%
-% (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,
- mkMagicUnfolding,
- modifyUnfoldingDetails,
- calcUnfoldingGuidance,
- mentionedInUnfolding
+ Unfolding(..), UnfoldingGuidance(..), -- types
+
+ noUnfolding, mkMagicUnfolding, mkUnfolding, getUnfoldingTemplate,
+ isEvaldUnfolding, hasUnfolding,
+
+ smallEnoughToInline, couldBeSmallEnoughToInline,
+ certainlySmallEnoughToInline,
+ okToUnfoldInHiFile,
+
+ calcUnfoldingGuidance
) where
-import Ubiq
-import IdLoop -- for paranoia checking
-import PrelLoop -- for paranoia checking
+#include "HsVersions.h"
+
+import {-# SOURCE #-} MagicUFs ( MagicUnfoldingFun, mkMagicUnfoldingFun )
-import Bag ( emptyBag, unitBag, unionBags, Bag )
-import BinderInfo ( oneTextualOcc, oneSafeOcc )
-import CgCompInfo ( uNFOLDING_CHEAP_OP_COST,
+import CmdLineOpts ( opt_UnfoldingCreationThreshold,
+ opt_UnfoldingUseThreshold,
+ opt_UnfoldingConDiscount,
+ opt_UnfoldingKeenessFactor,
+ opt_UnfoldCasms
+ )
+import Constants ( uNFOLDING_CHEAP_OP_COST,
uNFOLDING_DEAR_OP_COST,
uNFOLDING_NOREP_LIT_COST
)
import CoreSyn
-import CoreUtils ( coreExprType )
-import CostCentre ( ccMentionsId )
-import Id ( IdSet(..), GenId{-instances-} )
-import IdInfo ( bottomIsGuaranteed )
-import Literal ( isNoRepLit, isLitLitLit )
-import MagicUFs ( mkMagicUnfoldingFun, MagicUnfoldingFun )
-import Pretty
-import PrimOp ( PrimOp(..) )
-import Type ( getAppDataTyCon )
-import UniqSet ( emptyUniqSet, singletonUniqSet, mkUniqSet,
- unionUniqSets
- )
-import Usage ( UVar(..) )
+import OccurAnal ( occurAnalyseGlobalExpr )
+import CoreUtils ( coreExprType, exprIsTrivial, mkFormSummary,
+ FormSummary(..) )
+import Id ( Id, idType, isId )
+import Const ( Con(..), isLitLitLit )
+import PrimOp ( PrimOp(..), primOpOutOfLine )
+import IdInfo ( ArityInfo(..), InlinePragInfo(..) )
+import TyCon ( tyConFamilySize )
+import Type ( splitAlgTyConApp_maybe )
+import Const ( isNoRepLit )
+import Unique ( Unique )
import Util ( isIn, panic )
-
-manifestlyWHNF = panic "manifestlyWHNF (CoreUnfold)"
-primOpCanTriggerGC = panic "primOpCanTriggerGC (CoreUnfold)"
-getTyConFamilySize = panic "getTyConFamilySize (CoreUnfold)"
-whatsMentionedInId = panic "whatsMentionedInId (CoreUnfold)"
-getMentionedTyConsAndClassesFromType = panic "getMentionedTyConsAndClassesFromType (CoreUnfold)"
+import Outputable
\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
+
+ | 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
+ FormSummary -- Tells whether the template is a WHNF or bottom
+ UnfoldingGuidance -- Tells about the *size* of the template.
+ CoreExpr -- Template; binder-info is correct
+
+ | 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 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}
\begin{code}
-data UnfoldingGuidance
- = UnfoldNever -- Don't do it!
+noUnfolding = NoUnfolding
+
+mkUnfolding expr
+ = let
+ -- strictness mangling (depends on there being no CSE)
+ ufg = calcUnfoldingGuidance opt_UnfoldingCreationThreshold expr
+ occ = occurAnalyseGlobalExpr expr
+ in
+ CoreUnfolding (mkFormSummary expr) ufg occ
+mkMagicUnfolding :: Unique -> Unfolding
+mkMagicUnfolding tag = MagicUnfolding tag (mkMagicUnfoldingFun tag)
+
+getUnfoldingTemplate :: Unfolding -> CoreExpr
+getUnfoldingTemplate (CoreUnfolding _ _ expr) = expr
+getUnfoldingTemplate other = panic "getUnfoldingTemplate"
+
+isEvaldUnfolding :: Unfolding -> Bool
+isEvaldUnfolding (OtherCon _) = True
+isEvaldUnfolding (CoreUnfolding ValueForm _ expr) = True
+isEvaldUnfolding other = False
+
+hasUnfolding :: Unfolding -> Bool
+hasUnfolding NoUnfolding = False
+hasUnfolding 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.
- | 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
+ Int -- and "n" value args
- | 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
+ [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
+ Int -- Scrutinee discount: the discount to substract if the thing is in
+ -- a context (case (thing args) of ...),
+ -- (where there are the right number of arguments.)
\end{code}
\begin{code}
instance Outputable UnfoldingGuidance where
- ppr sty 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,
+ ppr UnfoldAlways = ptext SLIT("_ALWAYS_")
+ ppr (UnfoldIfGoodArgs t v cs size discount)
+ = hsep [ptext SLIT("_IF_ARGS_"), int t, int 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'
-\end{code}
-
-
-%************************************************************************
-%* *
-\subsection{@mkGenForm@ and @modifyUnfoldingDetails@}
-%* *
-%************************************************************************
-
-\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}
-
-\begin{code}
-modifyUnfoldingDetails
- :: Bool -- OK to dup
- -> BinderInfo -- New occurrence info for the thing
- -> UnfoldingDetails
- -> UnfoldingDetails
-
-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
-
-modifyUnfoldingDetails ok_to_dup occ_info other = other
+ then char 'X'
+ else hcat (map (text . show) cs),
+ int size,
+ int discount ]
\end{code}
\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 scc_s_OK bOMB_OUT_SIZE expr
- = let
- (use_binders, ty_binders, val_binders, body) = digForLambdas expr
- in
- case (sizeExpr scc_s_OK bOMB_OUT_SIZE val_binders body) of
-
- Nothing -> UnfoldNever
-
- Just (size, cased_args)
- -> let
- uf = UnfoldIfGoodArgs
+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 collectTyAndValBinders expr of { (ty_binders, val_binders, body) ->
+ case (sizeExpr bOMB_OUT_SIZE val_binders body) of
+
+ TooBig -> UnfoldNever
+
+ SizeIs size cased_args scrut_discount
+ -> UnfoldIfGoodArgs
(length ty_binders)
(length val_binders)
- [ b `is_elem` cased_args | b <- val_binders ]
- size
- in
- -- pprTrace "calcUnfold:" (ppAbove (ppr PprDebug uf) (ppr PprDebug expr))
- uf
- where
- is_elem = isIn "calcUnfoldingGuidance"
+ (map discount_for val_binders)
+ (I# size)
+ (I# scrut_discount)
+ where
+ discount_for b
+ | num_cases == 0 = 0
+ | otherwise
+ = if is_data
+ then tyConFamilySize tycon * num_cases
+ else num_cases -- prim cases are pretty cheap
+
+ where
+ (is_data, tycon)
+ = case (splitAlgTyConApp_maybe (idType b)) of
+ Nothing -> (False, panic "discount")
+ Just (tc,_,_) -> (True, tc)
+ num_cases = length (filter (==b) cased_args)
+ }
\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 (I# bOMB_OUT_SIZE) args expr
= size_up expr
where
+ size_up (Type t) = sizeZero -- Types cost nothing
+ size_up (Note _ body) = size_up body -- Notes cost nothing
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 (SCC _ (Con _ _)) = Nothing -- **** HACK *****
- size_up (SCC lbl body)
- = if scc_s_OK then size_up body else Nothing
-
- size_up (Con con args) = -- 1 + # of val args
- sizeN (1 + length [ va | va <- args, isValArg va ])
- 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 (App fun arg) = size_up fun `addSize` size_up arg
- size_up expr@(Lam _ _)
- = let
- (uvars, tyvars, args, body) = digForLambdas expr
- in
- size_up body `addSizeN` length args
+ size_up (Con con args) = foldr (addSize . size_up)
+ (size_up_con con (valArgCount 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)
- = size_up rhs
- `addSize`
- size_up body
- `addSizeN`
- 1
+ = nukeScrutDiscount (size_up rhs) `addSize`
+ size_up body `addSizeN`
+ 1 -- For the allocation
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_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`
- (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.)
+ = nukeScrutDiscount rhs_size `addSize`
+ size_up body `addSizeN`
+ length pairs -- For the allocation
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`
+ case (splitAlgTyConApp_maybe (coreExprType scrut)) of
+ Nothing -> 1
+ Just (tc,_,_) -> tyConFamilySize tc
+
+ ------------
+ size_up_alt (con, bndrs, rhs) = size_up rhs
-- Don't charge for args, so that wrappers look cheap
- (tycon, _, _) = getAppDataTyCon scrut_ty
+ ------------
+ size_up_con (Literal lit) nv | isNoRepLit lit = sizeN uNFOLDING_NOREP_LIT_COST
+ | otherwise = sizeOne
- size_up_alts _ (PrimAlts alts deflt)
- = foldr (addSize . size_prim_alt) (size_up_deflt deflt) alts
- -- *no charge* for a primitive "case"!
+ size_up_con (DataCon dc) n_val_args = conSizeN n_val_args
+
+ size_up_con (PrimOp op) nv = sizeN op_cost
where
- size_prim_alt (lit,rhs) = size_up rhs
-
- ------------
- size_up_deflt NoDefault = sizeZero
- size_up_deflt (BindDefault binder rhs) = size_up rhs
+ op_cost = if primOpOutOfLine op
+ then uNFOLDING_DEAR_OP_COST
+ -- these *tend* to be more expensive;
+ -- number chosen to avoid unfolding (HACK)
+ else uNFOLDING_CHEAP_OP_COST
------------
- -- 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
+ -- We want to record if we're case'ing an argument
+ arg_discount (Var v) | v `is_elem` args = scrutArg v
+ arg_discount other = sizeZero
is_elem :: Id -> [Id] -> Bool
is_elem = isIn "size_up_scrut"
------------
- sizeZero = Just (0, [])
- sizeOne = Just (1, [])
- sizeN n = Just (n, [])
- sizeVar v = Just (0, [v])
-
- addSizeN Nothing _ = Nothing
- addSizeN (Just (n, xs)) m
- | tot < bOMB_OUT_SIZE = Just (tot, xs)
- | otherwise = Nothing
- where
- tot = n+m
+ -- These addSize things have to be here because
+ -- I don't want to give them bOMB_OUT_SIZE as an argument
- addSize Nothing _ = Nothing
- addSize _ Nothing = Nothing
- addSize (Just (n, xs)) (Just (m, ys))
- | tot < bOMB_OUT_SIZE = Just (tot, xys)
- | otherwise = Nothing
+ 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
- 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}
+ 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
+ n_tot = n1 +# n2
+ d_tot = d1 +# d2
+ xys = xs ++ ys
-A little stuff for in-scopery:
-\begin{code}
-no_in_scopes :: IdSet
-add1 :: IdSet -> Id -> IdSet
-add_some :: IdSet -> [Id] -> IdSet
-no_in_scopes = emptyUniqSet
-in_scopes `add1` x = in_scopes `unionUniqSets` singletonUniqSet x
-in_scopes `add_some` xs = in_scopes `unionUniqSets` mkUniqSet xs
\end{code}
-The can-see-inside-monad functions are the usual sorts of things.
-
-\begin{code}
-thenUf :: UnfoldM bndr a -> (a -> UnfoldM bndr b) -> UnfoldM bndr b
-thenUf m k in_scopes get_id mentioneds
- = case m in_scopes get_id mentioneds of { (v, mentioneds1) ->
- k v in_scopes get_id mentioneds1 }
-
-thenUf_ :: UnfoldM bndr a -> UnfoldM bndr b -> UnfoldM bndr b
-thenUf_ m k in_scopes get_id mentioneds
- = case m in_scopes get_id mentioneds of { (_, mentioneds1) ->
- k in_scopes get_id mentioneds1 }
-
-mapUf :: (a -> UnfoldM bndr b) -> [a] -> UnfoldM bndr [b]
-mapUf f [] = returnUf []
-mapUf f (x:xs)
- = f x `thenUf` \ r ->
- mapUf f xs `thenUf` \ rs ->
- returnUf (r:rs)
-
-returnUf :: a -> UnfoldM bndr a
-returnUf v in_scopes get_id mentioneds = (v, mentioneds)
-
-addInScopesUf :: [Id] -> UnfoldM bndr a -> UnfoldM bndr a
-addInScopesUf more_in_scopes m in_scopes get_id mentioneds
- = m (in_scopes `add_some` more_in_scopes) get_id mentioneds
-
-getInScopesUf :: UnfoldM bndr IdSet
-getInScopesUf in_scopes get_id mentioneds = (in_scopes, mentioneds)
-
-extractIdsUf :: [bndr] -> UnfoldM bndr [Id]
-extractIdsUf binders in_scopes get_id mentioneds
- = (map get_id binders, mentioneds)
-
-consider_Id :: Id -> UnfoldM bndr ()
-consider_Id var in_scopes get_id (ids, tcs, clss, has_litlit)
- = let
- (ids2, tcs2, clss2) = whatsMentionedInId in_scopes var
- in
- ((), (ids `unionBags` ids2,
- tcs `unionBags` tcs2,
- clss `unionBags`clss2,
- has_litlit))
-\end{code}
+Code for manipulating sizes
\begin{code}
-addToMentionedIdsUf :: Id -> UnfoldM bndr ()
-addToMentionedTyConsUf :: Bag TyCon -> UnfoldM bndr ()
-addToMentionedClassesUf :: Bag Class -> UnfoldM bndr ()
-litlit_oops :: UnfoldM bndr ()
-addToMentionedIdsUf add_me in_scopes get_id (ids, tcs, clss, has_litlit)
- = ((), (ids `unionBags` unitBag add_me, tcs, clss, has_litlit))
-
-addToMentionedTyConsUf add_mes in_scopes get_id (ids, tcs, clss, has_litlit)
- = ((), (ids, tcs `unionBags` add_mes, clss, has_litlit))
-
-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 Int# -- Size found
+ [Id] -- Arguments cased herein
+ Int# -- Size to subtract if result is scrutinised
+ -- by a case expression
+
+sizeZero = SizeIs 0# [] 0#
+sizeOne = SizeIs 1# [] 0#
+sizeN (I# n) = SizeIs n [] 0#
+conSizeN (I# n) = SizeIs 0# [] n -- We don't count 1 for the constructor because we're
+ -- quite keen to get constructors into the open
+scrutArg v = SizeIs 0# [v] 0#
+
+nukeScrutDiscount (SizeIs n vs d) = SizeIs n vs 0#
+nukeScrutDiscount TooBig = TooBig
\end{code}
-
%************************************************************************
%* *
-\subsubsection{Gathering up info for an interface-unfolding}
+\subsection[considerUnfolding]{Given all the info, do (not) do the unfolding}
%* *
%************************************************************************
-\begin{code}
-{-
-mentionedInUnfolding
- :: (bndr -> Id) -- so we can get Ids out of binders
- -> 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 <expr > of A .. -> ...;.. )})
+and the expression in question will evaluate to a constructor, we use
+the computed discount size *for the result only* rather than
+computing the argument discounts. Since we know the result of
+the expression is going to be taken apart, discounting its size
+is more accurate (see @sizeExpr@ above for how this discount size
+is computed).
\begin{code}
---ment_expr :: 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) = digForLambdas 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 :: Id -- The function (trace msg only)
+ -> [Bool] -- Evaluated-ness of value arguments
+ -> Bool -- Result is scrutinised
+ -> UnfoldingGuidance
+ -> Bool -- True => unfold it
+
+smallEnoughToInline _ _ _ UnfoldAlways = True
+smallEnoughToInline _ _ _ UnfoldNever = False
+smallEnoughToInline id arg_is_evald_s result_is_scruted
+ (UnfoldIfGoodArgs m_tys_wanted n_vals_wanted discount_vec size scrut_discount)
+ = if enough_args n_vals_wanted arg_is_evald_s &&
+ size - discount <= opt_UnfoldingUseThreshold
+ then
+ True
+ else
+ False
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
-
--------------
-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 ()
+ enough_args n [] | n > 0 = False -- A function with no value args => don't unfold
+ enough_args _ _ = True -- Otherwise it's ok to try
+
+ -- 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).
+
+ discount :: Int
+ discount = length (take n_vals_wanted arg_is_evald_s) +
+ round (
+ opt_UnfoldingKeenessFactor *
+ fromInt (args_discount + result_discount)
+ )
+
+ args_discount = sum (zipWith arg_discount discount_vec arg_is_evald_s)
+ result_discount | result_is_scruted = scrut_discount
+ | otherwise = 0
+
+ arg_discount no_of_constrs is_evald
+ | is_evald = no_of_constrs * opt_UnfoldingConDiscount
+ | otherwise = 0
\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 :: Id -> UnfoldingGuidance -> Bool
+couldBeSmallEnoughToInline id guidance = smallEnoughToInline id (repeat True) True guidance
-ppr_Unfolding = PprUnfolding (panic "CoreUnfold:ppr_Unfolding")
+certainlySmallEnoughToInline :: Id -> UnfoldingGuidance -> Bool
+certainlySmallEnoughToInline id guidance = smallEnoughToInline id (repeat False) 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 )
+@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.
-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}
+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}
-ppr_uf_Binder :: Id -> Pretty
-ppr_uf_Binder v
- = ppBesides [ppLparen, pprIdInUnfolding (singletonUniqSet 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 -}
+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}
projects / ghc-hetmet.git / blobdiff