%
-% (c) The AQUA Project, Glasgow University, 1994-1995
+% (c) The AQUA Project, Glasgow University, 1994-1998
%
-\section[CoreUnfold]{Core-syntax functions to do with unfoldings}
+\section[CoreUnfold]{Core-syntax unfoldings}
-\begin{code}
-#include "HsVersions.h"
+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 @CoreUnfolding@ unfolding, you will
+find, unsurprisingly, a Core expression.
+\begin{code}
module CoreUnfold (
- calcUnfoldingGuidance,
+ Unfolding, UnfoldingGuidance, -- types
+
+ noUnfolding, mkUnfolding,
+ mkOtherCon, otherCons,
+ unfoldingTemplate, maybeUnfoldingTemplate,
+ isEvaldUnfolding, isCheapUnfolding,
+ hasUnfolding, hasSomeUnfolding,
- pprCoreUnfolding,
- mentionedInUnfolding
+ couldBeSmallEnoughToInline,
+ certainlySmallEnoughToInline,
+ okToUnfoldInHiFile,
+ calcUnfoldingGuidance,
+
+ callSiteInline, blackListed
) where
-import AbsPrel ( primOpCanTriggerGC, PrimOp(..), PrimKind
- IF_ATTACK_PRAGMAS(COMMA tagOf_PrimOp)
- IF_ATTACK_PRAGMAS(COMMA pprPrimOp)
+#include "HsVersions.h"
+
+import CmdLineOpts ( opt_UF_CreationThreshold,
+ opt_UF_UseThreshold,
+ opt_UF_ScrutConDiscount,
+ opt_UF_FunAppDiscount,
+ opt_UF_PrimArgDiscount,
+ opt_UF_KeenessFactor,
+ opt_UF_CheapOp, opt_UF_DearOp, opt_UF_NoRepLit,
+ opt_UnfoldCasms, opt_PprStyle_Debug,
+ opt_D_dump_inlinings
)
-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 CoreSyn
+import PprCore ( pprCoreExpr )
+import OccurAnal ( occurAnalyseGlobalExpr )
+import BinderInfo ( )
+import CoreUtils ( coreExprType, exprIsTrivial, exprIsValue, exprIsCheap )
+import Id ( Id, idType, idUnique, isId,
+ getIdSpecialisation, getInlinePragma, getIdUnfolding
)
+import VarSet
+import Name ( isLocallyDefined )
+import Const ( Con(..), isLitLitLit, isWHNFCon )
+import PrimOp ( PrimOp(..), primOpIsDupable )
+import IdInfo ( ArityInfo(..), InlinePragInfo(..), OccInfo(..) )
+import TyCon ( tyConFamilySize )
+import Type ( splitAlgTyConApp_maybe, splitFunTy_maybe, isUnLiftedType )
+import Const ( isNoRepLit )
+import Unique ( Unique, buildIdKey, augmentIdKey, runSTRepIdKey )
+import Maybes ( maybeToBool )
import Bag
-import BasicLit ( isNoRepLit, isLitLitLit, BasicLit(..){-.. is for pragmas-} )
-import CgCompInfo ( 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 IdInfo
-import Maybes
+import Util ( isIn, lengthExceeds )
import Outputable
-import PlainCore ( instCoreExpr )
-import Pretty
-import SimplEnv ( UnfoldingGuidance(..) )
-import UniqSet
-import Unique ( uniqSupply_u, UniqueSupply )
-import Util
\end{code}
%************************************************************************
%* *
+\subsection{@Unfolding@ and @UnfoldingGuidance@ types}
+%* *
+%************************************************************************
+
+\begin{code}
+data Unfolding
+ = NoUnfolding
+
+ | OtherCon [Con] -- It ain't one of these
+ -- (OtherCon xs) also indicates that something has been evaluated
+ -- and hence there's no point in re-evaluating it.
+ -- OtherCon [] is used even for non-data-type values
+ -- to indicated evaluated-ness. Notably:
+ -- data C = C !(Int -> Int)
+ -- case x of { C f -> ... }
+ -- Here, f gets an OtherCon [] unfolding.
+
+ | CoreUnfolding -- An unfolding with redundant cached information
+ CoreExpr -- Template; binder-info is correct
+ Bool -- exprIsCheap template (cached); it won't duplicate (much) work
+ -- if you inline this in more than one place
+ Bool -- exprIsValue template (cached); it is ok to discard a `seq` on
+ -- this variable
+ UnfoldingGuidance -- Tells about the *size* of the template.
+\end{code}
+
+\begin{code}
+noUnfolding = NoUnfolding
+mkOtherCon = OtherCon
+
+mkUnfolding expr
+ = CoreUnfolding (occurAnalyseGlobalExpr expr)
+ (exprIsCheap expr)
+ (exprIsValue expr)
+ (calcUnfoldingGuidance opt_UF_CreationThreshold expr)
+
+unfoldingTemplate :: Unfolding -> CoreExpr
+unfoldingTemplate (CoreUnfolding expr _ _ _) = expr
+unfoldingTemplate other = panic "getUnfoldingTemplate"
+
+maybeUnfoldingTemplate :: Unfolding -> Maybe CoreExpr
+maybeUnfoldingTemplate (CoreUnfolding expr _ _ _) = Just expr
+maybeUnfoldingTemplate other = Nothing
+
+otherCons (OtherCon cons) = cons
+otherCons other = []
+
+isEvaldUnfolding :: Unfolding -> Bool
+isEvaldUnfolding (OtherCon _) = True
+isEvaldUnfolding (CoreUnfolding _ _ is_evald _) = is_evald
+isEvaldUnfolding other = False
+
+isCheapUnfolding :: Unfolding -> Bool
+isCheapUnfolding (CoreUnfolding _ is_cheap _ _) = is_cheap
+isCheapUnfolding other = False
+
+hasUnfolding :: Unfolding -> Bool
+hasUnfolding (CoreUnfolding _ _ _ _) = True
+hasUnfolding other = False
+
+hasSomeUnfolding :: Unfolding -> Bool
+hasSomeUnfolding NoUnfolding = False
+hasSomeUnfolding other = True
+
+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 -- 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 UnfoldAlways = ptext SLIT("ALWAYS")
+ ppr UnfoldNever = ptext SLIT("NEVER")
+ ppr (UnfoldIfGoodArgs v cs size discount)
+ = hsep [ptext SLIT("IF_ARGS"), int v,
+ if null cs -- always print *something*
+ then char 'X'
+ else hcat (map (text . show) 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
- -> PlainCoreExpr -- expression to look at
+ :: 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
+calcUnfoldingGuidance bOMB_OUT_SIZE expr
+ | exprIsTrivial expr -- Often trivial expressions are never bound
+ -- to an expression, but it can happen. For
+ -- example, the Id for a nullary constructor has
+ -- a trivial expression as its unfolding, and
+ -- we want to make sure that we always unfold it.
+ = UnfoldAlways
+
+ | otherwise
+ = case collectBinders expr of { (binders, body) ->
+ let
+ val_binders = filter isId binders
in
- case (sizeExpr scc_s_OK bOMB_OUT_SIZE val_binders body) of
+ case (sizeExpr bOMB_OUT_SIZE val_binders body) of
- Nothing -> UnfoldNever
+ TooBig -> UnfoldNever
- Just (size, cased_args)
- -> let
- uf = UnfoldIfGoodArgs
- (length ty_binders)
+ SizeIs size cased_args scrut_discount
+ -> UnfoldIfGoodArgs
(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
+ | num_cases == 0 = 0
+ | is_fun_ty = num_cases * opt_UF_FunAppDiscount
+ | is_data_ty = num_cases * opt_UF_ScrutConDiscount
+ | otherwise = num_cases * opt_UF_PrimArgDiscount
+ where
+ num_cases = foldlBag (\n b' -> if b==b' then n+1 else n) 0 cased_args
+ -- Count occurrences of b in cased_args
+ arg_ty = idType b
+ is_fun_ty = maybeToBool (splitFunTy_maybe arg_ty)
+ (is_data_ty, tycon) = case (splitAlgTyConApp_maybe (idType b)) of
+ Nothing -> (False, panic "discount")
+ Just (tc,_,_) -> (True, tc)
+ }
\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 (Type t) = sizeZero -- Types cost nothing
+ size_up (Var v) = sizeOne
+
+ size_up (Note InlineMe _) = sizeTwo -- The idea is that this is one more
+ -- than the size of the "call" (i.e. 1)
+ -- We want to reply "no" to noSizeIncrease
+ -- for a bare reference (i.e. applied to no args)
+ -- to an INLINE thing
+
+ size_up (Note _ body) = size_up body -- Notes cost nothing
+
+ size_up (App fun (Type t)) = size_up fun
+ size_up (App fun arg) = size_up_app fun [arg]
+
+ size_up (Con con args) = foldr (addSize . size_up)
+ (size_up_con con args)
+ args
+
+ size_up (Lam b e) | isId b = size_up e `addSizeN` 1
+ | otherwise = size_up e
+
+ 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 (Let (Rec pairs) body)
+ = nukeScrutDiscount rhs_size `addSize`
+ size_up body `addSizeN`
+ length pairs -- For the allocation
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 (CoLam binders body) = size_up body `addSizeN` length binders
- size_up (CoTyLam tyvar body) = size_up body
-
- size_up (CoLet (CoNonRec binder rhs) body)
- = size_up rhs
- `addSize`
- size_up body
- `addSizeN`
- 1
-
- size_up (CoLet (CoRec pairs) body)
- = foldr addSize sizeZero [size_up rhs | (_,rhs) <- pairs]
- `addSize`
- size_up body
- `addSizeN`
- length pairs
-
- size_up (CoCase scrut alts)
- = size_up_scrut scrut
- `addSize`
- size_up_alts (typeOfCoreExpr 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.)
- where
- size_alg_alt (con,args,rhs) = size_up rhs
+ rhs_size = foldr (addSize . size_up . snd) sizeZero pairs
+
+ size_up (Case scrut _ alts)
+ = nukeScrutDiscount (size_up scrut) `addSize`
+ arg_discount scrut `addSize`
+ foldr (addSize . size_up_alt) sizeZero alts
+ `addSizeN` 1 -- charge one for the case itself.
+
+-- Just charge for the alts that exist, not the ones that might exist
+-- `addSizeN`
+-- case (splitAlgTyConApp_maybe (coreExprType scrut)) of
+-- Nothing -> 1
+-- Just (tc,_,_) -> tyConFamilySize tc
+
+ ------------
+ size_up_app (App fun arg) args = size_up_app fun (arg:args)
+ size_up_app fun args = foldr (addSize . size_up) (fun_discount fun) 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
+ fun_discount (Var fun) | idUnique fun == buildIdKey = buildSize
+ | idUnique fun == augmentIdKey = augmentSize
+ | fun `is_elem` args = scrutArg fun
+ fun_discount other = sizeZero
+
+ ------------
+ size_up_alt (con, bndrs, 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
- -- *no charge* for a primitive "case"!
+ ------------
+ size_up_con (Literal lit) args | isNoRepLit lit = sizeN opt_UF_NoRepLit
+ | otherwise = sizeOne
+
+ size_up_con (DataCon dc) args = conSizeN (valArgCount args)
+
+ size_up_con (PrimOp op) args = foldr addSize (sizeN op_cost) (map arg_discount args)
+ -- Give an arg-discount if a primop is applies to
+ -- one of the function's arguments
where
- size_prim_alt (lit,rhs) = size_up rhs
+ op_cost | primOpIsDupable op = opt_UF_CheapOp
+ | otherwise = opt_UF_DearOp
- ------------
- size_up_deflt CoNoDefault = sizeZero
- size_up_deflt (CoBindDefault binder rhs) = size_up rhs
+ -- We want to record if we're case'ing, or applying, an argument
+ arg_discount (Var v) | v `is_elem` args = scrutArg v
+ arg_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 (CoVar 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 = -- 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
+ n_tot = n1 +# n2
+ d_tot = d1 +# d2
+ xys = xs `unionBags` ys
\end{code}
-%************************************************************************
-%* *
-\subsection[unfoldings-for-ifaces]{Processing unfoldings for interfaces}
-%* *
-%************************************************************************
+Code for manipulating sizes
+
+\begin{code}
+
+data ExprSize = TooBig
+ | SizeIs Int# -- Size found
+ (Bag Id) -- Arguments cased herein
+ Int# -- Size to subtract if result is scrutinised
+ -- by a case expression
+
+sizeZero = SizeIs 0# emptyBag 0#
+sizeOne = SizeIs 1# emptyBag 0#
+sizeTwo = SizeIs 2# emptyBag 0#
+sizeN (I# n) = SizeIs n emptyBag 0#
+conSizeN (I# n) = SizeIs 1# emptyBag (n +# 1#)
+ -- Treat constructors as size 1, that unfoldAlways responsds 'False'
+ -- when asked about 'x' when x is bound to (C 3#).
+ -- This avoids gratuitous 'ticks' when x itself appears as an
+ -- atomic constructor argument.
+
+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
+
+scrutArg v = SizeIs 0# (unitBag v) 0#
+
+nukeScrutDiscount (SizeIs n vs d) = SizeIs n vs 0#
+nukeScrutDiscount TooBig = TooBig
+\end{code}
-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}
+\subsection[considerUnfolding]{Given all the info, do (not) do the unfolding}
%* *
%************************************************************************
-\begin{code}
-type UnfoldM bndr thing
- = IdSet -- in-scope Ids (passed downwards only)
- -> (bndr -> Id) -- to extract an Id from a binder (down only)
+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).
+
+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.
- -> (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
+couldBeSmallEnoughToInline :: UnfoldingGuidance -> Bool
+couldBeSmallEnoughToInline UnfoldNever = False
+couldBeSmallEnoughToInline other = True
+
+certainlySmallEnoughToInline :: UnfoldingGuidance -> Bool
+certainlySmallEnoughToInline UnfoldNever = False
+certainlySmallEnoughToInline UnfoldAlways = True
+certainlySmallEnoughToInline (UnfoldIfGoodArgs _ _ size _) = size <= opt_UF_UseThreshold
\end{code}
-The can-see-inside-monad functions are the usual sorts of things.
+@okToUnfoldInHifile@ is used when emitting unfolding info into an interface
+file to determine whether an unfolding candidate really should be unfolded.
+The predicate is needed to prevent @_casm_@s (+ lit-lits) from being emitted
+into interface files.
-\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}
+The reason for inlining expressions containing _casm_s into interface files
+is that these fragments of C are likely to mention functions/#defines that
+will be out-of-scope when inlined into another module. This is not an
+unfixable problem for the user (just need to -#include the approp. header
+file), but turning it off seems to the simplest thing to do.
\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))
+okToUnfoldInHiFile :: CoreExpr -> Bool
+okToUnfoldInHiFile e = opt_UnfoldCasms || go e
+ where
+ -- Race over an expression looking for CCalls..
+ go (Var _) = True
+ go (Con (Literal lit) _) = not (isLitLitLit lit)
+ go (Con (PrimOp op) args) = okToUnfoldPrimOp op && all go args
+ go (Con con args) = True -- con args are always atomic
+ go (App fun arg) = go fun && go arg
+ go (Lam _ body) = go body
+ go (Let binds body) = and (map go (body :rhssOfBind binds))
+ go (Case scrut bndr alts) = and (map go (scrut:rhssOfAlts alts))
+ go (Note _ body) = go body
+ go (Type _) = True
+
+ -- ok to unfold a PrimOp as long as it's not a _casm_
+ okToUnfoldPrimOp (CCallOp _ is_casm _ _) = not is_casm
+ okToUnfoldPrimOp _ = True
\end{code}
%************************************************************************
%* *
-\subsubsection{Gathering up info for an interface-unfolding}
+\subsection{callSiteInline}
%* *
%************************************************************************
-\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}
+This is the key function. It decides whether to inline a variable at a call site
+
+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
+
+If the thing is in WHNF, there's no danger of duplicating work,
+so we can inline if it occurs once, or is small
\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 ()
+callSiteInline :: Bool -- True <=> the Id is black listed
+ -> Bool -- 'inline' note at call site
+ -> 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 black_listed inline_call id arg_infos interesting_cont
+ = case getIdUnfolding id of {
+ NoUnfolding -> Nothing ;
+ OtherCon _ -> Nothing ;
+ CoreUnfolding unf_template is_cheap _ guidance ->
+
+ let
+ result | yes_or_no = Just unf_template
+ | otherwise = Nothing
+
+ inline_prag = getInlinePragma id
+ n_val_args = length arg_infos
+
+ yes_or_no =
+ case inline_prag of
+ IAmDead -> pprTrace "callSiteInline: dead" (ppr id) False
+ IMustNotBeINLINEd -> False
+ IAmALoopBreaker -> False
+ IMustBeINLINEd -> True -- Overrides absolutely everything, including the black list
+ ICanSafelyBeINLINEd in_lam one_br -> consider in_lam True one_br
+ NoInlinePragInfo -> consider InsideLam False False
+
+ consider in_lam once once_in_one_branch
+ | black_listed = False
+ | inline_call = True
+ | once_in_one_branch -- Be very keen to inline something if this is its unique occurrence; that
+ -- gives a good chance of eliminating the original binding for the thing.
+ -- The only time we hold back is when substituting inside a lambda;
+ -- then if the context is totally uninteresting (not applied, not scrutinised)
+ -- there is no point in substituting because it might just increase allocation.
+ = WARN( case in_lam of { NotInsideLam -> True; other -> False },
+ text "callSiteInline:oneOcc" <+> ppr id )
+ -- If it has one occurrence, not inside a lambda, PreInlineUnconditionally
+ -- should have zapped it already
+ is_cheap && (not (null arg_infos) || interesting_cont)
+
+ | otherwise -- Occurs (textually) more than once, so look at its size
+ = case guidance of
+ UnfoldAlways -> True
+ UnfoldNever -> False
+ UnfoldIfGoodArgs n_vals_wanted arg_discounts size res_discount
+ | enough_args && size <= (n_vals_wanted + 1)
+ -- No size increase
+ -- Size of call is n_vals_wanted (+1 for the function)
+ -> case in_lam of
+ NotInsideLam -> True
+ InsideLam -> is_cheap
+
+ | not (or arg_infos || really_interesting_cont || once)
+ -- If it occurs more than once, there must be something interesting
+ -- about some argument, or the result, to make it worth inlining
+ -- We also drop this case if the thing occurs once, although perhaps in
+ -- several branches. In this case we are keener about inlining in the hope
+ -- that we'll be able to drop the allocation for the function altogether.
+ -> False
+
+ | otherwise
+ -> case in_lam of
+ NotInsideLam -> small_enough
+ InsideLam -> is_cheap && small_enough
+
+ where
+ 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
+ -- This rather elaborate defn for really_interesting_cont is important
+ -- Consider an I# = INLINE (\x -> I# {x})
+ -- The unfolding guidance deems it to have size 2, and no arguments.
+ -- So in an application (I# y) we must take the extra arg 'y' as
+ -- evidence of 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
+#ifdef DEBUG
+ if opt_D_dump_inlinings then
+ pprTrace "Considering inlining"
+ (ppr id <+> vcat [text "black listed" <+> ppr black_listed,
+ text "inline prag:" <+> ppr inline_prag,
+ text "arg infos" <+> ppr arg_infos,
+ text "interesting continuation" <+> ppr interesting_cont,
+ text "is cheap" <+> ppr is_cheap,
+ text "guidance" <+> ppr guidance,
+ text "ANSWER =" <+> if yes_or_no then text "YES" else text "NO",
+ if yes_or_no then
+ text "Unfolding =" <+> pprCoreExpr unf_template
+ else empty])
+ result
+ else
+#endif
+ 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).
+ = length (take n_vals_wanted arg_infos) +
+ -- Discount of 1 for each arg supplied, because the
+ -- result replaces the call
+ round (opt_UF_KeenessFactor *
+ fromInt (arg_discount + result_discount))
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
+ arg_discount = sum (zipWith mk_arg_discount arg_discounts arg_infos)
--------------
+ mk_arg_discount discount is_evald | is_evald = discount
+ | otherwise = 0
-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 ()
+ -- 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}
+
%************************************************************************
%* *
-\subsubsection{Printing unfoldings in interfaces}
+\subsection{Black-listing}
%* *
%************************************************************************
-Printing Core-expression unfoldings is sufficiently delicate that we
-give it its own function.
-\begin{code}
-pprCoreUnfolding
- :: PlainCoreExpr
- -> 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
+Inlining is controlled by the "Inline phase" number, which is set
+by the per-simplification-pass '-finline-phase' flag.
-ppr_Unfolding = PprUnfolding (panic "CoreUnfold:ppr_Unfolding")
-\end{code}
+For optimisation we use phase 1,2 and nothing (i.e. no -finline-phase flag)
+in that order. The meanings of these are determined by the @blackListed@ function
+here.
\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
+blackListed :: IdSet -- Used in transformation rules
+ -> Maybe Int -- Inline phase
+ -> Id -> Bool -- True <=> blacklisted
+
+-- The blackListed function sees whether a variable should *not* be
+-- inlined because of the inline phase we are in. This is the sole
+-- place that the inline phase number is looked at.
+
+-- Phase 0: used for 'no imported inlinings please'
+-- This prevents wrappers getting inlined which in turn is bad for full laziness
+blackListed rule_vars (Just 0)
+ = \v -> not (isLocallyDefined v)
+
+-- Phase 1: don't inline any rule-y things or things with specialisations
+blackListed rule_vars (Just 1)
+ = \v -> let v_uniq = idUnique v
+ in v `elemVarSet` rule_vars
+ || not (isEmptyCoreRules (getIdSpecialisation v))
+ || v_uniq == runSTRepIdKey
+
+-- Phase 2: allow build/augment to inline, and specialisations
+blackListed rule_vars (Just 2)
+ = \v -> let v_uniq = idUnique v
+ in (v `elemVarSet` rule_vars && not (v_uniq == buildIdKey ||
+ v_uniq == augmentIdKey))
+ || v_uniq == runSTRepIdKey
+
+-- Otherwise just go for it
+blackListed rule_vars phase
+ = \v -> False
+\end{code}
- 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 []
+SLPJ 95/04: Why @runST@ must be inlined very late:
+\begin{verbatim}
+f x =
+ runST ( \ s -> let
+ (a, s') = newArray# 100 [] s
+ (_, s'') = fill_in_array_or_something a x s'
+ in
+ freezeArray# a s'' )
+\end{verbatim}
+If we inline @runST@, we'll get:
+\begin{verbatim}
+f x = let
+ (a, s') = newArray# 100 [] realWorld#{-NB-}
+ (_, s'') = fill_in_array_or_something a x s'
+ in
+ freezeArray# a s''
+\end{verbatim}
+And now the @newArray#@ binding can be floated to become a CAF, which
+is totally and utterly wrong:
+\begin{verbatim}
+f = let
+ (a, s') = newArray# 100 [] realWorld#{-NB-} -- YIKES!!!
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
+ \ x ->
+ let (_, s'') = fill_in_array_or_something a x s' in
+ freezeArray# a s''
+\end{verbatim}
+All calls to @f@ will share a {\em single} array!
- pp_pair (b, rhs) = ppCat [ppr_uf_Binder b, ppEquals, ppr_uf_Expr new_in_scopes rhs]
+Yet we do want to inline runST sometime, so we can avoid
+needless code. Solution: black list it until the last moment.
-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]
-\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]
-
-ppr_uf_Atom in_scopes (CoLitAtom l) = ppr ppr_Unfolding l
-ppr_uf_Atom in_scopes (CoVarAtom v) = pprIdInUnfolding in_scopes v
-\end{code}
projects / ghc-hetmet.git / blobdiff