%
-% (c) The AQUA Project, Glasgow University, 1994-1995
+% (c) The AQUA Project, Glasgow University, 1994-1996
%
-\section[CoreUnfold]{Core-syntax functions to do with unfoldings}
+\section[CoreUnfold]{Core-syntax unfoldings}
+
+Unfoldings (which can travel across module boundaries) are in Core
+syntax (namely @CoreExpr@s).
+
+The type @Unfolding@ sits ``above'' simply-Core-expressions
+unfoldings, capturing ``higher-level'' things we know about a binding,
+usually things that the simplifier found out (e.g., ``it's a
+literal''). In the corner of a @SimpleUnfolding@ unfolding, you will
+find, unsurprisingly, a Core expression.
\begin{code}
#include "HsVersions.h"
module CoreUnfold (
- calcUnfoldingGuidance,
+ SimpleUnfolding(..), Unfolding(..), UnfoldingGuidance(..), -- types
+ UfExpr, RdrName, -- For closure (delete in 1.3)
+
+ FormSummary(..), mkFormSummary, whnfOrBottom, exprSmallEnoughToDup, exprIsTrivial,
+
+ noUnfolding, mkMagicUnfolding, mkUnfolding, getUnfoldingTemplate,
- pprCoreUnfolding,
- mentionedInUnfolding
+ smallEnoughToInline, couldBeSmallEnoughToInline, certainlySmallEnoughToInline,
+ okToInline,
+ calcUnfoldingGuidance,
+
+ PragmaInfo(..) -- Re-export
) where
-import AbsPrel ( primOpCanTriggerGC, PrimOp(..), PrimKind
- IF_ATTACK_PRAGMAS(COMMA tagOf_PrimOp)
- IF_ATTACK_PRAGMAS(COMMA pprPrimOp)
+IMP_Ubiq()
+#if defined (__GLASGOW_HASKELL__) && __GLASGOW_HASKELL__ <= 201
+IMPORT_DELOOPER(IdLoop) -- for paranoia checking;
+ -- and also to get mkMagicUnfoldingFun
+IMPORT_DELOOPER(PrelLoop) -- for paranoia checking
+IMPORT_DELOOPER(SmplLoop)
+#else
+import {-# SOURCE #-} MagicUFs
+import {-# SOURCE #-} Id ( Id )
+#endif
+
+import Bag ( emptyBag, unitBag, unionBags, Bag )
+
+import CmdLineOpts ( opt_UnfoldingCreationThreshold,
+ opt_UnfoldingUseThreshold,
+ opt_UnfoldingConDiscount
)
-import AbsUniType ( getMentionedTyConsAndClassesFromUniType,
- getUniDataTyCon, getTyConFamilySize,
- pprParendUniType, Class, TyCon, TyVar,
- UniType, TauType(..)
- IF_ATTACK_PRAGMAS(COMMA cmpTyCon COMMA cmpClass)
- IF_ATTACK_PRAGMAS(COMMA cmpTyVar)
- IF_ATTACK_PRAGMAS(COMMA cmpUniType)
- )
-import Bag
-import BasicLit ( isNoRepLit, isLitLitLit, BasicLit(..){-.. is for pragmas-} )
-import CgCompInfo ( uNFOLDING_CHEAP_OP_COST,
+import Constants ( uNFOLDING_CHEAP_OP_COST,
uNFOLDING_DEAR_OP_COST,
uNFOLDING_NOREP_LIT_COST
)
-import CoreFuns ( digForLambdas, typeOfCoreExpr )
-import CoreSyn -- mostly re-exporting this stuff
-import CostCentre ( showCostCentre, noCostCentreAttached,
- currentOrSubsumedCosts, ccMentionsId, CostCentre
- )
-import Id ( pprIdInUnfolding, getIdUniType,
- whatsMentionedInId, Id, DataCon(..)
+import BinderInfo ( BinderInfo(..), FunOrArg, DuplicationDanger, InsideSCC, isDupDanger )
+import PragmaInfo ( PragmaInfo(..) )
+import CoreSyn
+import CoreUtils ( unTagBinders )
+import HsCore ( UfExpr )
+import RdrHsSyn ( RdrName )
+import OccurAnal ( occurAnalyseGlobalExpr )
+import CoreUtils ( coreExprType )
+--import CostCentre ( ccMentionsId )
+import Id ( idType, getIdArity, isBottomingId, isDataCon, isPrimitiveId_maybe,
+ SYN_IE(IdSet), GenId{-instances-} )
+import PrimOp ( primOpCanTriggerGC, fragilePrimOp, PrimOp(..) )
+import IdInfo ( ArityInfo(..), bottomIsGuaranteed )
+import Literal ( isNoRepLit, isLitLitLit )
+import Pretty
+import TyCon ( tyConFamilySize )
+import Type ( maybeAppDataTyConExpandingDicts )
+import Unique ( Unique )
+import UniqSet ( emptyUniqSet, unitUniqSet, mkUniqSet,
+ addOneToUniqSet, unionUniqSets
)
-import IdInfo
-import Maybes
+import Usage ( SYN_IE(UVar) )
+import Maybes ( maybeToBool )
+import Util ( isIn, panic, assertPanic )
+#if __GLASGOW_HASKELL__ >= 202
import Outputable
-import PlainCore ( instCoreExpr )
-import Pretty
-import SimplEnv ( UnfoldingGuidance(..) )
-import UniqSet
-import Unique ( uniqSupply_u, UniqueSupply )
-import Util
+
+#endif
+\end{code}
+
+%************************************************************************
+%* *
+\subsection{@Unfolding@ and @UnfoldingGuidance@ types}
+%* *
+%************************************************************************
+
+\begin{code}
+data Unfolding
+ = NoUnfolding
+
+ | CoreUnfolding SimpleUnfolding
+
+ | MagicUnfolding
+ Unique -- Unique of the Id whose magic unfolding this is
+ MagicUnfoldingFun
+
+
+data SimpleUnfolding
+ = SimpleUnfolding -- An unfolding with redundant cached information
+ FormSummary -- Tells whether the template is a WHNF or bottom
+ UnfoldingGuidance -- Tells about the *size* of the template.
+ SimplifiableCoreExpr -- Template
+
+
+noUnfolding = NoUnfolding
+
+mkUnfolding inline_prag expr
+ = let
+ -- strictness mangling (depends on there being no CSE)
+ ufg = calcUnfoldingGuidance inline_prag opt_UnfoldingCreationThreshold expr
+ occ = occurAnalyseGlobalExpr expr
+ cuf = CoreUnfolding (SimpleUnfolding (mkFormSummary expr) ufg occ)
+
+ cont = case occ of { Var _ -> cuf; _ -> cuf }
+ in
+ case ufg of { UnfoldAlways -> cont; _ -> cont }
+
+mkMagicUnfolding :: Unique -> Unfolding
+mkMagicUnfolding tag = MagicUnfolding tag (mkMagicUnfoldingFun tag)
+
+getUnfoldingTemplate :: Unfolding -> CoreExpr
+getUnfoldingTemplate (CoreUnfolding (SimpleUnfolding _ _ expr))
+ = unTagBinders expr
+getUnfoldingTemplate other = panic "getUnfoldingTemplate"
+
+
+data UnfoldingGuidance
+ = UnfoldNever
+ | UnfoldAlways -- There is no "original" definition,
+ -- so you'd better unfold. Or: something
+ -- so cheap to unfold (e.g., 1#) that
+ -- you should do it absolutely always.
+
+ | UnfoldIfGoodArgs Int -- if "m" type args
+ Int -- and "n" value args
+
+ [Int] -- Discount if the argument is evaluated.
+ -- (i.e., a simplification will definitely
+ -- be possible). One elt of the list per *value* arg.
+
+ Int -- The "size" of the unfolding; to be elaborated
+ -- later. ToDo
+
+ Int -- Scrutinee discount: the discount to substract if the thing is in
+ -- a context (case (thing args) of ...),
+ -- (where there are the right number of arguments.)
+\end{code}
+
+\begin{code}
+instance Outputable UnfoldingGuidance where
+ ppr sty UnfoldAlways = ptext SLIT("_ALWAYS_")
+ ppr sty (UnfoldIfGoodArgs t v cs size discount)
+ = hsep [ptext SLIT("_IF_ARGS_"), int t, int v,
+ if null cs -- always print *something*
+ then char 'X'
+ else hcat (map (text . show) cs),
+ int size,
+ int discount ]
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{Figuring out things about expressions}
+%* *
+%************************************************************************
+
+\begin{code}
+data FormSummary
+ = VarForm -- Expression is a variable (or scc var, etc)
+ | ValueForm -- Expression is a value: i.e. a value-lambda,constructor, or literal
+ | BottomForm -- Expression is guaranteed to be bottom. We're more gung
+ -- ho about inlining such things, because it can't waste work
+ | OtherForm -- Anything else
+
+instance Outputable FormSummary where
+ ppr sty VarForm = ptext SLIT("Var")
+ ppr sty ValueForm = ptext SLIT("Value")
+ ppr sty BottomForm = ptext SLIT("Bot")
+ ppr sty OtherForm = ptext SLIT("Other")
+
+mkFormSummary ::GenCoreExpr bndr Id tyvar uvar -> FormSummary
+
+mkFormSummary expr
+ = go (0::Int) expr -- The "n" is the number of (value) arguments so far
+ where
+ go n (Lit _) = ASSERT(n==0) ValueForm
+ go n (Con _ _) = ASSERT(n==0) ValueForm
+ go n (Prim _ _) = OtherForm
+ go n (SCC _ e) = go n e
+ go n (Coerce _ _ e) = go n e
+
+ go n (Let (NonRec b r) e) | exprIsTrivial r = go n e -- let f = f' alpha in (f,g)
+ -- should be treated as a value
+ go n (Let _ e) = OtherForm
+ go n (Case _ _) = OtherForm
+
+ go 0 (Lam (ValBinder x) e) = ValueForm -- NB: \x.bottom /= bottom!
+ go n (Lam (ValBinder x) e) = go (n-1) e -- Applied lambda
+ go n (Lam other_binder e) = go n e
+
+ go n (App fun arg) | isValArg arg = go (n+1) fun
+ go n (App fun other_arg) = go n fun
+
+ go n (Var f) | isBottomingId f = BottomForm
+ | isDataCon f = ValueForm -- Can happen inside imported unfoldings
+ go 0 (Var f) = VarForm
+ go n (Var f) = case getIdArity f of
+ ArityExactly a | n < a -> ValueForm
+ ArityAtLeast a | n < a -> ValueForm
+ other -> OtherForm
+
+whnfOrBottom :: GenCoreExpr bndr Id tyvar uvar -> Bool
+whnfOrBottom e = case mkFormSummary e of
+ VarForm -> True
+ ValueForm -> True
+ BottomForm -> True
+ OtherForm -> False
+\end{code}
+
+@exprIsTrivial@ is true of expressions we are unconditionally happy to duplicate;
+simple variables and constants, and type applications.
+
+\begin{code}
+exprIsTrivial (Var v) = True
+exprIsTrivial (Lit lit) = not (isNoRepLit lit)
+exprIsTrivial (App e (TyArg _)) = exprIsTrivial e
+exprIsTrivial (Coerce _ _ e) = exprIsTrivial e
+exprIsTrivial other = False
\end{code}
+\begin{code}
+exprSmallEnoughToDup (Con _ _) = True -- Could check # of args
+exprSmallEnoughToDup (Prim op _) = not (fragilePrimOp op) -- Could check # of args
+exprSmallEnoughToDup (Lit lit) = not (isNoRepLit lit)
+exprSmallEnoughToDup (Coerce _ _ e) = exprSmallEnoughToDup e
+exprSmallEnoughToDup expr
+ = case (collectArgs expr) of { (fun, _, _, vargs) ->
+ case fun of
+ Var v | length vargs <= 4 -> True
+ _ -> False
+ }
+
+\end{code}
+
+
%************************************************************************
%* *
\subsection[calcUnfoldingGuidance]{Calculate ``unfolding guidance'' for an expression}
\begin{code}
calcUnfoldingGuidance
- :: Bool -- True <=> OK if _scc_s appear in expr
- -> Int -- bomb out if size gets bigger than this
- -> PlainCoreExpr -- expression to look at
+ :: PragmaInfo -- INLINE pragma stuff
+ -> Int -- bomb out if size gets bigger than this
+ -> CoreExpr -- expression to look at
-> UnfoldingGuidance
-calcUnfoldingGuidance scc_s_OK bOMB_OUT_SIZE expr
- = let
- (ty_binders, val_binders, body) = digForLambdas expr
- in
- case (sizeExpr scc_s_OK bOMB_OUT_SIZE val_binders body) of
+calcUnfoldingGuidance IMustBeINLINEd bOMB_OUT_SIZE expr = UnfoldAlways -- Always inline if the INLINE pragma says so
+calcUnfoldingGuidance IWantToBeINLINEd bOMB_OUT_SIZE expr = UnfoldAlways -- Always inline if the INLINE pragma says so
+calcUnfoldingGuidance IMustNotBeINLINEd bOMB_OUT_SIZE expr = UnfoldNever -- ...and vice versa...
+
+calcUnfoldingGuidance NoPragmaInfo bOMB_OUT_SIZE expr
+ = case collectBinders expr of { (use_binders, ty_binders, val_binders, body) ->
+ case (sizeExpr bOMB_OUT_SIZE val_binders body) of
- Nothing -> UnfoldNever
+ TooBig -> UnfoldNever
- Just (size, cased_args)
- -> let
- uf = UnfoldIfGoodArgs
+ SizeIs size cased_args scrut_discount
+ -> UnfoldIfGoodArgs
(length ty_binders)
(length val_binders)
- [ b `is_elem` cased_args | b <- val_binders ]
- size
- in
- -- pprTrace "calcUnfold:" (ppAbove (ppr PprDebug uf) (ppr PprDebug expr))
- uf
- where
- is_elem = isIn "calcUnfoldingGuidance"
+ (map discount_for val_binders)
+ (I# size)
+ (I# scrut_discount)
+ where
+ discount_for b
+ | is_data && b `is_elem` cased_args = tyConFamilySize tycon
+ | otherwise = 0
+ where
+ (is_data, tycon)
+ = case (maybeAppDataTyConExpandingDicts (idType b)) of
+ Nothing -> (False, panic "discount")
+ Just (tc,_,_) -> (True, tc)
+
+ is_elem = isIn "calcUnfoldingGuidance" }
\end{code}
\begin{code}
-sizeExpr :: Bool -- True <=> _scc_s OK
- -> Int -- Bomb out if it gets bigger than this
+sizeExpr :: Int -- Bomb out if it gets bigger than this
-> [Id] -- Arguments; we're interested in which of these
-- get case'd
- -> PlainCoreExpr
- -> Maybe (Int, -- Size
- [Id] -- Subset of args which are cased
- )
+ -> CoreExpr
+ -> ExprSize
-sizeExpr scc_s_OK bOMB_OUT_SIZE args expr
+sizeExpr (I# bOMB_OUT_SIZE) args expr
= size_up expr
where
- size_up (CoVar v) = sizeOne
- size_up (CoApp fun arg) = size_up fun `addSizeN` 1
- size_up (CoTyApp fun ty) = size_up fun -- They're free
- size_up (CoLit lit) = if isNoRepLit lit
- then sizeN uNFOLDING_NOREP_LIT_COST
- else sizeOne
-
- size_up (CoSCC _ (CoCon _ _ _)) = Nothing -- **** HACK *****
- size_up (CoSCC lbl body)
- = if scc_s_OK then size_up body else Nothing
-
- size_up (CoCon con tys args) = sizeN (length args + 1)
- size_up (CoPrim op tys args) = sizeN op_cost -- NB: no charge for PrimOp args
+ size_up (Var v) = sizeZero
+ size_up (Lit lit) | isNoRepLit lit = sizeN uNFOLDING_NOREP_LIT_COST
+ | otherwise = sizeZero
+
+ size_up (SCC lbl body) = size_up body -- SCCs cost nothing
+ size_up (Coerce _ _ body) = size_up body -- Coercions cost nothing
+
+ size_up (App fun arg) = size_up fun `addSize` size_up_arg arg
+ -- NB Zero cost for for type applications;
+ -- others cost 1 or more
+
+ size_up (Con con args) = conSizeN (numValArgs args)
+ -- We don't count 1 for the constructor because we're
+ -- quite keen to get constructors into the open
+
+ size_up (Prim op args) = sizeN op_cost -- NB: no charge for PrimOp args
where
op_cost = if primOpCanTriggerGC op
then uNFOLDING_DEAR_OP_COST
-- number chosen to avoid unfolding (HACK)
else uNFOLDING_CHEAP_OP_COST
- size_up (CoLam binders body) = size_up body `addSizeN` length binders
- size_up (CoTyLam tyvar body) = size_up body
+ size_up expr@(Lam _ _)
+ = let
+ (uvars, tyvars, args, body) = collectBinders expr
+ in
+ size_up body `addSizeN` length args
- size_up (CoLet (CoNonRec binder rhs) body)
- = size_up rhs
+ size_up (Let (NonRec binder rhs) body)
+ = nukeScrutDiscount (size_up rhs)
`addSize`
size_up body
- `addSizeN`
- 1
- size_up (CoLet (CoRec pairs) body)
- = foldr addSize sizeZero [size_up rhs | (_,rhs) <- pairs]
+ size_up (Let (Rec pairs) body)
+ = nukeScrutDiscount (foldr addSize sizeZero [size_up rhs | (_,rhs) <- pairs])
`addSize`
size_up body
- `addSizeN`
- length pairs
-
- size_up (CoCase scrut alts)
- = size_up_scrut scrut
+
+ size_up (Case scrut alts)
+ = nukeScrutDiscount (size_up scrut)
`addSize`
- size_up_alts (typeOfCoreExpr scrut) alts
+ arg_discount scrut
+ `addSize`
+ size_up_alts (coreExprType scrut) alts
-- We charge for the "case" itself in "size_up_alts"
------------
- size_up_alts scrut_ty (CoAlgAlts alts deflt)
- = foldr (addSize . size_alg_alt) (size_up_deflt deflt) alts
- `addSizeN`
- (case (getTyConFamilySize tycon) of { Just n -> n })
- -- NB: we charge N for an alg. "case", where N is
- -- the number of constructors in the thing being eval'd.
- -- (You'll eventually get a "discount" of N if you
- -- think the "case" is likely to go away.)
+ -- In an application we charge 0 for type application
+ -- 1 for most anything else
+ -- N for norep_lits
+ size_up_arg (LitArg lit) | isNoRepLit lit = sizeN uNFOLDING_NOREP_LIT_COST
+ size_up_arg (TyArg _) = sizeZero
+ size_up_arg other = sizeOne
+
+ ------------
+ size_up_alts scrut_ty (AlgAlts alts deflt)
+ = (foldr (addSize . size_alg_alt) (size_up_deflt deflt) alts)
+ `addSizeN`
+ alt_cost
where
size_alg_alt (con,args,rhs) = size_up rhs
-- Don't charge for args, so that wrappers look cheap
- (tycon, _, _) = getUniDataTyCon scrut_ty
-
-
- size_up_alts _ (CoPrimAlts alts deflt)
- = foldr (addSize . size_prim_alt) (size_up_deflt deflt) alts
+ -- NB: we charge N for an alg. "case", where N is
+ -- the number of constructors in the thing being eval'd.
+ -- (You'll eventually get a "discount" of N if you
+ -- think the "case" is likely to go away.)
+ -- It's important to charge for alternatives. If you don't then you
+ -- get size 1 for things like:
+ -- case x of { A -> 1#; B -> 2#; ... lots }
+
+ alt_cost :: Int
+ alt_cost
+ = case (maybeAppDataTyConExpandingDicts scrut_ty) of
+ Nothing -> 1
+ Just (tc,_,_) -> tyConFamilySize tc
+
+ size_up_alts _ (PrimAlts alts deflt)
+ = foldr (addSize . size_prim_alt) (size_up_deflt deflt) alts
-- *no charge* for a primitive "case"!
where
size_prim_alt (lit,rhs) = size_up rhs
------------
- size_up_deflt CoNoDefault = sizeZero
- size_up_deflt (CoBindDefault binder rhs) = size_up rhs
+ size_up_deflt NoDefault = sizeZero
+ size_up_deflt (BindDefault binder rhs) = size_up rhs
------------
- -- Scrutinees. There are two things going on here.
- -- First, we want to record if we're case'ing an argument
- -- Second, we want to charge nothing for the srutinee if it's just
- -- a variable. That way wrapper-like things look cheap.
- size_up_scrut (CoVar v) | v `is_elem` args = Just (0, [v])
- | otherwise = Just (0, [])
- size_up_scrut other = size_up other
+ -- We want to record if we're case'ing an argument
+ arg_discount (Var v) | v `is_elem` args = scrutArg v
+ arg_discount other = sizeZero
+ is_elem :: Id -> [Id] -> Bool
is_elem = isIn "size_up_scrut"
------------
- sizeZero = Just (0, [])
- sizeOne = Just (1, [])
- sizeN n = Just (n, [])
- sizeVar v = Just (0, [v])
-
- addSizeN Nothing _ = Nothing
- addSizeN (Just (n, xs)) m
- | tot < bOMB_OUT_SIZE = Just (tot, xs)
- | otherwise = -- pprTrace "bomb1:" (ppCat [ppInt tot, ppInt bOMB_OUT_SIZE, ppr PprDebug expr])
- Nothing
+ -- These addSize things have to be here because
+ -- I don't want to give them bOMB_OUT_SIZE as an argument
+
+ addSizeN TooBig _ = TooBig
+ addSizeN (SizeIs n xs d) (I# m)
+ | n_tot -# d <# bOMB_OUT_SIZE = SizeIs n_tot xs d
+ | otherwise = TooBig
where
- tot = n+m
-
- addSize Nothing _ = Nothing
- addSize _ Nothing = Nothing
- addSize (Just (n, xs)) (Just (m, ys))
- | tot < bOMB_OUT_SIZE = Just (tot, xys)
- | otherwise = -- pprTrace "bomb2:" (ppCat [ppInt tot, ppInt bOMB_OUT_SIZE, ppr PprDebug expr])
- Nothing
+ n_tot = n +# m
+
+ addSize TooBig _ = TooBig
+ addSize _ TooBig = TooBig
+ addSize (SizeIs n1 xs d1) (SizeIs n2 ys d2)
+ | (n_tot -# d_tot) <# bOMB_OUT_SIZE = SizeIs n_tot xys d_tot
+ | otherwise = TooBig
where
- tot = n+m
- xys = xs ++ ys
-\end{code}
-
-%************************************************************************
-%* *
-\subsection[unfoldings-for-ifaces]{Processing unfoldings for interfaces}
-%* *
-%************************************************************************
-
-Of course, the main thing we do to unfoldings-for-interfaces is {\em
-print} them. But, while we're at it, we collect info about
-``mentioned'' Ids, etc., etc.---we're going to need this stuff anyway.
+ n_tot = n1 +# n2
+ d_tot = d1 +# d2
+ xys = xs ++ ys
-%************************************************************************
-%* *
-\subsubsection{Monad stuff for the unfolding-generation game}
-%* *
-%************************************************************************
-\begin{code}
-type UnfoldM bndr thing
- = IdSet -- in-scope Ids (passed downwards only)
- -> (bndr -> Id) -- to extract an Id from a binder (down only)
-
- -> (Bag Id, -- mentioned global vars (ditto)
- Bag TyCon, -- ditto, tycons
- Bag Class, -- ditto, classes
- Bool) -- True <=> mentions something litlit-ish
-
- -> (thing, (Bag Id, Bag TyCon, Bag Class, Bool)) -- accumulated...
\end{code}
-A little stuff for in-scopery:
-\begin{code}
-no_in_scopes :: IdSet
-add1 :: IdSet -> Id -> IdSet
-add_some :: IdSet -> [Id] -> IdSet
-
-no_in_scopes = emptyUniqSet
-in_scopes `add1` x = in_scopes `unionUniqSets` singletonUniqSet x
-in_scopes `add_some` xs = in_scopes `unionUniqSets` mkUniqSet xs
-\end{code}
-
-The can-see-inside-monad functions are the usual sorts of things.
-
-\begin{code}
-thenUf :: UnfoldM bndr a -> (a -> UnfoldM bndr b) -> UnfoldM bndr b
-thenUf m k in_scopes get_id mentioneds
- = case m in_scopes get_id mentioneds of { (v, mentioneds1) ->
- k v in_scopes get_id mentioneds1 }
-
-thenUf_ :: UnfoldM bndr a -> UnfoldM bndr b -> UnfoldM bndr b
-thenUf_ m k in_scopes get_id mentioneds
- = case m in_scopes get_id mentioneds of { (_, mentioneds1) ->
- k in_scopes get_id mentioneds1 }
-
-mapUf :: (a -> UnfoldM bndr b) -> [a] -> UnfoldM bndr [b]
-mapUf f [] = returnUf []
-mapUf f (x:xs)
- = f x `thenUf` \ r ->
- mapUf f xs `thenUf` \ rs ->
- returnUf (r:rs)
-
-returnUf :: a -> UnfoldM bndr a
-returnUf v in_scopes get_id mentioneds = (v, mentioneds)
-
-addInScopesUf :: [Id] -> UnfoldM bndr a -> UnfoldM bndr a
-addInScopesUf more_in_scopes m in_scopes get_id mentioneds
- = m (in_scopes `add_some` more_in_scopes) get_id mentioneds
-
-getInScopesUf :: UnfoldM bndr IdSet
-getInScopesUf in_scopes get_id mentioneds = (in_scopes, mentioneds)
-
-extractIdsUf :: [bndr] -> UnfoldM bndr [Id]
-extractIdsUf binders in_scopes get_id mentioneds
- = (map get_id binders, mentioneds)
-
-consider_Id :: Id -> UnfoldM bndr ()
-consider_Id var in_scopes get_id (ids, tcs, clss, has_litlit)
- = let
- (ids2, tcs2, clss2) = whatsMentionedInId in_scopes var
- in
- ((), (ids `unionBags` ids2,
- tcs `unionBags` tcs2,
- clss `unionBags`clss2,
- has_litlit))
-\end{code}
+Code for manipulating sizes
\begin{code}
-addToMentionedIdsUf :: Id -> UnfoldM bndr ()
-addToMentionedTyConsUf :: Bag TyCon -> UnfoldM bndr ()
-addToMentionedClassesUf :: Bag Class -> UnfoldM bndr ()
-litlit_oops :: UnfoldM bndr ()
-
-addToMentionedIdsUf add_me in_scopes get_id (ids, tcs, clss, has_litlit)
- = ((), (ids `unionBags` unitBag add_me, tcs, clss, has_litlit))
-addToMentionedTyConsUf add_mes in_scopes get_id (ids, tcs, clss, has_litlit)
- = ((), (ids, tcs `unionBags` add_mes, clss, has_litlit))
+data ExprSize = TooBig
+ | SizeIs Int# -- Size found
+ [Id] -- Arguments cased herein
+ Int# -- Size to subtract if result is scrutinised
+ -- by a case expression
-addToMentionedClassesUf add_mes in_scopes get_id (ids, tcs, clss, has_litlit)
- = ((), (ids, tcs, clss `unionBags` add_mes, has_litlit))
+sizeZero = SizeIs 0# [] 0#
+sizeOne = SizeIs 1# [] 0#
+sizeN (I# n) = SizeIs n [] 0#
+conSizeN (I# n) = SizeIs n [] n
+scrutArg v = SizeIs 0# [v] 0#
-litlit_oops in_scopes get_id (ids, tcs, clss, _)
- = ((), (ids, tcs, clss, True))
+nukeScrutDiscount (SizeIs n vs d) = SizeIs n vs 0#
+nukeScrutDiscount TooBig = TooBig
\end{code}
-
%************************************************************************
%* *
-\subsubsection{Gathering up info for an interface-unfolding}
+\subsection[considerUnfolding]{Given all the info, do (not) do the unfolding}
%* *
%************************************************************************
-\begin{code}
-mentionedInUnfolding
- :: (bndr -> Id) -- so we can get Ids out of binders
- -> CoreExpr bndr Id -- input expression
- -> ([Id], [TyCon], [Class],
- -- what we found mentioned in the expr
- Bool -- True <=> mentions a ``litlit''-ish thing
- -- (the guy on the other side of an interface
- -- may not be able to handle it)
- )
-
-mentionedInUnfolding get_id expr
- = case (ment_expr expr no_in_scopes get_id (emptyBag, emptyBag, emptyBag, False)) of
- (_, (ids_bag, tcs_bag, clss_bag, has_litlit)) ->
- (bagToList ids_bag, bagToList tcs_bag, bagToList clss_bag, has_litlit)
-\end{code}
+We have very limited information about an unfolding expression: (1)~so
+many type arguments and so many value arguments expected---for our
+purposes here, we assume we've got those. (2)~A ``size'' or ``cost,''
+a single integer. (3)~An ``argument info'' vector. For this, what we
+have at the moment is a Boolean per argument position that says, ``I
+will look with great favour on an explicit constructor in this
+position.'' (4)~The ``discount'' to subtract if the expression
+is being scrutinised.
+
+Assuming we have enough type- and value arguments (if not, we give up
+immediately), then we see if the ``discounted size'' is below some
+(semi-arbitrary) threshold. It works like this: for every argument
+position where we're looking for a constructor AND WE HAVE ONE in our
+hands, we get a (again, semi-arbitrary) discount [proportion to the
+number of constructors in the type being scrutinized].
+
+If we're in the context of a scrutinee ( \tr{(case <expr > of A .. -> ...;.. )})
+and the expression in question will evaluate to a constructor, we use
+the computed discount size *for the result only* rather than
+computing the argument discounts. Since we know the result of
+the expression is going to be taken apart, discounting its size
+is more accurate (see @sizeExpr@ above for how this discount size
+is computed).
\begin{code}
-ment_expr :: CoreExpr bndr Id -> UnfoldM bndr ()
-
-ment_expr (CoVar v) = consider_Id v
-ment_expr (CoLit l) = consider_lit l
-
-ment_expr (CoLam bs body)
- = extractIdsUf bs `thenUf` \ bs_ids ->
- addInScopesUf bs_ids (
- -- this considering is just to extract any mentioned types/classes
- mapUf consider_Id bs_ids `thenUf_`
- ment_expr body
- )
-
-ment_expr (CoTyLam _ body) = ment_expr body
-
-ment_expr (CoApp fun arg)
- = ment_expr fun `thenUf_`
- ment_atom arg
-
-ment_expr (CoTyApp expr ty)
- = ment_ty ty `thenUf_`
- ment_expr expr
-
-ment_expr (CoCon c ts as)
- = consider_Id c `thenUf_`
- mapUf ment_ty ts `thenUf_`
- mapUf ment_atom as `thenUf_`
- returnUf ()
-
-ment_expr (CoPrim op ts as)
- = ment_op op `thenUf_`
- mapUf ment_ty ts `thenUf_`
- mapUf ment_atom as `thenUf_`
- returnUf ()
+smallEnoughToInline :: [Bool] -- Evaluated-ness of value arguments
+ -> Bool -- Result is scrutinised
+ -> UnfoldingGuidance
+ -> Bool -- True => unfold it
+
+smallEnoughToInline _ _ UnfoldAlways = True
+smallEnoughToInline _ _ UnfoldNever = False
+smallEnoughToInline arg_is_evald_s result_is_scruted
+ (UnfoldIfGoodArgs m_tys_wanted n_vals_wanted discount_vec size scrut_discount)
+ = enough_args n_vals_wanted arg_is_evald_s &&
+ discounted_size <= opt_UnfoldingUseThreshold
where
- ment_op (CCallOp str is_asm may_gc arg_tys res_ty)
- = mapUf ment_ty arg_tys `thenUf_`
- ment_ty res_ty
- ment_op other_op = returnUf ()
-
-ment_expr (CoCase scrutinee alts)
- = ment_expr scrutinee `thenUf_`
- ment_alts alts
-
-ment_expr (CoLet (CoNonRec bind rhs) body)
- = ment_expr rhs `thenUf_`
- extractIdsUf [bind] `thenUf` \ bi@[bind_id] ->
- addInScopesUf bi (
- ment_expr body `thenUf_`
- consider_Id bind_id )
-
-ment_expr (CoLet (CoRec pairs) body)
- = let
- binders = map fst pairs
- rhss = map snd pairs
- in
- extractIdsUf binders `thenUf` \ binder_ids ->
- addInScopesUf binder_ids (
- mapUf ment_expr rhss `thenUf_`
- mapUf consider_Id binder_ids `thenUf_`
- ment_expr body )
-
-ment_expr (CoSCC cc expr)
- = (case (ccMentionsId cc) of
- Just id -> consider_Id id
- Nothing -> returnUf ()
- )
- `thenUf_` ment_expr expr
-
--------------
-ment_ty ty
- = let
- (tycons, clss) = getMentionedTyConsAndClassesFromUniType ty
- in
- addToMentionedTyConsUf tycons `thenUf_`
- addToMentionedClassesUf clss
--------------
+ enough_args n [] | n > 0 = False -- A function with no value args => don't unfold
+ enough_args _ _ = True -- Otherwise it's ok to try
-ment_alts alg_alts@(CoAlgAlts alts deflt)
- = mapUf ment_alt alts `thenUf_`
- ment_deflt deflt
- where
- ment_alt alt@(con, params, rhs)
- = consider_Id con `thenUf_`
- extractIdsUf params `thenUf` \ param_ids ->
- addInScopesUf param_ids (
- -- "consider" them so we can chk out their types...
- mapUf consider_Id param_ids `thenUf_`
- ment_expr rhs )
-
-ment_alts (CoPrimAlts alts deflt)
- = mapUf ment_alt alts `thenUf_`
- ment_deflt deflt
- where
- ment_alt alt@(lit, rhs) = ment_expr rhs
-
-----------------
-ment_deflt CoNoDefault
- = returnUf ()
-
-ment_deflt d@(CoBindDefault b rhs)
- = extractIdsUf [b] `thenUf` \ bi@[b_id] ->
- addInScopesUf bi (
- consider_Id b_id `thenUf_`
- ment_expr rhs )
-
------------
-ment_atom (CoVarAtom v) = consider_Id v
-ment_atom (CoLitAtom l) = consider_lit l
-
------------
-consider_lit lit
- | isLitLitLit lit = litlit_oops `thenUf_` returnUf ()
- | otherwise = returnUf ()
-\end{code}
+{- OLD: require saturated args
+ enough_args 0 evals = True
+ enough_args n [] = False
+ enough_args n (e:es) = enough_args (n-1) es
+ -- NB: don't take the length of arg_is_evald_s because when
+ -- called from couldBeSmallEnoughToInline it is infinite!
+-}
-%************************************************************************
-%* *
-\subsubsection{Printing unfoldings in interfaces}
-%* *
-%************************************************************************
+ discounted_size = size - args_discount - result_discount
-Printing Core-expression unfoldings is sufficiently delicate that we
-give it its own function.
-\begin{code}
-pprCoreUnfolding
- :: PlainCoreExpr
- -> Pretty
+ args_discount = sum (zipWith arg_discount discount_vec arg_is_evald_s)
+ result_discount | result_is_scruted = scrut_discount
+ | otherwise = 0
-pprCoreUnfolding expr
- = let
- (_, renamed) = instCoreExpr uniqSupply_u expr
- -- We rename every unfolding with a "steady" unique supply,
- -- so that the names won't constantly change.
- -- One place we *MUST NOT* use a splittable UniqueSupply!
- in
- ppr_uf_Expr emptyUniqSet renamed
-
-ppr_Unfolding = PprUnfolding (panic "CoreUnfold:ppr_Unfolding")
+ arg_discount no_of_constrs is_evald
+ | is_evald = 1 + no_of_constrs * opt_UnfoldingConDiscount
+ | otherwise = 1
\end{code}
-\begin{code}
-ppr_uf_Expr in_scopes (CoVar v) = pprIdInUnfolding in_scopes v
-ppr_uf_Expr in_scopes (CoLit l) = ppr ppr_Unfolding l
-
-ppr_uf_Expr in_scopes (CoCon c ts as)
- = ppBesides [ppPStr SLIT("_!_ "), pprIdInUnfolding no_in_scopes c, ppSP,
- ppLbrack, ppIntersperse pp'SP{-'-} (map (pprParendUniType ppr_Unfolding) ts), ppRbrack,
- ppSP, ppLbrack, ppIntersperse pp'SP{-'-} (map (ppr_uf_Atom in_scopes) as), ppRbrack]
-ppr_uf_Expr in_scopes (CoPrim op ts as)
- = ppBesides [ppPStr SLIT("_#_ "), ppr ppr_Unfolding op, ppSP,
- ppLbrack, ppIntersperse pp'SP{-'-} (map (pprParendUniType ppr_Unfolding) ts), ppRbrack,
- ppSP, ppLbrack, ppIntersperse pp'SP{-'-} (map (ppr_uf_Atom in_scopes) as), ppRbrack]
-
-ppr_uf_Expr in_scopes (CoLam binders body)
- = ppCat [ppChar '\\', ppIntersperse ppSP (map ppr_uf_Binder binders),
- ppPStr SLIT("->"), ppr_uf_Expr (in_scopes `add_some` binders) body]
-
-ppr_uf_Expr in_scopes (CoTyLam tyvar expr)
- = ppCat [ppPStr SLIT("_/\\_"), interppSP ppr_Unfolding (tyvar:tyvars), ppStr "->",
- ppr_uf_Expr in_scopes body]
- where
- (tyvars, body) = collect_tyvars expr
-
- collect_tyvars (CoTyLam tyv e) = ( tyv:tyvs, e_after )
- where (tyvs, e_after) = collect_tyvars e
- collect_tyvars other_e = ( [], other_e )
-
-ppr_uf_Expr in_scopes expr@(CoApp fun_expr atom)
- = let
- (fun, args) = collect_args expr []
- in
- ppCat [ppPStr SLIT("_APP_ "), ppr_uf_Expr in_scopes fun, ppLbrack,
- ppIntersperse pp'SP{-'-} (map (ppr_uf_Atom in_scopes) args), ppRbrack]
- where
- collect_args (CoApp fun arg) args = collect_args fun (arg:args)
- collect_args fun args = (fun, args)
-
-ppr_uf_Expr in_scopes (CoTyApp expr ty)
- = ppCat [ppPStr SLIT("_TYAPP_ "), ppr_uf_Expr in_scopes expr,
- ppChar '{', pprParendUniType ppr_Unfolding ty, ppChar '}']
-
-ppr_uf_Expr in_scopes (CoCase scrutinee alts)
- = ppCat [ppPStr SLIT("case"), ppr_uf_Expr in_scopes scrutinee, ppStr "of {",
- pp_alts alts, ppChar '}']
- where
- pp_alts (CoAlgAlts alts deflt)
- = ppCat [ppPStr SLIT("_ALG_"), ppCat (map pp_alg alts), pp_deflt deflt]
- pp_alts (CoPrimAlts alts deflt)
- = ppCat [ppPStr SLIT("_PRIM_"), ppCat (map pp_prim alts), pp_deflt deflt]
-
- pp_alg (con, params, rhs)
- = ppBesides [pprIdInUnfolding no_in_scopes con, ppSP,
- ppIntersperse ppSP (map ppr_uf_Binder params),
- ppPStr SLIT(" -> "), ppr_uf_Expr (in_scopes `add_some` params) rhs, ppSemi]
-
- pp_prim (lit, rhs)
- = ppBesides [ppr ppr_Unfolding lit,
- ppPStr SLIT(" -> "), ppr_uf_Expr in_scopes rhs, ppSemi]
-
- pp_deflt CoNoDefault = ppPStr SLIT("_NO_DEFLT_")
- pp_deflt (CoBindDefault binder rhs)
- = ppBesides [ppr_uf_Binder binder, ppPStr SLIT(" -> "),
- ppr_uf_Expr (in_scopes `add1` binder) rhs]
-
-ppr_uf_Expr in_scopes (CoLet (CoNonRec binder rhs) body)
- = ppBesides [ppStr "let {", ppr_uf_Binder binder, ppPStr SLIT(" = "), ppr_uf_Expr in_scopes rhs,
- ppStr "} in ", ppr_uf_Expr (in_scopes `add1` binder) body]
-
-ppr_uf_Expr in_scopes (CoLet (CoRec pairs) body)
- = ppBesides [ppStr "_LETREC_ {", ppIntersperse sep (map pp_pair pairs),
- ppStr "} in ", ppr_uf_Expr new_in_scopes body]
- where
- sep = ppBeside ppSemi ppSP
- new_in_scopes = in_scopes `add_some` map fst pairs
+We use this one to avoid exporting inlinings that we ``couldn't possibly
+use'' on the other side. Can be overridden w/ flaggery.
+Just the same as smallEnoughToInline, except that it has no actual arguments.
- pp_pair (b, rhs) = ppCat [ppr_uf_Binder b, ppEquals, ppr_uf_Expr new_in_scopes rhs]
+\begin{code}
+--UNUSED?
+couldBeSmallEnoughToInline :: UnfoldingGuidance -> Bool
+couldBeSmallEnoughToInline guidance = smallEnoughToInline (repeat True) True guidance
-ppr_uf_Expr in_scopes (CoSCC cc body)
- = ASSERT(not (noCostCentreAttached cc))
- ASSERT(not (currentOrSubsumedCosts cc))
- ppBesides [ppStr "_scc_ { ", ppStr (showCostCentre ppr_Unfolding False{-not as string-} cc), ppStr " } ", ppr_uf_Expr in_scopes body]
+certainlySmallEnoughToInline :: UnfoldingGuidance -> Bool
+certainlySmallEnoughToInline guidance = smallEnoughToInline (repeat False) False guidance
\end{code}
-\begin{code}
-ppr_uf_Binder :: Id -> Pretty
-ppr_uf_Binder v
- = ppBesides [ppLparen, pprIdInUnfolding (singletonUniqSet v) v, ppPStr SLIT(" :: "),
- ppr ppr_Unfolding (getIdUniType v), ppRparen]
+Predicates
+~~~~~~~~~~
-ppr_uf_Atom in_scopes (CoLitAtom l) = ppr ppr_Unfolding l
-ppr_uf_Atom in_scopes (CoVarAtom v) = pprIdInUnfolding in_scopes v
+\begin{code}
+okToInline
+ :: FormSummary -- What the thing to be inlined is like
+ -> BinderInfo -- How the thing to be inlined occurs
+ -> Bool -- True => it's small enough to inline
+ -> Bool -- True => yes, inline it
+
+-- If there's no danger of duplicating work, we can inline if it occurs once, or is small
+okToInline form occ_info small_enough
+ | no_dup_danger form
+ = small_enough || one_occ
+ where
+ one_occ = case occ_info of
+ OneOcc _ _ _ n_alts _ -> n_alts <= 1
+ other -> False
+
+ no_dup_danger VarForm = True
+ no_dup_danger ValueForm = True
+ no_dup_danger BottomForm = True
+ no_dup_danger other = False
+
+-- A non-WHNF can be inlined if it doesn't occur inside a lambda,
+-- and occurs exactly once or
+-- occurs once in each branch of a case and is small
+okToInline OtherForm (OneOcc _ dup_danger _ n_alts _) small_enough
+ = not (isDupDanger dup_danger) && (n_alts <= 1 || small_enough)
+
+okToInline form any_occ small_enough = False
\end{code}
+
projects / ghc-hetmet.git / blobdiff