Unfoldings (which can travel across module boundaries) are in Core
syntax (namely @CoreExpr@s).
-The type @UnfoldingDetails@ sits ``above'' simply-Core-expressions
+The type @Unfolding@ sits ``above'' simply-Core-expressions
unfoldings, capturing ``higher-level'' things we know about a binding,
usually things that the simplifier found out (e.g., ``it's a
-literal''). In the corner of a @GenForm@ unfolding, you will
+literal''). In the corner of a @SimpleUnfolding@ unfolding, you will
find, unsurprisingly, a Core expression.
\begin{code}
#include "HsVersions.h"
module CoreUnfold (
- UnfoldingDetails(..), UnfoldingGuidance(..), -- types
- FormSummary(..),
-
- mkFormSummary,
- mkGenForm,
- mkMagicUnfolding,
- modifyUnfoldingDetails,
- calcUnfoldingGuidance,
- mentionedInUnfolding
+ SimpleUnfolding(..), Unfolding(..), UnfoldingGuidance(..), -- types
+ UfExpr, RdrName, -- For closure (delete in 1.3)
+
+ FormSummary(..), mkFormSummary, whnfOrBottom, exprSmallEnoughToDup,
+
+ noUnfolding, mkMagicUnfolding, mkUnfolding, getUnfoldingTemplate,
+
+ smallEnoughToInline, couldBeSmallEnoughToInline, certainlySmallEnoughToInline,
+ okToInline,
+
+ calcUnfoldingGuidance
) where
-import Ubiq
-import IdLoop -- for paranoia checking;
+IMP_Ubiq()
+IMPORT_DELOOPER(IdLoop) -- for paranoia checking;
-- and also to get mkMagicUnfoldingFun
-import PrelLoop -- for paranoia checking
+IMPORT_DELOOPER(PrelLoop) -- for paranoia checking
import Bag ( emptyBag, unitBag, unionBags, Bag )
-import BinderInfo ( oneTextualOcc, oneSafeOcc )
-import CgCompInfo ( uNFOLDING_CHEAP_OP_COST,
+
+import CmdLineOpts ( opt_UnfoldingCreationThreshold,
+ opt_UnfoldingUseThreshold,
+ opt_UnfoldingConDiscount
+ )
+import Constants ( uNFOLDING_CHEAP_OP_COST,
uNFOLDING_DEAR_OP_COST,
uNFOLDING_NOREP_LIT_COST
)
+import BinderInfo ( BinderInfo(..), FunOrArg, DuplicationDanger, InsideSCC, isDupDanger )
import CoreSyn
-import CoreUtils ( coreExprType, manifestlyWHNF )
+import CoreUtils ( unTagBinders )
+import HsCore ( UfExpr )
+import RdrHsSyn ( RdrName )
+import OccurAnal ( occurAnalyseGlobalExpr )
+import CoreUtils ( coreExprType )
import CostCentre ( ccMentionsId )
-import Id ( IdSet(..), GenId{-instances-} )
-import IdInfo ( bottomIsGuaranteed )
+import Id ( idType, getIdArity, isBottomingId, isDataCon, isPrimitiveId_maybe,
+ SYN_IE(IdSet), GenId{-instances-} )
+import PrimOp ( primOpCanTriggerGC, fragilePrimOp, PrimOp(..) )
+import IdInfo ( ArityInfo(..), bottomIsGuaranteed )
import Literal ( isNoRepLit, isLitLitLit )
import Pretty
-import PrimOp ( primOpCanTriggerGC, PrimOp(..) )
import TyCon ( tyConFamilySize )
-import Type ( getAppDataTyCon )
+import Type ( maybeAppDataTyConExpandingDicts )
import UniqSet ( emptyUniqSet, unitUniqSet, mkUniqSet,
addOneToUniqSet, unionUniqSets
)
-import Usage ( UVar(..) )
-import Util ( isIn, panic )
+import Usage ( SYN_IE(UVar) )
+import Maybes ( maybeToBool )
+import Util ( isIn, panic, assertPanic )
-whatsMentionedInId = panic "whatsMentionedInId (CoreUnfold)"
-getMentionedTyConsAndClassesFromType = panic "getMentionedTyConsAndClassesFromType (CoreUnfold)"
\end{code}
%************************************************************************
%* *
-\subsection{@UnfoldingDetails@ and @UnfoldingGuidance@ types}
+\subsection{@Unfolding@ and @UnfoldingGuidance@ types}
%* *
%************************************************************************
-(And @FormSummary@, too.)
-
\begin{code}
-data UnfoldingDetails
- = NoUnfoldingDetails
-
- | LitForm
- Literal
-
- | OtherLitForm
- [Literal] -- It is a literal, but definitely not one of these
-
- | ConForm
- Id -- The constructor
- [CoreArg] -- Value arguments; NB OutArgs, already cloned
-
- | OtherConForm
- [Id] -- It definitely isn't one of these constructors
- -- This captures the situation in the default branch of
- -- a case: case x of
- -- c1 ... -> ...
- -- c2 ... -> ...
- -- v -> default-rhs
- -- Then in default-rhs we know that v isn't c1 or c2.
- --
- -- NB. In the degenerate: case x of {v -> default-rhs}
- -- x will be bound to
- -- OtherConForm []
- -- which captures the idea that x is eval'd but we don't
- -- know which constructor.
-
-
- | GenForm
- Bool -- True <=> At most one textual occurrence of the
- -- binder in its scope, *or*
- -- if we are happy to duplicate this
- -- binding.
- FormSummary -- Tells whether the template is a WHNF or bottom
- TemplateOutExpr -- The template
- UnfoldingGuidance -- Tells about the *size* of the template.
-
- | MagicForm
- Unique -- of the Id whose magic unfolding this is
+data Unfolding
+ = NoUnfolding
+
+ | CoreUnfolding SimpleUnfolding
+
+ | MagicUnfolding
+ Unique -- Unique of the Id whose magic unfolding this is
MagicUnfoldingFun
-type TemplateOutExpr = GenCoreExpr (Id, BinderInfo) Id TyVar UVar
- -- An OutExpr with occurrence info attached. This is used as
- -- a template in GeneralForms.
-mkMagicUnfolding :: Unique -> UnfoldingDetails
-mkMagicUnfolding tag = MagicForm tag (mkMagicUnfoldingFun tag)
+data SimpleUnfolding
+ = SimpleUnfolding -- An unfolding with redundant cached information
+ FormSummary -- Tells whether the template is a WHNF or bottom
+ UnfoldingGuidance -- Tells about the *size* of the template.
+ SimplifiableCoreExpr -- Template
-data FormSummary
- = WhnfForm -- Expression is WHNF
- | BottomForm -- Expression is guaranteed to be bottom. We're more gung
- -- ho about inlining such things, because it can't waste work
- | OtherForm -- Anything else
-instance Outputable FormSummary where
- ppr sty WhnfForm = ppStr "WHNF"
- ppr sty BottomForm = ppStr "Bot"
- ppr sty OtherForm = ppStr "Other"
-
---???mkFormSummary :: StrictnessInfo -> GenCoreExpr bndr Id -> FormSummary
-mkFormSummary si expr
- | manifestlyWHNF expr = WhnfForm
- | bottomIsGuaranteed si = BottomForm
-
- -- Chances are that the Id will be decorated with strictness info
- -- telling that the RHS is definitely bottom. This *might* not be the
- -- case, if it's been a while since strictness analysis, but leaving out
- -- the test for manifestlyBottom makes things a little more efficient.
- -- We can always put it back...
- -- | manifestlyBottom expr = BottomForm
-
- | otherwise = OtherForm
-\end{code}
+noUnfolding = NoUnfolding
-\begin{code}
-data UnfoldingGuidance
- = UnfoldNever -- Don't do it!
+mkUnfolding inline_me expr
+ = let
+ -- strictness mangling (depends on there being no CSE)
+ ufg = calcUnfoldingGuidance inline_me opt_UnfoldingCreationThreshold expr
+ occ = occurAnalyseGlobalExpr expr
+ cuf = CoreUnfolding (SimpleUnfolding (mkFormSummary expr) ufg occ)
+
+ cont = case occ of { Var _ -> cuf; _ -> cuf }
+ in
+ case ufg of { UnfoldAlways -> cont; _ -> cont }
+
+mkMagicUnfolding :: Unique -> Unfolding
+mkMagicUnfolding tag = MagicUnfolding tag (mkMagicUnfoldingFun tag)
+getUnfoldingTemplate :: Unfolding -> CoreExpr
+getUnfoldingTemplate (CoreUnfolding (SimpleUnfolding _ _ expr))
+ = unTagBinders expr
+getUnfoldingTemplate other = panic "getUnfoldingTemplate"
+
+
+data UnfoldingGuidance
+ = UnfoldNever
| UnfoldAlways -- There is no "original" definition,
-- so you'd better unfold. Or: something
-- so cheap to unfold (e.g., 1#) that
-- you should do it absolutely always.
- | EssentialUnfolding -- Like UnfoldAlways, but you *must* do
- -- it absolutely always.
- -- This is what we use for data constructors
- -- and PrimOps, because we don't feel like
- -- generating curried versions "just in case".
-
- | UnfoldIfGoodArgs Int -- if "m" type args and "n" value args; and
- Int -- those val args are manifestly data constructors
- [Bool] -- the val-arg positions marked True
+ | UnfoldIfGoodArgs Int -- if "m" type args
+ Int -- and "n" value args
+ [Int] -- Discount if the argument is evaluated.
-- (i.e., a simplification will definitely
- -- be possible).
+ -- be possible). One elt of the list per *value* arg.
Int -- The "size" of the unfolding; to be elaborated
-- later. ToDo
-
- | BadUnfolding -- This is used by TcPragmas if the *lazy*
- -- lintUnfolding test fails
- -- It will never escape from the IdInfo as
- -- it is caught by getInfo_UF and converted
- -- to NoUnfoldingDetails
\end{code}
\begin{code}
instance Outputable UnfoldingGuidance where
- ppr sty UnfoldNever = ppStr "_N_"
- ppr sty UnfoldAlways = ppStr "_ALWAYS_"
- ppr sty EssentialUnfolding = ppStr "_ESSENTIAL_" -- shouldn't appear in an iface
+ ppr sty UnfoldAlways = ppPStr SLIT("_ALWAYS_")
+-- ppr sty EssentialUnfolding = ppPStr SLIT("_ESSENTIAL_") -- shouldn't appear in an iface
ppr sty (UnfoldIfGoodArgs t v cs size)
- = ppCat [ppStr "_IF_ARGS_", ppInt t, ppInt v,
+ = ppCat [ppPStr SLIT("_IF_ARGS_"), ppInt t, ppInt v,
if null cs -- always print *something*
then ppChar 'X'
- else ppBesides (map pp_c cs),
+ else ppBesides (map (ppStr . show) cs),
ppInt size ]
- where
- pp_c False = ppChar 'X'
- pp_c True = ppChar 'C'
\end{code}
%************************************************************************
%* *
-\subsection{@mkGenForm@ and @modifyUnfoldingDetails@}
+\subsection{Figuring out things about expressions}
%* *
%************************************************************************
\begin{code}
-mkGenForm :: Bool -- Ok to Dup code down different case branches,
- -- because of either a flag saying so,
- -- or alternatively the object is *SMALL*
- -> BinderInfo --
- -> FormSummary
- -> TemplateOutExpr -- Template
- -> UnfoldingGuidance -- Tells about the *size* of the template.
- -> UnfoldingDetails
-
-mkGenForm safe_to_dup occ_info WhnfForm template guidance
- = GenForm (oneTextualOcc safe_to_dup occ_info) WhnfForm template guidance
-
-mkGenForm safe_to_dup occ_info form_summary template guidance
- | oneSafeOcc safe_to_dup occ_info -- Non-WHNF with only safe occurrences
- = GenForm True form_summary template guidance
-
- | otherwise -- Not a WHNF, many occurrences
- = NoUnfoldingDetails
-\end{code}
+data FormSummary
+ = VarForm -- Expression is a variable (or scc var, etc)
+ | ValueForm -- Expression is a value: i.e. a value-lambda,constructor, or literal
+ | BottomForm -- Expression is guaranteed to be bottom. We're more gung
+ -- ho about inlining such things, because it can't waste work
+ | OtherForm -- Anything else
-\begin{code}
-modifyUnfoldingDetails
- :: Bool -- OK to dup
- -> BinderInfo -- New occurrence info for the thing
- -> UnfoldingDetails
- -> UnfoldingDetails
+instance Outputable FormSummary where
+ ppr sty VarForm = ppPStr SLIT("Var")
+ ppr sty ValueForm = ppPStr SLIT("Value")
+ ppr sty BottomForm = ppPStr SLIT("Bot")
+ ppr sty OtherForm = ppPStr SLIT("Other")
-modifyUnfoldingDetails ok_to_dup occ_info
- (GenForm only_one form_summary template guidance)
- | only_one = mkGenForm ok_to_dup occ_info form_summary template guidance
+mkFormSummary ::GenCoreExpr bndr Id tyvar uvar -> FormSummary
-modifyUnfoldingDetails ok_to_dup occ_info other = other
+mkFormSummary expr
+ = go (0::Int) expr -- The "n" is the number of (value) arguments so far
+ where
+ go n (Lit _) = ASSERT(n==0) ValueForm
+ go n (Con _ _) = ASSERT(n==0) ValueForm
+ go n (Prim _ _) = OtherForm
+ go n (SCC _ e) = go n e
+ go n (Coerce _ _ e) = go n e
+ go n (Let _ e) = OtherForm
+ go n (Case _ _) = OtherForm
+
+ go 0 (Lam (ValBinder x) e) = ValueForm -- NB: \x.bottom /= bottom!
+ go n (Lam (ValBinder x) e) = go (n-1) e -- Applied lambda
+ go n (Lam other_binder e) = go n e
+
+ go n (App fun arg) | isValArg arg = go (n+1) fun
+ go n (App fun other_arg) = go n fun
+
+ go n (Var f) | isBottomingId f = BottomForm
+ | isDataCon f = ValueForm -- Can happen inside imported unfoldings
+ go 0 (Var f) = VarForm
+ go n (Var f) = case getIdArity f of
+ ArityExactly a | n < a -> ValueForm
+ ArityAtLeast a | n < a -> ValueForm
+ other -> OtherForm
+
+whnfOrBottom :: GenCoreExpr bndr Id tyvar uvar -> Bool
+whnfOrBottom e = case mkFormSummary e of
+ VarForm -> True
+ ValueForm -> True
+ BottomForm -> True
+ OtherForm -> False
\end{code}
+\begin{code}
+exprSmallEnoughToDup (Con _ _) = True -- Could check # of args
+exprSmallEnoughToDup (Prim op _) = not (fragilePrimOp op) -- Could check # of args
+exprSmallEnoughToDup (Lit lit) = not (isNoRepLit lit)
+exprSmallEnoughToDup expr
+ = case (collectArgs expr) of { (fun, _, _, vargs) ->
+ case fun of
+ Var v | length vargs == 0 -> True
+ _ -> False
+ }
+
+{- LATER:
+WAS: MORE CLEVER:
+exprSmallEnoughToDup expr -- for now, just: <var> applied to <args>
+ = case (collectArgs expr) of { (fun, _, _, vargs) ->
+ case fun of
+ Var v -> v /= buildId
+ && v /= augmentId
+ && length vargs <= 6 -- or 10 or 1 or 4 or anything smallish.
+ _ -> False
+ }
+-}
+\end{code}
+Question (ADR): What is the above used for? Is a _ccall_ really small
+enough?
+
%************************************************************************
%* *
\subsection[calcUnfoldingGuidance]{Calculate ``unfolding guidance'' for an expression}
\begin{code}
calcUnfoldingGuidance
- :: Bool -- True <=> OK if _scc_s appear in expr
- -> Int -- bomb out if size gets bigger than this
- -> CoreExpr -- expression to look at
+ :: Bool -- True <=> there's an INLINE pragma on this thing
+ -> Int -- bomb out if size gets bigger than this
+ -> CoreExpr -- expression to look at
-> UnfoldingGuidance
-calcUnfoldingGuidance scc_s_OK bOMB_OUT_SIZE expr
- = let
- (use_binders, ty_binders, val_binders, body) = collectBinders expr
- in
- case (sizeExpr scc_s_OK bOMB_OUT_SIZE val_binders body) of
+calcUnfoldingGuidance True bOMB_OUT_SIZE expr = UnfoldAlways -- Always inline if the INLINE pragma says so
+
+calcUnfoldingGuidance False bOMB_OUT_SIZE expr
+ = case collectBinders expr of { (use_binders, ty_binders, val_binders, body) ->
+ case (sizeExpr bOMB_OUT_SIZE val_binders body) of
- Nothing -> UnfoldNever
+ Nothing -> UnfoldNever
Just (size, cased_args)
- -> let
- uf = UnfoldIfGoodArgs
+ -> UnfoldIfGoodArgs
(length ty_binders)
(length val_binders)
- [ b `is_elem` cased_args | b <- val_binders ]
- size
- in
- -- pprTrace "calcUnfold:" (ppAbove (ppr PprDebug uf) (ppr PprDebug expr))
- uf
- where
- is_elem = isIn "calcUnfoldingGuidance"
+ (map discount_for val_binders)
+ size
+ where
+ discount_for b
+ | is_data && b `is_elem` cased_args = tyConFamilySize tycon
+ | otherwise = 0
+ where
+ (is_data, tycon)
+ = case (maybeAppDataTyConExpandingDicts (idType b)) of
+ Nothing -> (False, panic "discount")
+ Just (tc,_,_) -> (True, tc)
+
+ is_elem = isIn "calcUnfoldingGuidance" }
\end{code}
\begin{code}
-sizeExpr :: Bool -- True <=> _scc_s OK
- -> Int -- Bomb out if it gets bigger than this
+sizeExpr :: Int -- Bomb out if it gets bigger than this
-> [Id] -- Arguments; we're interested in which of these
-- get case'd
-> CoreExpr
[Id] -- Subset of args which are cased
)
-sizeExpr scc_s_OK bOMB_OUT_SIZE args expr
+sizeExpr bOMB_OUT_SIZE args expr
+
+ | data_or_prim fun
+-- We are very keen to inline literals, constructors, or primitives
+-- including their slightly-disguised forms as applications (the latter
+-- can show up in the bodies of things imported from interfaces).
+ = Just (0, [])
+
+ | otherwise
= size_up expr
where
- size_up (Var v) = sizeOne
- size_up (App fun arg) = size_up fun `addSize` size_up_arg arg
+ (fun, _) = splitCoreApps expr
+ data_or_prim (Var v) = maybeToBool (isPrimitiveId_maybe v) ||
+ isDataCon v
+ data_or_prim (Con _ _) = True
+ data_or_prim (Prim _ _) = True
+ data_or_prim (Lit _) = True
+ data_or_prim other = False
+
+ size_up (Var v) = sizeZero
+ size_up (App fun arg) = size_up fun `addSize` size_up_arg arg `addSizeN` 1
+ -- 1 for application node
+
size_up (Lit lit) = if isNoRepLit lit
- then sizeN uNFOLDING_NOREP_LIT_COST
- else sizeOne
+ then sizeN uNFOLDING_NOREP_LIT_COST
+ else sizeZero
- size_up (SCC _ (Con _ _)) = Nothing -- **** HACK *****
- size_up (SCC lbl body)
- = if scc_s_OK then size_up body else Nothing
+-- I don't understand this hack so I'm removing it! SLPJ Nov 96
+-- size_up (SCC _ (Con _ _)) = Nothing -- **** HACK *****
- size_up (Con con args) = -- 1 + # of val args
- sizeN (1 + numValArgs args)
+ size_up (SCC lbl body) = size_up body -- SCCs cost nothing
+ size_up (Coerce _ _ body) = size_up body -- Coercions cost nothing
+
+ size_up (Con con args) = sizeN (numValArgs args)
+ -- We don't count 1 for the constructor because we're
+ -- quite keen to get constructors into the open
+
size_up (Prim op args) = sizeN op_cost -- NB: no charge for PrimOp args
where
op_cost = if primOpCanTriggerGC op
-- We charge for the "case" itself in "size_up_alts"
------------
- size_up_arg arg = if isValArg arg then sizeOne else sizeZero{-it's free-}
+ size_up_arg (LitArg lit) | isNoRepLit lit = sizeN uNFOLDING_NOREP_LIT_COST
+ size_up_arg other = sizeZero
------------
size_up_alts scrut_ty (AlgAlts alts deflt)
- = foldr (addSize . size_alg_alt) (size_up_deflt deflt) alts
- `addSizeN` (tyConFamilySize tycon)
+ = foldr (addSize . size_alg_alt) (size_up_deflt deflt) alts
+ `addSizeN`
+ alt_cost
+ where
+ size_alg_alt (con,args,rhs) = size_up rhs
+ -- Don't charge for args, so that wrappers look cheap
+
-- NB: we charge N for an alg. "case", where N is
-- the number of constructors in the thing being eval'd.
-- (You'll eventually get a "discount" of N if you
-- think the "case" is likely to go away.)
- where
- size_alg_alt (con,args,rhs) = size_up rhs
- -- Don't charge for args, so that wrappers look cheap
+ -- It's important to charge for alternatives. If you don't then you
+ -- get size 1 for things like:
+ -- case x of { A -> 1#; B -> 2#; ... lots }
- (tycon, _, _) = _trace "getAppDataTyCon.CoreUnfold" $ getAppDataTyCon scrut_ty
+ alt_cost :: Int
+ alt_cost
+ = --trace "CoreUnfold.getAppDataTyConExpandingDicts:2" $
+ case (maybeAppDataTyConExpandingDicts scrut_ty) of
+ Nothing -> 1
+ Just (tc,_,_) -> tyConFamilySize tc
size_up_alts _ (PrimAlts alts deflt)
= foldr (addSize . size_prim_alt) (size_up_deflt deflt) alts
-- Second, we want to charge nothing for the srutinee if it's just
-- a variable. That way wrapper-like things look cheap.
size_up_scrut (Var v) | v `is_elem` args = Just (0, [v])
- | otherwise = Just (0, [])
- size_up_scrut other = size_up other
+ | otherwise = Just (0, [])
+ size_up_scrut other = size_up other
is_elem :: Id -> [Id] -> Bool
is_elem = isIn "size_up_scrut"
sizeZero = Just (0, [])
sizeOne = Just (1, [])
sizeN n = Just (n, [])
- sizeVar v = Just (0, [v])
addSizeN Nothing _ = Nothing
addSizeN (Just (n, xs)) m
where
tot = n+m
xys = xs ++ ys
-\end{code}
-%************************************************************************
-%* *
-\subsection[unfoldings-for-ifaces]{Processing unfoldings for interfaces}
-%* *
-%************************************************************************
-
-Of course, the main thing we do to unfoldings-for-interfaces is {\em
-print} them. But, while we're at it, we collect info about
-``mentioned'' Ids, etc., etc.---we're going to need this stuff anyway.
-
-%************************************************************************
-%* *
-\subsubsection{Monad stuff for the unfolding-generation game}
-%* *
-%************************************************************************
-
-\begin{code}
-type UnfoldM bndr thing
- = IdSet -- in-scope Ids (passed downwards only)
- -> (bndr -> Id) -- to extract an Id from a binder (down only)
-
- -> (Bag Id, -- mentioned global vars (ditto)
- Bag TyCon, -- ditto, tycons
- Bag Class, -- ditto, classes
- Bool) -- True <=> mentions something litlit-ish
-
- -> (thing, (Bag Id, Bag TyCon, Bag Class, Bool)) -- accumulated...
-\end{code}
-
-A little stuff for in-scopery:
-\begin{code}
-no_in_scopes :: IdSet
-add1 :: IdSet -> Id -> IdSet
-add_some :: IdSet -> [Id] -> IdSet
-
-no_in_scopes = emptyUniqSet
-in_scopes `add1` x = addOneToUniqSet in_scopes x
-in_scopes `add_some` xs = in_scopes `unionUniqSets` mkUniqSet xs
-\end{code}
-
-The can-see-inside-monad functions are the usual sorts of things.
-
-\begin{code}
-thenUf :: UnfoldM bndr a -> (a -> UnfoldM bndr b) -> UnfoldM bndr b
-thenUf m k in_scopes get_id mentioneds
- = case m in_scopes get_id mentioneds of { (v, mentioneds1) ->
- k v in_scopes get_id mentioneds1 }
-
-thenUf_ :: UnfoldM bndr a -> UnfoldM bndr b -> UnfoldM bndr b
-thenUf_ m k in_scopes get_id mentioneds
- = case m in_scopes get_id mentioneds of { (_, mentioneds1) ->
- k in_scopes get_id mentioneds1 }
-
-mapUf :: (a -> UnfoldM bndr b) -> [a] -> UnfoldM bndr [b]
-mapUf f [] = returnUf []
-mapUf f (x:xs)
- = f x `thenUf` \ r ->
- mapUf f xs `thenUf` \ rs ->
- returnUf (r:rs)
-
-returnUf :: a -> UnfoldM bndr a
-returnUf v in_scopes get_id mentioneds = (v, mentioneds)
-
-addInScopesUf :: [Id] -> UnfoldM bndr a -> UnfoldM bndr a
-addInScopesUf more_in_scopes m in_scopes get_id mentioneds
- = m (in_scopes `add_some` more_in_scopes) get_id mentioneds
-
-getInScopesUf :: UnfoldM bndr IdSet
-getInScopesUf in_scopes get_id mentioneds = (in_scopes, mentioneds)
-
-extractIdsUf :: [bndr] -> UnfoldM bndr [Id]
-extractIdsUf binders in_scopes get_id mentioneds
- = (map get_id binders, mentioneds)
-
-consider_Id :: Id -> UnfoldM bndr ()
-consider_Id var in_scopes get_id (ids, tcs, clss, has_litlit)
- = let
- (ids2, tcs2, clss2) = whatsMentionedInId in_scopes var
- in
- ((), (ids `unionBags` ids2,
- tcs `unionBags` tcs2,
- clss `unionBags`clss2,
- has_litlit))
-\end{code}
-
-\begin{code}
-addToMentionedIdsUf :: Id -> UnfoldM bndr ()
-addToMentionedTyConsUf :: Bag TyCon -> UnfoldM bndr ()
-addToMentionedClassesUf :: Bag Class -> UnfoldM bndr ()
-litlit_oops :: UnfoldM bndr ()
-
-addToMentionedIdsUf add_me in_scopes get_id (ids, tcs, clss, has_litlit)
- = ((), (ids `unionBags` unitBag add_me, tcs, clss, has_litlit))
-
-addToMentionedTyConsUf add_mes in_scopes get_id (ids, tcs, clss, has_litlit)
- = ((), (ids, tcs `unionBags` add_mes, clss, has_litlit))
-
-addToMentionedClassesUf add_mes in_scopes get_id (ids, tcs, clss, has_litlit)
- = ((), (ids, tcs, clss `unionBags` add_mes, has_litlit))
-
-litlit_oops in_scopes get_id (ids, tcs, clss, _)
- = ((), (ids, tcs, clss, True))
+splitCoreApps e
+ = go e []
+ where
+ go (App fun arg) args = go fun (arg:args)
+ go fun args = (fun,args)
\end{code}
-
%************************************************************************
%* *
-\subsubsection{Gathering up info for an interface-unfolding}
+\subsection[considerUnfolding]{Given all the info, do (not) do the unfolding}
%* *
%************************************************************************
-\begin{code}
-{-
-mentionedInUnfolding
- :: (bndr -> Id) -- so we can get Ids out of binders
- -> GenCoreExpr bndr Id -- input expression
- -> (Bag Id, Bag TyCon, Bag Class,
- -- what we found mentioned in the expr
- Bool -- True <=> mentions a ``litlit''-ish thing
- -- (the guy on the other side of an interface
- -- may not be able to handle it)
- )
--}
-
-mentionedInUnfolding get_id expr
- = case (ment_expr expr no_in_scopes get_id (emptyBag, emptyBag, emptyBag, False)) of
- (_, (ids_bag, tcs_bag, clss_bag, has_litlit)) ->
- (ids_bag, tcs_bag, clss_bag, has_litlit)
-\end{code}
+We have very limited information about an unfolding expression: (1)~so
+many type arguments and so many value arguments expected---for our
+purposes here, we assume we've got those. (2)~A ``size'' or ``cost,''
+a single integer. (3)~An ``argument info'' vector. For this, what we
+have at the moment is a Boolean per argument position that says, ``I
+will look with great favour on an explicit constructor in this
+position.''
+
+Assuming we have enough type- and value arguments (if not, we give up
+immediately), then we see if the ``discounted size'' is below some
+(semi-arbitrary) threshold. It works like this: for every argument
+position where we're looking for a constructor AND WE HAVE ONE in our
+hands, we get a (again, semi-arbitrary) discount [proportion to the
+number of constructors in the type being scrutinized].
\begin{code}
---ment_expr :: GenCoreExpr bndr Id -> UnfoldM bndr ()
-
-ment_expr (Var v) = consider_Id v
-ment_expr (Lit l) = consider_lit l
-
-ment_expr expr@(Lam _ _)
- = let
- (uvars, tyvars, args, body) = collectBinders expr
- in
- extractIdsUf args `thenUf` \ bs_ids ->
- addInScopesUf bs_ids (
- -- this considering is just to extract any mentioned types/classes
- mapUf consider_Id bs_ids `thenUf_`
- ment_expr body
- )
-
-ment_expr (App fun arg)
- = ment_expr fun `thenUf_`
- ment_arg arg
-
-ment_expr (Con c as)
- = consider_Id c `thenUf_`
- mapUf ment_arg as `thenUf_`
- returnUf ()
-
-ment_expr (Prim op as)
- = ment_op op `thenUf_`
- mapUf ment_arg as `thenUf_`
- returnUf ()
+smallEnoughToInline :: [Bool] -- Evaluated-ness of value arguments
+ -> UnfoldingGuidance
+ -> Bool -- True => unfold it
+
+smallEnoughToInline _ UnfoldAlways = True
+smallEnoughToInline _ UnfoldNever = False
+smallEnoughToInline arg_is_evald_s
+ (UnfoldIfGoodArgs m_tys_wanted n_vals_wanted discount_vec size)
+ = enough_args n_vals_wanted arg_is_evald_s &&
+ discounted_size <= opt_UnfoldingUseThreshold
where
- ment_op (CCallOp str is_asm may_gc arg_tys res_ty)
- = mapUf ment_ty arg_tys `thenUf_`
- ment_ty res_ty
- ment_op other_op = returnUf ()
-
-ment_expr (Case scrutinee alts)
- = ment_expr scrutinee `thenUf_`
- ment_alts alts
-
-ment_expr (Let (NonRec bind rhs) body)
- = ment_expr rhs `thenUf_`
- extractIdsUf [bind] `thenUf` \ bi@[bind_id] ->
- addInScopesUf bi (
- ment_expr body `thenUf_`
- consider_Id bind_id )
-
-ment_expr (Let (Rec pairs) body)
- = let
- binders = map fst pairs
- rhss = map snd pairs
- in
- extractIdsUf binders `thenUf` \ binder_ids ->
- addInScopesUf binder_ids (
- mapUf ment_expr rhss `thenUf_`
- mapUf consider_Id binder_ids `thenUf_`
- ment_expr body )
-
-ment_expr (SCC cc expr)
- = (case (ccMentionsId cc) of
- Just id -> consider_Id id
- Nothing -> returnUf ()
- )
- `thenUf_` ment_expr expr
-
--------------
-ment_ty ty
- = let
- (tycons, clss) = getMentionedTyConsAndClassesFromType ty
- in
- addToMentionedTyConsUf tycons `thenUf_`
- addToMentionedClassesUf clss
+ enough_args 0 evals = True
+ enough_args n [] = False
+ enough_args n (e:es) = enough_args (n-1) es
+ -- NB: don't take the length of arg_is_evald_s because when
+ -- called from couldBeSmallEnoughToInline it is infinite!
--------------
+ discounted_size = size - sum (zipWith arg_discount discount_vec arg_is_evald_s)
-ment_alts alg_alts@(AlgAlts alts deflt)
- = mapUf ment_alt alts `thenUf_`
- ment_deflt deflt
- where
- ment_alt alt@(con, params, rhs)
- = consider_Id con `thenUf_`
- extractIdsUf params `thenUf` \ param_ids ->
- addInScopesUf param_ids (
- -- "consider" them so we can chk out their types...
- mapUf consider_Id param_ids `thenUf_`
- ment_expr rhs )
-
-ment_alts (PrimAlts alts deflt)
- = mapUf ment_alt alts `thenUf_`
- ment_deflt deflt
- where
- ment_alt alt@(lit, rhs) = ment_expr rhs
-
-----------------
-ment_deflt NoDefault
- = returnUf ()
-
-ment_deflt d@(BindDefault b rhs)
- = extractIdsUf [b] `thenUf` \ bi@[b_id] ->
- addInScopesUf bi (
- consider_Id b_id `thenUf_`
- ment_expr rhs )
-
------------
-ment_arg (VarArg v) = consider_Id v
-ment_arg (LitArg l) = consider_lit l
-ment_arg (TyArg ty) = ment_ty ty
-ment_arg (UsageArg _) = returnUf ()
-
------------
-consider_lit lit
- | isLitLitLit lit = litlit_oops `thenUf_` returnUf ()
- | otherwise = returnUf ()
+ arg_discount no_of_constrs is_evald
+ | is_evald = 1 + no_of_constrs * opt_UnfoldingConDiscount
+ | otherwise = 1
\end{code}
-%************************************************************************
-%* *
-\subsubsection{Printing unfoldings in interfaces}
-%* *
-%************************************************************************
+We use this one to avoid exporting inlinings that we ``couldn't possibly
+use'' on the other side. Can be overridden w/ flaggery.
+Just the same as smallEnoughToInline, except that it has no actual arguments.
-Printing Core-expression unfoldings is sufficiently delicate that we
-give it its own function.
\begin{code}
-{- OLD:
-pprCoreUnfolding
- :: CoreExpr
- -> Pretty
-
-pprCoreUnfolding expr
- = let
- (_, renamed) = instCoreExpr uniqSupply_u expr
- -- We rename every unfolding with a "steady" unique supply,
- -- so that the names won't constantly change.
- -- One place we *MUST NOT* use a splittable UniqueSupply!
- in
- ppr_uf_Expr emptyUniqSet renamed
+couldBeSmallEnoughToInline :: UnfoldingGuidance -> Bool
+couldBeSmallEnoughToInline guidance = smallEnoughToInline (repeat True) guidance
-ppr_Unfolding = PprUnfolding (panic "CoreUnfold:ppr_Unfolding")
+certainlySmallEnoughToInline :: UnfoldingGuidance -> Bool
+certainlySmallEnoughToInline guidance = smallEnoughToInline (repeat False) guidance
\end{code}
-\begin{code}
-ppr_uf_Expr in_scopes (Var v) = pprIdInUnfolding in_scopes v
-ppr_uf_Expr in_scopes (Lit l) = ppr ppr_Unfolding l
-
-ppr_uf_Expr in_scopes (Con c as)
- = ppBesides [ppPStr SLIT("_!_ "), pprIdInUnfolding no_in_scopes c, ppSP,
- ppLbrack, ppIntersperse pp'SP{-'-} (map (pprParendUniType ppr_Unfolding) ts), ppRbrack,
- ppSP, ppLbrack, ppIntersperse pp'SP{-'-} (map (ppr_uf_Atom in_scopes) as), ppRbrack]
-ppr_uf_Expr in_scopes (Prim op as)
- = ppBesides [ppPStr SLIT("_#_ "), ppr ppr_Unfolding op, ppSP,
- ppLbrack, ppIntersperse pp'SP{-'-} (map (pprParendUniType ppr_Unfolding) ts), ppRbrack,
- ppSP, ppLbrack, ppIntersperse pp'SP{-'-} (map (ppr_uf_Atom in_scopes) as), ppRbrack]
-
-ppr_uf_Expr in_scopes (Lam binder body)
- = ppCat [ppChar '\\', ppr_uf_Binder binder,
- ppPStr SLIT("->"), ppr_uf_Expr (in_scopes `add1` binder) body]
-
-ppr_uf_Expr in_scopes (CoTyLam tyvar expr)
- = ppCat [ppPStr SLIT("_/\\_"), interppSP ppr_Unfolding (tyvar:tyvars), ppStr "->",
- ppr_uf_Expr in_scopes body]
- where
- (tyvars, body) = collect_tyvars expr
-
- collect_tyvars (CoTyLam tyv e) = ( tyv:tyvs, e_after )
- where (tyvs, e_after) = collect_tyvars e
- collect_tyvars other_e = ( [], other_e )
-
-ppr_uf_Expr in_scopes expr@(App fun_expr atom)
- = let
- (fun, args) = collect_args expr []
- in
- ppCat [ppPStr SLIT("_APP_ "), ppr_uf_Expr in_scopes fun, ppLbrack,
- ppIntersperse pp'SP{-'-} (map (ppr_uf_Atom in_scopes) args), ppRbrack]
- where
- collect_args (App fun arg) args = collect_args fun (arg:args)
- collect_args fun args = (fun, args)
-
-ppr_uf_Expr in_scopes (CoTyApp expr ty)
- = ppCat [ppPStr SLIT("_TYAPP_ "), ppr_uf_Expr in_scopes expr,
- ppChar '{', pprParendUniType ppr_Unfolding ty, ppChar '}']
-
-ppr_uf_Expr in_scopes (Case scrutinee alts)
- = ppCat [ppPStr SLIT("case"), ppr_uf_Expr in_scopes scrutinee, ppStr "of {",
- pp_alts alts, ppChar '}']
- where
- pp_alts (AlgAlts alts deflt)
- = ppCat [ppPStr SLIT("_ALG_"), ppCat (map pp_alg alts), pp_deflt deflt]
- pp_alts (PrimAlts alts deflt)
- = ppCat [ppPStr SLIT("_PRIM_"), ppCat (map pp_prim alts), pp_deflt deflt]
-
- pp_alg (con, params, rhs)
- = ppBesides [pprIdInUnfolding no_in_scopes con, ppSP,
- ppIntersperse ppSP (map ppr_uf_Binder params),
- ppPStr SLIT(" -> "), ppr_uf_Expr (in_scopes `add_some` params) rhs, ppSemi]
-
- pp_prim (lit, rhs)
- = ppBesides [ppr ppr_Unfolding lit,
- ppPStr SLIT(" -> "), ppr_uf_Expr in_scopes rhs, ppSemi]
-
- pp_deflt NoDefault = ppPStr SLIT("_NO_DEFLT_")
- pp_deflt (BindDefault binder rhs)
- = ppBesides [ppr_uf_Binder binder, ppPStr SLIT(" -> "),
- ppr_uf_Expr (in_scopes `add1` binder) rhs]
-
-ppr_uf_Expr in_scopes (Let (NonRec binder rhs) body)
- = ppBesides [ppStr "let {", ppr_uf_Binder binder, ppPStr SLIT(" = "), ppr_uf_Expr in_scopes rhs,
- ppStr "} in ", ppr_uf_Expr (in_scopes `add1` binder) body]
-
-ppr_uf_Expr in_scopes (Let (Rec pairs) body)
- = ppBesides [ppStr "_LETREC_ {", ppIntersperse sep (map pp_pair pairs),
- ppStr "} in ", ppr_uf_Expr new_in_scopes body]
- where
- sep = ppBeside ppSemi ppSP
- new_in_scopes = in_scopes `add_some` map fst pairs
-
- pp_pair (b, rhs) = ppCat [ppr_uf_Binder b, ppEquals, ppr_uf_Expr new_in_scopes rhs]
-
-ppr_uf_Expr in_scopes (SCC cc body)
- = ASSERT(not (noCostCentreAttached cc))
- ASSERT(not (currentOrSubsumedCosts cc))
- ppBesides [ppStr "_scc_ { ", ppStr (showCostCentre ppr_Unfolding False{-not as string-} cc), ppStr " } ", ppr_uf_Expr in_scopes body]
-\end{code}
+Predicates
+~~~~~~~~~~
\begin{code}
-ppr_uf_Binder :: Id -> Pretty
-ppr_uf_Binder v
- = ppBesides [ppLparen, pprIdInUnfolding (unitUniqSet v) v, ppPStr SLIT(" :: "),
- ppr ppr_Unfolding (idType v), ppRparen]
-
-ppr_uf_Atom in_scopes (LitArg l) = ppr ppr_Unfolding l
-ppr_uf_Atom in_scopes (VarArg v) = pprIdInUnfolding in_scopes v
-END OLD -}
+okToInline
+ :: FormSummary -- What the thing to be inlined is like
+ -> BinderInfo -- How the thing to be inlined occurs
+ -> Bool -- True => it's small enough to inline
+ -> Bool -- True => yes, inline it
+
+-- If there's no danger of duplicating work, we can inline if it occurs once, or is small
+okToInline form occ_info small_enough
+ | no_dup_danger form
+ = small_enough || one_occ
+ where
+ one_occ = case occ_info of
+ OneOcc _ _ _ n_alts _ -> n_alts <= 1
+ other -> False
+
+ no_dup_danger VarForm = True
+ no_dup_danger ValueForm = True
+ no_dup_danger BottomForm = True
+ no_dup_danger other = False
+
+-- A non-WHNF can be inlined if it doesn't occur inside a lambda,
+-- and occurs exactly once or
+-- occurs once in each branch of a case and is small
+okToInline OtherForm (OneOcc _ dup_danger _ n_alts _) small_enough
+ = not (isDupDanger dup_danger) && (n_alts <= 1 || small_enough)
+
+okToInline form any_occ small_enough = False
\end{code}
+
projects / ghc-hetmet.git / blobdiff