X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FsimplCore%2FSimplUtils.lhs;h=fa14e39a33b411975d2d42084af5e62c0fcf177a;hb=5eb1c77c795f92ed0f4c8023847e9d4be1a4fd0d;hp=3d4961f1614b7712ba30d07583f388e257123191;hpb=e0befe921f5bbfa6daba3f8ff46cdf2a2abad1da;p=ghc-hetmet.git diff --git a/ghc/compiler/simplCore/SimplUtils.lhs b/ghc/compiler/simplCore/SimplUtils.lhs index 3d4961f..fa14e39 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} @@ -9,11 +9,11 @@ module SimplUtils ( floatExposesHNF, - - mkCoTyLamTryingEta, mkCoLamTryingEta, + + mkTyLamTryingEta, mkValLamTryingEta, etaExpandCount, - + mkIdentityAlts, simplIdWantsToBeINLINEd, @@ -21,36 +21,27 @@ module SimplUtils ( type_ok_for_let_to_case ) where -IMPORT_Trace -- ToDo: rm (debugging) -import Pretty +IMP_Ubiq(){-uitous-} +IMPORT_DELOOPER(SmplLoop) -- paranoia checking -import TaggedCore -import PlainCore +import BinderInfo +import CmdLineOpts ( SimplifierSwitch(..) ) +import CoreSyn +import CoreUnfold ( SimpleUnfolding, mkFormSummary, FormSummary(..) ) +import Id ( idType, isBottomingId, idWantsToBeINLINEd, dataConArgTys, + getIdArity, GenId{-instance Eq-} + ) +import IdInfo ( arityMaybe ) +import Maybes ( maybeToBool ) +import PrelVals ( augmentId, buildId ) +import PrimOp ( primOpIsCheap ) import SimplEnv import SimplMonad +import Type ( eqTy, isPrimType, maybeAppDataTyConExpandingDicts, getTyVar_maybe ) +import TysWiredIn ( realWorldStateTy ) +import TyVar ( GenTyVar{-instance Eq-} ) +import Util ( isIn, panic ) -import BinderInfo - -import AbsPrel ( primOpIsCheap, realWorldStateTy, - buildId, augmentId - IF_ATTACK_PRAGMAS(COMMA realWorldTy) - IF_ATTACK_PRAGMAS(COMMA tagOf_PrimOp) - IF_ATTACK_PRAGMAS(COMMA pprPrimOp) - ) -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 -import CmdLineOpts ( SimplifierSwitch(..) ) -import Maybes ( maybeToBool, Maybe(..) ) -import Outputable -- isExported ... -import Util \end{code} @@ -65,28 +56,31 @@ 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. -- likewise for `augment g h' -- - try (CoApp (CoTyApp (CoVar bld) _) _) | bld == buildId = True - try (CoApp (CoApp (CoTyApp (CoVar bld) _) _) _) | bld == augmentId = True + 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: @@ -102,10 +96,10 @@ 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} @@ -116,7 +110,7 @@ We have a go at doing \ x y -> f x y ===> f 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 @@ -130,39 +124,41 @@ gives rise to a recursive function for the list comprehension, and f turns out to be just a single call to this recursive function. \begin{code} -mkCoLamTryingEta :: [Id] -- Args to the lambda - -> PlainCoreExpr -- Lambda body - -> PlainCoreExpr +mkValLamTryingEta :: [Id] -- Args to the lambda + -> CoreExpr -- Lambda body + -> CoreExpr -mkCoLamTryingEta [] body = body +mkValLamTryingEta [] body = body -mkCoLamTryingEta orig_ids body +mkValLamTryingEta orig_ids body = reduce_it (reverse orig_ids) body where - bale_out = mkCoLam orig_ids body + bale_out = mkValLam orig_ids body reduce_it [] residual | residual_ok residual = residual | otherwise = bale_out - reduce_it (id:ids) (CoApp fun (CoVarAtom arg)) + reduce_it (id:ids) (App fun (VarArg arg)) | id == arg - && getIdUniType id /= realWorldStateTy - -- *never* eta-reduce away a PrimIO state token! (WDP 94/11) + && not (idType id `eqTy` 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" + is_elem = isIn "mkValLamTryingEta" ----------- - 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 + residual_ok :: CoreExpr -> Bool -- Checks for type application + -- and function not one of the + -- bound vars + + residual_ok (Var v) = not (v `is_elem` orig_ids) + -- Fun mustn't be one of the bound ids + residual_ok (App fun arg) + | notValArg arg = residual_ok fun + residual_ok other = False \end{code} Eta expansion @@ -172,61 +168,64 @@ 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 +eta_fun expr@(Var 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 other = 0 -- Give up +eta_fun other = 0 -- Give up \end{code} @manifestlyCheap@ looks at a Core expression and returns \tr{True} if @@ -235,7 +234,7 @@ 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 @@ -250,66 +249,48 @@ which aren't WHNF but are ``cheap'' are: where op is a cheap primitive operator \begin{code} -manifestlyCheap :: CoreExpr bndr Id -> Bool - -manifestlyCheap (CoVar _) = True -manifestlyCheap (CoLit _) = True -manifestlyCheap (CoCon _ _ _) = True -manifestlyCheap (CoLam _ _) = True -manifestlyCheap (CoTyLam _ e) = manifestlyCheap e -manifestlyCheap (CoSCC _ e) = manifestlyCheap e +manifestlyCheap :: GenCoreExpr bndr Id tv uv -> Bool -manifestlyCheap (CoPrim op _ _) = primOpIsCheap op +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 (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 + case (arityMaybe (getIdArity f)) of + Nothing -> False + Just arity -> num_val_args < arity _ -> 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 +We have a go at doing /\a -> a ===> @@ -319,17 +300,17 @@ 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 ==> +specialise ==> f.Int b = letrec f' b x = ...dInt...(f' b)... in f' b -float ==> +float ==> f' b x = ...dInt...(f' b)... f.Int b = f' b -Now we really want to simplify to +Now we really want to simplify to f.Int = f' @@ -341,9 +322,9 @@ applications since this breaks the specialiser: /\ a -> f Char# a =NO=> f Char# \begin{code} -mkCoTyLamTryingEta :: [TyVar] -> PlainCoreExpr -> PlainCoreExpr +mkTyLamTryingEta :: [TyVar] -> CoreExpr -> CoreExpr -mkCoTyLamTryingEta tyvars tylam_body +mkTyLamTryingEta tyvars tylam_body = if tyvars == tyvar_args && -- Same args in same order check_fun fun -- Function left is ok @@ -352,46 +333,23 @@ mkCoTyLamTryingEta tyvars tylam_body fun else -- The vastly common case - mkCoTyLam tyvars tylam_body + mkTyLam 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 + strip_tyvar_args args_so_far tyapp@(App fun (TyArg ty)) + = case getTyVar_maybe 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 (App _ (UsageArg _)) + = panic "SimplUtils.mkTyLamTryingEta: strip_tyvar_args UsageArg" + 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 (Var 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 @@ -410,33 +368,33 @@ if there's many, or if it's a primitive type. \begin{code} mkIdentityAlts - :: UniType -- type of RHS + :: Type -- type of RHS -> SmplM InAlts -- result mkIdentityAlts rhs_ty | isPrimType rhs_ty = newId rhs_ty `thenSmpl` \ binder -> - returnSmpl (CoPrimAlts [] (CoBindDefault (binder, bad_occ_info) (CoVar binder))) + returnSmpl (PrimAlts [] (BindDefault (binder, bad_occ_info) (Var binder))) | otherwise - = case getUniDataTyCon_maybe rhs_ty of + = 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 + _ -> -- Multi-constructor or abstract algebraic type newId rhs_ty `thenSmpl` \ binder -> - returnSmpl (CoAlgAlts [] (CoBindDefault (binder,bad_occ_info) (CoVar binder))) + returnSmpl (AlgAlts [] (BindDefault (binder,bad_occ_info) (Var binder))) where bad_occ_info = ManyOcc 0 -- Non-committal! \end{code} @@ -444,15 +402,15 @@ mkIdentityAlts rhs_ty \begin{code} simplIdWantsToBeINLINEd :: Id -> SimplEnv -> Bool -simplIdWantsToBeINLINEd id env - = if switchIsSet env IgnoreINLINEPragma +simplIdWantsToBeINLINEd id env + = if switchIsSet env IgnoreINLINEPragma then False else idWantsToBeINLINEd id -type_ok_for_let_to_case :: UniType -> Bool +type_ok_for_let_to_case :: Type -> Bool -type_ok_for_let_to_case ty - = case getUniDataTyCon_maybe ty of +type_ok_for_let_to_case ty + = case (maybeAppDataTyConExpandingDicts ty) of Nothing -> False Just (tycon, ty_args, []) -> False Just (tycon, ty_args, non_null_data_cons) -> True