%
-% (c) The GRASP/AQUA Project, Glasgow University, 1993-1995
+% (c) The GRASP/AQUA Project, Glasgow University, 1993-1998
%
\section[SaAbsInt]{Abstract interpreter for strictness analysis}
\begin{code}
-#include "HsVersions.h"
-
module SaAbsInt (
findStrictness,
- findDemand,
+ findDemand, findDemandAlts,
absEval,
widen,
fixpoint,
isBot
) where
-IMPORT_Trace -- ToDo: rm
-import Pretty
---import FiniteMap
-import Outputable
-
-import AbsPrel ( PrimOp(..),
- intTyCon, integerTyCon, doubleTyCon,
- floatTyCon, wordTyCon, addrTyCon,
- PrimKind
- )
-import AbsUniType ( isPrimType, getUniDataTyCon_maybe,
- maybeSingleConstructorTyCon,
- returnsRealWorld,
- isEnumerationTyCon, TyVarTemplate, TyCon
- IF_ATTACK_PRAGMAS(COMMA cmpTyCon)
- )
-import Id ( getIdStrictness, getIdUniType, getIdUnfolding,
- getDataConSig, getInstantiatedDataConSig,
- DataCon(..), isBottomingId
- )
-
-import IdInfo -- various bits
-import IdEnv
-import CoreFuns ( unTagBinders )
-import Maybes ( maybeToBool, Maybe(..) )
-import PlainCore
+#include "HsVersions.h"
+
+import CmdLineOpts ( opt_AllStrict, opt_NumbersStrict )
+import CoreSyn
+import CoreUnfold ( Unfolding(..) )
+import PrimOp ( primOpStrictness )
+import Id ( Id, idType, getIdStrictness, getIdUnfolding )
+import Const ( Con(..) )
+import DataCon ( dataConTyCon, dataConArgTys )
+import IdInfo ( StrictnessInfo(..) )
+import Demand ( Demand(..), wwPrim, wwStrict, wwEnum, wwUnpackData,
+ wwUnpackNew )
import SaLib
-import SimplEnv ( FormSummary(..) ) -- nice data abstraction, huh? (WDP 95/03)
-import Util
+import TyCon ( isProductTyCon, isEnumerationTyCon, isNewTyCon )
+import BasicTypes ( NewOrData(..) )
+import Type ( splitAlgTyConApp_maybe,
+ isUnLiftedType, Type )
+import TyCon ( tyConUnique )
+import PrelInfo ( numericTyKeys )
+import Util ( isIn, nOfThem, zipWithEqual )
+import Outputable
+
+returnsRealWorld x = False -- ToDo: panic "SaAbsInt.returnsRealWorld (ToDo)"
\end{code}
%************************************************************************
-- always returns bottom, such as \y.x,
-- when x is bound to bottom.
-lub (AbsProd xs) (AbsProd ys) = ASSERT (length xs == length ys)
- AbsProd (zipWith lub xs ys)
+lub (AbsProd xs) (AbsProd ys) = AbsProd (zipWithEqual "lub" lub xs ys)
lub _ _ = AbsTop -- Crude, but conservative
- -- The crudity only shows up if there
+ -- The crudity only shows up if there
-- are functions involved
-- Slightly funny glb; for absence analysis only;
--
-- f = \a b -> ...
--
--- g = \x y z -> case x of
+-- g = \x y z -> case x of
-- [] -> f x
-- (p:ps) -> f p
--
-- Deal with functions specially, because AbsTop isn't the
-- top of their domain.
-glb v1 v2
+glb v1 v2
| is_fun v1 || is_fun v2
- = if not (anyBot v1) && not (anyBot v2)
+ = if not (anyBot v1) && not (anyBot v2)
then
AbsTop
else
AbsBot
where
- is_fun (AbsFun _ _ _) = True
- is_fun (AbsApproxFun _) = True -- Not used, but the glb works ok
- is_fun other = False
+ is_fun (AbsFun _ _ _) = True
+ is_fun (AbsApproxFun _ _) = True -- Not used, but the glb works ok
+ is_fun other = False
-- The non-functional cases are quite straightforward
-glb (AbsProd xs) (AbsProd ys) = ASSERT (length xs == length ys)
- AbsProd (zipWith glb xs ys)
+glb (AbsProd xs) (AbsProd ys) = AbsProd (zipWithEqual "glb" glb xs ys)
glb AbsTop v2 = v2
glb v1 AbsTop = v1
glb _ _ = AbsBot -- Be pessimistic
-
-
-
-combineCaseValues
- :: AnalysisKind
- -> AbsVal -- Value of scrutinee
- -> [AbsVal] -- Value of branches (at least one)
- -> AbsVal -- Result
-
--- For strictness analysis, see if the scrutinee is bottom; if so
--- return bottom; otherwise, the lub of the branches.
-
-combineCaseValues StrAnal AbsBot branches = AbsBot
-combineCaseValues StrAnal other_scrutinee branches
- -- Scrutinee can only be AbsBot, AbsProd or AbsTop
- = ASSERT(ok_scrutinee)
- foldr1 lub branches
- where
- ok_scrutinee
- = case other_scrutinee of {
- AbsTop -> True; -- i.e., cool
- AbsProd _ -> True; -- ditto
- _ -> False -- party over
- }
-
--- For absence analysis, check if the scrutinee is all poison (isBot)
--- If so, return poison (AbsBot); otherwise, any nested poison will come
--- out from looking at the branches, so just glb together the branches
--- to get the worst one.
-
-combineCaseValues AbsAnal AbsBot branches = AbsBot
-combineCaseValues AbsAnal other_scrutinee branches
- -- Scrutinee can only be AbsBot, AbsProd or AbsTop
- = ASSERT(ok_scrutinee)
- let
- result = foldr1 glb branches
-
- tracer = if at_least_one_AbsFun && at_least_one_AbsTop
- && no_AbsBots then
- pprTrace "combineCase:" (ppr PprDebug branches)
- else
- id
- in
--- tracer (
- result
--- )
- where
- ok_scrutinee
- = case other_scrutinee of {
- AbsTop -> True; -- i.e., cool
- AbsProd _ -> True; -- ditto
- _ -> False -- party over
- }
-
- at_least_one_AbsFun = foldr ((||) . is_AbsFun) False branches
- at_least_one_AbsTop = foldr ((||) . is_AbsTop) False branches
- no_AbsBots = foldr ((&&) . is_not_AbsBot) True branches
-
- is_AbsFun x = case x of { AbsFun _ _ _ -> True; _ -> False }
- is_AbsTop x = case x of { AbsTop -> True; _ -> False }
- is_not_AbsBot x = case x of { AbsBot -> False; _ -> True }
\end{code}
@isBot@ returns True if its argument is (a representation of) bottom. The
\begin{code}
isBot :: AbsVal -> Bool
-isBot AbsBot = True
-isBot (AbsFun args body env) = isBot (absEval StrAnal body env)
- -- Don't bother to extend the envt because
- -- unbound variables default to AbsTop anyway
-isBot other = False
+isBot AbsBot = True
+isBot other = False -- Functions aren't bottom any more
+
\end{code}
Used only in absence analysis:
anyBot AbsBot = True -- poisoned!
anyBot AbsTop = False
anyBot (AbsProd vals) = any anyBot vals
-anyBot (AbsFun args body env) = anyBot (absEval AbsAnal body env)
-anyBot (AbsApproxFun demands) = False
-
- -- AbsApproxFun can only arise in absence analysis from the Demand
- -- info of an imported value; whatever it is we're looking for is
- -- certainly not present over in the imported value.
+anyBot (AbsFun bndr body env) = anyBot (absEval AbsAnal body (addOneToAbsValEnv env bndr AbsTop))
+anyBot (AbsApproxFun _ val) = anyBot val
\end{code}
@widen@ takes an @AbsVal@, $val$, and returns and @AbsVal@ which is
\begin{code}
widen :: AnalysisKind -> AbsVal -> AbsVal
-widen StrAnal (AbsFun args body env)
- | isBot (absEval StrAnal body env) = AbsBot
- | otherwise
- = ASSERT (not (null args))
- AbsApproxFun (map (findDemandStrOnly env body) args)
+-- Widening is complicated by the fact that funtions are lifted
+widen StrAnal the_fn@(AbsFun bndr body env)
+ = case widened_body of
+ AbsApproxFun ds val -> AbsApproxFun (d : ds) val
+ where
+ d = findRecDemand str_fn abs_fn bndr_ty
+ str_fn val = foldl (absApply StrAnal) the_fn
+ (val : [AbsTop | d <- ds])
+
+ other -> AbsApproxFun [d] widened_body
+ where
+ d = findRecDemand str_fn abs_fn bndr_ty
+ str_fn val = absApply StrAnal the_fn val
+ where
+ bndr_ty = idType bndr
+ widened_body = widen StrAnal (absApply StrAnal the_fn AbsTop)
+ abs_fn val = AbsBot -- Always says poison; so it looks as if
+ -- nothing is absent; safe
+
+{- OLD comment...
+ This stuff is now instead handled neatly by the fact that AbsApproxFun
+ contains an AbsVal inside it. SLPJ Jan 97
+ | isBot abs_body = AbsBot
-- It's worth checking for a function which is unconditionally
-- bottom. Consider
--
-- alternative here would be to bind g to its exact abstract
-- value, but that entails lots of potential re-computation, at
-- every application of g.)
-
+-}
+
widen StrAnal (AbsProd vals) = AbsProd (map (widen StrAnal) vals)
widen StrAnal other_val = other_val
-widen AbsAnal (AbsFun args body env)
- | anyBot (absEval AbsAnal body env) = AbsBot
+widen AbsAnal the_fn@(AbsFun bndr body env)
+ | anyBot widened_body = AbsBot
-- In the absence-analysis case it's *essential* to check
-- that the function has no poison in its body. If it does,
-- anywhere, then the whole function is poisonous.
| otherwise
- = ASSERT (not (null args))
- AbsApproxFun (map (findDemandAbsOnly env body) args)
-
+ = case widened_body of
+ AbsApproxFun ds val -> AbsApproxFun (d : ds) val
+ where
+ d = findRecDemand str_fn abs_fn bndr_ty
+ abs_fn val = foldl (absApply AbsAnal) the_fn
+ (val : [AbsTop | d <- ds])
+
+ other -> AbsApproxFun [d] widened_body
+ where
+ d = findRecDemand str_fn abs_fn bndr_ty
+ abs_fn val = absApply AbsAnal the_fn val
+ where
+ bndr_ty = idType bndr
+ widened_body = widen AbsAnal (absApply AbsAnal the_fn AbsTop)
+ str_fn val = AbsBot -- Always says non-termination;
+ -- that'll make findRecDemand peer into the
+ -- structure of the value.
+
widen AbsAnal (AbsProd vals) = AbsProd (map (widen AbsAnal) vals)
-- It's desirable to do a good job of widening for product
widen AbsAnal other_val = other_val
--- OLD if anyBot val then AbsBot else AbsTop
+-- WAS: if anyBot val then AbsBot else AbsTop
-- Nowadays widen is doing a better job on functions for absence analysis.
\end{code}
sameVal AbsTop AbsTop = True
sameVal AbsTop other = False -- Right?
-sameVal (AbsProd vals1) (AbsProd vals2) = ASSERT (length vals1 == length vals2)
- and (zipWith sameVal vals1 vals2)
+sameVal (AbsProd vals1) (AbsProd vals2) = and (zipWithEqual "sameVal" sameVal vals1 vals2)
sameVal (AbsProd _) AbsTop = False
sameVal (AbsProd _) AbsBot = False
-sameVal (AbsApproxFun str1) (AbsApproxFun str2) = str1 == str2
-sameVal (AbsApproxFun _) AbsTop = False
-sameVal (AbsApproxFun _) AbsBot = False
+sameVal (AbsApproxFun str1 v1) (AbsApproxFun str2 v2) = str1 == str2 && sameVal v1 v2
+sameVal (AbsApproxFun _ _) AbsTop = False
+sameVal (AbsApproxFun _ _) AbsBot = False
sameVal val1 val2 = panic "sameVal: type mismatch or AbsFun encountered"
\end{code}
(@True@ is the exciting answer; @False@ is always safe.)
\begin{code}
-evalStrictness :: Demand
- -> AbsVal
- -> Bool -- True iff the value is sure
+evalStrictness :: Demand
+ -> AbsVal
+ -> Bool -- True iff the value is sure
-- to be less defined than the Demand
evalStrictness (WwLazy _) _ = False
evalStrictness WwStrict val = isBot val
evalStrictness WwEnum val = isBot val
-evalStrictness (WwUnpack demand_info) val
+evalStrictness (WwUnpack NewType _ (demand:_)) val
+ = evalStrictness demand val
+
+evalStrictness (WwUnpack DataType _ demand_info) val
= case val of
AbsTop -> False
AbsBot -> True
- AbsProd vals -> ASSERT (length vals == length demand_info)
- or (zipWith evalStrictness demand_info vals)
- _ -> trace "evalStrictness?" False
+ AbsProd vals -> or (zipWithEqual "evalStrictness" evalStrictness demand_info vals)
+ _ -> pprTrace "evalStrictness?" empty False
evalStrictness WwPrim val
= case val of
- AbsTop -> False
+ AbsTop -> False
+ AbsBot -> True -- Can happen: consider f (g x), where g is a
+ -- recursive function returning an Int# that diverges
- other -> -- A primitive value should be defined, never bottom;
- -- hence this paranoia check
- pprPanic "evalStrictness: WwPrim:" (ppr PprDebug other)
+ other -> pprPanic "evalStrictness: WwPrim:" (ppr other)
\end{code}
For absence analysis, we're interested in whether "poison" in the
possibly} hit poison.
\begin{code}
-evalAbsence (WwLazy True) _ = False -- Can't possibly hit poison
+evalAbsence (WwLazy True) _ = False -- Can't possibly hit poison
-- with Absent demand
-evalAbsence (WwUnpack demand_info) val
+evalAbsence (WwUnpack NewType _ (demand:_)) val
+ = evalAbsence demand val
+
+evalAbsence (WwUnpack DataType _ demand_info) val
= case val of
AbsTop -> False -- No poison in here
AbsBot -> True -- Pure poison
- AbsProd vals -> ASSERT (length demand_info == length vals)
- or (zipWith evalAbsence demand_info vals)
+ AbsProd vals -> or (zipWithEqual "evalAbsence" evalAbsence demand_info vals)
_ -> panic "evalAbsence: other"
evalAbsence other val = anyBot val
-- error's arg
absId anal var env
- = let
- result =
- case (lookupAbsValEnv env var, getIdStrictness var, getIdUnfolding var) of
+ = case (lookupAbsValEnv env var, getIdStrictness var, getIdUnfolding var) of
- (Just abs_val, _, _) ->
+ (Just abs_val, _, _) ->
abs_val -- Bound in the environment
- (Nothing, NoStrictnessInfo, LiteralForm _) ->
- AbsTop -- Literals all terminate, and have no poison
-
- (Nothing, NoStrictnessInfo, ConstructorForm _ _ _) ->
- AbsTop -- An imported constructor won't have
- -- bottom components, nor poison!
-
- (Nothing, NoStrictnessInfo, GeneralForm _ _ unfolding _) ->
+ (Nothing, NoStrictnessInfo, CoreUnfolding _ _ unfolding) ->
-- We have an unfolding for the expr
-- Assume the unfolding has no free variables since it
-- came from inside the Id
- absEval anal (unTagBinders unfolding) env
+ absEval anal unfolding env
-- Notice here that we only look in the unfolding if we don't
-- have strictness info (an unusual situation).
-- We could have chosen to look in the unfolding if it exists,
-- "U(U(U(U(SL)LLLLLLLLL)LL)LLLLLSLLLLL)" _N_ _N_ #-}
- (Nothing, strictness_info, _) ->
- -- Includes MagicForm, IWantToBeINLINEd, NoUnfoldingDetails
+ (Nothing, strictness_info, _) ->
+ -- Includes NoUnfolding
-- Try the strictness info
absValFromStrictness anal strictness_info
-
-
- -- Done via strictness now
- -- GeneralForm _ BottomForm _ _ -> AbsBot
- in
- -- pprTrace "absId:" (ppBesides [ppr PprDebug var, ppStr "=:", pp_anal anal, ppStr ":=",ppr PprDebug result]) (
- result
- -- )
- where
- pp_anal StrAnal = ppStr "STR"
- pp_anal AbsAnal = ppStr "ABS"
-
-absEvalAtom anal (CoVarAtom v) env = absId anal v env
-absEvalAtom anal (CoLitAtom _) env = AbsTop
\end{code}
\begin{code}
-absEval :: AnalysisKind -> PlainCoreExpr -> AbsValEnv -> AbsVal
-
-absEval anal (CoVar var) env = absId anal var env
-
-absEval anal (CoLit _) env = AbsTop
- -- What if an unboxed literal? That's OK: it terminates, so its
- -- abstract value is AbsTop.
+absEval :: AnalysisKind -> CoreExpr -> AbsValEnv -> AbsVal
- -- For absence analysis, a literal certainly isn't the "poison" variable
+absEval anal (Type ty) env = AbsTop
+absEval anal (Var var) env = absId anal var env
\end{code}
-Discussion about \tr{error} (following/quoting Lennart): Any expression
-\tr{error e} is regarded as bottom (with HBC, with the
-\tr{-ffail-strict} flag, on with \tr{-O}).
+Discussion about error (following/quoting Lennart): Any expression
+'error e' is regarded as bottom (with HBC, with the -ffail-strict
+flag, on with -O).
Regarding it as bottom gives much better strictness properties for
some functions. E.g.
-\begin{verbatim}
+
f [x] y = x+y
f (x:xs) y = f xs (x+y)
i.e.
f [] _ = error "no match"
f [x] y = x+y
f (x:xs) y = f xs (x+y)
-\end{verbatim}
-is strict in \tr{y}, which you really want. But, it may lead to
+
+is strict in y, which you really want. But, it may lead to
transformations that turn a call to \tr{error} into non-termination.
(The odds of this happening aren't good.)
-
Things are a little different for absence analysis, because we want
to make sure that any poison (?????)
\begin{code}
-absEval StrAnal (CoPrim SeqOp [t] [e]) env
- = if isBot (absEvalAtom StrAnal e env) then AbsBot else AbsTop
- -- This is a special case to ensure that seq# is strict in its argument.
- -- The comments below (for most normal PrimOps) do not apply.
-
-absEval StrAnal (CoPrim op ts es) env = AbsTop
- -- The arguments are all of unboxed type, so they will already
- -- have been eval'd. If the boxed version was bottom, we'll
- -- already have returned bottom.
-
- -- Actually, I believe we are saying that either (1) the
- -- primOp uses unboxed args and they've been eval'ed, so
- -- there's no need to force strictness here, _or_ the primOp
- -- uses boxed args and we don't know whether or not it's
- -- strict, so we assume laziness. (JSM)
-
-absEval AbsAnal (CoPrim op ts as) env
- = if any anyBot [absEvalAtom AbsAnal a env | a <- as]
+absEval anal (Con (Literal _) args) env
+ = -- Literals terminate (strictness) and are not poison (absence)
+ AbsTop
+
+absEval anal (Con (PrimOp op) args) env
+ = -- Not all PrimOps evaluate all their arguments
+ if or (zipWith (check_arg anal)
+ [absEval anal arg env | arg <- args, isValArg arg]
+ arg_demands)
then AbsBot
- else AbsTop
- -- For absence analysis, we want to see if the poison shows up...
+ else case anal of
+ StrAnal | result_bot -> AbsBot
+ other -> AbsTop
+ where
+ (arg_demands, result_bot) = primOpStrictness op
+ check_arg StrAnal arg dmd = evalStrictness dmd arg
+ check_arg AbsAnal arg dmd = evalAbsence dmd arg
-absEval anal (CoCon con ts as) env
- | has_single_con
- = AbsProd [absEvalAtom anal a env | a <- as]
+absEval anal (Con (DataCon con) args) env
+ | isProductTyCon (dataConTyCon con)
+ = -- Products; filter out type arguments
+ AbsProd [absEval anal a env | a <- args, isValArg a]
| otherwise -- Not single-constructor
= case anal of
StrAnal -> -- Strictness case: it's easy: it certainly terminates
- AbsTop
- AbsAnal -> -- In the absence case we need to be more
+ AbsTop
+ AbsAnal -> -- In the absence case we need to be more
-- careful: look to see if there's any
-- poison in the components
- if any anyBot [absEvalAtom AbsAnal a env | a <- as]
+ if any anyBot [absEval AbsAnal arg env | arg <- args]
then AbsBot
else AbsTop
- where
- (_,_,_, tycon) = getDataConSig con
- has_single_con = maybeToBool (maybeSingleConstructorTyCon tycon)
\end{code}
\begin{code}
-absEval anal (CoLam [] body) env = absEval anal body env -- paranoia
-absEval anal (CoLam binders body) env = AbsFun binders body env
-absEval anal (CoTyLam ty expr) env = absEval anal expr env
-absEval anal (CoApp e1 e2) env = absApply anal (absEval anal e1 env)
- (absEvalAtom anal e2 env)
-absEval anal (CoTyApp expr ty) env = absEval anal expr env
+absEval anal (Lam bndr body) env
+ | isTyVar bndr = absEval anal body env -- Type lambda
+ | otherwise = AbsFun bndr body env -- Value lambda
+
+absEval anal (App expr (Type ty)) env
+ = absEval anal expr env -- Type appplication
+absEval anal (App f val_arg) env
+ = absApply anal (absEval anal f env) -- Value applicationn
+ (absEval anal val_arg env)
\end{code}
-For primitive cases, just GLB the branches, then LUB with the expr part.
-
\begin{code}
-absEval anal (CoCase expr (CoPrimAlts alts deflt)) env
+absEval anal expr@(Case scrut case_bndr alts) env
= let
- expr_val = absEval anal expr env
- abs_alts = [ absEval anal rhs env | (_, rhs) <- alts ]
- -- Don't bother to extend envt, because unbound vars
- -- default to the conservative AbsTop
-
- abs_deflt = absEvalDefault anal expr_val deflt env
+ scrut_val = absEval anal scrut env
+ alts_env = addOneToAbsValEnv env case_bndr scrut_val
in
- combineCaseValues anal expr_val
- (abs_deflt ++ abs_alts)
+ case (scrut_val, alts) of
+ (AbsBot, _) -> AbsBot
+
+ (AbsProd arg_vals, [(con, bndrs, rhs)])
+ | con /= DEFAULT ->
+ -- The scrutinee is a product value, so it must be of a single-constr
+ -- type; so the constructor in this alternative must be the right one
+ -- so we can go ahead and bind the constructor args to the components
+ -- of the product value.
+ ASSERT(length arg_vals == length val_bndrs)
+ absEval anal rhs rhs_env
+ where
+ val_bndrs = filter isId bndrs
+ rhs_env = growAbsValEnvList alts_env (val_bndrs `zip` arg_vals)
-absEval anal (CoCase expr (CoAlgAlts alts deflt)) env
- = let
- expr_val = absEval anal expr env
- abs_alts = [ absEvalAlgAlt anal expr_val alt env | alt <- alts ]
- abs_deflt = absEvalDefault anal expr_val deflt env
- in
- let
- result =
- combineCaseValues anal expr_val
- (abs_deflt ++ abs_alts)
- in
-{-
- (case anal of
- StrAnal -> id
- _ -> pprTrace "absCase:ABS:" (ppAbove (ppCat [ppr PprDebug expr, ppr PprDebug result, ppr PprDebug expr_val, ppr PprDebug abs_deflt, ppr PprDebug abs_alts]) (ppr PprDebug (keysFM env `zip` eltsFM env)))
- )
--}
- result
+ other -> absEvalAlts anal alts alts_env
\end{code}
-For @CoLets@ we widen the value we get. This is nothing to
+For @Lets@ we widen the value we get. This is nothing to
do with fixpointing. The reason is so that we don't get an explosion
in the amount of computation. For example, consider:
\begin{verbatim}
f x = case x of
p1 -> ...g r...
p2 -> ...g s...
- in
+ in
f e
\end{verbatim}
If we bind @f@ and @g@ to their exact abstract value, then we'll
and be prepared to bale out.
\begin{code}
-absEval anal (CoLet (CoNonRec binder e1) e2) env
+absEval anal (Let (NonRec binder e1) e2) env
= let
new_env = addOneToAbsValEnv env binder (widen anal (absEval anal e1 env))
in
- -- The binder of a CoNonRec should *not* be of unboxed type,
+ -- The binder of a NonRec should *not* be of unboxed type,
-- hence no need to strictly evaluate the Rhs.
absEval anal e2 new_env
-absEval anal (CoLet (CoRec pairs) body) env
+absEval anal (Let (Rec pairs) body) env
= let
(binders,rhss) = unzip pairs
rhs_vals = cheapFixpoint anal binders rhss env -- Returns widened values
new_env = growAbsValEnvList env (binders `zip` rhs_vals)
in
absEval anal body new_env
-\end{code}
-\begin{code}
-absEval anal (CoSCC cc expr) env = absEval anal expr env
-
--- ToDo: add DPH stuff here
+absEval anal (Note note expr) env = absEval anal expr env
\end{code}
\begin{code}
-absEvalAlgAlt :: AnalysisKind -> AbsVal -> (Id,[Id],PlainCoreExpr) -> AbsValEnv -> AbsVal
-
-absEvalAlgAlt anal (AbsProd arg_vals) (con, args, rhs) env
- = -- The scrutinee is a product value, so it must be of a single-constr
- -- type; so the constructor in this alternative must be the right one
- -- so we can go ahead and bind the constructor args to the components
- -- of the product value.
- ASSERT(length arg_vals == length args)
- let
- new_env = growAbsValEnvList env (args `zip` arg_vals)
- in
- absEval anal rhs new_env
-
-absEvalAlgAlt anal other_scrutinee (con, args, rhs) env
- = -- Scrutinised value is Top or Bot (it can't be a function!)
- -- So just evaluate the rhs with all constr args bound to Top.
- -- (If the scrutinee is Top we'll never evaluated this function
- -- call anyway!)
- ASSERT(ok_scrutinee)
- absEval anal rhs env
+absEvalAlts :: AnalysisKind -> [CoreAlt] -> AbsValEnv -> AbsVal
+absEvalAlts anal alts env
+ = combine anal (map go alts)
where
- ok_scrutinee
- = case other_scrutinee of {
- AbsTop -> True; -- i.e., OK
- AbsBot -> True; -- ditto
- _ -> False -- party over
- }
-
-
-absEvalDefault :: AnalysisKind
- -> AbsVal -- Value of scrutinee
- -> PlainCoreCaseDefault
- -> AbsValEnv
- -> [AbsVal] -- Empty or singleton
-
-absEvalDefault anal scrut_val CoNoDefault env = []
-absEvalDefault anal scrut_val (CoBindDefault binder expr) env
- = [absEval anal expr (addOneToAbsValEnv env binder scrut_val)]
+ combine StrAnal = foldr1 lub -- Diverge only if all diverge
+ combine AbsAnal = foldr1 glb -- Find any poison
+
+ go (con, bndrs, rhs)
+ = absEval anal rhs rhs_env
+ where
+ rhs_env = growAbsValEnvList env (filter isId bndrs `zip` repeat AbsTop)
\end{code}
%************************************************************************
-- AbsBot represents the abstract bottom *function* too
absApply StrAnal AbsTop arg = AbsTop
-absApply AbsAnal AbsTop arg = if anyBot arg
+absApply AbsAnal AbsTop arg = if anyBot arg
then AbsBot
else AbsTop
-- To be conservative, we have to assume that a function about
\end{code}
An @AbsFun@ with only one more argument needed---bind it and eval the
-result. A @CoLam@ with two or more args: return another @AbsFun@ with
+result. A @Lam@ with two or more args: return another @AbsFun@ with
an augmented environment.
\begin{code}
-absApply anal (AbsFun [binder] body env) arg
+absApply anal (AbsFun binder body env) arg
= absEval anal body (addOneToAbsValEnv env binder arg)
-
-absApply anal (AbsFun (binder:bs) body env) arg
- = AbsFun bs body (addOneToAbsValEnv env binder arg)
\end{code}
\begin{code}
-absApply StrAnal (AbsApproxFun (arg1_demand:ds)) arg
- = if evalStrictness arg1_demand arg
- then AbsBot
- else case ds of
- [] -> AbsTop
- other -> AbsApproxFun ds
+absApply StrAnal (AbsApproxFun (d:ds) val) arg
+ = case ds of
+ [] -> val'
+ other -> AbsApproxFun ds val' -- Result is non-bot if there are still args
+ where
+ val' | evalStrictness d arg = AbsBot
+ | otherwise = val
-absApply AbsAnal (AbsApproxFun (arg1_demand:ds)) arg
- = if evalAbsence arg1_demand arg
- then AbsBot
+absApply AbsAnal (AbsApproxFun (d:ds) val) arg
+ = if evalAbsence d arg
+ then AbsBot -- Poison in arg means poison in the application
else case ds of
- [] -> AbsTop
- other -> AbsApproxFun ds
+ [] -> val
+ other -> AbsApproxFun ds val
#ifdef DEBUG
-absApply anal (AbsApproxFun []) arg = panic ("absApply: Duff function: AbsApproxFun." ++ show anal)
-absApply anal (AbsFun [] _ _) arg = panic ("absApply: Duff function: AbsFun." ++ show anal)
-absApply anal (AbsProd _) arg = panic ("absApply: Duff function: AbsProd." ++ show anal)
+absApply anal f@(AbsProd _) arg = pprPanic ("absApply: Duff function: AbsProd." ++ show anal) ((ppr f) <+> (ppr arg))
#endif
\end{code}
See notes on @addStrictnessInfoToId@.
\begin{code}
-findStrictness :: StrAnalFlags
- -> [UniType] -- Types of args in which strictness is wanted
- -> AbsVal -- Abstract strictness value of function
- -> AbsVal -- Abstract absence value of function
- -> [Demand] -- Resulting strictness annotation
+findStrictness :: [Type] -- Types of args in which strictness is wanted
+ -> AbsVal -- Abstract strictness value of function
+ -> AbsVal -- Abstract absence value of function
+ -> ([Demand], Bool) -- Resulting strictness annotation
-findStrictness strflags [] str_val abs_val = []
+findStrictness tys str_val abs_val
+ = (map find_str tys_w_index, isBot (foldl (absApply StrAnal) str_val all_tops))
+ where
+ tys_w_index = tys `zip` [(1::Int) ..]
-findStrictness strflags (ty:tys) str_val abs_val
- = let
- demand = findRecDemand strflags [] str_fn abs_fn ty
- str_fn val = absApply StrAnal str_val val
- abs_fn val = absApply AbsAnal abs_val val
+ find_str (ty,n) = findRecDemand str_fn abs_fn ty
+ where
+ str_fn val = foldl (absApply StrAnal) str_val
+ (map (mk_arg val n) tys_w_index)
- demands = findStrictness strflags tys
- (absApply StrAnal str_val AbsTop)
- (absApply AbsAnal abs_val AbsTop)
- in
- demand : demands
+ abs_fn val = foldl (absApply AbsAnal) abs_val
+ (map (mk_arg val n) tys_w_index)
+
+ mk_arg val n (_,m) | m==n = val
+ | otherwise = AbsTop
+
+ all_tops = [AbsTop | _ <- tys]
\end{code}
\begin{code}
-findDemandStrOnly str_env expr binder -- Only strictness environment available
- = findRecDemand strflags [] str_fn abs_fn (getIdUniType binder)
+findDemand str_env abs_env expr binder
+ = findRecDemand str_fn abs_fn (idType binder)
where
str_fn val = absEval StrAnal expr (addOneToAbsValEnv str_env binder val)
- abs_fn val = AbsBot -- Always says poison; so it looks as if
- -- nothing is absent; safe
- strflags = getStrAnalFlags str_env
-
-findDemandAbsOnly abs_env expr binder -- Only absence environment available
- = findRecDemand strflags [] str_fn abs_fn (getIdUniType binder)
- where
- str_fn val = AbsBot -- Always says non-termination;
- -- that'll make findRecDemand peer into the
- -- structure of the value.
abs_fn val = absEval AbsAnal expr (addOneToAbsValEnv abs_env binder val)
- strflags = getStrAnalFlags abs_env
-
-findDemand str_env abs_env expr binder
- = findRecDemand strflags [] str_fn abs_fn (getIdUniType binder)
+findDemandAlts str_env abs_env alts binder
+ = findRecDemand str_fn abs_fn (idType binder)
where
- str_fn val = absEval StrAnal expr (addOneToAbsValEnv str_env binder val)
- abs_fn val = absEval AbsAnal expr (addOneToAbsValEnv abs_env binder val)
- strflags = getStrAnalFlags str_env
+ str_fn val = absEvalAlts StrAnal alts (addOneToAbsValEnv str_env binder val)
+ abs_fn val = absEvalAlts AbsAnal alts (addOneToAbsValEnv abs_env binder val)
\end{code}
@findRecDemand@ is where we finally convert strictness/absence info
Ho hum.
\begin{code}
-findRecDemand :: StrAnalFlags
- -> [TyCon] -- TyCons already seen; used to avoid
- -- zooming into recursive types
- -> (AbsVal -> AbsVal) -- The strictness function
+findRecDemand :: (AbsVal -> AbsVal) -- The strictness function
-> (AbsVal -> AbsVal) -- The absence function
- -> UniType -- The type of the argument
+ -> Type -- The type of the argument
-> Demand
-findRecDemand strflags seen str_fn abs_fn ty
- = if isPrimType ty then -- It's a primitive type!
+findRecDemand str_fn abs_fn ty
+ = if isUnLiftedType ty then -- It's a primitive type!
wwPrim
else if not (anyBot (abs_fn AbsBot)) then -- It's absent
-- We prefer absence over strictness: see NOTE above.
WwLazy True
- else if not (all_strict ||
- (num_strict && is_numeric_type ty) ||
- (isBot (str_fn AbsBot))) then
+ else if not (opt_AllStrict ||
+ (opt_NumbersStrict && is_numeric_type ty) ||
+ (isBot (str_fn AbsBot))) then
WwLazy False -- It's not strict and we're not pretending
else -- It's strict (or we're pretending it is)!
- case getUniDataTyCon_maybe ty of
+ case (splitAlgTyConApp_maybe ty) of
Nothing -> wwStrict
- Just (tycon,tycon_arg_tys,[data_con]) | tycon `not_elem` seen ->
- -- Single constructor case, tycon not already seen higher up
+ Just (tycon,tycon_arg_tys,[data_con]) | isProductTyCon tycon ->
+ -- Non-recursive, single constructor case
let
- (_,cmpnt_tys,_) = getInstantiatedDataConSig data_con tycon_arg_tys
+ cmpnt_tys = dataConArgTys data_con tycon_arg_tys
prod_len = length cmpnt_tys
+ in
+ if isNewTyCon tycon then -- A newtype!
+ ASSERT( null (tail cmpnt_tys) )
+ let
+ demand = findRecDemand str_fn abs_fn (head cmpnt_tys)
+ in
+ wwUnpackNew demand
+ else -- A data type!
+ let
compt_strict_infos
- = [ findRecDemand strflags (tycon:seen)
+ = [ findRecDemand
(\ cmpnt_val ->
str_fn (mkMainlyTopProd prod_len i cmpnt_val)
)
if null compt_strict_infos then
if isEnumerationTyCon tycon then wwEnum else wwStrict
else
- wwUnpack compt_strict_infos
- where
- not_elem = isn'tIn "findRecDemand"
+ wwUnpackData compt_strict_infos
Just (tycon,_,_) ->
-- Multi-constr data types, *or* an abstract data
else
wwStrict
where
- (all_strict, num_strict) = strflags
-
is_numeric_type ty
- = case (getUniDataTyCon_maybe ty) of -- NB: duplicates stuff done above
+ = case (splitAlgTyConApp_maybe ty) of -- NB: duplicates stuff done above
Nothing -> False
Just (tycon, _, _)
- | tycon `is_elem`
- [intTyCon, integerTyCon,
- doubleTyCon, floatTyCon,
- wordTyCon, addrTyCon]
+ | tyConUnique tycon `is_elem` numericTyKeys
-> True
_{-something else-} -> False
where
approximation.
\begin{code}
-cheapFixpoint :: AnalysisKind -> [Id] -> [PlainCoreExpr] -> AbsValEnv -> [AbsVal]
+cheapFixpoint :: AnalysisKind -> [Id] -> [CoreExpr] -> AbsValEnv -> [AbsVal]
cheapFixpoint AbsAnal [id] [rhs] env
= [crudeAbsWiden (absEval AbsAnal rhs new_env)]
= [widen anal (absEval anal rhs new_env) | rhs <- rhss]
-- We do just one iteration, starting from a safe
-- approximation. This won't do a good job in situations
- -- like:
+ -- like:
-- \x -> letrec f = ...g...
-- g = ...f...x...
-- in
\end{verbatim}
\begin{code}
-fixpoint :: AnalysisKind -> [Id] -> [PlainCoreExpr] -> AbsValEnv -> [AbsVal]
+fixpoint :: AnalysisKind -> [Id] -> [CoreExpr] -> AbsValEnv -> [AbsVal]
fixpoint anal [] _ env = []
-fixpoint anal ids rhss env
+fixpoint anal ids rhss env
= fix_loop initial_vals
where
initial_val id
= case anal of -- The (unsafe) starting point
- StrAnal -> if (returnsRealWorld (getIdUniType id))
+ StrAnal -> if (returnsRealWorld (idType id))
then AbsTop -- this is a massively horrible hack (SLPJ 95/05)
else AbsBot
AbsAnal -> AbsTop
fix_loop :: [AbsVal] -> [AbsVal]
- fix_loop current_widened_vals
+ fix_loop current_widened_vals
= let
new_env = growAbsValEnvList env (ids `zip` current_widened_vals)
new_vals = [ absEval anal rhs new_env | rhs <- rhss ]
new_widened_vals = map (widen anal) new_vals
- in
+ in
if (and (zipWith sameVal current_widened_vals new_widened_vals)) then
current_widened_vals
+ -- NB: I was too chicken to make that a zipWithEqual,
+ -- lest I jump into a black hole. WDP 96/02
+
-- Return the widened values. We might get a slightly
-- better value by returning new_vals (which we used to
-- do, see below), but alas that means that whenever the
letrec
x = ...p..d...
d = (x,y)
- in
+ in
...
\end{verbatim}
Here, if p is @AbsBot@, then we'd better {\em not} end up with a ``fixed
projects / ghc-hetmet.git / blobdiff