhs))) body') + + go fn (Let (Rec prs) body) + = mapAndUnzipSmpl mk_poly vars `thenSmpl` \ (vars', rhss') -> + let + gn body = fn $ foldr Let body (zipWith mk_silly_bind vars rhss') + in + go gn body `thenSmpl` \ body' -> + returnSmpl (Let (Rec (vars' `zip` [mkTyLam tyvars (gn rhs) | rhs <- rhss])) body') + where + (vars,rhss) = unzip prs + + go fn body = returnSmpl (mkTyLam tyvars (fn body)) + + mk_poly var + = newId (mkForAllTys tyvars (idType var)) `thenSmpl` \ poly_id -> + returnSmpl (poly_id, mkTyApp (Var poly_id) tyvar_tys) + + mk_silly_bind var rhs = NonRec (addInlinePragma var) rhs + -- The addInlinePragma is really important! If we don't say + -- INLINE on these silly little bindings then look what happens! + -- Suppose we start with: + -- + -- x = let g = /\a -> \x -> f x x + -- in + -- /\ b -> let g* = g b in E + -- + -- Then: * the binding for g gets floated out + -- * but then it gets inlined into the rhs of g* + -- * then the binding for g* is floated out of the /\b + -- * so we're back to square one + -- The silly binding for g* must be INLINE, so that no inlining + -- will happen in its RHS. +\end{code} + +Eta reduction +~~~~~~~~~~~~~ +@etaCoreExpr@ trys an eta reduction at the top level of a Core Expr. + +e.g. \ x y -> f x y ===> f + +It is used + a) Before constructing an Unfolding, to + try to make the unfolding smaller; + b) In tidyCoreExpr, which is done just before converting to STG. But we only do this if it gets rid of a whole lambda, not part. -The idea is that lambdas are often quite helpful: they indicate +The idea is that lambdas are often quite helpful: they indicate head normal forms, so we don't want to chuck them away lightly. But if they expose a simple variable then we definitely win. Even if they expose a type application we win. So we check for this special @@ -125,41 +225,75 @@ It does arise: gives rise to a recursive function for the list comprehension, and f turns out to be just a single call to this recursive function. +Doing eta on type lambdas is useful too: + + /\a -> a ===> + +where doesn't mention a. +This is sometimes quite useful, because we can get the sequence: + + f ab d = let d1 = ...d... in + letrec f' b x = ...d...(f' b)... in + f' b +specialise ==> + + f.Int b = letrec f' b x = ...dInt...(f' b)... in + f' b + +float ==> + + f' b x = ...dInt...(f' b)... + f.Int b = f' b + +Now we really want to simplify to + + f.Int = f' + +and then replace all the f's with f.Ints. + +N.B. We are careful not to partially eta-reduce a sequence of type +applications since this breaks the specialiser: + + /\ a -> f Char# a =NO=> f Char# + \begin{code} -mkCoLamTryingEta :: [Id] -- Args to the lambda - -> PlainCoreExpr -- Lambda body - -> PlainCoreExpr +etaCoreExpr :: CoreExpr -> CoreExpr -mkCoLamTryingEta [] body = body -mkCoLamTryingEta orig_ids body - = reduce_it (reverse orig_ids) body +etaCoreExpr expr@(Lam bndr body) + | opt_DoEtaReduction + = case etaCoreExpr body of + App fun arg | eta_match bndr arg && + residual_ok fun + -> fun -- Eta + other -> expr -- Can't eliminate it, so do nothing at all where - bale_out = mkCoLam orig_ids body - - reduce_it [] residual - | residual_ok residual = residual - | otherwise = bale_out - - reduce_it (id:ids) (CoApp fun (CoVarAtom arg)) - | id == arg - && getIdUniType id /= realWorldStateTy - -- *never* eta-reduce away a PrimIO state token! (WDP 94/11) - = reduce_it ids fun - - reduce_it ids other = bale_out - - is_elem = isIn "mkCoLamTryingEta" - - ----------- - residual_ok :: PlainCoreExpr -> Bool -- Checks for type application - -- and function not one of the - -- bound vars - residual_ok (CoTyApp fun ty) = residual_ok fun - residual_ok (CoVar v) = not (v `is_elem` orig_ids) -- Fun mustn't be one of - -- the bound ids - residual_ok other = False + eta_match (ValBinder v) (VarArg v') = v == v' + eta_match (TyBinder tv) (TyArg ty) = tv `elementOfTyVarSet` tyVarsOfType ty + eta_match bndr arg = False + + residual_ok :: CoreExpr -> Bool -- Checks for type application + -- and function not one of the + -- bound vars + + residual_ok (Var v) + = not (eta_match bndr (VarArg v)) + residual_ok (App fun arg) + | eta_match bndr arg = False + | otherwise = residual_ok fun + residual_ok (Coerce coercion ty body) + | eta_match bndr (TyArg ty) = False + | otherwise = residual_ok body + + residual_ok other = False -- Safe answer + -- This last clause may seem conservative, but consider: + -- primops, constructors, and literals, are impossible here + -- let and case are unlikely (the argument would have been floated inside) + -- SCCs we probably want to be conservative about (not sure, but it's safe to be) + +etaCoreExpr expr = expr -- The common case \end{code} + Eta expansion ~~~~~~~~~~~~~ @@ -168,61 +302,59 @@ such that E ===> (\x1::t1 x1::t2 ... xn::tn -> E x1 x2 ... xn) -is a safe transformation. In particular, the transformation should not -cause work to be duplicated, unless it is ``cheap'' (see @manifestlyCheap@ below). +is a safe transformation. In particular, the transformation should +not cause work to be duplicated, unless it is ``cheap'' (see +@manifestlyCheap@ below). -@etaExpandCount@ errs on the conservative side. It is always safe to return 0. +@etaExpandCount@ errs on the conservative side. It is always safe to +return 0. An application of @error@ is special, because it can absorb as many -arguments as you care to give it. For this special case we return 100, -to represent "infinity", which is a bit of a hack. +arguments as you care to give it. For this special case we return +100, to represent "infinity", which is a bit of a hack. \begin{code} -etaExpandCount :: CoreExpr bdr Id - -> Int -- Number of extra args you can safely abstract +etaExpandCount :: GenCoreExpr bdr Id tyvar uvar + -> Int -- Number of extra args you can safely abstract -etaExpandCount (CoLam ids body) - = length ids + etaExpandCount body +etaExpandCount (Lam (ValBinder _) body) + = 1 + etaExpandCount body -etaExpandCount (CoLet bind body) - | all manifestlyCheap (rhssOfBind bind) +etaExpandCount (Let bind body) + | all manifestlyCheap (rhssOfBind bind) = etaExpandCount body - -etaExpandCount (CoCase scrut alts) - | manifestlyCheap scrut - = minimum [etaExpandCount rhs | rhs <- rhssOfAlts alts] -etaExpandCount (CoApp fun _) = case etaExpandCount fun of - 0 -> 0 - n -> n-1 -- Knock off one +etaExpandCount (Case scrut alts) + | manifestlyCheap scrut + = minimum [etaExpandCount rhs | rhs <- rhssOfAlts alts] -etaExpandCount fun@(CoTyApp _ _) = eta_fun fun -etaExpandCount fun@(CoVar _) = eta_fun fun +etaExpandCount fun@(Var _) = eta_fun fun +etaExpandCount (App fun arg) + | notValArg arg = eta_fun fun + | otherwise = case etaExpandCount fun of + 0 -> 0 + n -> n-1 -- Knock off one -etaExpandCount other = 0 -- Give up - -- CoLit, CoCon, CoPrim, - -- CoTyLam, - -- CoScc (pessimistic; ToDo), - -- CoLet with non-whnf rhs(s), - -- CoCase with non-whnf scrutinee +etaExpandCount other = 0 -- Give up + -- Lit, Con, Prim, + -- non-val Lam, + -- Scc (pessimistic; ToDo), + -- Let with non-whnf rhs(s), + -- Case with non-whnf scrutinee -eta_fun :: CoreExpr bdr Id -- The function - -> Int -- How many args it can safely be applied to +----------------------------- +eta_fun :: GenCoreExpr bdr Id tv uv -- The function + -> Int -- How many args it can safely be applied to -eta_fun (CoTyApp fun ty) = eta_fun fun +eta_fun (App fun arg) | notValArg arg = eta_fun fun -eta_fun expr@(CoVar v) - | isBottomingId v -- Bottoming ids have "infinite arity" - = 10000 -- Blargh. Infinite enough! +eta_fun expr@(Var v) + | isBottomingId v -- Bottoming ids have "infinite arity" + = 10000 -- Blargh. Infinite enough! -eta_fun expr@(CoVar v) - | maybeToBool arity_maybe -- We know the arity - = arity - where - arity_maybe = arityMaybe (getIdArity v) - arity = case arity_maybe of { Just arity -> arity } +eta_fun expr@(Var v) = idMinArity v -eta_fun other = 0 -- Give up +eta_fun other = 0 -- Give up \end{code} @manifestlyCheap@ looks at a Core expression and returns \tr{True} if @@ -231,7 +363,7 @@ By ``cheap'' we mean a computation we're willing to duplicate in order to bring a couple of lambdas together. The main examples of things which aren't WHNF but are ``cheap'' are: - * case e of + * case e of pi -> ei where e, and all the ei are cheap; and @@ -246,149 +378,44 @@ which aren't WHNF but are ``cheap'' are: where op is a cheap primitive operator \begin{code} -manifestlyCheap :: CoreExpr bndr Id -> Bool +manifestlyCheap :: GenCoreExpr bndr Id tv uv -> Bool -manifestlyCheap (CoVar _) = True -manifestlyCheap (CoLit _) = True -manifestlyCheap (CoCon _ _ _) = True -manifestlyCheap (CoLam _ _) = True -manifestlyCheap (CoTyLam _ e) = manifestlyCheap e -manifestlyCheap (CoSCC _ e) = manifestlyCheap e +manifestlyCheap (Var _) = True +manifestlyCheap (Lit _) = True +manifestlyCheap (Con _ _) = True +manifestlyCheap (SCC _ e) = manifestlyCheap e +manifestlyCheap (Coerce _ _ e) = manifestlyCheap e +manifestlyCheap (Lam x e) = if isValBinder x then True else manifestlyCheap e +manifestlyCheap (Prim op _) = primOpIsCheap op -manifestlyCheap (CoPrim op _ _) = primOpIsCheap op - -manifestlyCheap (CoLet bind body) +manifestlyCheap (Let bind body) = manifestlyCheap body && all manifestlyCheap (rhssOfBind bind) -manifestlyCheap (CoCase scrut alts) +manifestlyCheap (Case scrut alts) = manifestlyCheap scrut && all manifestlyCheap (rhssOfAlts alts) manifestlyCheap other_expr -- look for manifest partial application - = case (collectArgs other_expr) of { (fun, args) -> + = case (collectArgs other_expr) of { (fun, _, _, vargs) -> case fun of - CoVar f | isBottomingId f -> True -- Application of a function which - -- always gives bottom; we treat this as - -- a WHNF, because it certainly doesn't - -- need to be shared! - - CoVar f -> let - num_val_args = length [ a | (ValArg a) <- args ] - in - num_val_args == 0 || -- Just a type application of - -- a variable (f t1 t2 t3) - -- counts as WHNF - case (arityMaybe (getIdArity f)) of - Nothing -> False - Just arity -> num_val_args < arity + Var f | isBottomingId f -> True -- Application of a function which + -- always gives bottom; we treat this as + -- a WHNF, because it certainly doesn't + -- need to be shared! + + Var f -> let + num_val_args = length vargs + in + num_val_args == 0 || -- Just a type application of + -- a variable (f t1 t2 t3) + -- counts as WHNF + num_val_args < idMinArity f _ -> False } - --- ToDo: Move to CoreFuns - -rhssOfBind :: CoreBinding bndr bdee -> [CoreExpr bndr bdee] - -rhssOfBind (CoNonRec _ rhs) = [rhs] -rhssOfBind (CoRec pairs) = [rhs | (_,rhs) <- pairs] - -rhssOfAlts :: CoreCaseAlternatives bndr bdee -> [CoreExpr bndr bdee] - -rhssOfAlts (CoAlgAlts alts deflt) = rhssOfDeflt deflt ++ - [rhs | (_,_,rhs) <- alts] -rhssOfAlts (CoPrimAlts alts deflt) = rhssOfDeflt deflt ++ - [rhs | (_,rhs) <- alts] -rhssOfDeflt CoNoDefault = [] -rhssOfDeflt (CoBindDefault _ rhs) = [rhs] \end{code} -Eta reduction on type lambdas -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -We have a go at doing - - /\a -> a ===> - -where doesn't mention a. -This is sometimes quite useful, because we can get the sequence: - - f ab d = let d1 = ...d... in - letrec f' b x = ...d...(f' b)... in - f' b -specialise ==> - - f.Int b = letrec f' b x = ...dInt...(f' b)... in - f' b - -float ==> - - f' b x = ...dInt...(f' b)... - f.Int b = f' b - -Now we really want to simplify to - - f.Int = f' - -and then replace all the f's with f.Ints. - -N.B. We are careful not to partially eta-reduce a sequence of type -applications since this breaks the specialiser: - - /\ a -> f Char# a =NO=> f Char# - -\begin{code} -mkCoTyLamTryingEta :: [TyVar] -> PlainCoreExpr -> PlainCoreExpr - -mkCoTyLamTryingEta tyvars tylam_body - = if - tyvars == tyvar_args && -- Same args in same order - check_fun fun -- Function left is ok - then - -- Eta reduction worked - fun - else - -- The vastly common case - mkCoTyLam tyvars tylam_body - where - (tyvar_args, fun) = strip_tyvar_args [] tylam_body - - strip_tyvar_args args_so_far tyapp@(CoTyApp fun ty) - = case getTyVarMaybe ty of - Just tyvar_arg -> strip_tyvar_args (tyvar_arg:args_so_far) fun - Nothing -> (args_so_far, tyapp) - - strip_tyvar_args args_so_far fun - = (args_so_far, fun) - - check_fun (CoVar f) = True -- Claim: tyvars not mentioned by type of f - check_fun other = False - -{- OLD: -mkCoTyLamTryingEta :: TyVar -> PlainCoreExpr -> PlainCoreExpr - -mkCoTyLamTryingEta tyvar body - = case body of - CoTyApp fun ty -> - case getTyVarMaybe ty of - Just tyvar' | tyvar == tyvar' && - ok fun -> fun - -- Ha! So it's /\ a -> fun a, and fun is "ok" - - other -> CoTyLam tyvar body - other -> CoTyLam tyvar body - where - is_elem = isIn "mkCoTyLamTryingEta" - - ok :: PlainCoreExpr -> Bool -- Returns True iff the expression doesn't - -- mention tyvar - - ok (CoVar v) = True -- Claim: tyvar not mentioned by type of v - ok (CoApp fun arg) = ok fun -- Claim: tyvar not mentioned by type of arg - ok (CoTyApp fun ty) = not (tyvar `is_elem` extractTyVarsFromTy ty) && - ok fun - ok other = False --} -\end{code} Let to case ~~~~~~~~~~~ @@ -406,51 +433,98 @@ if there's many, or if it's a primitive type. \begin{code} mkIdentityAlts - :: UniType -- type of RHS + :: Type -- type of RHS + -> DemandInfo -- Appropriate demand info -> SmplM InAlts -- result -mkIdentityAlts rhs_ty - | isPrimType rhs_ty - = newId rhs_ty `thenSmpl` \ binder -> - returnSmpl (CoPrimAlts [] (CoBindDefault (binder, bad_occ_info) (CoVar binder))) - - | otherwise - = case getUniDataTyCon_maybe rhs_ty of +mkIdentityAlts rhs_ty demand_info + = case (maybeAppDataTyConExpandingDicts rhs_ty) of Just (tycon, ty_args, [data_con]) -> -- algebraic type suitable for unpacking let - (_,inst_con_arg_tys,_) = getInstantiatedDataConSig data_con ty_args + inst_con_arg_tys = dataConArgTys data_con ty_args in newIds inst_con_arg_tys `thenSmpl` \ new_bindees -> let - new_binders = [ (b, bad_occ_info) | b <- new_bindees ] + new_binders = [ (b, bad_occ_info) | b <- new_bindees ] in returnSmpl ( - CoAlgAlts - [(data_con, new_binders, CoCon data_con ty_args (map CoVarAtom new_bindees))] - CoNoDefault + AlgAlts + [(data_con, new_binders, mkCon data_con [] ty_args (map VarArg new_bindees))] + NoDefault ) - _ -> -- Multi-constructor or abstract algebraic type - newId rhs_ty `thenSmpl` \ binder -> - returnSmpl (CoAlgAlts [] (CoBindDefault (binder,bad_occ_info) (CoVar binder))) + _ -> panic "mkIdentityAlts" -- Should never happen; only called for single-constructor types where bad_occ_info = ManyOcc 0 -- Non-committal! + + +{- SHOULD NEVER HAPPEN + | isPrimType rhs_ty + = newId rhs_ty `thenSmpl` \ binder -> + let + binder_w_info = binder `addIdDemandInfo` demand_info + -- It's occasionally really worth adding the right demand info. Consider + -- let x = E in B + -- where x is sure to be demanded in B + -- We will transform to: + -- case E of x -> B + -- Now suppose that E simplifies to just y; we get + -- case y of x -> B + -- Because x is sure to be demanded, we can eliminate the case + -- even if pedantic-bottoms is on; but we need to have the right + -- demand-info on the default branch of the case. That's what + -- we are doing here. + in + returnSmpl (PrimAlts [] (BindDefault (binder, bad_occ_info) (Var binder))) +-} \end{code} \begin{code} simplIdWantsToBeINLINEd :: Id -> SimplEnv -> Bool -simplIdWantsToBeINLINEd id env - = if switchIsSet env IgnoreINLINEPragma +simplIdWantsToBeINLINEd id env + = {- We used to arrange that in the final simplification pass we'd switch + off all INLINE pragmas, so that we'd inline workers back into the + body of their wrapper if the wrapper hadn't itself been inlined by then. + This occurred especially for methods in dictionaries. + + We no longer do this: + a) there's a good chance that the exported wrapper will get + inlined in some importing scope, in which case we don't + want to lose the w/w idea. + + b) The occurrence analyser must agree about what has an + INLINE pragma. Not hard, but delicate. + + c) if the worker gets inlined we have to tell the wrapepr + that it's no longer a wrapper, else the interface file stuff + asks for a worker that no longer exists. + + if switchIsSet env IgnoreINLINEPragma then False - else idWantsToBeINLINEd id + else + -} + + idWantsToBeINLINEd id + +idMinArity id = case getIdArity id of + UnknownArity -> 0 + ArityAtLeast n -> n + ArityExactly n -> n -type_ok_for_let_to_case :: UniType -> Bool +singleConstructorType :: Type -> Bool +singleConstructorType ty + = case (maybeAppDataTyConExpandingDicts ty) of + Just (tycon, ty_args, [con]) -> True + other -> False -type_ok_for_let_to_case ty - = case getUniDataTyCon_maybe ty of +typeOkForCase :: Type -> Bool +typeOkForCase ty + = case (maybeAppDataTyConExpandingDicts ty) of Nothing -> False Just (tycon, ty_args, []) -> False Just (tycon, ty_args, non_null_data_cons) -> True - -- Null data cons => type is abstract + -- Null data cons => type is abstract, which code gen can't + -- currently handle. (ToDo: when return-in-heap is universal we + -- don't need to worry about this.) \end{code}