%
-% (c) The AQUA Project, Glasgow University, 1993-1995
+% (c) The AQUA Project, Glasgow University, 1993-1996
%
\section[SimplUtils]{The simplifier utilities}
module SimplUtils (
floatExposesHNF,
-
+
mkCoTyLamTryingEta, mkCoLamTryingEta,
etaExpandCount,
-
+
mkIdentityAlts,
simplIdWantsToBeINLINEd,
IMPORT_Trace -- ToDo: rm (debugging)
import Pretty
-import TaggedCore
-import PlainCore
import SimplEnv
import SimplMonad
import BinderInfo
-import AbsPrel ( primOpIsCheap, realWorldStateTy,
+import PrelInfo ( primOpIsCheap, realWorldStateTy,
buildId, augmentId
IF_ATTACK_PRAGMAS(COMMA realWorldTy)
IF_ATTACK_PRAGMAS(COMMA tagOf_PrimOp)
IF_ATTACK_PRAGMAS(COMMA pprPrimOp)
)
-import AbsUniType ( extractTyVarsFromTy, getTyVarMaybe, isPrimType,
- splitTypeWithDictsAsArgs, getUniDataTyCon_maybe,
+import Type ( extractTyVarsFromTy, getTyVarMaybe, isPrimType,
+ splitTypeWithDictsAsArgs, maybeDataTyCon,
applyTy, isFunType, TyVar, TyVarTemplate
- IF_ATTACK_PRAGMAS(COMMA cmpTyVar COMMA cmpClass)
)
-import Id ( getInstantiatedDataConSig, isDataCon, getIdUniType,
+import Id ( getInstantiatedDataConSig, isDataCon, idType,
getIdArity, isBottomingId, idWantsToBeINLINEd,
DataCon(..), Id
)
:: Bool -- Float let(rec)s out of rhs
-> Bool -- Float cheap primops out of rhs
-> Bool -- OK to duplicate code
- -> CoreExpr bdr Id
+ -> GenCoreExpr bdr Id
-> Bool
floatExposesHNF float_lets float_primops ok_to_dup rhs
= try rhs
where
- try (CoCase (CoPrim _ _ _) (CoPrimAlts alts deflt) )
+ try (Case (Prim _ _ _) (PrimAlts alts deflt) )
| float_primops && (null alts || ok_to_dup)
= or (try_deflt deflt : map try_alt alts)
- try (CoLet bind body) | float_lets = try body
+ try (Let bind body) | float_lets = try body
-- `build g'
-- is like a HNF,
-- because it *will* become one.
-- likewise for `augment g h'
--
- try (CoApp (CoTyApp (CoVar bld) _) _) | bld == buildId = True
- try (CoApp (CoApp (CoTyApp (CoVar bld) _) _) _) | bld == augmentId = True
+ try (App (CoTyApp (Var bld) _) _) | bld == buildId = True
+ try (App (App (CoTyApp (Var bld) _) _) _) | bld == augmentId = True
try other = manifestlyWHNF other
{- but *not* necessarily "manifestlyBottom other"...
try_alt (lit,rhs) = try rhs
- try_deflt CoNoDefault = False
- try_deflt (CoBindDefault _ rhs) = try rhs
+ try_deflt NoDefault = False
+ try_deflt (BindDefault _ rhs) = try rhs
\end{code}
\ x y -> f x y ===> f
But we only do this if it gets rid of a whole lambda, not part.
-The idea is that lambdas are often quite helpful: they indicate
+The idea is that lambdas are often quite helpful: they indicate
head normal forms, so we don't want to chuck them away lightly.
But if they expose a simple variable then we definitely win. Even
if they expose a type application we win. So we check for this special
\begin{code}
mkCoLamTryingEta :: [Id] -- Args to the lambda
- -> PlainCoreExpr -- Lambda body
- -> PlainCoreExpr
+ -> CoreExpr -- Lambda body
+ -> CoreExpr
mkCoLamTryingEta [] body = body
mkCoLamTryingEta orig_ids body
= reduce_it (reverse orig_ids) body
where
- bale_out = mkCoLam orig_ids body
+ bale_out = mkValLam orig_ids body
reduce_it [] residual
| residual_ok residual = residual
| otherwise = bale_out
- reduce_it (id:ids) (CoApp fun (CoVarAtom arg))
+ reduce_it (id:ids) (App fun (VarArg arg))
| id == arg
- && getIdUniType id /= realWorldStateTy
- -- *never* eta-reduce away a PrimIO state token! (WDP 94/11)
+ && idType id /= realWorldStateTy
+ -- *never* eta-reduce away a PrimIO state token! (WDP 94/11)
= reduce_it ids fun
reduce_it ids other = bale_out
is_elem = isIn "mkCoLamTryingEta"
-----------
- residual_ok :: PlainCoreExpr -> Bool -- Checks for type application
- -- and function not one of the
+ residual_ok :: CoreExpr -> Bool -- Checks for type application
+ -- and function not one of the
-- bound vars
residual_ok (CoTyApp fun ty) = residual_ok fun
- residual_ok (CoVar v) = not (v `is_elem` orig_ids) -- Fun mustn't be one of
+ residual_ok (Var v) = not (v `is_elem` orig_ids) -- Fun mustn't be one of
-- the bound ids
residual_ok other = False
\end{code}
to represent "infinity", which is a bit of a hack.
\begin{code}
-etaExpandCount :: CoreExpr bdr Id
+etaExpandCount :: GenCoreExpr bdr Id
-> Int -- Number of extra args you can safely abstract
-etaExpandCount (CoLam ids body)
- = length ids + etaExpandCount body
+etaExpandCount (Lam _ body)
+ = 1 + etaExpandCount body
-etaExpandCount (CoLet bind body)
- | all manifestlyCheap (rhssOfBind bind)
+etaExpandCount (Let bind body)
+ | all manifestlyCheap (rhssOfBind bind)
= etaExpandCount body
-
-etaExpandCount (CoCase scrut alts)
- | manifestlyCheap scrut
+
+etaExpandCount (Case scrut alts)
+ | manifestlyCheap scrut
= minimum [etaExpandCount rhs | rhs <- rhssOfAlts alts]
-etaExpandCount (CoApp fun _) = case etaExpandCount fun of
+etaExpandCount (App fun _) = case etaExpandCount fun of
0 -> 0
n -> n-1 -- Knock off one
etaExpandCount fun@(CoTyApp _ _) = eta_fun fun
-etaExpandCount fun@(CoVar _) = eta_fun fun
+etaExpandCount fun@(Var _) = eta_fun fun
etaExpandCount other = 0 -- Give up
- -- CoLit, CoCon, CoPrim,
+ -- Lit, Con, Prim,
-- CoTyLam,
- -- CoScc (pessimistic; ToDo),
- -- CoLet with non-whnf rhs(s),
- -- CoCase with non-whnf scrutinee
+ -- Scc (pessimistic; ToDo),
+ -- Let with non-whnf rhs(s),
+ -- Case with non-whnf scrutinee
-eta_fun :: CoreExpr bdr Id -- The function
+eta_fun :: GenCoreExpr bdr Id -- The function
-> Int -- How many args it can safely be applied to
eta_fun (CoTyApp fun ty) = eta_fun fun
-eta_fun expr@(CoVar v)
+eta_fun expr@(Var v)
| isBottomingId v -- Bottoming ids have "infinite arity"
= 10000 -- Blargh. Infinite enough!
-eta_fun expr@(CoVar v)
+eta_fun expr@(Var v)
| maybeToBool arity_maybe -- We know the arity
= arity
where
to bring a couple of lambdas together. The main examples of things
which aren't WHNF but are ``cheap'' are:
- * case e of
+ * case e of
pi -> ei
where e, and all the ei are cheap; and
where op is a cheap primitive operator
\begin{code}
-manifestlyCheap :: CoreExpr bndr Id -> Bool
+manifestlyCheap :: GenCoreExpr bndr Id -> Bool
-manifestlyCheap (CoVar _) = True
-manifestlyCheap (CoLit _) = True
-manifestlyCheap (CoCon _ _ _) = True
-manifestlyCheap (CoLam _ _) = True
+manifestlyCheap (Var _) = True
+manifestlyCheap (Lit _) = True
+manifestlyCheap (Con _ _ _) = True
+manifestlyCheap (Lam _ _) = True
manifestlyCheap (CoTyLam _ e) = manifestlyCheap e
-manifestlyCheap (CoSCC _ e) = manifestlyCheap e
+manifestlyCheap (SCC _ e) = manifestlyCheap e
-manifestlyCheap (CoPrim op _ _) = primOpIsCheap op
+manifestlyCheap (Prim op _ _) = primOpIsCheap op
-manifestlyCheap (CoLet bind body)
+manifestlyCheap (Let bind body)
= manifestlyCheap body && all manifestlyCheap (rhssOfBind bind)
-manifestlyCheap (CoCase scrut alts)
+manifestlyCheap (Case scrut alts)
= manifestlyCheap scrut && all manifestlyCheap (rhssOfAlts alts)
manifestlyCheap other_expr -- look for manifest partial application
= case (collectArgs other_expr) of { (fun, args) ->
case fun of
- CoVar f | isBottomingId f -> True -- Application of a function which
+ Var f | isBottomingId f -> True -- Application of a function which
-- always gives bottom; we treat this as
-- a WHNF, because it certainly doesn't
-- need to be shared!
- CoVar f -> let
+ Var f -> let
num_val_args = length [ a | (ValArg a) <- args ]
- in
+ in
num_val_args == 0 || -- Just a type application of
-- a variable (f t1 t2 t3)
-- counts as WHNF
_ -> False
}
-
-
--- ToDo: Move to CoreFuns
-
-rhssOfBind :: CoreBinding bndr bdee -> [CoreExpr bndr bdee]
-
-rhssOfBind (CoNonRec _ rhs) = [rhs]
-rhssOfBind (CoRec pairs) = [rhs | (_,rhs) <- pairs]
-
-rhssOfAlts :: CoreCaseAlternatives bndr bdee -> [CoreExpr bndr bdee]
-
-rhssOfAlts (CoAlgAlts alts deflt) = rhssOfDeflt deflt ++
- [rhs | (_,_,rhs) <- alts]
-rhssOfAlts (CoPrimAlts alts deflt) = rhssOfDeflt deflt ++
- [rhs | (_,rhs) <- alts]
-rhssOfDeflt CoNoDefault = []
-rhssOfDeflt (CoBindDefault _ rhs) = [rhs]
\end{code}
Eta reduction on type lambdas
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-We have a go at doing
+We have a go at doing
/\a -> <expr> a ===> <expr>
f ab d = let d1 = ...d... in
letrec f' b x = ...d...(f' b)... in
f' b
-specialise ==>
+specialise ==>
f.Int b = letrec f' b x = ...dInt...(f' b)... in
f' b
-float ==>
+float ==>
f' b x = ...dInt...(f' b)...
f.Int b = f' b
-Now we really want to simplify to
+Now we really want to simplify to
f.Int = f'
/\ a -> f Char# a =NO=> f Char#
\begin{code}
-mkCoTyLamTryingEta :: [TyVar] -> PlainCoreExpr -> PlainCoreExpr
+mkCoTyLamTryingEta :: [TyVar] -> CoreExpr -> CoreExpr
mkCoTyLamTryingEta tyvars tylam_body
= if
strip_tyvar_args args_so_far fun
= (args_so_far, fun)
- check_fun (CoVar f) = True -- Claim: tyvars not mentioned by type of f
+ check_fun (Var f) = True -- Claim: tyvars not mentioned by type of f
check_fun other = False
-
-{- OLD:
-mkCoTyLamTryingEta :: TyVar -> PlainCoreExpr -> PlainCoreExpr
-
-mkCoTyLamTryingEta tyvar body
- = case body of
- CoTyApp fun ty ->
- case getTyVarMaybe ty of
- Just tyvar' | tyvar == tyvar' &&
- ok fun -> fun
- -- Ha! So it's /\ a -> fun a, and fun is "ok"
-
- other -> CoTyLam tyvar body
- other -> CoTyLam tyvar body
- where
- is_elem = isIn "mkCoTyLamTryingEta"
-
- ok :: PlainCoreExpr -> Bool -- Returns True iff the expression doesn't
- -- mention tyvar
-
- ok (CoVar v) = True -- Claim: tyvar not mentioned by type of v
- ok (CoApp fun arg) = ok fun -- Claim: tyvar not mentioned by type of arg
- ok (CoTyApp fun ty) = not (tyvar `is_elem` extractTyVarsFromTy ty) &&
- ok fun
- ok other = False
--}
\end{code}
Let to case
\begin{code}
mkIdentityAlts
- :: UniType -- type of RHS
+ :: Type -- type of RHS
-> SmplM InAlts -- result
mkIdentityAlts rhs_ty
| isPrimType rhs_ty
= newId rhs_ty `thenSmpl` \ binder ->
- returnSmpl (CoPrimAlts [] (CoBindDefault (binder, bad_occ_info) (CoVar binder)))
+ returnSmpl (PrimAlts [] (BindDefault (binder, bad_occ_info) (Var binder)))
| otherwise
- = case getUniDataTyCon_maybe rhs_ty of
+ = case maybeDataTyCon rhs_ty of
Just (tycon, ty_args, [data_con]) -> -- algebraic type suitable for unpacking
let
(_,inst_con_arg_tys,_) = getInstantiatedDataConSig data_con ty_args
in
newIds inst_con_arg_tys `thenSmpl` \ new_bindees ->
let
- new_binders = [ (b, bad_occ_info) | b <- new_bindees ]
+ new_binders = [ (b, bad_occ_info) | b <- new_bindees ]
in
returnSmpl (
- CoAlgAlts
- [(data_con, new_binders, CoCon data_con ty_args (map CoVarAtom new_bindees))]
- CoNoDefault
+ AlgAlts
+ [(data_con, new_binders, Con data_con ty_args (map VarArg new_bindees))]
+ NoDefault
)
- _ -> -- Multi-constructor or abstract algebraic type
+ _ -> -- Multi-constructor or abstract algebraic type
newId rhs_ty `thenSmpl` \ binder ->
- returnSmpl (CoAlgAlts [] (CoBindDefault (binder,bad_occ_info) (CoVar binder)))
+ returnSmpl (AlgAlts [] (BindDefault (binder,bad_occ_info) (Var binder)))
where
bad_occ_info = ManyOcc 0 -- Non-committal!
\end{code}
\begin{code}
simplIdWantsToBeINLINEd :: Id -> SimplEnv -> Bool
-simplIdWantsToBeINLINEd id env
- = if switchIsSet env IgnoreINLINEPragma
+simplIdWantsToBeINLINEd id env
+ = if switchIsSet env IgnoreINLINEPragma
then False
else idWantsToBeINLINEd id
-type_ok_for_let_to_case :: UniType -> Bool
+type_ok_for_let_to_case :: Type -> Bool
-type_ok_for_let_to_case ty
- = case getUniDataTyCon_maybe ty of
+type_ok_for_let_to_case ty
+ = case maybeDataTyCon ty of
Nothing -> False
Just (tycon, ty_args, []) -> False
Just (tycon, ty_args, non_null_data_cons) -> True
projects / ghc-hetmet.git / blobdiff