X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FcoreSyn%2FCoreUnfold.lhs;h=d57f1886fc0377e7b7d91397a2c169374a9915a2;hb=28a464a75e14cece5db40f2765a29348273ff2d2;hp=9090e7702ec3e38e708ee6d1c6bb35058afb797a;hpb=573ef10b2afd99d3c6a36370a9367609716c97d2;p=ghc-hetmet.git diff --git a/ghc/compiler/coreSyn/CoreUnfold.lhs b/ghc/compiler/coreSyn/CoreUnfold.lhs index 9090e77..d57f188 100644 --- a/ghc/compiler/coreSyn/CoreUnfold.lhs +++ b/ghc/compiler/coreSyn/CoreUnfold.lhs @@ -1,734 +1,632 @@ % -% (c) The AQUA Project, Glasgow University, 1994-1996 +% (c) The AQUA Project, Glasgow University, 1994-1998 % \section[CoreUnfold]{Core-syntax unfoldings} 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 @CoreUnfolding@ unfolding, you will find, unsurprisingly, a Core expression. \begin{code} -#include "HsVersions.h" - module CoreUnfold ( - UnfoldingDetails(..), UnfoldingGuidance(..), -- types - FormSummary(..), - - mkFormSummary, - mkGenForm, mkLitForm, mkConForm, - whnfDetails, - mkMagicUnfolding, - calcUnfoldingGuidance, - mentionedInUnfolding + Unfolding, UnfoldingGuidance, -- Abstract types + + noUnfolding, mkTopUnfolding, mkUnfolding, mkCompulsoryUnfolding, seqUnfolding, + evaldUnfolding, mkOtherCon, otherCons, + unfoldingTemplate, maybeUnfoldingTemplate, + isEvaldUnfolding, isValueUnfolding, isCheapUnfolding, isCompulsoryUnfolding, + hasUnfolding, hasSomeUnfolding, neverUnfold, + + couldBeSmallEnoughToInline, + certainlyWillInline, smallEnoughToInline, + + callSiteInline ) where -IMP_Ubiq() -IMPORT_DELOOPER(IdLoop) -- for paranoia checking; - -- and also to get mkMagicUnfoldingFun -IMPORT_DELOOPER(PrelLoop) -- for paranoia checking +#include "HsVersions.h" -import Bag ( emptyBag, unitBag, unionBags, Bag ) -import BinderInfo ( oneTextualOcc, oneSafeOcc ) -import CgCompInfo ( uNFOLDING_CHEAP_OP_COST, - uNFOLDING_DEAR_OP_COST, - uNFOLDING_NOREP_LIT_COST +import StaticFlags ( opt_UF_CreationThreshold, opt_UF_UseThreshold, + opt_UF_FunAppDiscount, opt_UF_KeenessFactor, + opt_UF_DearOp, ) +import DynFlags ( DynFlags, DynFlag(..), dopt ) import CoreSyn -import CoreUtils ( coreExprType, manifestlyWHNF ) -import CostCentre ( ccMentionsId ) -import Id ( SYN_IE(IdSet), GenId{-instances-} ) -import IdInfo ( bottomIsGuaranteed ) -import Literal ( isNoRepLit, isLitLitLit ) -import Pretty -import PrimOp ( primOpCanTriggerGC, PrimOp(..) ) -import TyCon ( tyConFamilySize ) -import Type ( getAppDataTyConExpandingDicts ) -import UniqSet ( emptyUniqSet, unitUniqSet, mkUniqSet, - addOneToUniqSet, unionUniqSets +import PprCore ( pprCoreExpr ) +import OccurAnal ( occurAnalyseExpr ) +import CoreUtils ( exprIsHNF, exprIsCheap, exprIsTrivial ) +import Id ( Id, idType, isId, + idUnfolding, globalIdDetails ) -import Usage ( SYN_IE(UVar) ) -import Util ( isIn, panic ) - -whatsMentionedInId = panic "whatsMentionedInId (CoreUnfold)" -getMentionedTyConsAndClassesFromType = panic "getMentionedTyConsAndClassesFromType (CoreUnfold)" +import DataCon ( isUnboxedTupleCon ) +import Literal ( litSize ) +import PrimOp ( primOpIsDupable, primOpOutOfLine ) +import IdInfo ( OccInfo(..), GlobalIdDetails(..) ) +import Type ( isUnLiftedType ) +import PrelNames ( hasKey, buildIdKey, augmentIdKey ) +import Bag +import FastTypes +import Outputable + +#if __GLASGOW_HASKELL__ >= 404 +import GLAEXTS ( Int# ) +#endif \end{code} + %************************************************************************ %* * -\subsection{@UnfoldingDetails@ and @UnfoldingGuidance@ types} +\subsection{Making unfoldings} %* * %************************************************************************ -(And @FormSummary@, too.) - \begin{code} -data UnfoldingDetails - = NoUnfoldingDetails - - | OtherLitForm - [Literal] -- It is a literal, but definitely not one of these - - | 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 - 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 - 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 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 - -whnfDetails :: UnfoldingDetails -> Bool -- True => thing is evaluated -whnfDetails (GenForm WhnfForm _ _) = True -whnfDetails (OtherLitForm _) = True -whnfDetails (OtherConForm _) = True -whnfDetails other = False -\end{code} - -\begin{code} -data UnfoldingGuidance - = UnfoldNever -- Don't do it! - - | 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 - -- (i.e., a simplification will definitely - -- be possible). - 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 (UnfoldIfGoodArgs t v cs size) - = ppCat [ppStr "_IF_ARGS_", ppInt t, ppInt v, - if null cs -- always print *something* - then ppChar 'X' - else ppBesides (map pp_c cs), - ppInt size ] - where - pp_c False = ppChar 'X' - pp_c True = ppChar 'C' +mkTopUnfolding expr = mkUnfolding True {- Top level -} expr + +mkUnfolding top_lvl expr + = CoreUnfolding (occurAnalyseExpr expr) + top_lvl + + (exprIsHNF expr) + -- Already evaluated + + (exprIsCheap expr) + -- OK to inline inside a lambda + + (calcUnfoldingGuidance opt_UF_CreationThreshold expr) + -- Sometimes during simplification, there's a large let-bound thing + -- which has been substituted, and so is now dead; so 'expr' contains + -- two copies of the thing while the occurrence-analysed expression doesn't + -- Nevertheless, we don't occ-analyse before computing the size because the + -- size computation bales out after a while, whereas occurrence analysis does not. + -- + -- This can occasionally mean that the guidance is very pessimistic; + -- it gets fixed up next round + +mkCompulsoryUnfolding expr -- Used for things that absolutely must be unfolded + = CompulsoryUnfolding (occurAnalyseExpr expr) \end{code} %************************************************************************ %* * -\subsection{@mkGenForm@ and friends} +\subsection{The UnfoldingGuidance type} %* * %************************************************************************ \begin{code} -mkGenForm :: FormSummary - -> TemplateOutExpr -- Template - -> UnfoldingGuidance -- Tells about the *size* of the template. - -> UnfoldingDetails - -mkGenForm = GenForm - --- two shorthand variants: -mkLitForm lit = mk_go_for_it (Lit lit) -mkConForm con args = mk_go_for_it (Con con args) - -mk_go_for_it expr = mkGenForm WhnfForm expr UnfoldAlways +instance Outputable UnfoldingGuidance where + ppr UnfoldNever = ptext SLIT("NEVER") + ppr (UnfoldIfGoodArgs v cs size discount) + = hsep [ ptext SLIT("IF_ARGS"), int v, + brackets (hsep (map int cs)), + int size, + int discount ] \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 - -> CoreExpr -- expression to look at + :: Int -- bomb out if size gets bigger than this + -> CoreExpr -- expression to look at -> UnfoldingGuidance +calcUnfoldingGuidance bOMB_OUT_SIZE expr + = case collect_val_bndrs expr of { (inline, val_binders, body) -> + let + n_val_binders = length val_binders + + max_inline_size = n_val_binders+2 + -- The idea is that if there is an INLINE pragma (inline is True) + -- and there's a big body, we give a size of n_val_binders+2. This + -- This is just enough to fail the no-size-increase test in callSiteInline, + -- so that INLINE things don't get inlined into entirely boring contexts, + -- but no more. -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 - - Nothing -> UnfoldNever - - Just (size, cased_args) - -> let - uf = 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 + case (sizeExpr (iUnbox bOMB_OUT_SIZE) val_binders body) of + + TooBig + | not inline -> UnfoldNever + -- A big function with an INLINE pragma must + -- have an UnfoldIfGoodArgs guidance + | otherwise -> UnfoldIfGoodArgs n_val_binders + (map (const 0) val_binders) + max_inline_size 0 + + SizeIs size cased_args scrut_discount + -> UnfoldIfGoodArgs + n_val_binders + (map discount_for val_binders) + final_size + (iBox scrut_discount) + where + boxed_size = iBox size + + final_size | inline = boxed_size `min` max_inline_size + | otherwise = boxed_size + + -- Sometimes an INLINE thing is smaller than n_val_binders+2. + -- A particular case in point is a constructor, which has size 1. + -- We want to inline this regardless, hence the `min` + + discount_for b = foldlBag (\acc (b',n) -> if b==b' then acc+n else acc) + 0 cased_args + } where - is_elem = isIn "calcUnfoldingGuidance" + collect_val_bndrs e = go False [] e + -- We need to be a bit careful about how we collect the + -- value binders. In ptic, if we see + -- __inline_me (\x y -> e) + -- We want to say "2 value binders". Why? So that + -- we take account of information given for the arguments + + go inline rev_vbs (Note InlineMe e) = go True rev_vbs e + go inline rev_vbs (Lam b e) | isId b = go inline (b:rev_vbs) e + | otherwise = go inline rev_vbs e + go inline rev_vbs e = (inline, reverse rev_vbs, e) \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 - -> Maybe (Int, -- Size - [Id] -- Subset of args which are cased - ) + -> ExprSize -sizeExpr scc_s_OK bOMB_OUT_SIZE args expr +sizeExpr bOMB_OUT_SIZE top_args expr = size_up expr where - size_up (Var v) = sizeOne - size_up (App fun arg) = size_up fun `addSize` size_up_arg arg - size_up (Lit lit) = if isNoRepLit lit - then sizeN uNFOLDING_NOREP_LIT_COST - else sizeOne + size_up (Type t) = sizeZero -- Types cost nothing + size_up (Var v) = sizeOne - size_up (SCC _ (Con _ _)) = Nothing -- **** HACK ***** - size_up (SCC lbl body) - = if scc_s_OK then size_up body else Nothing + size_up (Note InlineMe body) = sizeOne -- Inline notes make it look very small + -- This can be important. If you have an instance decl like this: + -- instance Foo a => Foo [a] where + -- {-# INLINE op1, op2 #-} + -- op1 = ... + -- op2 = ... + -- then we'll get a dfun which is a pair of two INLINE lambdas - size_up (Coerce _ _ body) = size_up body -- Coercions cost nothing + size_up (Note _ body) = size_up body -- Other notes cost nothing - size_up (Con con args) = -- 1 + # of val args - sizeN (1 + numValArgs args) - 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 - -- these *tend* to be more expensive; - -- number chosen to avoid unfolding (HACK) - else uNFOLDING_CHEAP_OP_COST - - size_up expr@(Lam _ _) - = let - (uvars, tyvars, args, body) = collectBinders expr - in - size_up body `addSizeN` length args + size_up (App fun (Type t)) = size_up fun + size_up (App fun arg) = size_up_app fun [arg] - size_up (Let (NonRec binder rhs) body) - = size_up rhs - `addSize` - size_up body - `addSizeN` - 1 + size_up (Lit lit) = sizeN (litSize lit) - size_up (Let (Rec pairs) body) - = foldr addSize sizeZero [size_up rhs | (_,rhs) <- pairs] - `addSize` - size_up body - `addSizeN` - length pairs - - size_up (Case scrut alts) - = size_up_scrut scrut - `addSize` - size_up_alts (coreExprType scrut) alts - -- We charge for the "case" itself in "size_up_alts" + size_up (Lam b e) | isId b = lamScrutDiscount (size_up e `addSizeN` 1) + | otherwise = size_up e - ------------ - size_up_arg arg = if isValArg arg then sizeOne else sizeZero{-it's free-} - - ------------ - size_up_alts scrut_ty (AlgAlts alts deflt) - = foldr (addSize . size_alg_alt) (size_up_deflt deflt) alts - `addSizeN` (tyConFamilySize tycon) - -- 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 - - (tycon, _, _) = --trace "CoreUnfold.getAppDataTyConExpandingDicts" $ - getAppDataTyConExpandingDicts scrut_ty + size_up (Let (NonRec binder rhs) body) + = nukeScrutDiscount (size_up rhs) `addSize` + size_up body `addSizeN` + (if isUnLiftedType (idType binder) then 0 else 1) + -- For the allocation + -- If the binder has an unlifted type there is no allocation - size_up_alts _ (PrimAlts alts deflt) - = foldr (addSize . size_prim_alt) (size_up_deflt deflt) alts - -- *no charge* for a primitive "case"! + size_up (Let (Rec pairs) body) + = nukeScrutDiscount rhs_size `addSize` + size_up body `addSizeN` + length pairs -- For the allocation where - size_prim_alt (lit,rhs) = size_up rhs + rhs_size = foldr (addSize . size_up . snd) sizeZero pairs + + size_up (Case (Var v) _ _ alts) + | v `elem` top_args -- We are scrutinising an argument variable + = +{- I'm nuking this special case; BUT see the comment with case alternatives. + + (a) It's too eager. We don't want to inline a wrapper into a + context with no benefit. + E.g. \ x. f (x+x) no point in inlining (+) here! + + (b) It's ineffective. Once g's wrapper is inlined, its case-expressions + aren't scrutinising arguments any more + + case alts of + + [alt] -> size_up_alt alt `addSize` SizeIs 0# (unitBag (v, 1)) 0# + -- We want to make wrapper-style evaluation look cheap, so that + -- when we inline a wrapper it doesn't make call site (much) bigger + -- Otherwise we get nasty phase ordering stuff: + -- f x = g x x + -- h y = ...(f e)... + -- If we inline g's wrapper, f looks big, and doesn't get inlined + -- into h; if we inline f first, while it looks small, then g's + -- wrapper will get inlined later anyway. To avoid this nasty + -- ordering difference, we make (case a of (x,y) -> ...), + -- *where a is one of the arguments* look free. + + other -> +-} + alts_size (foldr addSize sizeOne alt_sizes) -- The 1 is for the scrutinee + (foldr1 maxSize alt_sizes) + + -- Good to inline if an arg is scrutinised, because + -- that may eliminate allocation in the caller + -- And it eliminates the case itself + + where + alt_sizes = map size_up_alt alts + + -- alts_size tries to compute a good discount for + -- the case when we are scrutinising an argument variable + alts_size (SizeIs tot tot_disc tot_scrut) -- Size of all alternatives + (SizeIs max max_disc max_scrut) -- Size of biggest alternative + = SizeIs tot (unitBag (v, iBox (_ILIT 1 +# tot -# max)) `unionBags` max_disc) max_scrut + -- If the variable is known, we produce a discount that + -- will take us back to 'max', the size of rh largest alternative + -- The 1+ is a little discount for reduced allocation in the caller + alts_size tot_size _ = tot_size + +-- gaw 2004 + size_up (Case e _ _ alts) = nukeScrutDiscount (size_up e) `addSize` + foldr (addSize . size_up_alt) sizeZero alts + -- We don't charge for the case itself + -- It's a strict thing, and the price of the call + -- is paid by scrut. Also consider + -- case f x of DEFAULT -> e + -- This is just ';'! Don't charge for it. + + ------------ + size_up_app (App fun arg) args + | isTypeArg arg = size_up_app fun args + | otherwise = size_up_app fun (arg:args) + size_up_app fun args = foldr (addSize . nukeScrutDiscount . size_up) + (size_up_fun fun args) + args + + -- A function application with at least one value argument + -- so if the function is an argument give it an arg-discount + -- + -- Also behave specially if the function is a build + -- + -- Also if the function is a constant Id (constr or primop) + -- compute discounts specially + size_up_fun (Var fun) args + | fun `hasKey` buildIdKey = buildSize + | fun `hasKey` augmentIdKey = augmentSize + | otherwise + = case globalIdDetails fun of + DataConWorkId dc -> conSizeN dc (valArgCount args) + + FCallId fc -> sizeN opt_UF_DearOp + PrimOpId op -> primOpSize op (valArgCount args) + -- foldr addSize (primOpSize op) (map arg_discount args) + -- At one time I tried giving an arg-discount if a primop + -- is applied to one of the function's arguments, but it's + -- not good. At the moment, any unlifted-type arg gets a + -- 'True' for 'yes I'm evald', so we collect the discount even + -- if we know nothing about it. And just having it in a primop + -- doesn't help at all if we don't know something more. + + other -> fun_discount fun `addSizeN` + (1 + length (filter (not . exprIsTrivial) args)) + -- The 1+ is for the function itself + -- Add 1 for each non-trivial arg; + -- the allocation cost, as in let(rec) + -- Slight hack here: for constructors the args are almost always + -- trivial; and for primops they are almost always prim typed + -- We should really only count for non-prim-typed args in the + -- general case, but that seems too much like hard work + + size_up_fun other args = size_up other + + ------------ + size_up_alt (con, bndrs, rhs) = size_up rhs + -- Don't charge for args, so that wrappers look cheap + -- (See comments about wrappers with Case) ------------ - size_up_deflt NoDefault = sizeZero - size_up_deflt (BindDefault binder rhs) = size_up rhs + -- We want to record if we're case'ing, or applying, an argument + fun_discount v | v `elem` top_args = SizeIs 0# (unitBag (v, opt_UF_FunAppDiscount)) 0# + fun_discount other = sizeZero ------------ - -- 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 (Var v) | v `is_elem` args = Just (0, [v]) - | otherwise = Just (0, []) - size_up_scrut other = size_up other - - 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 = Nothing - 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 = Nothing - where - tot = n+m - xys = xs ++ ys + -- 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) m = mkSizeIs bOMB_OUT_SIZE (n +# iUnbox m) xs d + + addSize TooBig _ = TooBig + addSize _ TooBig = TooBig + addSize (SizeIs n1 xs d1) (SizeIs n2 ys d2) + = mkSizeIs bOMB_OUT_SIZE (n1 +# n2) (xs `unionBags` ys) (d1 +# d2) \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} -%* * -%************************************************************************ +Code for manipulating sizes \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)) +data ExprSize = TooBig + | SizeIs FastInt -- Size found + (Bag (Id,Int)) -- Arguments cased herein, and discount for each such + FastInt -- Size to subtract if result is scrutinised + -- by a case expression + +-- subtract the discount before deciding whether to bale out. eg. we +-- want to inline a large constructor application into a selector: +-- tup = (a_1, ..., a_99) +-- x = case tup of ... +-- +mkSizeIs max n xs d | (n -# d) ># max = TooBig + | otherwise = SizeIs n xs d + +maxSize TooBig _ = TooBig +maxSize _ TooBig = TooBig +maxSize s1@(SizeIs n1 _ _) s2@(SizeIs n2 _ _) | n1 ># n2 = s1 + | otherwise = s2 + +sizeZero = SizeIs (_ILIT 0) emptyBag (_ILIT 0) +sizeOne = SizeIs (_ILIT 1) emptyBag (_ILIT 0) +sizeN n = SizeIs (iUnbox n) emptyBag (_ILIT 0) +conSizeN dc n + | isUnboxedTupleCon dc = SizeIs (_ILIT 0) emptyBag (iUnbox n +# _ILIT 1) + | otherwise = SizeIs (_ILIT 1) emptyBag (iUnbox n +# _ILIT 1) + -- Treat constructors as size 1; we are keen to expose them + -- (and we charge separately for their args). We can't treat + -- them as size zero, else we find that (iBox x) has size 1, + -- which is the same as a lone variable; and hence 'v' will + -- always be replaced by (iBox x), where v is bound to iBox x. + -- + -- However, unboxed tuples count as size zero + -- I found occasions where we had + -- f x y z = case op# x y z of { s -> (# s, () #) } + -- and f wasn't getting inlined + +primOpSize op n_args + | not (primOpIsDupable op) = sizeN opt_UF_DearOp + | not (primOpOutOfLine op) = sizeN (2 - n_args) + -- Be very keen to inline simple primops. + -- We give a discount of 1 for each arg so that (op# x y z) costs 2. + -- We can't make it cost 1, else we'll inline let v = (op# x y z) + -- at every use of v, which is excessive. + -- + -- A good example is: + -- let x = +# p q in C {x} + -- Even though x get's an occurrence of 'many', its RHS looks cheap, + -- and there's a good chance it'll get inlined back into C's RHS. Urgh! + | otherwise = sizeOne + +buildSize = SizeIs (-2#) emptyBag 4# + -- We really want to inline applications of build + -- build t (\cn -> e) should cost only the cost of e (because build will be inlined later) + -- Indeed, we should add a result_discount becuause build is + -- very like a constructor. We don't bother to check that the + -- build is saturated (it usually is). The "-2" discounts for the \c n, + -- The "4" is rather arbitrary. + +augmentSize = SizeIs (-2#) emptyBag 4# + -- Ditto (augment t (\cn -> e) ys) should cost only the cost of + -- e plus ys. The -2 accounts for the \cn + +nukeScrutDiscount (SizeIs n vs d) = SizeIs n vs 0# +nukeScrutDiscount TooBig = TooBig + +-- When we return a lambda, give a discount if it's used (applied) +lamScrutDiscount (SizeIs n vs d) = case opt_UF_FunAppDiscount of { d -> SizeIs n vs (iUnbox d) } +lamScrutDiscount 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 - -> 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.'' (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 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). + +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. \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 () - 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_expr (Coerce _ _ _) = panic "ment_expr:Coerce" - -------------- -ment_ty ty - = let - (tycons, clss) = getMentionedTyConsAndClassesFromType ty - in - addToMentionedTyConsUf tycons `thenUf_` - addToMentionedClassesUf clss - -------------- - -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 () +couldBeSmallEnoughToInline :: Int -> CoreExpr -> Bool +couldBeSmallEnoughToInline threshold rhs = case calcUnfoldingGuidance threshold rhs of + UnfoldNever -> False + other -> True + +certainlyWillInline :: Unfolding -> Bool + -- Sees if the unfolding is pretty certain to inline +certainlyWillInline (CoreUnfolding _ _ _ is_cheap (UnfoldIfGoodArgs n_vals _ size _)) + = is_cheap && size - (n_vals +1) <= opt_UF_UseThreshold +certainlyWillInline other + = False + +smallEnoughToInline :: Unfolding -> Bool +smallEnoughToInline (CoreUnfolding _ _ _ _ (UnfoldIfGoodArgs _ _ size _)) + = size <= opt_UF_UseThreshold +smallEnoughToInline other + = False \end{code} %************************************************************************ %* * -\subsubsection{Printing unfoldings in interfaces} +\subsection{callSiteInline} %* * %************************************************************************ -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 - -ppr_Unfolding = PprUnfolding (panic "CoreUnfold:ppr_Unfolding") -\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 +This is the key function. It decides whether to inline a variable at a call site - collect_tyvars (CoTyLam tyv e) = ( tyv:tyvs, e_after ) - where (tyvs, e_after) = collect_tyvars e - collect_tyvars other_e = ( [], other_e ) +callSiteInline is used at call sites, so it is a bit more generous. +It's a very important function that embodies lots of heuristics. +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 -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) +If the thing is in WHNF, there's no danger of duplicating work, +so we can inline if it occurs once, or is small -ppr_uf_Expr in_scopes (CoTyApp expr ty) - = ppCat [ppPStr SLIT("_TYAPP_ "), ppr_uf_Expr in_scopes expr, - ppChar '{', pprParendUniType ppr_Unfolding ty, ppChar '}'] +NOTE: we don't want to inline top-level functions that always diverge. +It just makes the code bigger. Tt turns out that the convenient way to prevent +them inlining is to give them a NOINLINE pragma, which we do in +StrictAnal.addStrictnessInfoToTopId -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] +\begin{code} +callSiteInline :: DynFlags + -> Bool -- True <=> the Id can be inlined + -> Bool -- 'inline' note at call site + -> OccInfo + -> Id -- The Id + -> [Bool] -- One for each value arg; True if it is interesting + -> Bool -- True <=> continuation is interesting + -> Maybe CoreExpr -- Unfolding, if any + + +callSiteInline dflags active_inline inline_call occ id arg_infos interesting_cont + = case idUnfolding id of { + NoUnfolding -> Nothing ; + OtherCon cs -> Nothing ; + + CompulsoryUnfolding unf_template -> Just unf_template ; + -- CompulsoryUnfolding => there is no top-level binding + -- for these things, so we must inline it. + -- Only a couple of primop-like things have + -- compulsory unfoldings (see MkId.lhs). + -- We don't allow them to be inactive + + CoreUnfolding unf_template is_top is_value is_cheap guidance -> + + let + result | yes_or_no = Just unf_template + | otherwise = Nothing + + n_val_args = length arg_infos + + yes_or_no + | not active_inline = False + | otherwise = case occ of + IAmDead -> pprTrace "callSiteInline: dead" (ppr id) False + IAmALoopBreaker -> False + --OneOcc in_lam _ _ -> (not in_lam || is_cheap) && consider_safe True + other -> is_cheap && consider_safe False + -- we consider even the once-in-one-branch + -- occurrences, because they won't all have been + -- caught by preInlineUnconditionally. In particular, + -- if the occurrence is once inside a lambda, and the + -- rhs is cheap but not a manifest lambda, then + -- pre-inline will not have inlined it for fear of + -- invalidating the occurrence info in the rhs. + + consider_safe once + -- consider_safe decides whether it's a good idea to + -- inline something, given that there's no + -- work-duplication issue (the caller checks that). + | inline_call = True + + | otherwise + = case guidance of + UnfoldNever -> False + UnfoldIfGoodArgs n_vals_wanted arg_discounts size res_discount + + | enough_args && size <= (n_vals_wanted + 1) + -- Inline unconditionally if there no size increase + -- Size of call is n_vals_wanted (+1 for the function) + -> True + + | otherwise + -> some_benefit && small_enough + + where + some_benefit = or arg_infos || really_interesting_cont || + (not is_top && ({- once || -} (n_vals_wanted > 0 && enough_args))) + -- [was (once && not in_lam)] + -- If it occurs more than once, there must be + -- something interesting about some argument, or the + -- result context, to make it worth inlining + -- + -- If a function has a nested defn we also record + -- some-benefit, on the grounds that we are often able + -- to eliminate the binding, and hence the allocation, + -- for the function altogether; this is good for join + -- points. But this only makes sense for *functions*; + -- inlining a constructor doesn't help allocation + -- unless the result is scrutinised. UNLESS the + -- constructor occurs just once, albeit possibly in + -- multiple case branches. Then inlining it doesn't + -- increase allocation, but it does increase the + -- chance that the constructor won't be allocated at + -- all in the branches that don't use it. + + enough_args = n_val_args >= n_vals_wanted + really_interesting_cont | n_val_args < n_vals_wanted = False -- Too few args + | n_val_args == n_vals_wanted = interesting_cont + | otherwise = True -- Extra args + -- really_interesting_cont tells if the result of the + -- call is in an interesting context. + + small_enough = (size - discount) <= opt_UF_UseThreshold + discount = computeDiscount n_vals_wanted arg_discounts res_discount + arg_infos really_interesting_cont + + in + if dopt Opt_D_dump_inlinings dflags then + pprTrace "Considering inlining" + (ppr id <+> vcat [text "active:" <+> ppr active_inline, + text "occ info:" <+> ppr occ, + text "arg infos" <+> ppr arg_infos, + text "interesting continuation" <+> ppr interesting_cont, + text "is value:" <+> ppr is_value, + text "is cheap:" <+> ppr is_cheap, + text "guidance" <+> ppr guidance, + text "ANSWER =" <+> if yes_or_no then text "YES" else text "NO"]) + result + else + result + } + +computeDiscount :: Int -> [Int] -> Int -> [Bool] -> Bool -> Int +computeDiscount n_vals_wanted arg_discounts res_discount arg_infos result_used + -- We multiple the raw discounts (args_discount and result_discount) + -- ty opt_UnfoldingKeenessFactor because the former have to do with + -- *size* whereas the discounts imply that there's some extra + -- *efficiency* to be gained (e.g. beta reductions, case reductions) + -- by inlining. + + -- we also discount 1 for each argument passed, because these will + -- reduce with the lambdas in the function (we count 1 for a lambda + -- in size_up). + = 1 + -- Discount of 1 because the result replaces the call + -- so we count 1 for the function itself + length (take n_vals_wanted arg_infos) + + -- Discount of 1 for each arg supplied, because the + -- result replaces the call + round (opt_UF_KeenessFactor * + fromIntegral (arg_discount + result_discount)) 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] + arg_discount = sum (zipWith mk_arg_discount arg_discounts arg_infos) -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] + mk_arg_discount discount is_evald | is_evald = discount + | otherwise = 0 -ppr_uf_Expr in_scopes (Coerce _ _ _) = panic "ppr_uf_Expr:Coerce" -\end{code} - -\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 -} + -- Don't give a result discount unless there are enough args + result_discount | result_used = res_discount -- Over-applied, or case scrut + | otherwise = 0 \end{code}