X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FcoreSyn%2FCoreUnfold.lhs;h=f2077ba738370a7e01e4208ae1a545141f3d9ce7;hb=1fb1ab5d53a09607e7f6d2450806760688396387;hp=146b1f31c47545eb5a2d78e67300557f0eca8f3b;hpb=a77abe6a30ea2763cfa1c0ca83cdce9b7200ced2;p=ghc-hetmet.git diff --git a/ghc/compiler/coreSyn/CoreUnfold.lhs b/ghc/compiler/coreSyn/CoreUnfold.lhs index 146b1f3..f2077ba 100644 --- a/ghc/compiler/coreSyn/CoreUnfold.lhs +++ b/ghc/compiler/coreSyn/CoreUnfold.lhs @@ -6,231 +6,227 @@ Unfoldings (which can travel across module boundaries) are in Core syntax (namely @CoreExpr@s). -The type @UnfoldingDetails@ sits ``above'' simply-Core-expressions +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 @GenForm@ unfolding, you will +literal''). In the corner of a @SimpleUnfolding@ unfolding, you will find, unsurprisingly, a Core expression. \begin{code} #include "HsVersions.h" module CoreUnfold ( - UnfoldingDetails(..), UnfoldingGuidance(..), -- types - FormSummary(..), - - mkFormSummary, - mkGenForm, - mkMagicUnfolding, - modifyUnfoldingDetails, - calcUnfoldingGuidance, - mentionedInUnfolding + SimpleUnfolding(..), Unfolding(..), UnfoldingGuidance(..), -- types + UfExpr, RdrName, -- For closure (delete in 1.3) + + FormSummary(..), mkFormSummary, whnfOrBottom, exprSmallEnoughToDup, + + noUnfolding, mkMagicUnfolding, mkUnfolding, getUnfoldingTemplate, + + smallEnoughToInline, couldBeSmallEnoughToInline, certainlySmallEnoughToInline, + okToInline, + + calcUnfoldingGuidance ) where -import Ubiq -import IdLoop -- for paranoia checking; +IMP_Ubiq() +IMPORT_DELOOPER(IdLoop) -- for paranoia checking; -- and also to get mkMagicUnfoldingFun -import PrelLoop -- for paranoia checking +IMPORT_DELOOPER(PrelLoop) -- for paranoia checking import Bag ( emptyBag, unitBag, unionBags, Bag ) -import BinderInfo ( oneTextualOcc, oneSafeOcc ) -import CgCompInfo ( uNFOLDING_CHEAP_OP_COST, + +import CmdLineOpts ( opt_UnfoldingCreationThreshold, + opt_UnfoldingUseThreshold, + opt_UnfoldingConDiscount + ) +import Constants ( uNFOLDING_CHEAP_OP_COST, uNFOLDING_DEAR_OP_COST, uNFOLDING_NOREP_LIT_COST ) +import BinderInfo ( BinderInfo(..), FunOrArg, DuplicationDanger, InsideSCC, isDupDanger ) import CoreSyn -import CoreUtils ( coreExprType, manifestlyWHNF ) +import CoreUtils ( unTagBinders ) +import HsCore ( UfExpr ) +import RdrHsSyn ( RdrName ) +import OccurAnal ( occurAnalyseGlobalExpr ) +import CoreUtils ( coreExprType ) import CostCentre ( ccMentionsId ) -import Id ( IdSet(..), GenId{-instances-} ) -import IdInfo ( bottomIsGuaranteed ) +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 PrimOp ( primOpCanTriggerGC, PrimOp(..) ) import TyCon ( tyConFamilySize ) -import Type ( getAppDataTyCon ) +import Type ( maybeAppDataTyConExpandingDicts ) import UniqSet ( emptyUniqSet, unitUniqSet, mkUniqSet, addOneToUniqSet, unionUniqSets ) -import Usage ( UVar(..) ) -import Util ( isIn, panic ) +import Usage ( SYN_IE(UVar) ) +import Maybes ( maybeToBool ) +import Util ( isIn, panic, assertPanic ) -whatsMentionedInId = panic "whatsMentionedInId (CoreUnfold)" -getMentionedTyConsAndClassesFromType = panic "getMentionedTyConsAndClassesFromType (CoreUnfold)" \end{code} %************************************************************************ %* * -\subsection{@UnfoldingDetails@ and @UnfoldingGuidance@ types} +\subsection{@Unfolding@ and @UnfoldingGuidance@ types} %* * %************************************************************************ -(And @FormSummary@, too.) - \begin{code} -data UnfoldingDetails - = NoUnfoldingDetails - - | LitForm - Literal - - | OtherLitForm - [Literal] -- It is a literal, but definitely not one of these - - | ConForm - Id -- The constructor - [CoreArg] -- Value arguments; NB OutArgs, already cloned - - | OtherConForm - [Id] -- It definitely isn't one of these constructors - -- This captures the situation in the default branch of - -- a case: case x of - -- c1 ... -> ... - -- c2 ... -> ... - -- v -> default-rhs - -- Then in default-rhs we know that v isn't c1 or c2. - -- - -- NB. In the degenerate: case x of {v -> default-rhs} - -- x will be bound to - -- OtherConForm [] - -- which captures the idea that x is eval'd but we don't - -- know which constructor. - - - | GenForm - Bool -- True <=> At most one textual occurrence of the - -- binder in its scope, *or* - -- if we are happy to duplicate this - -- binding. - FormSummary -- Tells whether the template is a WHNF or bottom - TemplateOutExpr -- The template - UnfoldingGuidance -- Tells about the *size* of the template. - - | MagicForm - Unique -- of the Id whose magic unfolding this is +data Unfolding + = NoUnfolding + + | CoreUnfolding SimpleUnfolding + + | MagicUnfolding + Unique -- Unique of the Id whose magic unfolding this is MagicUnfoldingFun -type TemplateOutExpr = GenCoreExpr (Id, BinderInfo) Id TyVar UVar - -- An OutExpr with occurrence info attached. This is used as - -- a template in GeneralForms. -mkMagicUnfolding :: Unique -> UnfoldingDetails -mkMagicUnfolding tag = MagicForm tag (mkMagicUnfoldingFun tag) +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 -data FormSummary - = WhnfForm -- Expression is WHNF - | 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 WhnfForm = ppStr "WHNF" - ppr sty BottomForm = ppStr "Bot" - ppr sty OtherForm = ppStr "Other" - ---???mkFormSummary :: StrictnessInfo -> GenCoreExpr bndr Id -> FormSummary -mkFormSummary si expr - | manifestlyWHNF expr = WhnfForm - | bottomIsGuaranteed si = BottomForm - - -- Chances are that the Id will be decorated with strictness info - -- telling that the RHS is definitely bottom. This *might* not be the - -- case, if it's been a while since strictness analysis, but leaving out - -- the test for manifestlyBottom makes things a little more efficient. - -- We can always put it back... - -- | manifestlyBottom expr = BottomForm - - | otherwise = OtherForm -\end{code} +noUnfolding = NoUnfolding -\begin{code} -data UnfoldingGuidance - = UnfoldNever -- Don't do it! +mkUnfolding inline_me expr + = let + -- strictness mangling (depends on there being no CSE) + ufg = calcUnfoldingGuidance inline_me 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. - | EssentialUnfolding -- Like UnfoldAlways, but you *must* do - -- it absolutely always. - -- This is what we use for data constructors - -- and PrimOps, because we don't feel like - -- generating curried versions "just in case". - - | UnfoldIfGoodArgs Int -- if "m" type args and "n" value args; and - Int -- those val args are manifestly data constructors - [Bool] -- the val-arg positions marked True + | 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). + -- be possible). One elt of the list per *value* arg. Int -- The "size" of the unfolding; to be elaborated -- later. ToDo - - | BadUnfolding -- This is used by TcPragmas if the *lazy* - -- lintUnfolding test fails - -- It will never escape from the IdInfo as - -- it is caught by getInfo_UF and converted - -- to NoUnfoldingDetails \end{code} \begin{code} instance Outputable UnfoldingGuidance where - ppr sty UnfoldNever = ppStr "_N_" - ppr sty UnfoldAlways = ppStr "_ALWAYS_" - ppr sty EssentialUnfolding = ppStr "_ESSENTIAL_" -- shouldn't appear in an iface + ppr sty UnfoldAlways = ppPStr SLIT("_ALWAYS_") +-- ppr sty EssentialUnfolding = ppPStr SLIT("_ESSENTIAL_") -- shouldn't appear in an iface ppr sty (UnfoldIfGoodArgs t v cs size) - = ppCat [ppStr "_IF_ARGS_", ppInt t, ppInt v, + = ppCat [ppPStr SLIT("_IF_ARGS_"), ppInt t, ppInt v, if null cs -- always print *something* then ppChar 'X' - else ppBesides (map pp_c cs), + else ppBesides (map (ppStr . show) cs), ppInt size ] - where - pp_c False = ppChar 'X' - pp_c True = ppChar 'C' \end{code} %************************************************************************ %* * -\subsection{@mkGenForm@ and @modifyUnfoldingDetails@} +\subsection{Figuring out things about expressions} %* * %************************************************************************ \begin{code} -mkGenForm :: Bool -- Ok to Dup code down different case branches, - -- because of either a flag saying so, - -- or alternatively the object is *SMALL* - -> BinderInfo -- - -> FormSummary - -> TemplateOutExpr -- Template - -> UnfoldingGuidance -- Tells about the *size* of the template. - -> UnfoldingDetails - -mkGenForm safe_to_dup occ_info WhnfForm template guidance - = GenForm (oneTextualOcc safe_to_dup occ_info) WhnfForm template guidance - -mkGenForm safe_to_dup occ_info form_summary template guidance - | oneSafeOcc safe_to_dup occ_info -- Non-WHNF with only safe occurrences - = GenForm True form_summary template guidance - - | otherwise -- Not a WHNF, many occurrences - = NoUnfoldingDetails -\end{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 -\begin{code} -modifyUnfoldingDetails - :: Bool -- OK to dup - -> BinderInfo -- New occurrence info for the thing - -> UnfoldingDetails - -> UnfoldingDetails +instance Outputable FormSummary where + ppr sty VarForm = ppPStr SLIT("Var") + ppr sty ValueForm = ppPStr SLIT("Value") + ppr sty BottomForm = ppPStr SLIT("Bot") + ppr sty OtherForm = ppPStr SLIT("Other") -modifyUnfoldingDetails ok_to_dup occ_info - (GenForm only_one form_summary template guidance) - | only_one = mkGenForm ok_to_dup occ_info form_summary template guidance +mkFormSummary ::GenCoreExpr bndr Id tyvar uvar -> FormSummary -modifyUnfoldingDetails ok_to_dup occ_info other = other +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 _ 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} +\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 expr + = case (collectArgs expr) of { (fun, _, _, vargs) -> + case fun of + Var v | length vargs == 0 -> True + _ -> False + } + +{- LATER: +WAS: MORE CLEVER: +exprSmallEnoughToDup expr -- for now, just: applied to + = case (collectArgs expr) of { (fun, _, _, vargs) -> + case fun of + Var v -> v /= buildId + && v /= augmentId + && length vargs <= 6 -- or 10 or 1 or 4 or anything smallish. + _ -> False + } +-} +\end{code} +Question (ADR): What is the above used for? Is a _ccall_ really small +enough? + %************************************************************************ %* * \subsection[calcUnfoldingGuidance]{Calculate ``unfolding guidance'' for an expression} @@ -239,36 +235,40 @@ modifyUnfoldingDetails ok_to_dup occ_info other = other \begin{code} calcUnfoldingGuidance - :: Bool -- True <=> OK if _scc_s appear in expr - -> Int -- bomb out if size gets bigger than this - -> CoreExpr -- expression to look at + :: Bool -- True <=> there's an INLINE pragma on this thing + -> Int -- bomb out if size gets bigger than this + -> CoreExpr -- expression to look at -> UnfoldingGuidance -calcUnfoldingGuidance scc_s_OK bOMB_OUT_SIZE expr - = let - (use_binders, ty_binders, val_binders, body) = collectBinders expr - in - case (sizeExpr scc_s_OK bOMB_OUT_SIZE val_binders body) of +calcUnfoldingGuidance True bOMB_OUT_SIZE expr = UnfoldAlways -- Always inline if the INLINE pragma says so + +calcUnfoldingGuidance False 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 + Nothing -> UnfoldNever Just (size, cased_args) - -> let - uf = UnfoldIfGoodArgs + -> 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) + size + 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 -> CoreExpr @@ -276,21 +276,43 @@ sizeExpr :: Bool -- True <=> _scc_s OK [Id] -- Subset of args which are cased ) -sizeExpr scc_s_OK bOMB_OUT_SIZE args expr +sizeExpr bOMB_OUT_SIZE args expr + + | data_or_prim fun +-- We are very keen to inline literals, constructors, or primitives +-- including their slightly-disguised forms as applications (the latter +-- can show up in the bodies of things imported from interfaces). + = Just (0, []) + + | otherwise = size_up expr where - size_up (Var v) = sizeOne - size_up (App fun arg) = size_up fun `addSize` size_up_arg arg + (fun, _) = splitCoreApps expr + data_or_prim (Var v) = maybeToBool (isPrimitiveId_maybe v) || + isDataCon v + data_or_prim (Con _ _) = True + data_or_prim (Prim _ _) = True + data_or_prim (Lit _) = True + data_or_prim other = False + + size_up (Var v) = sizeZero + size_up (App fun arg) = size_up fun `addSize` size_up_arg arg `addSizeN` 1 + -- 1 for application node + size_up (Lit lit) = if isNoRepLit lit - then sizeN uNFOLDING_NOREP_LIT_COST - else sizeOne + then sizeN uNFOLDING_NOREP_LIT_COST + else sizeZero - size_up (SCC _ (Con _ _)) = Nothing -- **** HACK ***** - size_up (SCC lbl body) - = if scc_s_OK then size_up body else Nothing +-- I don't understand this hack so I'm removing it! SLPJ Nov 96 +-- size_up (SCC _ (Con _ _)) = Nothing -- **** HACK ***** - size_up (Con con args) = -- 1 + # of val args - sizeN (1 + numValArgs args) + size_up (SCC lbl body) = size_up body -- SCCs cost nothing + size_up (Coerce _ _ body) = size_up body -- Coercions cost nothing + + size_up (Con con args) = sizeN (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 @@ -326,21 +348,32 @@ sizeExpr scc_s_OK bOMB_OUT_SIZE args expr -- We charge for the "case" itself in "size_up_alts" ------------ - size_up_arg arg = if isValArg arg then sizeOne else sizeZero{-it's free-} + size_up_arg (LitArg lit) | isNoRepLit lit = sizeN uNFOLDING_NOREP_LIT_COST + size_up_arg other = sizeZero ------------ size_up_alts scrut_ty (AlgAlts alts deflt) - = foldr (addSize . size_alg_alt) (size_up_deflt deflt) alts - `addSizeN` (tyConFamilySize tycon) + = 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 + -- 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.) - where - size_alg_alt (con,args,rhs) = size_up rhs - -- Don't charge for args, so that wrappers look cheap + -- 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 } - (tycon, _, _) = _trace "getAppDataTyCon.CoreUnfold" $ getAppDataTyCon scrut_ty + alt_cost :: Int + alt_cost + = --trace "CoreUnfold.getAppDataTyConExpandingDicts:2" $ + 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 @@ -358,8 +391,8 @@ sizeExpr scc_s_OK bOMB_OUT_SIZE args expr -- 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 (Var v) | v `is_elem` args = Just (0, [v]) - | otherwise = Just (0, []) - size_up_scrut other = size_up other + | otherwise = Just (0, []) + size_up_scrut other = size_up other is_elem :: Id -> [Id] -> Bool is_elem = isIn "size_up_scrut" @@ -368,7 +401,6 @@ sizeExpr scc_s_OK bOMB_OUT_SIZE args expr sizeZero = Just (0, []) sizeOne = Just (1, []) sizeN n = Just (n, []) - sizeVar v = Just (0, [v]) addSizeN Nothing _ = Nothing addSizeN (Just (n, xs)) m @@ -385,369 +417,102 @@ sizeExpr scc_s_OK bOMB_OUT_SIZE args expr 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. - -%************************************************************************ -%* * -\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 = addOneToUniqSet in_scopes 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} - -\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)) - -addToMentionedClassesUf add_mes in_scopes get_id (ids, tcs, clss, has_litlit) - = ((), (ids, tcs, clss `unionBags` add_mes, has_litlit)) - -litlit_oops in_scopes get_id (ids, tcs, clss, _) - = ((), (ids, tcs, clss, True)) +splitCoreApps e + = go e [] + where + go (App fun arg) args = go fun (arg:args) + go fun args = (fun,args) \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 - -> GenCoreExpr bndr Id -- input expression - -> (Bag Id, Bag TyCon, Bag 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)) -> - (ids_bag, tcs_bag, 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.'' + +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]. \begin{code} ---ment_expr :: GenCoreExpr bndr Id -> UnfoldM bndr () - -ment_expr (Var v) = consider_Id v -ment_expr (Lit l) = consider_lit l - -ment_expr expr@(Lam _ _) - = let - (uvars, tyvars, args, body) = collectBinders expr - in - extractIdsUf args `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 (App fun arg) - = ment_expr fun `thenUf_` - ment_arg arg - -ment_expr (Con c as) - = consider_Id c `thenUf_` - mapUf ment_arg as `thenUf_` - returnUf () - -ment_expr (Prim op as) - = ment_op op `thenUf_` - mapUf ment_arg as `thenUf_` - returnUf () +smallEnoughToInline :: [Bool] -- Evaluated-ness of value arguments + -> UnfoldingGuidance + -> Bool -- True => unfold it + +smallEnoughToInline _ UnfoldAlways = True +smallEnoughToInline _ UnfoldNever = False +smallEnoughToInline arg_is_evald_s + (UnfoldIfGoodArgs m_tys_wanted n_vals_wanted discount_vec size) + = 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 (Case scrutinee alts) - = ment_expr scrutinee `thenUf_` - ment_alts alts - -ment_expr (Let (NonRec 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 (Let (Rec 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 (SCC cc expr) - = (case (ccMentionsId cc) of - Just id -> consider_Id id - Nothing -> returnUf () - ) - `thenUf_` ment_expr expr - -------------- -ment_ty ty - = let - (tycons, clss) = getMentionedTyConsAndClassesFromType ty - in - addToMentionedTyConsUf tycons `thenUf_` - addToMentionedClassesUf clss + 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! -------------- + discounted_size = size - sum (zipWith arg_discount discount_vec arg_is_evald_s) -ment_alts alg_alts@(AlgAlts 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 (PrimAlts alts deflt) - = mapUf ment_alt alts `thenUf_` - ment_deflt deflt - where - ment_alt alt@(lit, rhs) = ment_expr rhs - ----------------- -ment_deflt NoDefault - = returnUf () - -ment_deflt d@(BindDefault b rhs) - = extractIdsUf [b] `thenUf` \ bi@[b_id] -> - addInScopesUf bi ( - consider_Id b_id `thenUf_` - ment_expr rhs ) - ------------ -ment_arg (VarArg v) = consider_Id v -ment_arg (LitArg l) = consider_lit l -ment_arg (TyArg ty) = ment_ty ty -ment_arg (UsageArg _) = returnUf () - ------------ -consider_lit lit - | isLitLitLit lit = litlit_oops `thenUf_` returnUf () - | otherwise = returnUf () + arg_discount no_of_constrs is_evald + | is_evald = 1 + no_of_constrs * opt_UnfoldingConDiscount + | otherwise = 1 \end{code} -%************************************************************************ -%* * -\subsubsection{Printing unfoldings in interfaces} -%* * -%************************************************************************ +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. -Printing Core-expression unfoldings is sufficiently delicate that we -give it its own function. \begin{code} -{- OLD: -pprCoreUnfolding - :: CoreExpr - -> Pretty - -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 +couldBeSmallEnoughToInline :: UnfoldingGuidance -> Bool +couldBeSmallEnoughToInline guidance = smallEnoughToInline (repeat True) guidance -ppr_Unfolding = PprUnfolding (panic "CoreUnfold:ppr_Unfolding") +certainlySmallEnoughToInline :: UnfoldingGuidance -> Bool +certainlySmallEnoughToInline guidance = smallEnoughToInline (repeat False) guidance \end{code} -\begin{code} -ppr_uf_Expr in_scopes (Var v) = pprIdInUnfolding in_scopes v -ppr_uf_Expr in_scopes (Lit l) = ppr ppr_Unfolding l - -ppr_uf_Expr in_scopes (Con c 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 (Prim op 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 (Lam binder body) - = ppCat [ppChar '\\', ppr_uf_Binder binder, - ppPStr SLIT("->"), ppr_uf_Expr (in_scopes `add1` binder) 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@(App 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 (App 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 (Case scrutinee alts) - = ppCat [ppPStr SLIT("case"), ppr_uf_Expr in_scopes scrutinee, ppStr "of {", - pp_alts alts, ppChar '}'] - where - pp_alts (AlgAlts alts deflt) - = ppCat [ppPStr SLIT("_ALG_"), ppCat (map pp_alg alts), pp_deflt deflt] - pp_alts (PrimAlts 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 NoDefault = ppPStr SLIT("_NO_DEFLT_") - pp_deflt (BindDefault binder rhs) - = ppBesides [ppr_uf_Binder binder, ppPStr SLIT(" -> "), - ppr_uf_Expr (in_scopes `add1` binder) rhs] - -ppr_uf_Expr in_scopes (Let (NonRec 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 (Let (Rec 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 - - pp_pair (b, rhs) = ppCat [ppr_uf_Binder b, ppEquals, ppr_uf_Expr new_in_scopes rhs] - -ppr_uf_Expr in_scopes (SCC 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] -\end{code} +Predicates +~~~~~~~~~~ \begin{code} -ppr_uf_Binder :: Id -> Pretty -ppr_uf_Binder v - = ppBesides [ppLparen, pprIdInUnfolding (unitUniqSet v) v, ppPStr SLIT(" :: "), - ppr ppr_Unfolding (idType v), ppRparen] - -ppr_uf_Atom in_scopes (LitArg l) = ppr ppr_Unfolding l -ppr_uf_Atom in_scopes (VarArg v) = pprIdInUnfolding in_scopes v -END OLD -} +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} +