\begin{code}
module SimplUtils (
simplBinder, simplBinders, simplIds,
- transformRhs,
+ tryRhsTyLam, tryEtaExpansion,
mkCase, findAlt, findDefault,
-- The continuation type
opt_UF_UpdateInPlace
)
import CoreSyn
-import CoreUtils ( exprIsTrivial, cheapEqExpr, exprType, exprIsCheap, exprEtaExpandArity, bindNonRec )
+import CoreUtils ( exprIsTrivial, cheapEqExpr, exprType, exprIsCheap, etaExpand, exprEtaExpandArity, bindNonRec )
import Subst ( InScopeSet, mkSubst, substBndrs, substBndr, substIds, substExpr )
import Id ( idType, idName,
idUnfolding, idStrictness,
mkVanillaId, 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
)
%************************************************************************
%* *
-\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 (Let (NonRec x rhs) e) | isUnLiftedType (exprType rhs) = False
+ worth_it (Let _ e) = whnf_in_middle e
+ worth_it other = False
+
+ whnf_in_middle (Let (NonRec x rhs) e) | isUnLiftedType (exprType rhs) = 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 ->
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
-
- (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
+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)
- 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}
(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
+ arg_tys = tyConAppArgs (idType case_bndr)
\end{code}
The catch-all case
projects / ghc-hetmet.git / blobdiff