module WwLib (
WwBinding(..),
- mkWwBodies, mAX_WORKER_ARGS
+ worthSplitting, setUnpackStrategy,
+ mkWwBodies, mkWrapper
) where
IMP_Ubiq(){-uitous-}
import CoreSyn
import Id ( idType, mkSysLocal, dataConArgTys )
import IdInfo ( mkStrictnessInfo, nonAbsentArgs, Demand(..) )
-import PrelVals ( aBSENT_ERROR_ID )
-import SrcLoc ( mkUnknownSrcLoc )
+import PrelVals ( aBSENT_ERROR_ID, voidId )
+import TysPrim ( voidTy )
+import SrcLoc ( noSrcLoc )
import Type ( isPrimType, mkTyVarTys, mkForAllTys, mkFunTys,
+ splitForAllTy, splitFunTyExpandingDicts,
maybeAppDataTyConExpandingDicts
)
import UniqSupply ( returnUs, thenUs, thenMaybeUs,
- getUniques, UniqSM(..)
+ getUniques, getUnique, SYN_IE(UniqSM)
)
-import Util ( zipWithEqual, assertPanic, panic )
+import Util ( zipWithEqual, zipEqual, assertPanic, panic )
\end{code}
%************************************************************************
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}
+%* *
+%************************************************************************
-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
+\begin{code}
+mAX_WORKER_ARGS :: Int -- ToDo: set via flag
+mAX_WORKER_ARGS = 6
-\ x# ys -> -- worker
- let
- x = I# x#
- in
- <<HOLE>>
-\end{verbatim}
-(Actually, we add the lambda-bound arguments at the end...) (The big
-Lambdas are added on the front later.)
+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 _ cs : ds) | n' >= 0
+ = WwUnpack True cs' `cons` go n'' ds
+ | otherwise
+ = WwUnpack 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 -- True <=> the wrapper would not be an identity function
+worthSplitting [] = False
+worthSplitting (WwLazy True : ds) = True -- Absent arg
+worthSplitting (WwUnpack True _ : ds) = True -- Arg to unpack
+worthSplitting (d : ds) = worthSplitting ds
+
+allAbsent :: [Demand] -> Bool
+allAbsent (WwLazy True : ds) = allAbsent ds
+allAbsent (WwUnpack True cs : ds) = allAbsent cs && allAbsent ds
+allAbsent (d : ds) = False
+allAbsent [] = True
+\end{code}
-\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
- wrkr_strictness = mkStrictnessInfo wrkr_demands Nothing -- no worker-of-worker...
+%************************************************************************
+%* *
+\subsection{The worker wrapper core}
+%* *
+%************************************************************************
- wrapper_w_hole = \ worker_id ->
- mkLam tyvars args (
- wrap_frag (
- mkTyApp (Var worker_id) (mkTyVarTys tyvars)
- ))
+@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).
- worker_w_hole = \ orig_body ->
- mkLam tyvars work_args (
- work_frag orig_body
- )
+\begin{code}
+mkWrapper :: Type -- Wrapper type
+ -> [Demand] -- Wrapper strictness info
+ -> UniqSM (Id -> CoreExpr) -- Wrapper body, missing worker Id
- worker_ty_w_hole = \ body_ty ->
- mkForAllTys tyvars $
- mkFunTys (map idType work_args) body_ty
+mkWrapper fun_ty demands
+ = let
+ n_wrap_args = length demands
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
+ getUniques n_wrap_args `thenUs` \ wrap_uniqs ->
+ let
+ (tyvars, tau_ty) = splitForAllTy fun_ty
+ (arg_tys, body_ty) = splitFunTyExpandingDicts tau_ty
+ wrap_args = zipWith mk_ww_local wrap_uniqs arg_tys
+ leftover_arg_tys = drop n_wrap_args arg_tys
+ final_body_ty = mkFunTys leftover_arg_tys body_ty
+ in
+ mkWwBodies tyvars wrap_args final_body_ty demands `thenUs` \ (wrap_fn, _, _) ->
+ returnUs wrap_fn
\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.
+@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
+ -> 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 args body_ty demands
+ | allAbsent demands &&
+ isPrimType body_ty
+ = -- 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
+ --
+ getUnique `thenUs` \ void_arg_uniq ->
+ let
+ void_arg = mk_ww_local void_arg_uniq voidTy
+ in
+ returnUs (\ work_id -> mkLam tyvars args (App (mkTyApp (Var work_id) (mkTyVarTys tyvars)) (VarArg voidId)),
+ \ body -> mkLam tyvars [void_arg] body,
+ [WwLazy True])
+
+mkWwBodies tyvars args body_ty demands
+ | otherwise
+ = let
+ args_w_demands = zipEqual "mkWwBodies" args demands
+ in
+ mkWW args_w_demands `thenUs` \ (wrap_fn, work_args_w_demands, work_fn) ->
+ let
+ (work_args, work_demands) = unzip work_args_w_demands
+ in
+ returnUs (\ work_id -> mkLam tyvars args (wrap_fn (mkTyApp (Var work_id) (mkTyVarTys tyvars))),
+ \ body -> mkLam tyvars work_args (work_fn body),
+ work_demands)
+\end{code}
-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) (
+mkWW :: [(Id,Demand)]
+ -> UniqSM (CoreExpr -> CoreExpr, -- Wrapper body, lacking the inner call to the worker
+ -- and without its lambdas
+ [(Id,Demand)], -- Worker args and their demand infos
+ CoreExpr -> CoreExpr) -- Worker body, lacking the original body of the function
+
+
+ -- Empty case
+mkWW []
+ = returnUs (\ wrapper_body -> wrapper_body,
+ [],
+ \ worker_body -> worker_body)
+
+
+ -- Absent case
+mkWW ((arg,WwLazy True) : ds)
+ = mkWW ds `thenUs` \ (wrap_fn, worker_args, work_fn) ->
+ returnUs (\ wrapper_body -> wrap_fn wrapper_body,
+ worker_args,
+ \ worker_body -> mk_absent_let arg (work_fn worker_body))
+
+
+ -- Unpack case
+mkWW ((arg,WwUnpack True cs) : ds)
+ = getUniques (length inst_con_arg_tys) `thenUs` \ uniqs ->
let
- arg_ty = idType arg
+ unpk_args = zipWith mk_ww_local uniqs inst_con_arg_tys
+ unpk_args_w_ds = zipEqual "mkWW" unpk_args cs
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)
- ))
+ mkWW (unpk_args_w_ds ++ ds) `thenUs` \ (wrap_fn, worker_args, work_fn) ->
+ returnUs (\ wrapper_body -> mk_unpk_case arg unpk_args data_con arg_tycon (wrap_fn wrapper_body),
+ worker_args,
+ \ worker_body -> work_fn (mk_pk_let arg data_con tycon_arg_tys unpk_args worker_body))
where
- arg_ty = idType arg
+ inst_con_arg_tys = dataConArgTys data_con tycon_arg_tys
+ (arg_tycon, tycon_arg_tys, data_con)
+ = case (maybeAppDataTyConExpandingDicts (idType arg)) of
+
+ Just (arg_tycon, tycon_arg_tys, [data_con]) ->
+ -- The main event: a single-constructor data type
+ (arg_tycon, tycon_arg_tys, data_con)
- 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
+ Just (_, _, data_cons) -> panic "mk_ww_arg_processing: not one constr (interface files not consistent/up to date ?)"
+ Nothing -> panic "mk_ww_arg_processing: not datatype"
- 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
+ -- Other cases
+mkWW ((arg,other_demand) : ds)
+ = mkWW ds `thenUs` \ (wrap_fn, worker_args, work_fn) ->
+ returnUs (\ wrapper_body -> wrap_fn (App wrapper_body (VarArg arg)),
+ (arg,other_demand) : worker_args,
+ work_fn)
+\end{code}
-mk_ww_arg_processing (arg : args) (arg_demand : infos) max_extra_args
+
+%************************************************************************
+%* *
+\subsection{Utilities}
+%* *
+%************************************************************************
+
+
+\begin{code}
+mk_absent_let arg body
+ | not (isPrimType arg_ty)
+ = Let (NonRec arg (mkTyApp (Var aBSENT_ERROR_ID) [arg_ty])) body
| 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
- ))
- --)
+ = panic "WwLib: haven't done mk_absent_let for primitives yet"
+ where
+ arg_ty = idType arg
+
+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 con_args)) body
+ where
+ con_args = map TyArg con_tys ++ map VarArg unpk_args
+
+mk_ww_local uniq ty
+ = mkSysLocal SLIT("ww") uniq ty noSrcLoc
\end{code}
projects / ghc-hetmet.git / blobdiff