X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2Fstranal%2FWwLib.lhs;h=f15643046186485ddd6a4c2a020a9577f4a2f121;hb=ff833e2f75ff8ecef449ebe9dd9854b443a52e1a;hp=eeaafc9c0355ef40c4d4c6df2b587aeedee626f9;hpb=dabfa71f33eabc5a2d10959728f772aa016f1c84;p=ghc-hetmet.git diff --git a/ghc/compiler/stranal/WwLib.lhs b/ghc/compiler/stranal/WwLib.lhs index eeaafc9..f156430 100644 --- a/ghc/compiler/stranal/WwLib.lhs +++ b/ghc/compiler/stranal/WwLib.lhs @@ -1,57 +1,43 @@ % -% (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 + mkWwBodies, + worthSplitting, setUnpackStrategy ) where -import Ubiq{-uitous-} +#include "HsVersions.h" import CoreSyn -import Id ( idType, mkSysLocal, dataConArgTys ) -import IdInfo ( mkStrictnessInfo, nonAbsentArgs, Demand(..) ) -import PrelVals ( aBSENT_ERROR_ID ) -import SrcLoc ( mkUnknownSrcLoc ) -import Type ( isPrimType, mkTyVarTys, mkForAllTys, mkFunTys, - maybeAppDataTyConExpandingDicts +import CoreUtils ( exprType, mkInlineMe ) +import Id ( Id, idType, mkSysLocal, idDemandInfo, setIdDemandInfo, + isOneShotLambda, setOneShotLambda, + mkWildId, setIdInfo ) -import UniqSupply ( returnUs, thenUs, thenMaybeUs, - getUniques, UniqSM(..) +import IdInfo ( CprInfo(..), noCprInfo, vanillaIdInfo ) +import DataCon ( DataCon, splitProductType ) +import Demand ( Demand(..), wwLazy, wwPrim ) +import PrelInfo ( realWorldPrimId, aBSENT_ERROR_ID ) +import TysPrim ( realWorldStatePrimTy ) +import TysWiredIn ( tupleCon ) +import Type ( isUnLiftedType, + splitForAllTys, splitFunTys, isAlgType, + splitNewType_maybe, + mkTyConApp, mkFunTys, + Type ) -import Util ( zipWithEqual, assertPanic, panic ) +import BasicTypes ( NewOrData(..), Arity, Boxity(..) ) +import Var ( TyVar, Var, isId ) +import UniqSupply ( returnUs, thenUs, getUniqueUs, getUniquesUs, + mapUs, UniqSM ) +import Util ( zipWithEqual, zipEqual, lengthExceeds ) +import Outputable +import List ( zipWith4 ) \end{code} -%************************************************************************ -%* * -\subsection[datatype-WwLib]{@WwBinding@: a datatype for worker/wrapper-ing} -%* * -%************************************************************************ - -In the worker/wrapper stuff, we want to carry around @CoreBindings@ in -an ``intermediate form'' that can later be turned into a \tr{let} or -\tr{case} (depending on strictness info). - -\begin{code} -data WwBinding - = WwLet [CoreBinding] - | WwCase (CoreExpr -> CoreExpr) - -- the "case" will be a "strict let" of the form: - -- - -- case rhs of - -- -> body - -- - -- (instead of "let = rhs in body") - -- - -- The expr you pass to the function is "body" (the - -- expression that goes "in the corner"). -\end{code} %************************************************************************ %* * @@ -155,238 +141,430 @@ probably slightly paranoid, but OK in practice.) If it isn't the 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# -> <> x# ys +\begin{code} +mAX_WORKER_ARGS :: Int -- ToDo: set via flag +mAX_WORKER_ARGS = 6 -\ x# ys -> -- worker - let - x = I# x# - in - <> -\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 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 = any worth_it ds + -- We used not to split if the result is bottom. + -- [Justification: there's no efficiency to be gained.] + -- But it's sometimes bad not to make a wrapper. Consider + -- fw = \x# -> let x = I# x# in case e of + -- p1 -> error_fn x + -- p2 -> error_fn x + -- p3 -> the real stuff + -- The re-boxing code won't go away unless error_fn gets a wrapper too. + + 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} +%* * +%************************************************************************ + +@mkWwBodies@ is called when doing the worker/wrapper split inside a module. \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 +mkWwBodies :: Type -- Type of original function + -> Arity -- Arity of original function + -> [Demand] -- Strictness of original function + -> Bool -- True <=> function returns bottom + -> [Bool] -- One-shot-ness of the function + -> CprInfo -- Result of CPR analysis + -> UniqSM ([Demand], -- Demands for worker (value) args + Id -> CoreExpr, -- Wrapper body, lacking only the worker Id + CoreExpr -> CoreExpr) -- Worker body, lacking the original function rhs + +mkWwBodies fun_ty arity demands res_bot one_shots cpr_info + = mkWWargs fun_ty arity demands' res_bot one_shots' `thenUs` \ (wrap_args, wrap_fn_args, work_fn_args, res_ty) -> + mkWWstr wrap_args `thenUs` \ (work_dmds, wrap_fn_str, work_fn_str) -> + mkWWcpr res_ty cpr_info `thenUs` \ (wrap_fn_cpr, work_fn_cpr, cpr_res_ty) -> + mkWWfixup cpr_res_ty work_dmds `thenUs` \ (final_work_dmds, wrap_fn_fixup, work_fn_fixup) -> + + returnUs (final_work_dmds, + Note InlineMe . wrap_fn_args . wrap_fn_cpr . wrap_fn_str . wrap_fn_fixup . Var, + work_fn_fixup . work_fn_str . work_fn_cpr . work_fn_args) + -- We use an INLINE unconditionally, even if the wrapper turns out to be + -- something trivial like + -- fw = ... + -- f = __inline__ (coerce T fw) + -- The point is to propagate the coerce to f's call sites, so even though + -- f's RHS is now trivial (size 1) we still want the __inline__ to prevent + -- fw from being inlined into f's RHS + where + demands' = demands ++ repeat wwLazy + one_shots' = one_shots ++ repeat False +\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) - )) +%************************************************************************ +%* * +\subsection{Coercion stuff} +%* * +%************************************************************************ - worker_w_hole = \ orig_body -> - mkLam tyvars work_args ( - work_frag orig_body - ) - worker_ty_w_hole = \ body_ty -> - mkForAllTys tyvars $ - mkFunTys (map idType work_args) body_ty +We really want to "look through" coerces. +Reason: I've seen this situation: + + let f = coerce T (\s -> E) + in \x -> case x of + p -> coerce T' f + q -> \s -> E2 + r -> coerce T' f + +If only we w/w'd f, we'd get + let f = coerce T (\s -> fw s) + fw = \s -> E + in ... + +Now we'll inline f to get + + let fw = \s -> E + in \x -> case x of + p -> fw + q -> \s -> E2 + r -> fw + +Now we'll see that fw has arity 1, and will arity expand +the \x to get what we want. + +\begin{code} +-- mkWWargs is driven off the function type and arity. +-- It chomps bites off foralls, arrows, newtypes +-- and keeps repeating that until it's satisfied the supplied arity + +mkWWargs :: Type -> Arity + -> [Demand] -> Bool -> [Bool] -- Both these will in due course be derived + -- from the type. The [Bool] is True for a one-shot arg. + -- ** Both are infinite, extended with neutral values if necy ** + -> UniqSM ([Var], -- Wrapper args + CoreExpr -> CoreExpr, -- Wrapper fn + CoreExpr -> CoreExpr, -- Worker fn + Type) -- Type of wrapper body + +mkWWargs fun_ty arity demands res_bot one_shots + | (res_bot || arity > 0) && (not (null tyvars) || n_arg_tys > 0) + -- If the function returns bottom, we feel free to + -- build lots of wrapper args: + -- \x. let v=E in \y. bottom + -- = \xy. let v=E in bottom + = getUniquesUs n_args `thenUs` \ wrap_uniqs -> + let + val_args = zipWith4 mk_wrap_arg wrap_uniqs arg_tys demands one_shots + wrap_args = tyvars ++ val_args in - returnUs (Just (wrapper_w_hole, worker_w_hole, wrkr_strictness, worker_ty_w_hole)) + mkWWargs new_fun_ty + (arity - n_args) + (drop n_args demands) + res_bot + (drop n_args one_shots) `thenUs` \ (more_wrap_args, wrap_fn_args, work_fn_args, res_ty) -> + + returnUs (wrap_args ++ more_wrap_args, + mkLams wrap_args . wrap_fn_args, + work_fn_args . applyToVars wrap_args, + res_ty) 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 + (tyvars, tau) = splitForAllTys fun_ty + (arg_tys, body_ty) = splitFunTys tau + n_arg_tys = length arg_tys + n_args | res_bot = n_arg_tys + | otherwise = arity `min` n_arg_tys + new_fun_ty | n_args == n_arg_tys = body_ty + | otherwise = mkFunTys (drop n_args arg_tys) body_ty + +mkWWargs fun_ty arity demands res_bot one_shots + = case splitNewType_maybe fun_ty of + Nothing -> returnUs ([], id, id, fun_ty) + Just rep_ty -> mkWWargs rep_ty arity demands res_bot one_shots `thenUs` \ (wrap_args, wrap_fn_args, work_fn_args, res_ty) -> + returnUs (wrap_args, + Note (Coerce fun_ty rep_ty) . wrap_fn_args, + work_fn_args . Note (Coerce rep_ty fun_ty), + res_ty) + + +applyToVars :: [Var] -> CoreExpr -> CoreExpr +applyToVars vars fn = mkVarApps fn vars + +mk_wrap_arg uniq ty dmd one_shot + = set_one_shot one_shot (setIdDemandInfo (mkSysLocal SLIT("w") uniq ty) dmd) + where + set_one_shot True id = setOneShotLambda id + set_one_shot False id = id \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. -It returns Nothing only if it encounters an abstract type in mid-flight. +%************************************************************************ +%* * +\subsection{Fixup stuff} +%* * +%************************************************************************ \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) ( +mkWWfixup res_ty work_dmds + | null work_dmds && isUnLiftedType res_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 + -- + -- We use the state-token type which generates no code + = getUniqueUs `thenUs` \ void_arg_uniq -> let - arg_ty = idType arg + void_arg = mk_ww_local void_arg_uniq realWorldStatePrimTy 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) - )) - --) + returnUs ([wwPrim], + \ call_to_worker -> App call_to_worker (Var realWorldPrimId), + \ worker_body -> Lam void_arg worker_body) + + | otherwise + = returnUs (work_dmds, id, id) +\end{code} + + +%************************************************************************ +%* * +\subsection{Strictness stuff} +%* * +%************************************************************************ + +\begin{code} +mkWWstr :: [Var] -- Wrapper args; have their demand info on them + -- *Includes type variables* + -> UniqSM ([Demand], -- Demand on worker (value) args + CoreExpr -> CoreExpr, -- Wrapper body, lacking the worker call + -- and without its lambdas + -- This fn adds the unboxing, and makes the + -- call passing the unboxed things + + CoreExpr -> CoreExpr) -- Worker body, lacking the original body of the function, + -- but *with* lambdas + +mkWWstr wrap_args + = mk_ww_str wrap_args `thenUs` \ (work_args, wrap_fn, work_fn) -> + returnUs ( [idDemandInfo v | v <- work_args, isId v], + \ wrapper_body -> wrap_fn (mkVarApps wrapper_body work_args), + \ worker_body -> mkLams work_args (work_fn worker_body)) + + -- Empty case +mk_ww_str [] + = returnUs ([], + \ wrapper_body -> wrapper_body, + \ worker_body -> worker_body) + + +mk_ww_str (arg : ds) + | isTyVar arg + = mk_ww_str ds `thenUs` \ (worker_args, wrap_fn, work_fn) -> + returnUs (arg : worker_args, wrap_fn, work_fn) + + | otherwise + = case idDemandInfo arg of + + -- Absent case + WwLazy True -> + mk_ww_str 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_str" set_worker_arg_info unpk_args cs + in + mk_ww_str (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_str" (idType arg) + + -- Other cases + other_demand -> + mk_ww_str ds `thenUs` \ (worker_args, wrap_fn, work_fn) -> + returnUs (arg : worker_args, wrap_fn, work_fn) 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) - )) + -- If the wrapper argument is a one-shot lambda, then + -- so should (all) the corresponding worker arguments be + -- This bites when we do w/w on a case join point + set_worker_arg_info worker_arg demand = set_one_shot (setIdDemandInfo worker_arg demand) + + set_one_shot | isOneShotLambda arg = setOneShotLambda + | otherwise = \x -> x +\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} +mkWWcpr :: Type -- function body type + -> CprInfo -- CPR analysis results + -> UniqSM (CoreExpr -> CoreExpr, -- New wrapper + CoreExpr -> CoreExpr, -- New worker + Type) -- Type of worker's body + +mkWWcpr body_ty NoCPRInfo + = returnUs (id, id, body_ty) -- Must be just the strictness transf. + +mkWWcpr body_ty ReturnsCPR + | not (isAlgType body_ty) + = WARN( True, text "mkWWcpr: non-algebraic body type" <+> ppr body_ty ) + returnUs (id, id, body_ty) + + | n_con_args == 1 && isUnLiftedType con_arg_ty1 + -- Special case when there is a single result of unlifted type + = getUniquesUs 2 `thenUs` \ [work_uniq, arg_uniq] -> + let + work_wild = mk_ww_local work_uniq body_ty + arg = mk_ww_local arg_uniq con_arg_ty1 + in + returnUs (\ wkr_call -> Case wkr_call arg [(DEFAULT, [], mkConApp data_con (map Type tycon_arg_tys ++ [Var arg]))], + \ body -> Case body work_wild [(DataAlt data_con, [arg], Var arg)], + con_arg_ty1) + + | otherwise -- The general case + = getUniquesUs (n_con_args + 2) `thenUs` \ uniqs -> + let + (wrap_wild : work_wild : args) = zipWith mk_ww_local uniqs (ubx_tup_ty : body_ty : con_arg_tys) + arg_vars = map Var args + ubx_tup_con = tupleCon Unboxed n_con_args + ubx_tup_ty = exprType ubx_tup_app + ubx_tup_app = mkConApp ubx_tup_con (map Type con_arg_tys ++ arg_vars) + con_app = mkConApp data_con (map Type tycon_arg_tys ++ arg_vars) + in + returnUs (\ wkr_call -> Case wkr_call wrap_wild [(DataAlt ubx_tup_con, args, con_app)], + \ body -> Case body work_wild [(DataAlt data_con, args, ubx_tup_app)], + ubx_tup_ty) + where + (tycon, tycon_arg_tys, data_con, con_arg_tys) = splitProductType "mkWWcpr" body_ty + n_con_args = length con_arg_tys + con_arg_ty1 = head con_arg_tys +\end{code} + + +%************************************************************************ +%* * +\subsection{Utilities} +%* * +%************************************************************************ + + +\begin{code} +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) + [(DataAlt 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 (mkConApp 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 - )) - --) \end{code}