%
-% (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(..),
-
- worthSplitting, setUnpackStrategy,
- mkWwBodies, mkWrapper
+ mkWwBodies,
+ worthSplitting, setUnpackStrategy
) where
-IMP_Ubiq(){-uitous-}
-IMPORT_1_3(List(nub))
+#include "HsVersions.h"
import CoreSyn
-import Id ( GenId, idType, mkSysLocal, dataConArgTys, isDataCon, isNewCon, SYN_IE(Id) )
-import IdInfo ( mkStrictnessInfo, {-??nonAbsentArgs,-} Demand(..) )
-import PrelVals ( aBSENT_ERROR_ID, voidId )
-import TysPrim ( voidTy )
-import SrcLoc ( noSrcLoc )
-import Type ( isPrimType, mkTyVarTys, mkForAllTys, mkFunTys,
- splitForAllTyExpandingDicts, splitForAllTy, splitFunTyExpandingDicts,
- maybeAppDataTyConExpandingDicts,
- SYN_IE(Type)
+import CoreUtils ( exprType, mkInlineMe )
+import Id ( Id, idType, mkSysLocal, idDemandInfo, setIdDemandInfo,
+ isOneShotLambda, setOneShotLambda,
+ mkWildId, setIdInfo
)
-import TyCon ( isNewTyCon, isDataTyCon )
-import BasicTypes ( NewOrData(..) )
-import TyVar ( SYN_IE(TyVar) )
-import PprType ( GenType, GenTyVar )
-import UniqSupply ( returnUs, thenUs, thenMaybeUs,
- getUniques, getUnique, SYN_IE(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 ( unboxedTupleCon, unboxedTupleTyCon )
+import Type ( isUnLiftedType,
+ splitForAllTys, splitFunTys, isAlgType,
+ splitAlgTyConApp_maybe, splitNewType_maybe,
+ mkTyConApp, mkFunTys,
+ Type
)
-import Util ( zipWithEqual, zipEqual, assertPanic, panic, pprPanic )
-import Pretty
+import TyCon ( isNewTyCon, isProductTyCon, TyCon )
+import BasicTypes ( NewOrData(..), Arity )
+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}
%************************************************************************
%* *
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
+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 (WwLazy True : ds) = allAbsent ds
-allAbsent (WwUnpack _ True cs : ds) = allAbsent cs && allAbsent ds
-allAbsent (d : ds) = False
-allAbsent [] = True
+allAbsent ds = all absent ds
+ where
+ absent (WwLazy is_absent) = is_absent
+ absent (WwUnpack _ True cs) = allAbsent cs
+ absent other = False
\end{code}
%* *
%************************************************************************
-@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).
+@mkWwBodies@ is called when doing the worker/wrapper split inside a module.
\begin{code}
-mkWrapper :: Type -- Wrapper type
- -> [Demand] -- Wrapper strictness info
- -> UniqSM (Id -> CoreExpr) -- Wrapper body, missing worker Id
+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,
+ mkInlineMe . 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)
+ where
+ demands' = demands ++ repeat wwLazy
+ one_shots' = one_shots ++ repeat False
+\end{code}
-mkWrapper fun_ty demands
- = let
- n_wrap_args = length demands
- in
- getUniques n_wrap_args `thenUs` \ wrap_uniqs ->
+
+%************************************************************************
+%* *
+\subsection{Coercion stuff}
+%* *
+%************************************************************************
+
+
+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
--- (tyvars, tau_ty) = splitForAllTyExpandingDicts fun_ty
- (tyvars, tau_ty) = splitForAllTy fun_ty
- (arg_tys, body_ty) = splitFunTyExpandingDicts 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
- leftover_arg_tys = drop n_wrap_args arg_tys
- final_body_ty = mkFunTys leftover_arg_tys body_ty
+ val_args = zipWith4 mk_wrap_arg wrap_uniqs arg_tys demands one_shots
+ wrap_args = tyvars ++ val_args
in
- mkWwBodies tyvars wrap_args final_body_ty demands `thenUs` \ (wrap_fn, _, _) ->
- returnUs wrap_fn
+ 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
+ (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}
-@mkWwBodies@ is called when doing the worker/wrapper split inside a module.
+
+%************************************************************************
+%* *
+\subsection{Fixup stuff}
+%* *
+%************************************************************************
\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
+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
--
- getUnique `thenUs` \ void_arg_uniq ->
+ -- We use the state-token type which generates no code
+ = getUniqueUs `thenUs` \ void_arg_uniq ->
let
- void_arg = mk_ww_local void_arg_uniq voidTy
+ void_arg = mk_ww_local void_arg_uniq realWorldStatePrimTy
in
- returnUs (\ work_id -> mkLam tyvars args (App (mkTyApp (Var work_id) (mkTyVarTys tyvars)) (VarArg voidId)),
- \ body -> mkLam tyvars [void_arg] body,
- [WwLazy True])
+ returnUs ([wwPrim],
+ \ call_to_worker -> App call_to_worker (Var realWorldPrimId),
+ \ worker_body -> Lam void_arg worker_body)
-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}
+ = returnUs (work_dmds, id, id)
+\end{code}
+
+%************************************************************************
+%* *
+\subsection{Strictness stuff}
+%* *
+%************************************************************************
\begin{code}
-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
+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
-mkWW []
- = returnUs (\ wrapper_body -> wrapper_body,
- [],
+mk_ww_str []
+ = 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))
+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
-mkWW ((arg,WwUnpack new_or_data True cs) : ds)
- = getUniques (length inst_con_arg_tys) `thenUs` \ uniqs ->
- let
- unpk_args = zipWith mk_ww_local uniqs inst_con_arg_tys
- unpk_args_w_ds = zipEqual "mkWW" unpk_args cs
- in
- mkWW (unpk_args_w_ds ++ ds) `thenUs` \ (wrap_fn, worker_args, work_fn) ->
- returnUs (\ wrapper_body -> mk_unpk_case new_or_data arg unpk_args data_con arg_tycon (wrap_fn wrapper_body),
- worker_args,
- \ worker_body -> work_fn (mk_pk_let new_or_data arg data_con tycon_arg_tys unpk_args worker_body))
+ 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
- inst_con_arg_tys = dataConArgTys data_con tycon_arg_tys
- (arg_tycon, tycon_arg_tys, data_con)
- = case (maybeAppDataTyConExpandingDicts (idType arg)) of
+ -- 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}
+
- Just (arg_tycon, tycon_arg_tys, [data_con]) ->
- -- The main event: a single-constructor data type
- (arg_tycon, tycon_arg_tys, data_con)
+%************************************************************************
+%* *
+\subsection{CPR stuff}
+%* *
+%************************************************************************
- Just (_, _, data_cons) -> pprPanic "mk_ww_arg_processing: not one constr (interface files not consistent/up to date ?)" ((ppr PprDebug arg) <+> (ppr PprDebug (idType arg)))
- Nothing -> panic "mk_ww_arg_processing: not datatype"
+@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.
- -- 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)
+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 = unboxedTupleCon 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}
\begin{code}
mk_absent_let arg body
- | not (isPrimType arg_ty)
- = Let (NonRec arg (mkTyApp (Var aBSENT_ERROR_ID) [arg_ty])) 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
mk_unpk_case NewType arg unpk_args boxing_con boxing_tycon body
-- A newtype! Use a coercion not a case
- = ASSERT( null other_args && isNewTyCon boxing_tycon )
- Let (NonRec unpk_arg (Coerce (CoerceOut boxing_con) (idType unpk_arg) (Var arg)))
- body
+ = 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
- = ASSERT( isDataTyCon boxing_tycon )
- Case (Var arg)
- (AlgAlts [(boxing_con, unpk_args, body)]
- NoDefault
- )
+ = 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 && isNewCon boxing_con )
- Let (NonRec arg (Coerce (CoerceIn boxing_con) (idType arg) (Var unpk_arg))) 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
- = ASSERT( isDataCon boxing_con )
- Let (NonRec arg (Con boxing_con con_args)) body
+ = Let (NonRec arg (mkConApp boxing_con con_args)) body
where
- con_args = map TyArg con_tys ++ map VarArg unpk_args
+ con_args = map Type con_tys ++ map Var unpk_args
+
+mk_ww_local uniq ty = mkSysLocal SLIT("ww") uniq ty
-mk_ww_local uniq ty
- = mkSysLocal SLIT("ww") uniq ty noSrcLoc
\end{code}
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