%
-% (c) The GRASP/AQUA Project, Glasgow University, 1993-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1993-1998
%
\section[WwLib]{A library for the ``worker/wrapper'' back-end to the strictness analyser}
\begin{code}
-#include "HsVersions.h"
-
module WwLib (
WwBinding(..),
- mkWwBodies, mAX_WORKER_ARGS
+ worthSplitting, setUnpackStrategy,
+ mkWwBodies, mkWrapper
) where
-import Ubiq{-uitous-}
+#include "HsVersions.h"
import CoreSyn
-import Id ( idType, mkSysLocal, dataConArgTys )
-import IdInfo ( mkStrictnessInfo, nonAbsentArgs, Demand(..) )
-import PrelInfo ( aBSENT_ERROR_ID )
-import SrcLoc ( mkUnknownSrcLoc )
-import Type ( isPrimType, mkTyVarTys, mkForAllTys, mkFunTys,
- maybeAppDataTyConExpandingDicts
+import Id ( Id, idType, mkSysLocal, getIdDemandInfo, setIdDemandInfo,
+ mkWildId, setIdInfo
)
-import UniqSupply ( returnUs, thenUs, thenMaybeUs,
- getUniques, UniqSM(..)
+import IdInfo ( CprInfo(..), noCprInfo, vanillaIdInfo )
+import Const ( Con(..), DataCon )
+import DataCon ( splitProductType_maybe )
+import Demand ( Demand(..) )
+import PrelInfo ( realWorldPrimId, aBSENT_ERROR_ID )
+import TysPrim ( realWorldStatePrimTy )
+import TysWiredIn ( unboxedTupleCon, unboxedTupleTyCon )
+import Type ( isUnLiftedType, mkTyVarTys, mkTyVarTy, mkFunTys,
+ splitForAllTys, splitFunTys, splitFunTysN,
+ splitAlgTyConApp_maybe, splitAlgTyConApp,
+ mkTyConApp, splitNewType_maybe,
+ Type
)
-import Util ( zipWithEqual, assertPanic, panic )
+import TyCon ( isNewTyCon,
+ TyCon )
+import BasicTypes ( NewOrData(..) )
+import Var ( TyVar )
+import UniqSupply ( returnUs, thenUs, getUniqueUs, getUniquesUs,
+ mapUs, UniqSM )
+import Util ( zipWithEqual, zipEqual )
+import Outputable
\end{code}
%************************************************************************
\begin{code}
data WwBinding
- = WwLet [CoreBinding]
+ = WwLet [CoreBind]
| WwCase (CoreExpr -> CoreExpr)
-- the "case" will be a "strict let" of the form:
--
same, we ``revise'' the strictness info, so that we won't propagate
the unusable strictness-info into the interfaces.
-==========================
-Here's the real fun... The wrapper's ``deconstructing'' of arguments
-and the worker's putting them back together again are ``duals'' in
-some sense.
+%************************************************************************
+%* *
+\subsection{Functions over Demands}
+%* *
+%************************************************************************
+
+\begin{code}
+mAX_WORKER_ARGS :: Int -- ToDo: set via flag
+mAX_WORKER_ARGS = 6
+
+setUnpackStrategy :: [Demand] -> [Demand]
+setUnpackStrategy ds
+ = snd (go (mAX_WORKER_ARGS - nonAbsentArgs ds) ds)
+ where
+ go :: Int -- Max number of args available for sub-components of [Demand]
+ -> [Demand]
+ -> (Int, [Demand]) -- Args remaining after subcomponents of [Demand] are unpacked
+
+ go n (WwUnpack nd _ cs : ds) | n' >= 0
+ = WwUnpack nd True cs' `cons` go n'' ds
+ | otherwise
+ = WwUnpack nd False cs `cons` go n ds
+ where
+ n' = n + 1 - nonAbsentArgs cs
+ -- Add one because we don't pass the top-level arg any more
+ -- Delete # of non-absent args to which we'll now be committed
+ (n'',cs') = go n' cs
+
+ go n (d:ds) = d `cons` go n ds
+ go n [] = (n,[])
+
+ cons d (n,ds) = (n, d:ds)
+
+nonAbsentArgs :: [Demand] -> Int
+nonAbsentArgs [] = 0
+nonAbsentArgs (WwLazy True : ds) = nonAbsentArgs ds
+nonAbsentArgs (d : ds) = 1 + nonAbsentArgs ds
+
+worthSplitting :: [Demand]
+ -> Bool -- Result is bottom
+ -> Bool -- True <=> the wrapper would not be an identity function
+worthSplitting ds result_bot = not result_bot && any worth_it ds
+ -- Don't split if the result is bottom; there's no efficiency to
+ -- be gained, and (worse) the wrapper body may not look like a wrapper
+ -- body to getWorkerIdAndCons
+ where
+ worth_it (WwLazy True) = True -- Absent arg
+ worth_it (WwUnpack _ True _) = True -- Arg to unpack
+ worth_it WwStrict = False -- Don't w/w just because of strictness
+ worth_it other = False
+
+allAbsent :: [Demand] -> Bool
+allAbsent ds = all absent ds
+ where
+ absent (WwLazy is_absent) = is_absent
+ absent (WwUnpack _ True cs) = allAbsent cs
+ absent other = False
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{The worker wrapper core}
+%* *
+%************************************************************************
+
+@mkWrapper@ is called when importing a function. We have the type of
+the function and the name of its worker, and we want to make its body (the wrapper).
+
+\begin{code}
+mkWrapper :: Type -- Wrapper type
+ -> Int -- Arity
+ -> [Demand] -- Wrapper strictness info
+ -> CprInfo -- Wrapper cpr info
+ -> UniqSM (Id -> CoreExpr) -- Wrapper body, missing worker Id
+
+mkWrapper fun_ty arity demands cpr_info
+ = getUniquesUs arity `thenUs` \ wrap_uniqs ->
+ let
+ (tyvars, tau_ty) = splitForAllTys fun_ty
+ (arg_tys, body_ty) = splitFunTysN "mkWrapper" arity tau_ty
+ -- The "expanding dicts" part here is important, even for the splitForAll
+ -- The imported thing might be a dictionary, such as Functor Foo
+ -- But Functor Foo = forall a b. (a->b) -> Foo a -> Foo b
+ -- and as such might have some strictness info attached.
+ -- Then we need to have enough args to zip to the strictness info
+
+ wrap_args = zipWith mk_ww_local wrap_uniqs arg_tys
+ in
+ mkWwBodies tyvars wrap_args body_ty demands cpr_info `thenUs` \ (wrap_fn, _, _) ->
+ returnUs wrap_fn
+\end{code}
+
+@mkWwBodies@ is called when doing the worker/wrapper split inside a module.
+
+\begin{code}
+mkWwBodies :: [TyVar] -> [Id] -> Type -- Original fn args and body type
+ -> [Demand] -- Strictness info for original fn; corresp 1-1 with args
+ -> CprInfo -- Result of CPR analysis
+ -> UniqSM (Id -> CoreExpr, -- Wrapper body, lacking only the worker Id
+ CoreExpr -> CoreExpr, -- Worker body, lacking the original function body
+ [Demand]) -- Strictness info for worker
+
+mkWwBodies tyvars wrap_args body_ty demands cpr_info
+ = let
+ -- demands may be longer than number of args. If we aren't doing w/w
+ -- for strictness then demands is an infinite list of 'lazy' args.
+ wrap_args_w_demands = zipWith setIdDemandInfo wrap_args demands
+ (wrap_fn_coerce, work_fn_coerce) = mkWWcoerce body_ty
+ in
+ mkWWstr body_ty wrap_args_w_demands `thenUs` \ (work_args_w_demands, wrap_fn_str, work_fn_str) ->
+
+ mkWWcpr body_ty cpr_info `thenUs` \ (wrap_fn_cpr, work_fn_cpr) ->
+
+ returnUs (\ work_id -> Note InlineMe $
+ mkLams tyvars $ mkLams wrap_args_w_demands $
+ (wrap_fn_coerce . wrap_fn_str . wrap_fn_cpr) $
+ mkVarApps (Var work_id) (tyvars ++ work_args_w_demands),
+
+ \ work_body -> mkLams tyvars $ mkLams work_args_w_demands $
+ (work_fn_coerce . work_fn_str . work_fn_cpr)
+ work_body,
+
+ map getIdDemandInfo work_args_w_demands)
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{Coercion stuff}
+%* *
+%************************************************************************
+
+The "coerce" transformation is
+ f :: T1 -> T2 -> R
+ f = \xy -> e
+===>
+ f = \xy -> coerce R R' (fw x y)
+ fw = \xy -> coerce R' R e
+
+where R' is the representation type for R.
+
+\begin{code}
+mkWWcoerce body_ty
+ = case splitNewType_maybe body_ty of
+ Nothing -> (id, id)
+ Just rep_ty -> (mkNote (Coerce body_ty rep_ty),
+ mkNote (Coerce rep_ty body_ty))
+\end{code}
+
+
+
+%************************************************************************
+%* *
+\subsection{Strictness stuff}
+%* *
+%************************************************************************
-What we do is walk along the @Demand@ list, producing two
-expressions (one for wrapper, one for worker...), each with a ``hole''
-in it, where we will later plug in more information. For our previous
-example, the expressions-with-HOLES are:
-\begin{verbatim}
-\ x ys -> -- wrapper
- case x of
- I# x# -> <<HOLE>> x# ys
-\ x# ys -> -- worker
+\begin{code}
+mkWWstr :: Type -- Body type
+ -> [Id] -- Wrapper args; have their demand info on them
+ -> UniqSM ([Id], -- Worker args; have their demand info on them
+
+ CoreExpr -> CoreExpr, -- Wrapper body, lacking the inner call to the worker
+ -- and without its lambdas
+ -- At the call site, the worker args are bound
+
+ CoreExpr -> CoreExpr) -- Worker body, lacking the original body of the function,
+ -- and without its lambdas
+
+mkWWstr body_ty wrap_args
+ = mk_ww wrap_args `thenUs` \ (work_args, wrap_fn, work_fn) ->
+
+ if null work_args && isUnLiftedType body_ty then
+ -- Horrid special case. If the worker would have no arguments, and the
+ -- function returns a primitive type value, that would make the worker into
+ -- an unboxed value. We box it by passing a dummy void argument, thus:
+ --
+ -- f = /\abc. \xyz. fw abc void
+ -- fw = /\abc. \v. body
+ --
+ -- We use the state-token type which generates no code
+ getUniqueUs `thenUs` \ void_arg_uniq ->
let
- x = I# x#
+ void_arg = mk_ww_local void_arg_uniq realWorldStatePrimTy
in
- <<HOLE>>
-\end{verbatim}
-(Actually, we add the lambda-bound arguments at the end...) (The big
-Lambdas are added on the front later.)
+ returnUs ([void_arg],
+ wrap_fn . Let (NonRec void_arg (Var realWorldPrimId)),
+ work_fn)
+ else
+ returnUs (work_args, wrap_fn, work_fn)
+
+
+
+ -- Empty case
+mk_ww []
+ = returnUs ([],
+ \ wrapper_body -> wrapper_body,
+ \ worker_body -> worker_body)
+
+
+mk_ww (arg : ds)
+ = case getIdDemandInfo arg of
+
+ -- Absent case
+ WwLazy True ->
+ mk_ww ds `thenUs` \ (worker_args, wrap_fn, work_fn) ->
+ returnUs (worker_args, wrap_fn, mk_absent_let arg . work_fn)
+
+ -- Unpack case
+ WwUnpack new_or_data True cs ->
+ getUniquesUs (length inst_con_arg_tys) `thenUs` \ uniqs ->
+ let
+ unpk_args = zipWith mk_ww_local uniqs inst_con_arg_tys
+ unpk_args_w_ds = zipWithEqual "mk_ww" setIdDemandInfo unpk_args cs
+ in
+ mk_ww (unpk_args_w_ds ++ ds) `thenUs` \ (worker_args, wrap_fn, work_fn) ->
+ returnUs (worker_args,
+ mk_unpk_case new_or_data arg unpk_args data_con arg_tycon . wrap_fn,
+ work_fn . mk_pk_let new_or_data arg data_con tycon_arg_tys unpk_args)
+ where
+ (arg_tycon, tycon_arg_tys, data_con, inst_con_arg_tys) = splitProductType "mk_ww" (idType arg)
+
+ -- Other cases
+ other_demand ->
+ mk_ww ds `thenUs` \ (worker_args, wrap_fn, work_fn) ->
+ returnUs (arg : worker_args, wrap_fn, work_fn)
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{CPR stuff}
+%* *
+%************************************************************************
+
+
+@mkWWcpr@ takes the worker/wrapper pair produced from the strictness
+info and adds in the CPR transformation. The worker returns an
+unboxed tuple containing non-CPR components. The wrapper takes this
+tuple and re-produces the correct structured output.
+
+The non-CPR results appear ordered in the unboxed tuple as if by a
+left-to-right traversal of the result structure.
+
\begin{code}
-mkWwBodies
- :: Type -- Type of the *body* of the orig
- -- function; i.e. /\ tyvars -> \ vars -> body
- -> [TyVar] -- Type lambda vars of original function
- -> [Id] -- Args of original function
- -> [Demand] -- Strictness info for those args
-
- -> UniqSM (Maybe -- Nothing iff (a) no interesting split possible
- -- (b) any unpack on abstract type
- (Id -> CoreExpr, -- Wrapper expr w/
- -- hole for worker id
- CoreExpr -> CoreExpr, -- Worker expr w/ hole
- -- for original fn body
- StrictnessInfo, -- Worker strictness info
- Type -> Type) -- Worker type w/ hole
- ) -- for type of original fn body
-
-
-mkWwBodies body_ty tyvars args arg_infos
- = ASSERT(length args == length arg_infos)
- -- or you can get disastrous user/definer-module mismatches
- if (all_absent_args_and_unboxed_value body_ty arg_infos)
- then returnUs Nothing
-
- else -- the rest...
- mk_ww_arg_processing args arg_infos (mAX_WORKER_ARGS - nonAbsentArgs arg_infos)
- `thenMaybeUs` \ (wrap_frag, work_args_info, work_frag) ->
- let
- (work_args, wrkr_demands) = unzip work_args_info
+mkWWcpr :: Type -- function body type
+ -> CprInfo -- CPR analysis results
+ -> UniqSM (CoreExpr -> CoreExpr, -- New wrapper
+ CoreExpr -> CoreExpr) -- New worker
+
+mkWWcpr body_ty NoCPRInfo
+ = returnUs (id, id) -- Must be just the strictness transf.
+mkWWcpr body_ty (CPRInfo cpr_args)
+ = getUniqueUs `thenUs` \ body_arg_uniq ->
+ let
+ body_var = mk_ww_local body_arg_uniq body_ty
+ in
+ cpr_reconstruct body_ty cpr_info' `thenUs` \reconst_fn ->
+ cpr_flatten body_ty cpr_info' `thenUs` \flatten_fn ->
+ returnUs (reconst_fn, flatten_fn)
+ where
+ -- We only make use of the outer level of CprInfo, otherwise we
+ -- may lose laziness. :-( Hopefully, we will find a use for the
+ -- extra info some day (e.g. creating versions specialized to
+ -- the use made of the components of the result by the callee)
+ cpr_info' = CPRInfo (map (const NoCPRInfo) cpr_args)
+\end{code}
- wrkr_strictness = mkStrictnessInfo wrkr_demands Nothing -- no worker-of-worker...
- wrapper_w_hole = \ worker_id ->
- mkLam tyvars args (
- wrap_frag (
- mkTyApp (Var worker_id) (mkTyVarTys tyvars)
- ))
+@cpr_flatten@ takes the result type produced by the body and the info
+from the CPR analysis and flattens the constructed product components.
+These are returned in an unboxed tuple.
- worker_w_hole = \ orig_body ->
- mkLam tyvars work_args (
- work_frag orig_body
- )
+\begin{code}
+cpr_flatten :: Type -> CprInfo -> UniqSM (CoreExpr -> CoreExpr)
+cpr_flatten ty cpr_info
+ = mk_cpr_case (ty, cpr_info) `thenUs` \(res_id, tup_ids, flatten_exp) ->
+ returnUs (\body -> Case body res_id
+ [(DEFAULT, [], flatten_exp (fst $ mk_unboxed_tuple tup_ids))])
+
+
+
+mk_cpr_case :: (Type, CprInfo) ->
+ UniqSM (CoreBndr, -- Name of binder for this part of result
+ [(CoreExpr, Type)], -- expressions for flattened result
+ CoreExpr -> CoreExpr) -- add in code to flatten result
+
+mk_cpr_case (ty, NoCPRInfo)
+ -- this component must be returned as a component of the unboxed tuple result
+ = getUniqueUs `thenUs` \id_uniq ->
+ let id_id = mk_ww_local id_uniq ty in
+ returnUs (id_id, [(Var id_id, ty)], id)
+mk_cpr_case (ty, cpr_info@(CPRInfo ci_args))
+ | isNewTyCon tycon -- a new type: under the coercions must be a
+ -- constructed product
+ = ASSERT ( null $ tail inst_con_arg_tys )
+ mk_cpr_case (target_of_from_type, cpr_info)
+ `thenUs` \(arg, tup, exp) ->
+ getUniqueUs `thenUs` \id_uniq ->
+ let id_id = mk_ww_local id_uniq ty
+ new_exp_case = \var -> Case (Note (Coerce (idType arg) ty) (Var id_id))
+ arg
+ [(DEFAULT,[], exp var)]
+ in
+ returnUs (id_id, tup, new_exp_case)
+
+ | otherwise -- a data type
+ -- flatten components
+ = mapUs mk_cpr_case (zip inst_con_arg_tys ci_args)
+ `thenUs` \sub_builds ->
+ getUniqueUs `thenUs` \id_uniq ->
+ let id_id = mk_ww_local id_uniq ty
+ (args, tup, exp) = unzip3 sub_builds
+ con_app = mkConApp data_con (map Var args)
+ new_tup = concat tup
+ new_exp_case = \var -> Case (Var id_id) (mkWildId ty)
+ [(DataCon data_con, args,
+ foldl (\e f -> f e) var exp)]
+ in
+ returnUs (id_id, new_tup, new_exp_case)
+ where
+ (tycon, tycon_arg_tys, data_con, inst_con_arg_tys) = splitProductType "mk_cpr_case" ty
+ from_type = head inst_con_arg_tys
+ -- if coerced from a function 'look through' to find result type
+ target_of_from_type = (snd.splitFunTys.snd.splitForAllTys) from_type
- worker_ty_w_hole = \ body_ty ->
- mkForAllTys tyvars $
- mkFunTys (map idType work_args) body_ty
- in
- returnUs (Just (wrapper_w_hole, worker_w_hole, wrkr_strictness, worker_ty_w_hole))
- where
- -- "all_absent_args_and_unboxed_value":
- -- check for the obscure case of "\ x y z ... -> body" where
- -- (a) *all* of the args x, y, z,... are absent, and
- -- (b) the type of body is unboxed
- -- If these conditions are true, we must *not* play worker/wrapper games!
-
- all_absent_args_and_unboxed_value body_ty arg_infos
- = not (null arg_infos)
- && all is_absent_arg arg_infos
- && isPrimType body_ty
-
- is_absent_arg (WwLazy True) = True
- is_absent_arg _ = False
\end{code}
-Important: mk_ww_arg_processing doesn't check
-for an "interesting" split. It just races ahead and makes the
-split, even if there's no unpacking at all. This is important for
-when it calls itself recursively.
+@cpr_reconstruct@ does the opposite of @cpr_flatten@. It takes the unboxed
+tuple produced by the worker and reconstructs the structured result.
+
+\begin{code}
+cpr_reconstruct :: Type -> CprInfo -> UniqSM (CoreExpr -> CoreExpr)
+cpr_reconstruct ty cpr_info
+ = mk_cpr_let (ty,cpr_info) `thenUs` \(res_id, tup_ids, reconstruct_exp) ->
+ returnUs (\worker -> Case worker (mkWildId $ worker_type tup_ids)
+ [(DataCon $ unboxedTupleCon $ length tup_ids,
+ tup_ids, reconstruct_exp $ Var res_id)])
+
+ where
+ worker_type ids = mkTyConApp (unboxedTupleTyCon (length ids)) (map idType ids)
+
+
+mk_cpr_let :: (Type, CprInfo) ->
+ UniqSM (CoreBndr, -- Binder for this component of result
+ [CoreBndr], -- Binders which will appear in worker's result
+ CoreExpr -> CoreExpr) -- Code to produce structured result.
+mk_cpr_let (ty, NoCPRInfo)
+ -- this component will appear explicitly in the unboxed tuple.
+ = getUniqueUs `thenUs` \id_uniq ->
+ let
+ id_id = mk_ww_local id_uniq ty
+ in
+ returnUs (id_id, [id_id], id)
+
+mk_cpr_let (ty, cpr_info@(CPRInfo ci_args))
+ | isNewTyCon tycon -- a new type: must coerce the argument to this type
+ = ASSERT ( null $ tail inst_con_arg_tys )
+ mk_cpr_let (target_of_from_type, cpr_info)
+ `thenUs` \(arg, tup, exp) ->
+ getUniqueUs `thenUs` \id_uniq ->
+ let id_id = mk_ww_local id_uniq ty
+ new_exp = \var -> exp (Let (NonRec id_id (Note (Coerce ty (idType arg)) (Var arg))) var)
+ in
+ returnUs (id_id, tup, new_exp)
+
+ | otherwise -- a data type
+ -- reconstruct components then apply data con
+ = mapUs mk_cpr_let (zip inst_con_arg_tys ci_args)
+ `thenUs` \sub_builds ->
+ getUniqueUs `thenUs` \id_uniq ->
+ let id_id = mk_ww_local id_uniq ty
+ (args, tup, exp) = unzip3 sub_builds
+ con_app = mkConApp data_con $ (map Type tycon_arg_tys) ++ (map Var args)
+ new_tup = concat tup
+ new_exp = \var -> foldl (\e f -> f e) (Let (NonRec id_id con_app) var) exp
+ in
+ returnUs (id_id, new_tup, new_exp)
+ where
+ (tycon, tycon_arg_tys, data_con, inst_con_arg_tys) = splitProductType "mk_cpr_let" ty
+ from_type = head inst_con_arg_tys
+ -- if coerced from a function 'look through' to find result type
+ target_of_from_type = (snd.splitFunTys.snd.splitForAllTys) from_type
+
+
+splitProductType :: String -> Type -> (TyCon, [Type], DataCon, [Type])
+splitProductType fname ty = case splitProductType_maybe ty of
+ Just stuff -> stuff
+ Nothing -> pprPanic (fname ++ ": not a product") (ppr ty)
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{Utilities}
+%* *
+%************************************************************************
-It returns Nothing only if it encounters an abstract type in mid-flight.
\begin{code}
-mAX_WORKER_ARGS :: Int -- ToDo: set via flag
-mAX_WORKER_ARGS = 6 -- Hmm... but this is an everything-must-
- -- be-compiled-with-the-same-val thing...
-
-mk_ww_arg_processing
- :: [Id] -- Args of original function
- -> [Demand] -- Strictness info for those args
- -- must be at least as long as args
-
- -> Int -- Number of extra args we are prepared to add.
- -- This prevents over-eager unpacking, leading
- -- to huge-arity functions.
-
- -> UniqSM (Maybe -- Nothing iff any unpack on abstract type
- (CoreExpr -> CoreExpr, -- Wrapper expr w/
- -- hole for worker id
- -- applied to types
- [(Id,Demand)], -- Worker's args
- -- and their strictness info
- CoreExpr -> CoreExpr) -- Worker body expr w/ hole
- ) -- for original fn body
-
-mk_ww_arg_processing [] _ _ = returnUs (Just (id, [], id))
-
-mk_ww_arg_processing (arg : args) (WwLazy True : infos) max_extra_args
- = -- Absent argument
- -- So, finish args to the right...
- --pprTrace "Absent; num_wrkr_args=" (ppInt num_wrkr_args) (
- let
- arg_ty = idType arg
- in
- mk_ww_arg_processing args infos max_extra_args
- -- we've already discounted for absent args,
- -- so we don't change max_extra_args
- `thenMaybeUs` \ (wrap_rest, work_args_info, work_rest) ->
-
- -- wrapper doesn't pass this arg to worker:
- returnUs (Just (
- -- wrapper:
- \ hole -> wrap_rest hole,
-
- -- worker:
- work_args_info, -- NB: no argument added
- \ hole -> mk_absent_let arg arg_ty (work_rest hole)
- ))
- --)
- where
- mk_absent_let arg arg_ty body
- = if not (isPrimType arg_ty) then
- Let (NonRec arg (mkTyApp (Var aBSENT_ERROR_ID) [arg_ty])) body
- else -- quite horrible
- panic "WwLib: haven't done mk_absent_let for primitives yet"
-
-
-mk_ww_arg_processing (arg : args) (WwUnpack cmpnt_infos : infos) max_extra_args
- | new_max_extra_args > 0 -- Check that we are prepared to add arguments
- = -- this is the complicated one.
- --pprTrace "Unpack; num_wrkr_args=" (ppCat [ppInt num_wrkr_args, ppStr "; new_max=", ppInt new_num_wrkr_args, ppStr "; arg=", ppr PprDebug arg, ppr PprDebug (WwUnpack cmpnt_infos)]) $
-
- case (maybeAppDataTyConExpandingDicts arg_ty) of
-
- Nothing -> -- Not a data type
- panic "mk_ww_arg_processing: not datatype"
-
- Just (_, _, []) -> -- An abstract type
- -- We have to give up on the whole idea
- returnUs Nothing
- Just (_, _, (_:_:_)) -> -- Two or more constructors; that's odd
- panic "mk_ww_arg_processing: multi-constr"
-
- Just (arg_tycon, tycon_arg_tys, [data_con]) ->
- -- The main event: a single-constructor data type
-
- let
- inst_con_arg_tys = dataConArgTys data_con tycon_arg_tys
- in
- getUniques (length inst_con_arg_tys) `thenUs` \ uniqs ->
-
- let
- unpk_args = zipWithEqual "mk_ww_arg_processing"
- (\ u t -> mkSysLocal SLIT("upk") u t mkUnknownSrcLoc)
- uniqs inst_con_arg_tys
- in
- -- In processing the rest, push the sub-component args
- -- and infos on the front of the current bunch
- mk_ww_arg_processing (unpk_args ++ args) (cmpnt_infos ++ infos) new_max_extra_args
- `thenMaybeUs` \ (wrap_rest, work_args_info, work_rest) ->
-
- returnUs (Just (
- -- wrapper: unpack the value
- \ hole -> mk_unpk_case arg unpk_args
- data_con arg_tycon
- (wrap_rest hole),
-
- -- worker: expect the unpacked value;
- -- reconstruct the orig value with a "let"
- work_args_info,
- \ hole -> work_rest (mk_pk_let arg data_con tycon_arg_tys unpk_args hole)
- ))
+mk_absent_let arg body
+ | not (isUnLiftedType arg_ty)
+ = Let (NonRec arg (mkTyApps (Var aBSENT_ERROR_ID) [arg_ty])) body
+ | otherwise
+ = panic "WwLib: haven't done mk_absent_let for primitives yet"
where
arg_ty = idType arg
- new_max_extra_args
- = max_extra_args
- + 1 -- We won't pass the original arg now
- - nonAbsentArgs cmpnt_infos -- But we will pass an arg for each cmpt
+mk_unpk_case NewType arg unpk_args boxing_con boxing_tycon body
+ -- A newtype! Use a coercion not a case
+ = ASSERT( null other_args )
+ Case (Note (Coerce (idType unpk_arg) (idType arg)) (Var arg))
+ (sanitiseCaseBndr unpk_arg)
+ [(DEFAULT,[],body)]
+ where
+ (unpk_arg:other_args) = unpk_args
+
+mk_unpk_case DataType arg unpk_args boxing_con boxing_tycon body
+ -- A data type
+ = Case (Var arg)
+ (sanitiseCaseBndr arg)
+ [(DataCon boxing_con, unpk_args, body)]
+
+sanitiseCaseBndr :: Id -> Id
+-- The argument we are scrutinising has the right type to be
+-- a case binder, so it's convenient to re-use it for that purpose.
+-- But we *must* throw away all its IdInfo. In particular, the argument
+-- will have demand info on it, and that demand info may be incorrect for
+-- the case binder. e.g. case ww_arg of ww_arg { I# x -> ... }
+-- Quite likely ww_arg isn't used in '...'. The case may get discarded
+-- if the case binder says "I'm demanded". This happened in a situation
+-- like (x+y) `seq` ....
+sanitiseCaseBndr id = id `setIdInfo` vanillaIdInfo
+
+mk_pk_let NewType arg boxing_con con_tys unpk_args body
+ = ASSERT( null other_args )
+ Let (NonRec arg (Note (Coerce (idType arg) (idType unpk_arg)) (Var unpk_arg))) body
+ where
+ (unpk_arg:other_args) = unpk_args
+
+mk_pk_let DataType arg boxing_con con_tys unpk_args body
+ = Let (NonRec arg (Con (DataCon boxing_con) con_args)) body
+ where
+ con_args = map Type con_tys ++ map Var unpk_args
- mk_unpk_case arg unpk_args boxing_con boxing_tycon body
- = Case (Var arg) (
- AlgAlts [(boxing_con, unpk_args, body)]
- NoDefault
- )
- mk_pk_let arg boxing_con con_tys unpk_args body
- = Let (NonRec arg (Con boxing_con
- (map TyArg con_tys ++ map VarArg unpk_args)))
- body
+mk_ww_local uniq ty = mkSysLocal SLIT("ww") uniq ty
-mk_ww_arg_processing (arg : args) (arg_demand : infos) max_extra_args
- | otherwise
- = -- For all others at the moment, we just
- -- pass them to the worker unchanged.
- --pprTrace "Other; num_wrkr_args=" (ppCat [ppInt num_wrkr_args, ppStr ";arg=", ppr PprDebug arg, ppr PprDebug arg_demand]) (
-
- -- Finish args to the right...
- mk_ww_arg_processing args infos max_extra_args
- `thenMaybeUs` \ (wrap_rest, work_args_info, work_rest) ->
-
- returnUs (Just (
- -- wrapper:
- \ hole -> wrap_rest (App hole (VarArg arg)),
-
- -- worker:
- (arg, arg_demand) : work_args_info,
- \ hole -> work_rest hole
- ))
- --)
+
+mk_unboxed_tuple :: [(CoreExpr, Type)] -> (CoreExpr, Type)
+mk_unboxed_tuple contents
+ = (mkConApp (unboxedTupleCon (length contents))
+ (map (Type . snd) contents ++
+ map fst contents),
+ mkTyConApp (unboxedTupleTyCon (length contents))
+ (map snd contents))
\end{code}
projects / ghc-hetmet.git / blobdiff