%
-% (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
- -- <blah> -> body
- --
- -- (instead of "let <blah> = rhs in body")
- --
- -- The expr you pass to the function is "body" (the
- -- expression that goes "in the corner").
-\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 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}