\begin{code}
module SimplUtils (
- simplBinder, simplBinders, simplIds,
- transformRhs,
- mkCase, findAlt, findDefault,
+ simplBinder, simplBinders, simplRecIds, simplLetId,
+ tryRhsTyLam, tryEtaExpansion,
+ mkCase,
-- The continuation type
SimplCont(..), DupFlag(..), contIsDupable, contResultType,
opt_UF_UpdateInPlace
)
import CoreSyn
-import CoreUtils ( exprIsTrivial, cheapEqExpr, exprType, exprIsCheap, exprEtaExpandArity, bindNonRec )
-import Subst ( InScopeSet, mkSubst, substBndrs, substBndr, substIds, substExpr )
+import CoreUtils ( exprIsTrivial, cheapEqExpr, exprType, exprIsCheap,
+ etaExpand, exprEtaExpandArity, bindNonRec, mkCoerce,
+ findDefault
+ )
+import Subst ( InScopeSet, mkSubst, substExpr )
+import qualified Subst ( simplBndrs, simplBndr, simplLetId )
import Id ( idType, idName,
idUnfolding, idStrictness,
- mkVanillaId, idInfo
+ mkLocalId, idInfo
)
-import IdInfo ( StrictnessInfo(..), ArityInfo, atLeastArity )
+import IdInfo ( StrictnessInfo(..) )
import Maybes ( maybeToBool, catMaybes )
import Name ( setNameUnique )
import Demand ( isStrict )
import SimplMonad
import Type ( Type, mkForAllTys, seqType, repType,
- splitTyConApp_maybe, mkTyVarTys, splitFunTys,
+ splitTyConApp_maybe, tyConAppArgs, mkTyVarTys,
isDictTy, isDataType, isUnLiftedType,
splitRepFunTys
)
import TyCon ( tyConDataConsIfAvailable )
import DataCon ( dataConRepArity )
import VarEnv ( SubstEnv )
-import Util ( lengthExceeds )
+import Util ( lengthExceeds, mapAccumL )
import Outputable
\end{code}
where
interesting (InlinePlease _) = True
interesting (Select _ _ _ _ _) = some_args
- interesting (ApplyTo _ _ _ _) = some_args -- Can happen if we have (coerce t (f x)) y
+ interesting (ApplyTo _ _ _ _) = True -- Can happen if we have (coerce t (f x)) y
+ -- Perhaps True is a bit over-keen, but I've
+ -- seen (coerce f) x, where f has an INLINE prag,
+ -- So we have to give some motivaiton for inlining it
interesting (ArgOf _ _ _) = some_val_args
interesting (Stop ty upd_in_place) = some_val_args && upd_in_place
interesting (CoerceIt _ cont) = interesting cont
simplBinders bndrs thing_inside
= getSubst `thenSmpl` \ subst ->
let
- (subst', bndrs') = substBndrs subst bndrs
+ (subst', bndrs') = Subst.simplBndrs subst bndrs
in
seqBndrs bndrs' `seq`
setSubst subst' (thing_inside bndrs')
simplBinder bndr thing_inside
= getSubst `thenSmpl` \ subst ->
let
- (subst', bndr') = substBndr subst bndr
+ (subst', bndr') = Subst.simplBndr subst bndr
in
seqBndr bndr' `seq`
setSubst subst' (thing_inside bndr')
--- Same semantics as simplBinders, but a little less
--- plumbing and hence a little more efficient.
--- Maybe not worth the candle?
-simplIds :: [InBinder] -> ([OutBinder] -> SimplM a) -> SimplM a
-simplIds ids thing_inside
+simplRecIds :: [InBinder] -> ([OutBinder] -> SimplM a) -> SimplM a
+simplRecIds ids thing_inside
= getSubst `thenSmpl` \ subst ->
let
- (subst', bndrs') = substIds subst ids
+ (subst', ids') = mapAccumL Subst.simplLetId subst ids
in
- seqBndrs bndrs' `seq`
- setSubst subst' (thing_inside bndrs')
+ seqBndrs ids' `seq`
+ setSubst subst' (thing_inside ids')
+
+simplLetId :: InBinder -> (OutBinder -> SimplM a) -> SimplM a
+simplLetId id thing_inside
+ = getSubst `thenSmpl` \ subst ->
+ let
+ (subst', id') = Subst.simplLetId subst id
+ in
+ seqBndr id' `seq`
+ setSubst subst' (thing_inside id')
seqBndrs [] = ()
seqBndrs (b:bs) = seqBndr b `seq` seqBndrs bs
%************************************************************************
%* *
-\subsection{Transform a RHS}
-%* *
-%************************************************************************
-
-Try (a) eta expansion
- (b) type-lambda swizzling
-
-\begin{code}
-transformRhs :: OutExpr
- -> (ArityInfo -> OutExpr -> SimplM (OutStuff a))
- -> SimplM (OutStuff a)
-
-transformRhs rhs thing_inside
- = tryRhsTyLam rhs $ \ rhs1 ->
- tryEtaExpansion rhs1 thing_inside
-\end{code}
-
-
-%************************************************************************
-%* *
\subsection{Local tyvar-lifting}
%* *
%************************************************************************
\begin{code}
-tryRhsTyLam rhs thing_inside -- Only does something if there's a let
- | null tyvars || not (worth_it body) -- inside a type lambda, and a WHNF inside that
- = thing_inside rhs
+tryRhsTyLam :: OutExpr -> SimplM ([OutBind], OutExpr)
+
+tryRhsTyLam rhs -- Only does something if there's a let
+ | null tyvars || not (worth_it body) -- inside a type lambda,
+ = returnSmpl ([], rhs) -- and a WHNF inside that
+
| otherwise
- = go (\x -> x) body $ \ body' ->
- thing_inside (mkLams tyvars body')
+ = go (\x -> x) body `thenSmpl` \ (binds, body') ->
+ returnSmpl (binds, mkLams tyvars body')
where
(tyvars, body) = collectTyBinders rhs
- worth_it (Let _ e) = whnf_in_middle e
- worth_it other = False
+ worth_it e@(Let _ _) = whnf_in_middle e
+ worth_it e = False
+
+ whnf_in_middle (Let (NonRec x rhs) e) | isUnLiftedType (idType x) = False
whnf_in_middle (Let _ e) = whnf_in_middle e
whnf_in_middle e = exprIsCheap e
-
- go fn (Let bind@(NonRec var rhs) body) thing_inside
+ go fn (Let bind@(NonRec var rhs) body)
| exprIsTrivial rhs
- = go (fn . Let bind) body thing_inside
+ = go (fn . Let bind) body
- go fn (Let bind@(NonRec var rhs) body) thing_inside
- = mk_poly tyvars_here var `thenSmpl` \ (var', rhs') ->
- addAuxiliaryBind (NonRec var' (mkLams tyvars_here (fn rhs))) $
- go (fn . Let (mk_silly_bind var rhs')) body thing_inside
+ go fn (Let (NonRec var rhs) body)
+ = mk_poly tyvars_here var `thenSmpl` \ (var', rhs') ->
+ go (fn . Let (mk_silly_bind var rhs')) body `thenSmpl` \ (binds, body') ->
+ returnSmpl (NonRec var' (mkLams tyvars_here (fn rhs)) : binds, body')
where
tyvars_here = tyvars
-- abstracting wrt *all* the tyvars. We'll see if that
-- gives rise to problems. SLPJ June 98
- go fn (Let (Rec prs) body) thing_inside
+ go fn (Let (Rec prs) body)
= mapAndUnzipSmpl (mk_poly tyvars_here) vars `thenSmpl` \ (vars', rhss') ->
let
- gn body = fn (foldr Let body (zipWith mk_silly_bind vars rhss'))
+ gn body = fn (foldr Let body (zipWith mk_silly_bind vars rhss'))
+ new_bind = Rec (vars' `zip` [mkLams tyvars_here (gn rhs) | rhs <- rhss])
in
- addAuxiliaryBind (Rec (vars' `zip` [mkLams tyvars_here (gn rhs) | rhs <- rhss])) $
- go gn body thing_inside
+ go gn body `thenSmpl` \ (binds, body') ->
+ returnSmpl (new_bind : binds, body')
where
(vars,rhss) = unzip prs
tyvars_here = tyvars
-- var_tys = map idType vars
-- See notes with tyvars_here above
-
- go fn body thing_inside = thing_inside (fn body)
+ go fn body = returnSmpl ([], fn body)
mk_poly tyvars_here var
= getUniqueSmpl `thenSmpl` \ uniq ->
let
poly_name = setNameUnique (idName var) uniq -- Keep same name
poly_ty = mkForAllTys tyvars_here (idType var) -- But new type of course
- poly_id = mkVanillaId poly_name poly_ty
+ poly_id = mkLocalId poly_name poly_ty
-- In the olden days, it was crucial to copy the occInfo of the original var,
-- because we were looking at occurrence-analysed but as yet unsimplified code!
what the final test in the first equation is for.
\begin{code}
-tryEtaExpansion :: OutExpr
- -> (ArityInfo -> OutExpr -> SimplM (OutStuff a))
- -> SimplM (OutStuff a)
-tryEtaExpansion rhs thing_inside
- | not opt_SimplDoLambdaEtaExpansion
- || null y_tys -- No useful expansion
- || not (is_case1 || is_case2) -- Neither case matches
- = thing_inside final_arity rhs -- So, no eta expansion, but
- -- return a good arity
-
- | is_case1
- = make_y_bndrs $ \ y_bndrs ->
- thing_inside final_arity
- (mkLams x_bndrs $ mkLams y_bndrs $
- mkApps body (map Var y_bndrs))
-
- | otherwise -- Must be case 2
- = mapAndUnzipSmpl bind_z_arg arg_infos `thenSmpl` \ (maybe_z_binds, z_args) ->
- addAuxiliaryBinds (catMaybes maybe_z_binds) $
- make_y_bndrs $ \ y_bndrs ->
- thing_inside final_arity
- (mkLams y_bndrs $
- mkApps (mkApps fun z_args) (map Var y_bndrs))
- where
- all_trivial_args = all is_trivial arg_infos
- is_case1 = all_trivial_args
- is_case2 = null x_bndrs && not (any unlifted_non_trivial arg_infos)
-
- (x_bndrs, body) = collectBinders rhs -- NB: x_bndrs can include type variables
- x_arity = valBndrCount x_bndrs
+tryEtaExpansion :: OutExpr -> OutType -> SimplM ([OutBind], OutExpr)
+tryEtaExpansion rhs rhs_ty
+ | not opt_SimplDoLambdaEtaExpansion -- Not if switched off
+ || exprIsTrivial rhs -- Not if RHS is trivial
+ || final_arity == 0 -- Not if arity is zero
+ = returnSmpl ([], rhs)
+
+ | n_val_args == 0 && not arity_is_manifest
+ = -- Some lambdas but not enough: case 1
+ getUniqSupplySmpl `thenSmpl` \ us ->
+ returnSmpl ([], etaExpand final_arity us rhs rhs_ty)
+
+ | n_val_args > 0 && not (any cant_bind arg_infos)
+ = -- Partial application: case 2
+ mapAndUnzipSmpl bind_z_arg arg_infos `thenSmpl` \ (maybe_z_binds, z_args) ->
+ getUniqSupplySmpl `thenSmpl` \ us ->
+ returnSmpl (catMaybes maybe_z_binds,
+ etaExpand final_arity us (mkApps fun z_args) rhs_ty)
- (fun, args) = collectArgs body
- arg_infos = [(arg, exprType arg, exprIsTrivial arg) | arg <- args]
-
- is_trivial (_, _, triv) = triv
- unlifted_non_trivial (_, ty, triv) = not triv && isUnLiftedType ty
-
- fun_arity = exprEtaExpandArity fun
-
- final_arity | all_trivial_args = atLeastArity (x_arity + extra_args_wanted)
- | otherwise = atLeastArity x_arity
- -- Arity can be more than the number of lambdas
- -- because of coerces. E.g. \x -> coerce t (\y -> e)
- -- will have arity at least 2
- -- The worker/wrapper pass will bring the coerce out to the top
+ | otherwise
+ = returnSmpl ([], rhs)
+ where
+ (fun, args) = collectArgs rhs
+ n_val_args = valArgCount args
+ (fun_arity, arity_is_manifest) = exprEtaExpandArity fun
+ final_arity = 0 `max` (fun_arity - n_val_args)
+ arg_infos = [(arg, exprType arg, exprIsTrivial arg) | arg <- args]
+ cant_bind (_, ty, triv) = not triv && isUnLiftedType ty
bind_z_arg (arg, arg_ty, trivial_arg)
| trivial_arg = returnSmpl (Nothing, arg)
| otherwise = newId SLIT("z") arg_ty $ \ z ->
returnSmpl (Just (NonRec z arg), Var z)
-
- make_y_bndrs thing_inside
- = ASSERT( not (exprIsTrivial rhs) )
- newIds SLIT("y") y_tys $ \ y_bndrs ->
- tick (EtaExpansion (head y_bndrs)) `thenSmpl_`
- thing_inside y_bndrs
-
- (potential_extra_arg_tys, _) = splitFunTys (exprType body)
-
- y_tys :: [InType]
- y_tys = take extra_args_wanted potential_extra_arg_tys
-
- extra_args_wanted :: Int -- Number of extra args we want
- extra_args_wanted = 0 `max` (fun_arity - valArgCount args)
-
- -- We used to expand the arity to the previous arity fo the
- -- function; but this is pretty dangerous. Consdier
- -- f = \xy -> e
- -- so that f has arity 2. Now float something into f's RHS:
- -- f = let z = BIG in \xy -> e
- -- The last thing we want to do now is to put some lambdas
- -- outside, to get
- -- f = \xy -> let z = BIG in e
- --
- -- (bndr_arity - no_of_xs) `max`
\end{code}
mkCase scrut case_bndr alts
| all identity_alt alts
= tick (CaseIdentity case_bndr) `thenSmpl_`
- returnSmpl scrut
+ returnSmpl (re_note scrut)
where
- identity_alt (DEFAULT, [], Var v) = v == case_bndr
- identity_alt (DataAlt con, args, rhs) = cheapEqExpr rhs
- (mkConApp con (map Type arg_tys ++ map varToCoreExpr args))
- identity_alt other = False
-
- arg_tys = case splitTyConApp_maybe (idType case_bndr) of
- Just (tycon, arg_tys) -> arg_tys
+ identity_alt (con, args, rhs) = de_note rhs `cheapEqExpr` identity_rhs con args
+
+ identity_rhs (DataAlt con) args = mkConApp con (arg_tys ++ map varToCoreExpr args)
+ identity_rhs (LitAlt lit) _ = Lit lit
+ identity_rhs DEFAULT _ = Var case_bndr
+
+ arg_tys = map Type (tyConAppArgs (idType case_bndr))
+
+ -- We've seen this:
+ -- case coerce T e of x { _ -> coerce T' x }
+ -- And we definitely want to eliminate this case!
+ -- So we throw away notes from the RHS, and reconstruct
+ -- (at least an approximation) at the other end
+ de_note (Note _ e) = de_note e
+ de_note e = e
+
+ -- re_note wraps a coerce if it might be necessary
+ re_note scrut = case head alts of
+ (_,_,rhs1@(Note _ _)) -> mkCoerce (exprType rhs1) (idType case_bndr) scrut
+ other -> scrut
\end{code}
The catch-all case
\end{code}
-\begin{code}
-findDefault :: [CoreAlt] -> ([CoreAlt], Maybe CoreExpr)
-findDefault [] = ([], Nothing)
-findDefault ((DEFAULT,args,rhs) : alts) = ASSERT( null alts && null args )
- ([], Just rhs)
-findDefault (alt : alts) = case findDefault alts of
- (alts', deflt) -> (alt : alts', deflt)
-
-findAlt :: AltCon -> [CoreAlt] -> CoreAlt
-findAlt con alts
- = go alts
- where
- go [] = pprPanic "Missing alternative" (ppr con $$ vcat (map ppr alts))
- go (alt : alts) | matches alt = alt
- | otherwise = go alts
-
- matches (DEFAULT, _, _) = True
- matches (con1, _, _) = con == con1
-\end{code}
projects / ghc-hetmet.git / blobdiff