\section[SpecConstr]{Specialise over constructors}
\begin{code}
+-- 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
+-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
module SpecConstr(
specConstrProgram
) where
import PprCore ( pprRules )
import WwLib ( mkWorkerArgs )
import DataCon ( dataConRepArity, dataConUnivTyVars )
-import Type ( Type, tyConAppArgs )
-import Coercion ( coercionKind )
+import Coercion
+import Type hiding( substTy )
import Id ( Id, idName, idType, isDataConWorkId_maybe, idArity,
mkUserLocal, mkSysLocal, idUnfolding, isLocalId )
-import Var ( Var )
+import Var
import VarEnv
import VarSet
import Name
import OccName ( mkSpecOcc )
import ErrUtils ( dumpIfSet_dyn )
import DynFlags ( DynFlags(..), DynFlag(..) )
+import StaticFlags ( opt_SpecInlineJoinPoints )
import BasicTypes ( Activation(..) )
-import Maybes ( orElse, catMaybes, isJust )
+import Maybes ( orElse, catMaybes, isJust, isNothing )
import Util
import List ( nubBy, partition )
import UniqSupply
import Outputable
import FastString
import UniqFM
+import MonadUtils
+import Control.Monad ( zipWithM )
\end{code}
-----------------------------------------------------
So we want to spot the construtor application inside the cast.
That's why we have the Cast case in argToPat
+Note [Local recursive groups]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+For a *local* recursive group, we can see all the calls to the
+function, so we seed the specialisation loop from the calls in the
+body, not from the calls in the RHS. Consider:
+
+ bar m n = foo n (n,n) (n,n) (n,n) (n,n)
+ where
+ foo n p q r s
+ | n == 0 = m
+ | n > 3000 = case p of { (p1,p2) -> foo (n-1) (p2,p1) q r s }
+ | n > 2000 = case q of { (q1,q2) -> foo (n-1) p (q2,q1) r s }
+ | n > 1000 = case r of { (r1,r2) -> foo (n-1) p q (r2,r1) s }
+ | otherwise = case s of { (s1,s2) -> foo (n-1) p q r (s2,s1) }
+
+If we start with the RHSs of 'foo', we get lots and lots of specialisations,
+most of which are not needed. But if we start with the (single) call
+in the rhs of 'bar' we get exactly one fully-specialised copy, and all
+the recursive calls go to this fully-specialised copy. Indeed, the original
+function is later collected as dead code. This is very important in
+specialising the loops arising from stream fusion, for example in NDP where
+we were getting literally hundreds of (mostly unused) specialisations of
+a local function.
-----------------------------------------------------
Stuff not yet handled
return binds'
where
- go env [] = returnUs []
- go env (bind:binds) = scBind env bind `thenUs` \ (env', _, bind') ->
- go env' binds `thenUs` \ binds' ->
- returnUs (bind' : binds')
+ go _ [] = return []
+ go env (bind:binds) = do (env', bind') <- scTopBind env bind
+ binds' <- go env' binds
+ return (bind' : binds')
\end{code}
%************************************************************************
\begin{code}
-data ScEnv = SCE { sc_size :: Int, -- Size threshold
+data ScEnv = SCE { sc_size :: Maybe Int, -- Size threshold
+ sc_count :: Maybe Int, -- Max # of specialisations for any one fn
- sc_subst :: Subst, -- Current substitution
+ sc_subst :: Subst, -- Current substitution
+ -- Maps InIds to OutExprs
sc_how_bound :: HowBoundEnv,
-- Binds interesting non-top-level variables
instance Outputable Value where
ppr (ConVal con args) = ppr con <+> interpp'SP args
- ppr LambdaVal = ptext SLIT("<Lambda>")
+ ppr LambdaVal = ptext (sLit "<Lambda>")
---------------------
+initScEnv :: DynFlags -> ScEnv
initScEnv dflags
- = SCE { sc_size = specThreshold dflags,
+ = SCE { sc_size = specConstrThreshold dflags,
+ sc_count = specConstrCount dflags,
sc_subst = emptySubst,
sc_how_bound = emptyVarEnv,
sc_vals = emptyVarEnv }
-- 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
-}
instance Outputable ArgOcc where
- ppr (ScrutOcc xs) = ptext SLIT("scrut-occ") <> ppr xs
- ppr UnkOcc = ptext SLIT("unk-occ")
- ppr BothOcc = ptext SLIT("both-occ")
- ppr NoOcc = ptext SLIT("no-occ")
+ ppr (ScrutOcc xs) = ptext (sLit "scrut-occ") <> ppr xs
+ ppr UnkOcc = ptext (sLit "unk-occ")
+ ppr BothOcc = ptext (sLit "both-occ")
+ ppr NoOcc = ptext (sLit "no-occ")
-- Experimentally, this vesion of combineOcc makes ScrutOcc "win", so
-- 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' -> return (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 (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 (Lam b e) = do { let (env', b') = extendBndr env b
- ; (usg, e') <- scExpr env' e
- ; return (usg, Lam b' e') }
+scExpr' env (Type t) = return (nullUsage, Type (scSubstTy env t))
+scExpr' _ e@(Lit {}) = return (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')
scExpr' env (Case scrut b ty alts)
= 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
-- Record RecArg for the components
; (alt_usgs, alt_occs, alts')
- <- mapAndUnzip3Us (sc_alt alt_env scrut' b') alts
+ <- mapAndUnzip3M (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')
- } }
+ mkLets [NonRec b r | (b,r) <- specInfoBinds rhs_info specs] body')
+ }
+-}
+-- A *local* recursive group: see Note [Local recursive groups]
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
-
- ; (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') }
+ = do { let (bndrs,rhss) = unzip prs
+ (rhs_env1,bndrs') = extendRecBndrs env bndrs
+ rhs_env2 = extendHowBound rhs_env1 bndrs' RecFun
+ ; (rhs_usgs, rhs_infos) <- mapAndUnzipM (scRecRhs rhs_env2) (bndrs' `zip` rhss)
+ ; (body_usg, body') <- scExpr rhs_env2 body
+
+ -- NB: start specLoop from body_usg
+ ; (spec_usg, specs) <- specLoop rhs_env2 (scu_calls body_usg) rhs_infos nullUsage
+ [SI [] 0 (Just usg) | usg <- rhs_usgs]
+
+ ; let all_usg = spec_usg `combineUsage` body_usg
+ bind' = Rec (concat (zipWith specInfoBinds rhs_infos specs))
+
+ ; return (all_usg { scu_calls = scu_calls all_usg `delVarEnvList` bndrs' },
+ Let bind' body') }
+
+-----------------------------------
+scApp :: ScEnv -> (InExpr, [InExpr]) -> UniqSM (ScUsage, CoreExpr)
+
+scApp env (Var fn, args) -- Function is a variable
+ = ASSERT( not (null args) )
+ do { args_w_usgs <- mapM (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') <- mapAndUnzipM (scExpr env) args
+ ; return (combineUsages arg_usgs `combineUsage` fn_usg, mkApps fn' args') }
----------------------
-scBind :: ScEnv -> CoreBind -> UniqSM (ScEnv, ScUsage, CoreBind)
-scBind env (Rec prs)
- | not (all (couldBeSmallEnoughToInline (sc_size env)) rhss)
+scTopBind :: ScEnv -> CoreBind -> UniqSM (ScEnv, CoreBind)
+scTopBind env (Rec prs)
+ | Just threshold <- sc_size env
+ , not (all (couldBeSmallEnoughToInline threshold) rhss)
-- No specialisation
= do { let (rhs_env,bndrs') = extendRecBndrs env bndrs
- ; (rhs_usgs, rhss') <- mapAndUnzipUs (scExpr rhs_env) rhss
- ; return (rhs_env, combineUsages rhs_usgs, Rec (bndrs' `zip` rhss')) }
+ ; (_, rhss') <- mapAndUnzipM (scExpr rhs_env) rhss
+ ; return (rhs_env, Rec (bndrs' `zip` rhss')) }
| otherwise -- Do specialisation
= do { let (rhs_env1,bndrs') = extendRecBndrs env bndrs
rhs_env2 = extendHowBound rhs_env1 bndrs' RecFun
- ; (rhs_usgs, rhs_infos) <- mapAndUnzipUs (scRecRhs rhs_env2) (bndrs' `zip` rhss)
+ ; (rhs_usgs, rhs_infos) <- mapAndUnzipM (scRecRhs rhs_env2) (bndrs' `zip` rhss)
; let rhs_usg = combineUsages rhs_usgs
- ; (spec_usg, specs) <- spec_loop rhs_env2 (calls rhs_usg)
- (repeat [] `zip` rhs_infos)
-
- ; let all_usg = rhs_usg `combineUsage` spec_usg
+ ; (_, specs) <- specLoop rhs_env2 (scu_calls rhs_usg) rhs_infos nullUsage
+ [SI [] 0 Nothing | _ <- bndrs]
; return (rhs_env1, -- For the body of the letrec, delete the RecFun business
- all_usg { calls = calls rhs_usg `delVarEnvList` bndrs' },
- Rec (concat (zipWith addRules rhs_infos specs))) }
+ Rec (concat (zipWith specInfoBinds rhs_infos specs))) }
where
(bndrs,rhss) = unzip prs
- spec_loop :: ScEnv
- -> CallEnv
- -> [([CallPat], RhsInfo)] -- One per binder
- -> UniqSM (ScUsage, [[SpecInfo]]) -- One list per binder
- spec_loop env all_calls rhs_stuff
- = do { (spec_usg_s, new_pats_s, specs) <- mapAndUnzip3Us (specialise env all_calls) rhs_stuff
- ; 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)
- (zipWith add_pats new_pats_s rhs_stuff)
- ; return (spec_usg `combineUsage` spec_usg1, zipWith (++) specs specs1) } }
-
- add_pats :: [CallPat] -> ([CallPat], RhsInfo) -> ([CallPat], RhsInfo)
- add_pats new_pats (done_pats, rhs_info) = (done_pats ++ new_pats, rhs_info)
-
-scBind env (NonRec bndr rhs)
- = do { (usg, rhs') <- scExpr env rhs
+scTopBind env (NonRec bndr rhs)
+ = do { (_, rhs') <- scExpr env rhs
; let (env1, bndr') = extendBndr env bndr
env2 = extendValEnv env1 bndr' (isValue (sc_vals env) rhs')
- ; return (env2, usg, NonRec bndr' rhs') }
+ ; return (env2, NonRec bndr' rhs') }
----------------------
scRecRhs :: ScEnv -> (OutId, InExpr) -> UniqSM (ScUsage, RhsInfo)
-- Two pats are the same if they match both ways
----------------------
-addRules :: RhsInfo -> [SpecInfo] -> [(Id,CoreExpr)]
-addRules (fn, args, body, _) specs
- = [(id,rhs) | (_,id,rhs) <- specs] ++
+specInfoBinds :: RhsInfo -> SpecInfo -> [(Id,CoreExpr)]
+specInfoBinds (fn, args, body, _) (SI specs _ _)
+ = [(id,rhs) | OS _ _ id rhs <- specs] ++
[(fn `addIdSpecialisations` rules, mkLams args body)]
where
- rules = [r | (r,_,_) <- specs]
+ rules = [r | OS _ 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}
-- Original binding f = \xs.body
-- Plus info about usage of arguments
-type SpecInfo = (CoreRule, OutId, OutExpr)
- -- One specialisation: Rule plus definition
+data SpecInfo = SI [OneSpec] -- The specialisations we have generated
+ Int -- Length of specs; used for numbering them
+ (Maybe ScUsage) -- Nothing => we have generated specialisations
+ -- from calls in the *original* RHS
+ -- Just cs => we haven't, and this is the usage
+ -- of the original RHS
+ -- One specialisation: Rule plus definition
+data OneSpec = OS CallPat -- Call pattern that generated this specialisation
+ CoreRule -- Rule connecting original id with the specialisation
+ OutId OutExpr -- Spec id + its rhs
+
+
+specLoop :: ScEnv
+ -> CallEnv
+ -> [RhsInfo]
+ -> ScUsage -> [SpecInfo] -- One per binder; acccumulating parameter
+ -> UniqSM (ScUsage, [SpecInfo]) -- ...ditto...
+specLoop env all_calls rhs_infos usg_so_far specs_so_far
+ = do { specs_w_usg <- zipWithM (specialise env all_calls) rhs_infos specs_so_far
+ ; let (new_usg_s, all_specs) = unzip specs_w_usg
+ new_usg = combineUsages new_usg_s
+ new_calls = scu_calls new_usg
+ all_usg = usg_so_far `combineUsage` new_usg
+ ; if isEmptyVarEnv new_calls then
+ return (all_usg, all_specs)
+ else
+ specLoop env new_calls rhs_infos all_usg all_specs }
specialise
:: ScEnv
-> CallEnv -- Info on calls
- -> ([CallPat], RhsInfo) -- Original RHS plus patterns dealt with
- -> UniqSM (ScUsage, [CallPat], [SpecInfo]) -- Specialised calls
+ -> RhsInfo
+ -> SpecInfo -- Original RHS plus patterns dealt with
+ -> UniqSM (ScUsage, SpecInfo) -- New specialised versions and their usage
-- Note: the rhs here is the optimised version of the original rhs
-- So when we make a specialised copy of the RHS, we're starting
-- from an RHS whose nested functions have been optimised already.
-specialise env bind_calls (done_pats, (fn, arg_bndrs, body, arg_occs))
+specialise env bind_calls (fn, arg_bndrs, body, arg_occs)
+ spec_info@(SI specs spec_count mb_unspec)
| notNull arg_bndrs, -- Only specialise functions
Just all_calls <- lookupVarEnv bind_calls fn
- = do { pats <- callsToPats env done_pats arg_occs all_calls
+ = do { (boring_call, pats) <- callsToPats env specs arg_occs all_calls
-- ; pprTrace "specialise" (vcat [ppr fn <+> ppr arg_occs,
-- text "calls" <+> ppr all_calls,
-- text "good pats" <+> ppr pats]) $
-- return ()
- ; (spec_usgs, specs) <- mapAndUnzipUs (spec_one env fn arg_bndrs body)
- (pats `zip` [length done_pats..])
-
- ; return (combineUsages spec_usgs, pats, specs) }
+ -- Bale out if too many specialisations
+ -- Rather a hacky way to do so, but it'll do for now
+ ; let spec_count' = length pats + spec_count
+ ; case sc_count env of
+ Just max | spec_count' > max
+ -> pprTrace "SpecConstr: too many specialisations for one function (see -fspec-constr-count):"
+ (vcat [ptext (sLit "Function:") <+> ppr fn,
+ ptext (sLit "Specialisations:") <+> ppr (pats ++ [p | OS p _ _ _ <- specs])])
+ return (nullUsage, spec_info)
+
+ _normal_case -> do
+
+ { (spec_usgs, new_specs) <- mapAndUnzipM (spec_one env fn arg_bndrs body)
+ (pats `zip` [spec_count..])
+
+ ; let spec_usg = combineUsages spec_usgs
+ (new_usg, mb_unspec')
+ = case mb_unspec of
+ Just rhs_usg | boring_call -> (spec_usg `combineUsage` rhs_usg, Nothing)
+ _ -> (spec_usg, mb_unspec)
+
+ ; return (new_usg, SI (new_specs ++ specs) spec_count' mb_unspec') } }
| otherwise
- = return (nullUsage, [], []) -- The boring case
+ = return (nullUsage, spec_info) -- The boring case
---------------------
-> OutId -- Function
-> [Var] -- Lambda-binders of RHS; should match patterns
-> CoreExpr -- Body of the original function
- -> (([Var], [CoreArg]), Int)
- -> UniqSM (ScUsage, SpecInfo) -- Rule and binding
+ -> (CallPat, Int)
+ -> UniqSM (ScUsage, OneSpec) -- Rule and binding
-- spec_one creates a specialised copy of the function, together
-- with a rule for using it. I'm very proud of how short this
f (b,c) ((:) (a,(b,c)) (x,v) hw) = f_spec b c v hw
-}
-spec_one env fn arg_bndrs body ((qvars, pats), rule_number)
+spec_one env fn arg_bndrs body (call_pat@(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
body_ty = exprType spec_body
rule_rhs = mkVarApps (Var spec_id) spec_call_args
rule = mkLocalRule rule_name specConstrActivation fn_name qvars pats rule_rhs
- ; return (spec_usg, (rule, spec_id, spec_rhs)) }
+ ; return (spec_usg, OS call_pat rule spec_id spec_rhs) }
-- In which phase should the specialise-constructor rules be active?
-- Originally I made them always-active, but Manuel found that
type CallPat = ([Var], [CoreExpr]) -- Quantified variables and arguments
-callsToPats :: ScEnv -> [CallPat] -> [ArgOcc] -> [Call] -> UniqSM [CallPat]
+callsToPats :: ScEnv -> [OneSpec] -> [ArgOcc] -> [Call] -> UniqSM (Bool, [CallPat])
-- Result has no duplicate patterns,
-- nor ones mentioned in done_pats
-callsToPats env done_pats bndr_occs calls
+ -- Bool indicates that there was at least one boring pattern
+callsToPats env done_specs bndr_occs calls
= do { mb_pats <- mapM (callToPats env bndr_occs) calls
; let good_pats :: [([Var], [CoreArg])]
good_pats = catMaybes mb_pats
+ done_pats = [p | OS p _ _ _ <- done_specs]
is_done p = any (samePat p) done_pats
- ; return (filterOut is_done (nubBy samePat good_pats)) }
+ ; return (any isNothing mb_pats,
+ filterOut is_done (nubBy samePat good_pats)) }
callToPats :: ScEnv -> [ArgOcc] -> Call -> UniqSM (Maybe CallPat)
-- The [Var] is the variables to quantify over in the rule
| otherwise
= do { let in_scope = substInScope (sc_subst env)
; prs <- argsToPats in_scope con_env (args `zip` bndr_occs)
- ; let (good_pats, pats) = unzip prs
+ ; let (interesting_s, pats) = unzip prs
pat_fvs = varSetElems (exprsFreeVars pats)
qvars = filterOut (`elemInScopeSet` in_scope) pat_fvs
-- Quantify over variables that are not in sccpe
-- variable may mention a type variable
; -- pprTrace "callToPats" (ppr args $$ ppr prs $$ ppr bndr_occs) $
- if or good_pats
+ if or interesting_s
then return (Just (qvars', pats))
else return Nothing }
-- 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]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
argToPat in_scope val_env (Cast arg co) arg_occ
= do { (interesting, arg') <- argToPat in_scope val_env arg arg_occ
- ; if interesting then
- return (interesting, Cast arg' co)
- else
- wildCardPat (snd (coercionKind co)) }
+ ; let (ty1,ty2) = coercionKind co
+ ; if not interesting then
+ wildCardPat ty2
+ else do
+ { -- Make a wild-card pattern for the coercion
+ uniq <- getUniqueUs
+ ; let co_name = mkSysTvName uniq (fsLit "sg")
+ co_var = mkCoVar co_name (mkCoKind ty1 ty2)
+ ; return (interesting, Cast arg' (mkTyVarTy co_var)) } }
{- Disabling lambda specialisation for now
It's fragile, and the spec_loop can be infinite
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
-- variables that are in soope, which in turn can
-- expose the weakness in let-matching
-- See Note [Matching lets] in Rules
+
-- Check for a variable bound inside the function.
-- 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
- = return (False, Var v)
+-- argToPat _in_scope _val_env (Var v) _arg_occ
+-- = return (False, Var v)
+ -- SLPJ : disabling this to avoid proliferation of versions
+ -- also works badly when thinking about seeding the loop
+ -- from the body of the let
+ -- f x y = letrec g z = ... in g (x,y)
+ -- We don't want to specialise for that *particular* x,y
-- 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)
wildCardPat ty = do { uniq <- getUniqueUs
- ; let id = mkSysLocal FSLIT("sc") uniq ty
+ ; let id = mkSysLocal (fsLit "sc") uniq ty
; return (False, Var id) }
argsToPats :: InScopeSet -> ValueEnv
-> [(CoreArg, ArgOcc)]
-> UniqSM [(Bool, CoreArg)]
argsToPats in_scope val_env args
- = mapUs do_one args
+ = mapM do_one args
where
do_one (arg,occ) = argToPat in_scope val_env arg occ
\end{code}
\begin{code}
isValue :: ValueEnv -> CoreExpr -> Maybe Value
-isValue env (Lit lit)
+isValue _env (Lit lit)
= Just (ConVal (LitAlt lit) [])
isValue env (Var v)
-- as well, for let-bound constructors!
isValue env (Lam b e)
- | isTyVar b = isValue env e
+ | isTyVar b = case isValue env e of
+ Just _ -> Just LambdaVal
+ Nothing -> Nothing
| 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
same e1 e2 = WARN( bad e1 || bad e2, ppr e1 $$ ppr e2)
False -- Let, lambda, case should not occur
-#ifdef DEBUG
bad (Case {}) = True
bad (Let {}) = True
bad (Lam {}) = True
- bad other = False
-#endif
+ bad _other = False
\end{code}
Note [Ignore type differences]