\section[SpecConstr]{Specialise over constructors}
\begin{code}
-{-# OPTIONS -w #-}
-- The above warning supression flag is a temporary kludge.
-- While working on this module you are encouraged to remove it and fix
-- any warnings in the module. See
import OccName ( mkSpecOcc )
import ErrUtils ( dumpIfSet_dyn )
import DynFlags ( DynFlags(..), DynFlag(..) )
+import StaticFlags ( opt_SpecInlineJoinPoints )
import BasicTypes ( Activation(..) )
import Maybes ( orElse, catMaybes, isJust )
import Util
return binds'
where
- go env [] = returnUs []
+ go _ [] = returnUs []
go env (bind:binds) = scBind env bind `thenUs` \ (env', _, bind') ->
go env' binds `thenUs` \ binds' ->
returnUs (bind' : binds')
data ScEnv = SCE { sc_size :: Maybe Int, -- Size threshold
sc_subst :: Subst, -- Current substitution
+ -- Maps InIds to OutExprs
sc_how_bound :: HowBoundEnv,
-- Binds interesting non-top-level variables
ppr LambdaVal = ptext SLIT("<Lambda>")
---------------------
+initScEnv :: DynFlags -> ScEnv
initScEnv dflags
= SCE { sc_size = specConstrThreshold dflags,
sc_subst = emptySubst,
-- Bring the quantified variables into scope
extendScInScope env qvars = env { sc_subst = extendInScopeList (sc_subst env) qvars }
-extendScSubst :: ScEnv -> [(Var,CoreArg)] -> ScEnv
-- Extend the substitution
-extendScSubst env prs = env { sc_subst = extendSubstList (sc_subst env) prs }
+extendScSubst :: ScEnv -> Var -> OutExpr -> ScEnv
+extendScSubst env var expr = env { sc_subst = extendSubst (sc_subst env) var expr }
+
+extendScSubstList :: ScEnv -> [(Var,OutExpr)] -> ScEnv
+extendScSubstList env prs = env { sc_subst = extendSubstList (sc_subst env) prs }
extendHowBound :: ScEnv -> [Var] -> HowBound -> ScEnv
extendHowBound env bndrs how_bound
(subst', bndr') = substBndr (sc_subst env) bndr
extendValEnv :: ScEnv -> Id -> Maybe Value -> ScEnv
-extendValEnv env id Nothing = env
+extendValEnv env _ Nothing = env
extendValEnv env id (Just cv) = env { sc_vals = extendVarEnv (sc_vals env) id cv }
extendCaseBndrs :: ScEnv -> CoreExpr -> Id -> AltCon -> [Var] -> ScEnv
-- NB: Extends only the sc_vals part of the envt
extendCaseBndrs env scrut case_bndr con alt_bndrs
= case scrut of
- Var v -> extendValEnv env1 v cval
- other -> env1
+ Var v -> extendValEnv env1 v cval
+ _other -> env1
where
env1 = extendValEnv env case_bndr cval
cval = case con of
DEFAULT -> Nothing
- LitAlt lit -> Just (ConVal con [])
- DataAlt dc -> Just (ConVal con vanilla_args)
+ LitAlt {} -> Just (ConVal con [])
+ DataAlt {} -> Just (ConVal con vanilla_args)
where
vanilla_args = map Type (tyConAppArgs (idType case_bndr)) ++
varsToCoreExprs alt_bndrs
\begin{code}
data ScUsage
= SCU {
- calls :: CallEnv, -- Calls
+ scu_calls :: CallEnv, -- Calls
-- The functions are a subset of the
-- RecFuns in the ScEnv
- occs :: !(IdEnv ArgOcc) -- Information on argument occurrences
- } -- The variables are a subset of the
- -- RecArg in the ScEnv
+ scu_occs :: !(IdEnv ArgOcc) -- Information on argument occurrences
+ } -- The domain is OutIds
type CallEnv = IdEnv [Call]
type Call = (ValueEnv, [CoreArg])
-- The arguments of the call, together with the
-- env giving the constructor bindings at the call site
-nullUsage = SCU { calls = emptyVarEnv, occs = emptyVarEnv }
+nullUsage :: ScUsage
+nullUsage = SCU { scu_calls = emptyVarEnv, scu_occs = emptyVarEnv }
combineCalls :: CallEnv -> CallEnv -> CallEnv
combineCalls = plusVarEnv_C (++)
-combineUsage u1 u2 = SCU { calls = combineCalls (calls u1) (calls u2),
- occs = plusVarEnv_C combineOcc (occs u1) (occs u2) }
+combineUsage :: ScUsage -> ScUsage -> ScUsage
+combineUsage u1 u2 = SCU { scu_calls = combineCalls (scu_calls u1) (scu_calls u2),
+ scu_occs = plusVarEnv_C combineOcc (scu_occs u1) (scu_occs u2) }
+combineUsages :: [ScUsage] -> ScUsage
combineUsages [] = nullUsage
combineUsages us = foldr1 combineUsage us
-lookupOcc :: ScUsage -> Var -> (ScUsage, ArgOcc)
-lookupOcc (SCU { calls = sc_calls, occs = sc_occs }) bndr
- = (SCU {calls = sc_calls, occs = delVarEnv sc_occs bndr},
+lookupOcc :: ScUsage -> OutVar -> (ScUsage, ArgOcc)
+lookupOcc (SCU { scu_calls = sc_calls, scu_occs = sc_occs }) bndr
+ = (SCU {scu_calls = sc_calls, scu_occs = delVarEnv sc_occs bndr},
lookupVarEnv sc_occs bndr `orElse` NoOcc)
-lookupOccs :: ScUsage -> [Var] -> (ScUsage, [ArgOcc])
-lookupOccs (SCU { calls = sc_calls, occs = sc_occs }) bndrs
- = (SCU {calls = sc_calls, occs = delVarEnvList sc_occs bndrs},
+lookupOccs :: ScUsage -> [OutVar] -> (ScUsage, [ArgOcc])
+lookupOccs (SCU { scu_calls = sc_calls, scu_occs = sc_occs }) bndrs
+ = (SCU {scu_calls = sc_calls, scu_occs = delVarEnvList sc_occs bndrs},
[lookupVarEnv sc_occs b `orElse` NoOcc | b <- bndrs])
data ArgOcc = NoOcc -- Doesn't occur at all; or a type argument
-- that if the thing is scrutinised anywhere then we get to see that
-- in the overall result, even if it's also used in a boxed way
-- This might be too agressive; see Note [Reboxing] Alternative 3
+combineOcc :: ArgOcc -> ArgOcc -> ArgOcc
combineOcc NoOcc occ = occ
combineOcc occ NoOcc = occ
combineOcc (ScrutOcc xs) (ScrutOcc ys) = ScrutOcc (plusUFM_C combineOccs xs ys)
-combineOcc occ (ScrutOcc ys) = ScrutOcc ys
-combineOcc (ScrutOcc xs) occ = ScrutOcc xs
+combineOcc _occ (ScrutOcc ys) = ScrutOcc ys
+combineOcc (ScrutOcc xs) _occ = ScrutOcc xs
combineOcc UnkOcc UnkOcc = UnkOcc
combineOcc _ _ = BothOcc
combineOccs :: [ArgOcc] -> [ArgOcc] -> [ArgOcc]
combineOccs xs ys = zipWithEqual "combineOccs" combineOcc xs ys
-setScrutOcc :: ScEnv -> ScUsage -> CoreExpr -> ArgOcc -> ScUsage
+setScrutOcc :: ScEnv -> ScUsage -> OutExpr -> ArgOcc -> ScUsage
-- *Overwrite* the occurrence info for the scrutinee, if the scrutinee
-- is a variable, and an interesting variable
setScrutOcc env usg (Cast e _) occ = setScrutOcc env usg e occ
setScrutOcc env usg (Note _ e) occ = setScrutOcc env usg e occ
setScrutOcc env usg (Var v) occ
- | Just RecArg <- lookupHowBound env v = usg { occs = extendVarEnv (occs usg) v occ }
+ | Just RecArg <- lookupHowBound env v = usg { scu_occs = extendVarEnv (scu_occs usg) v occ }
| otherwise = usg
-setScrutOcc env usg other occ -- Catch-all
+setScrutOcc _env usg _other _occ -- Catch-all
= usg
conArgOccs :: ArgOcc -> AltCon -> [ArgOcc]
conArgOccs (ScrutOcc fm) (DataAlt dc)
| Just pat_arg_occs <- lookupUFM fm dc
- = [UnkOcc | tv <- dataConUnivTyVars dc] ++ pat_arg_occs
+ = [UnkOcc | _ <- dataConUnivTyVars dc] ++ pat_arg_occs
-conArgOccs other con = repeat UnkOcc
+conArgOccs _other _con = repeat UnkOcc
\end{code}
%************************************************************************
creates specialised versions of functions.
\begin{code}
-scExpr :: ScEnv -> CoreExpr -> UniqSM (ScUsage, CoreExpr)
+scExpr, scExpr' :: ScEnv -> CoreExpr -> UniqSM (ScUsage, CoreExpr)
-- The unique supply is needed when we invent
-- a new name for the specialised function and its args
scExpr' env (Var v) = case scSubstId env v of
- Var v' -> returnUs (varUsage env v UnkOcc, Var v')
+ Var v' -> returnUs (varUsage env v' UnkOcc, Var v')
e' -> scExpr (zapScSubst env) e'
-scExpr' env e@(Type t) = returnUs (nullUsage, Type (scSubstTy env t))
-scExpr' env e@(Lit l) = returnUs (nullUsage, e)
+scExpr' env (Type t) = returnUs (nullUsage, Type (scSubstTy env t))
+scExpr' _ e@(Lit {}) = returnUs (nullUsage, e)
scExpr' env (Note n e) = do { (usg,e') <- scExpr env e
; return (usg, Note n e') }
scExpr' env (Cast e co) = do { (usg, e') <- scExpr env e
; return (usg, Cast e' (scSubstTy env co)) }
+scExpr' env e@(App _ _) = scApp env (collectArgs e)
scExpr' env (Lam b e) = do { let (env', b') = extendBndr env b
; (usg, e') <- scExpr env' e
; return (usg, Lam b' e') }
= do { (scrut_usg, scrut') <- scExpr env scrut
; case isValue (sc_vals env) scrut' of
Just (ConVal con args) -> sc_con_app con args scrut'
- other -> sc_vanilla scrut_usg scrut'
+ _other -> sc_vanilla scrut_usg scrut'
}
where
sc_con_app con args scrut' -- Known constructor; simplify
= do { let (_, bs, rhs) = findAlt con alts
- alt_env' = extendScSubst env ((b,scrut') : bs `zip` trimConArgs con args)
+ alt_env' = extendScSubstList env ((b,scrut') : bs `zip` trimConArgs con args)
; scExpr alt_env' rhs }
sc_vanilla scrut_usg scrut' -- Normal case
; (alt_usgs, alt_occs, alts')
<- mapAndUnzip3Us (sc_alt alt_env scrut' b') alts
- ; let (alt_usg, b_occ) = lookupOcc (combineUsages alt_usgs) b
+ ; let (alt_usg, b_occ) = lookupOcc (combineUsages alt_usgs) b'
scrut_occ = foldr combineOcc b_occ alt_occs
scrut_usg' = setScrutOcc env scrut_usg scrut' scrut_occ
-- The combined usage of the scrutinee is given
= do { let (env1, bs') = extendBndrsWith RecArg env bs
env2 = extendCaseBndrs env1 scrut' b' con bs'
; (usg,rhs') <- scExpr env2 rhs
- ; let (usg', arg_occs) = lookupOccs usg bs
+ ; let (usg', arg_occs) = lookupOccs usg bs'
scrut_occ = case con of
DataAlt dc -> ScrutOcc (unitUFM dc arg_occs)
- other -> ScrutOcc emptyUFM
+ _ofther -> ScrutOcc emptyUFM
; return (usg', scrut_occ, (con,bs',rhs')) }
scExpr' env (Let (NonRec bndr rhs) body)
+ | isTyVar bndr -- Type-lets may be created by doBeta
+ = scExpr' (extendScSubst env bndr rhs) body
+ | otherwise
= do { let (body_env, bndr') = extendBndr env bndr
- ; (rhs_usg, rhs_info@(_, args', rhs_body', _)) <- scRecRhs env (bndr',rhs)
+ ; (rhs_usg, (_, args', rhs_body', _)) <- scRecRhs env (bndr',rhs)
+ ; let rhs' = mkLams args' rhs_body'
- ; if null args' || isEmptyVarEnv (calls rhs_usg) then do
+ ; if not opt_SpecInlineJoinPoints || null args' || isEmptyVarEnv (scu_calls rhs_usg) then do
do { -- Vanilla case
- let rhs' = mkLams args' rhs_body'
- body_env2 = extendValEnv body_env bndr' (isValue (sc_vals env) rhs')
+ let body_env2 = extendValEnv body_env bndr' (isValue (sc_vals env) rhs')
-- Record if the RHS is a value
; (body_usg, body') <- scExpr body_env2 body
; return (body_usg `combineUsage` rhs_usg, Let (NonRec bndr' rhs') body') }
- else
+ else -- For now, just brutally inline the join point
+ do { let body_env2 = extendScSubst env bndr rhs'
+ ; scExpr body_env2 body } }
+
+
+{- Old code
do { -- Join-point case
let body_env2 = extendHowBound body_env [bndr'] RecFun
-- If the RHS of this 'let' contains calls
-- as one to specialise
; (body_usg, body') <- scExpr body_env2 body
- ; (spec_usg, _, specs) <- specialise env (calls body_usg) ([], rhs_info)
+ ; (spec_usg, _, specs) <- specialise env (scu_calls body_usg) ([], rhs_info)
- ; return (body_usg { calls = calls body_usg `delVarEnv` bndr' }
+ ; return (body_usg { scu_calls = scu_calls body_usg `delVarEnv` bndr' }
`combineUsage` rhs_usg `combineUsage` spec_usg,
mkLets [NonRec b r | (b,r) <- addRules rhs_info specs] body')
- } }
+ }
+-}
scExpr' env (Let (Rec prs) body)
= do { (env', bind_usg, bind') <- scBind env (Rec prs)
; (body_usg, body') <- scExpr env' body
; return (bind_usg `combineUsage` body_usg, Let bind' body') }
-scExpr' env e@(App _ _)
- = do { let (fn, args) = collectArgs e
- ; (fn_usg, fn') <- scExpr env fn
- -- Process the function too. It's almost always a variable,
- -- but not always. In particular, if this pass follows float-in,
- -- which it may, we can get
- -- (let f = ...f... in f) arg1 arg2
- -- Also the substitution may replace a variable by a non-variable
-
- ; let fn_usg' = setScrutOcc env fn_usg fn' (ScrutOcc emptyUFM)
- -- We use setScrutOcc to record the fact that the function is called
- -- Perhaps we should check that it has at least one value arg,
- -- but currently we don't bother
+-----------------------------------
+scApp :: ScEnv -> (InExpr, [InExpr]) -> UniqSM (ScUsage, CoreExpr)
+
+scApp env (Var fn, args) -- Function is a variable
+ = ASSERT( not (null args) )
+ do { args_w_usgs <- mapUs (scExpr env) args
+ ; let (arg_usgs, args') = unzip args_w_usgs
+ arg_usg = combineUsages arg_usgs
+ ; case scSubstId env fn of
+ fn'@(Lam {}) -> scExpr (zapScSubst env) (doBeta fn' args')
+ -- Do beta-reduction and try again
+
+ Var fn' -> return (arg_usg `combineUsage` fn_usg, mkApps (Var fn') args')
+ where
+ fn_usg = case lookupHowBound env fn' of
+ Just RecFun -> SCU { scu_calls = unitVarEnv fn' [(sc_vals env, args')],
+ scu_occs = emptyVarEnv }
+ Just RecArg -> SCU { scu_calls = emptyVarEnv,
+ scu_occs = unitVarEnv fn' (ScrutOcc emptyUFM) }
+ Nothing -> nullUsage
+
+
+ other_fn' -> return (arg_usg, mkApps other_fn' args') }
+ -- NB: doing this ignores any usage info from the substituted
+ -- function, but I don't think that matters. If it does
+ -- we can fix it.
+ where
+ doBeta :: OutExpr -> [OutExpr] -> OutExpr
+ -- ToDo: adjust for System IF
+ doBeta (Lam bndr body) (arg : args) = Let (NonRec bndr arg) (doBeta body args)
+ doBeta fn args = mkApps fn args
+
+-- The function is almost always a variable, but not always.
+-- In particular, if this pass follows float-in,
+-- which it may, we can get
+-- (let f = ...f... in f) arg1 arg2
+scApp env (other_fn, args)
+ = do { (fn_usg, fn') <- scExpr env other_fn
; (arg_usgs, args') <- mapAndUnzipUs (scExpr env) args
- ; let call_usg = case fn' of
- Var f | Just RecFun <- lookupHowBound env f
- , not (null args) -- Not a proper call!
- -> SCU { calls = unitVarEnv f [(sc_vals env, args')],
- occs = emptyVarEnv }
- other -> nullUsage
- ; return (combineUsages arg_usgs `combineUsage` fn_usg'
- `combineUsage` call_usg,
- mkApps fn' args') }
-
+ ; return (combineUsages arg_usgs `combineUsage` fn_usg, mkApps fn' args') }
----------------------
scBind :: ScEnv -> CoreBind -> UniqSM (ScEnv, ScUsage, CoreBind)
; (rhs_usgs, rhs_infos) <- mapAndUnzipUs (scRecRhs rhs_env2) (bndrs' `zip` rhss)
; let rhs_usg = combineUsages rhs_usgs
- ; (spec_usg, specs) <- spec_loop rhs_env2 (calls rhs_usg)
+ ; (spec_usg, specs) <- spec_loop rhs_env2 (scu_calls rhs_usg)
(repeat [] `zip` rhs_infos)
; let all_usg = rhs_usg `combineUsage` spec_usg
; return (rhs_env1, -- For the body of the letrec, delete the RecFun business
- all_usg { calls = calls rhs_usg `delVarEnvList` bndrs' },
+ all_usg { scu_calls = scu_calls rhs_usg `delVarEnvList` bndrs' },
Rec (concat (zipWith addRules rhs_infos specs))) }
where
(bndrs,rhss) = unzip prs
; let spec_usg = combineUsages spec_usg_s
; if all null new_pats_s then
return (spec_usg, specs) else do
- { (spec_usg1, specs1) <- spec_loop env (calls spec_usg)
+ { (spec_usg1, specs1) <- spec_loop env (scu_calls spec_usg)
(zipWith add_pats new_pats_s rhs_stuff)
; return (spec_usg `combineUsage` spec_usg1, zipWith (++) specs specs1) } }
rules = [r | (r,_,_) <- specs]
----------------------
+varUsage :: ScEnv -> OutVar -> ArgOcc -> ScUsage
varUsage env v use
- | Just RecArg <- lookupHowBound env v = SCU { calls = emptyVarEnv,
- occs = unitVarEnv v use }
+ | Just RecArg <- lookupHowBound env v = SCU { scu_calls = emptyVarEnv
+ , scu_occs = unitVarEnv v use }
| otherwise = nullUsage
\end{code}
spec_one env fn arg_bndrs body ((qvars, pats), rule_number)
= do { -- Specialise the body
- let spec_env = extendScSubst (extendScInScope env qvars)
- (arg_bndrs `zip` pats)
+ let spec_env = extendScSubstList (extendScInScope env qvars)
+ (arg_bndrs `zip` pats)
; (spec_usg, spec_body) <- scExpr spec_env body
-- ; pprTrace "spec_one" (ppr fn <+> vcat [text "pats" <+> ppr pats,
--- text "calls" <+> (ppr (calls spec_usg))])
+-- text "calls" <+> (ppr (scu_calls spec_usg))])
-- (return ())
-- And build the results
-- lvl7 --> (True, lvl7) if lvl7 is bound
-- somewhere further out
-argToPat in_scope val_env arg@(Type ty) arg_occ
+argToPat _in_scope _val_env arg@(Type {}) _arg_occ
= return (False, arg)
-argToPat in_scope val_env (Note n arg) arg_occ
+argToPat in_scope val_env (Note _ arg) arg_occ
= argToPat in_scope val_env arg arg_occ
-- Note [Notes in call patterns]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ScrutOcc _ -> True -- Used only by case scrutinee
BothOcc -> case arg of -- Used elsewhere
App {} -> True -- see Note [Reboxing]
- other -> False
- other -> False -- No point; the arg is not decomposed
+ _other -> False
+ _other -> False -- No point; the arg is not decomposed
= do { args' <- argsToPats in_scope val_env (args `zip` conArgOccs arg_occ dc)
; return (True, mk_con_app dc (map snd args')) }
-- (a) it's used in an interesting way in the body
-- (b) we know what its value is
argToPat in_scope val_env (Var v) arg_occ
- | case arg_occ of { UnkOcc -> False; other -> True }, -- (a)
- is_value -- (b)
+ | case arg_occ of { UnkOcc -> False; _other -> True }, -- (a)
+ is_value -- (b)
= return (True, Var v)
where
is_value
-- Don't make a wild-card, because we may usefully share
-- e.g. f a = let x = ... in f (x,x)
-- NB: this case follows the lambda and con-app cases!!
-argToPat in_scope val_env (Var v) arg_occ
+argToPat _in_scope _val_env (Var v) _arg_occ
= return (False, Var v)
-- The default case: make a wild-card
-argToPat in_scope val_env arg arg_occ
+argToPat _in_scope _val_env arg _arg_occ
= wildCardPat (exprType arg)
wildCardPat :: Type -> UniqSM (Bool, CoreArg)
\begin{code}
isValue :: ValueEnv -> CoreExpr -> Maybe Value
-isValue env (Lit lit)
+isValue _env (Lit lit)
= Just (ConVal (LitAlt lit) [])
isValue env (Var v)
| isTyVar b = isValue env e
| otherwise = Just LambdaVal
-isValue env expr -- Maybe it's a constructor application
+isValue _env expr -- Maybe it's a constructor application
| (Var fun, args) <- collectArgs expr
= case isDataConWorkId_maybe fun of
-- arity excludes type args
-> Just (ConVal (DataAlt con) args)
- other | valArgCount args < idArity fun
+ _other | valArgCount args < idArity fun
-- Under-applied function
- -> Just LambdaVal -- Partial application
+ -> Just LambdaVal -- Partial application
- other -> Nothing
+ _other -> Nothing
-isValue env expr = Nothing
+isValue _env _expr = Nothing
mk_con_app :: AltCon -> [CoreArg] -> CoreExpr
mk_con_app (LitAlt lit) [] = Lit lit
mk_con_app (DataAlt con) args = mkConApp con args
-mk_con_app other args = panic "SpecConstr.mk_con_app"
+mk_con_app _other _args = panic "SpecConstr.mk_con_app"
samePat :: CallPat -> CallPat -> Bool
samePat (vs1, as1) (vs2, as2)
same (Lit l1) (Lit l2) = l1==l2
same (App f1 a1) (App f2 a2) = same f1 f2 && same a1 a2
- same (Type t1) (Type t2) = True -- Note [Ignore type differences]
+ same (Type {}) (Type {}) = True -- Note [Ignore type differences]
same (Note _ e1) e2 = same e1 e2 -- Ignore casts and notes
same (Cast e1 _) e2 = same e1 e2
same e1 (Note _ e2) = same e1 e2
bad (Case {}) = True
bad (Let {}) = True
bad (Lam {}) = True
- bad other = False
+ bad _other = False
\end{code}
Note [Ignore type differences]
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