\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
+-- http://hackage.haskell.org/trac/ghc/wiki/CodingStyle#Warnings
+-- for details
+
module SpecConstr(
specConstrProgram
) where
import DataCon ( dataConRepArity, dataConUnivTyVars )
import Type ( Type, tyConAppArgs )
import Coercion ( coercionKind )
-import Id ( Id, idName, idType, isDataConWorkId_maybe,
+import Id ( Id, idName, idType, isDataConWorkId_maybe, idArity,
mkUserLocal, mkSysLocal, idUnfolding, isLocalId )
import Var ( Var )
import VarEnv
import VarSet
-import Name ( nameOccName, nameSrcLoc )
+import Name
import Rules ( addIdSpecialisations, mkLocalRule, rulesOfBinds )
import OccName ( mkSpecOcc )
import ErrUtils ( dumpIfSet_dyn )
import DynFlags ( DynFlags(..), DynFlag(..) )
import BasicTypes ( Activation(..) )
-import Maybes ( orElse, catMaybes )
+import Maybes ( orElse, catMaybes, isJust )
import Util
import List ( nubBy, partition )
import UniqSupply
\begin{code}
data ScEnv = SCE { sc_size :: Int, -- Size threshold
- sc_subst :: Subst, -- Current subsitution
+ sc_subst :: Subst, -- Current substitution
sc_how_bound :: HowBoundEnv,
-- Binds interesting non-top-level variables
- -- Look up in here *after* applying the substitution
+ -- Domain is OutVars (*after* applying the substitution)
- sc_cons :: ConstrEnv
- -- Look up in here *after* applying the substitution
+ sc_vals :: ValueEnv
+ -- Domain is OutIds (*after* applying the substitution)
+ -- Used even for top-level bindings (but not imported ones)
}
-type HowBoundEnv = VarEnv HowBound
+---------------------
+-- As we go, we apply a substitution (sc_subst) to the current term
+type InExpr = CoreExpr -- *Before* applying the subst
+
+type OutExpr = CoreExpr -- *After* applying the subst
+type OutId = Id
+type OutVar = Var
-type ConstrEnv = IdEnv ConValue
-data ConValue = CV AltCon [CoreArg]
- -- Variables known to be bound to a constructor
- -- in a particular case alternative
+---------------------
+type HowBoundEnv = VarEnv HowBound -- Domain is OutVars
+---------------------
+type ValueEnv = IdEnv Value -- Domain is OutIds
+data Value = ConVal AltCon [CoreArg] -- *Saturated* constructors
+ | LambdaVal -- Inlinable lambdas or PAPs
-instance Outputable ConValue where
- ppr (CV con args) = ppr con <+> interpp'SP args
+instance Outputable Value where
+ ppr (ConVal con args) = ppr con <+> interpp'SP args
+ ppr LambdaVal = ptext SLIT("<Lambda>")
+---------------------
initScEnv dflags
= SCE { sc_size = specThreshold dflags,
sc_subst = emptySubst,
sc_how_bound = emptyVarEnv,
- sc_cons = emptyVarEnv }
+ sc_vals = emptyVarEnv }
data HowBound = RecFun -- These are the recursive functions for which
-- we seek interesting call patterns
where
(subst', bndr') = substBndr (sc_subst env) bndr
-extendConEnv :: ScEnv -> Id -> Maybe ConValue -> ScEnv
-extendConEnv env id Nothing = env
-extendConEnv env id (Just cv) = env { sc_cons = extendVarEnv (sc_cons env) id cv }
+extendValEnv :: ScEnv -> Id -> Maybe Value -> ScEnv
+extendValEnv env id Nothing = env
+extendValEnv env id (Just cv) = env { sc_vals = extendVarEnv (sc_vals env) id cv }
extendCaseBndrs :: ScEnv -> CoreExpr -> Id -> AltCon -> [Var] -> ScEnv
-- When we encounter
-- case scrut of b
-- C x y -> ...
-- we want to bind b, and perhaps scrut too, to (C x y)
--- NB: Extends only the sc_cons part of the envt
+-- NB: Extends only the sc_vals part of the envt
extendCaseBndrs env scrut case_bndr con alt_bndrs
= case scrut of
- Var v -> extendConEnv env1 v cval
+ Var v -> extendValEnv env1 v cval
other -> env1
where
- env1 = extendConEnv env case_bndr cval
+ env1 = extendValEnv env case_bndr cval
cval = case con of
DEFAULT -> Nothing
- LitAlt lit -> Just (CV con [])
- DataAlt dc -> Just (CV con vanilla_args)
+ LitAlt lit -> Just (ConVal con [])
+ DataAlt dc -> Just (ConVal con vanilla_args)
where
vanilla_args = map Type (tyConAppArgs (idType case_bndr)) ++
varsToCoreExprs alt_bndrs
-- RecArg in the ScEnv
type CallEnv = IdEnv [Call]
-type Call = (ConstrEnv, [CoreArg])
+type Call = (ValueEnv, [CoreArg])
-- The arguments of the call, together with the
-- env giving the constructor bindings at the call site
scExpr' env (Case scrut b ty alts)
= do { (scrut_usg, scrut') <- scExpr env scrut
- ; case isConApp (sc_cons env) scrut' of
- Nothing -> sc_vanilla scrut_usg scrut'
- Just cval -> sc_con_app cval scrut'
+ ; case isValue (sc_vals env) scrut' of
+ Just (ConVal con args) -> sc_con_app con args scrut'
+ other -> sc_vanilla scrut_usg scrut'
}
where
- sc_con_app cval@(CV con args) scrut' -- Known constructor; simplify
+ 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)
; scExpr alt_env' rhs }
-
sc_vanilla scrut_usg scrut' -- Normal case
= do { let (alt_env,b') = extendBndrWith RecArg env b
; return (usg', scrut_occ, (con,bs',rhs')) }
scExpr' env (Let (NonRec bndr rhs) body)
- = do { (rhs_usg, rhs_info@(_, args', rhs_body', _)) <- scRecRhs env (bndr,rhs)
+ = do { let (body_env, bndr') = extendBndr env bndr
+ ; (rhs_usg, rhs_info@(_, args', rhs_body', _)) <- scRecRhs env (bndr',rhs)
+
; if null args' || isEmptyVarEnv (calls rhs_usg) then do
do { -- Vanilla case
let rhs' = mkLams args' rhs_body'
- (body_env, bndr') = extendBndr env bndr
- body_env2 = extendConEnv body_env bndr' (isConApp (sc_cons env) rhs')
- -- Record if the RHS is a constructor
+ 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
do { -- Join-point case
- let (body_env, bndr') = extendBndrWith RecFun env bndr
+ let body_env2 = extendHowBound body_env [bndr'] RecFun
-- If the RHS of this 'let' contains calls
-- to recursive functions that we're trying
-- to specialise, then treat this let too
-- as one to specialise
- ; (body_usg, body') <- scExpr body_env body
+ ; (body_usg, body') <- scExpr body_env2 body
; (spec_usg, _, specs) <- specialise env (calls body_usg) ([], rhs_info)
; 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_cons env, args')],
+ -> SCU { calls = unitVarEnv f [(sc_vals env, args')],
occs = emptyVarEnv }
other -> nullUsage
; return (combineUsages arg_usgs `combineUsage` fn_usg'
; return (rhs_env, combineUsages rhs_usgs, Rec (bndrs' `zip` rhss')) }
| otherwise -- Do specialisation
= do { let (rhs_env1,bndrs') = extendRecBndrs env bndrs
- rhs_env2 = extendHowBound rhs_env1 bndrs RecFun
+ rhs_env2 = extendHowBound rhs_env1 bndrs' RecFun
; (rhs_usgs, rhs_infos) <- mapAndUnzipUs (scRecRhs rhs_env2) (bndrs' `zip` rhss)
; let rhs_usg = combineUsages rhs_usgs
scBind env (NonRec bndr rhs)
= do { (usg, rhs') <- scExpr env rhs
- ; let (env', bndr') = extendBndr env bndr
- ; return (env', usg, NonRec bndr' rhs') }
+ ; let (env1, bndr') = extendBndr env bndr
+ env2 = extendValEnv env1 bndr' (isValue (sc_vals env) rhs')
+ ; return (env2, usg, NonRec bndr' rhs') }
----------------------
-scRecRhs :: ScEnv -> (Id,CoreExpr) -> UniqSM (ScUsage, RhsInfo)
+scRecRhs :: ScEnv -> (OutId, InExpr) -> UniqSM (ScUsage, RhsInfo)
scRecRhs env (bndr,rhs)
= do { let (arg_bndrs,body) = collectBinders rhs
(body_env, arg_bndrs') = extendBndrsWith RecArg env arg_bndrs
%************************************************************************
\begin{code}
-type RhsInfo = (Id, [Var], CoreExpr, [ArgOcc])
+type RhsInfo = (OutId, [OutVar], OutExpr, [ArgOcc])
-- Info about the *original* RHS of a binding we are specialising
-- Original binding f = \xs.body
-- Plus info about usage of arguments
-type SpecInfo = (CoreRule, Var, CoreExpr)
+type SpecInfo = (CoreRule, OutId, OutExpr)
-- One specialisation: Rule plus definition
---------------------
spec_one :: ScEnv
- -> Id -- Function
+ -> OutId -- Function
-> [Var] -- Lambda-binders of RHS; should match patterns
-> CoreExpr -- Body of the original function
-> (([Var], [CoreArg]), Int)
-- a spec_rhs of unlifted type and no args
fn_name = idName fn
- fn_loc = nameSrcLoc fn_name
+ fn_loc = nameSrcSpan fn_name
spec_occ = mkSpecOcc (nameOccName fn_name)
rule_name = mkFastString ("SC:" ++ showSDoc (ppr fn <> int rule_number))
spec_rhs = mkLams spec_lam_args spec_body
-- C a (D (f x) (g y)) ==> C p1 (D p2 p3)
argToPat :: InScopeSet -- What's in scope at the fn defn site
- -> ConstrEnv -- ConstrEnv at the call site
+ -> ValueEnv -- ValueEnv at the call site
-> CoreArg -- A call arg (or component thereof)
-> ArgOcc
-> UniqSM (Bool, CoreArg)
-- lvl7 --> (True, lvl7) if lvl7 is bound
-- somewhere further out
-argToPat in_scope con_env arg@(Type ty) arg_occ
+argToPat in_scope val_env arg@(Type ty) arg_occ
= return (False, arg)
-argToPat in_scope con_env (Note n arg) arg_occ
- = argToPat in_scope con_env arg arg_occ
+argToPat in_scope val_env (Note n arg) arg_occ
+ = argToPat in_scope val_env arg arg_occ
-- Note [Notes in call patterns]
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- Ignore Notes. In particular, we want to ignore any InlineMe notes
-- ride roughshod over them all for now.
--- See Note [Notes in RULE matching] in Rules
-argToPat in_scope con_env (Let _ arg) arg_occ
- = argToPat in_scope con_env arg arg_occ
+argToPat in_scope val_env (Let _ arg) arg_occ
+ = argToPat in_scope val_env arg arg_occ
-- Look through let expressions
-- e.g. f (let v = rhs in \y -> ...v...)
-- Here we can specialise for f (\y -> ...)
-- because the rule-matcher will look through the let.
-argToPat in_scope con_env (Cast arg co) arg_occ
- = do { (interesting, arg') <- argToPat in_scope con_env arg arg_occ
+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
{- Disabling lambda specialisation for now
It's fragile, and the spec_loop can be infinite
-argToPat in_scope con_env arg arg_occ
+argToPat in_scope val_env arg arg_occ
| is_value_lam arg
= return (True, arg)
where
-- Check for a constructor application
-- NB: this *precedes* the Var case, so that we catch nullary constrs
-argToPat in_scope con_env arg arg_occ
- | Just (CV dc args) <- isConApp con_env arg
+argToPat in_scope val_env arg arg_occ
+ | Just (ConVal dc args) <- isValue val_env arg
, case arg_occ of
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
- = do { args' <- argsToPats in_scope con_env (args `zip` conArgOccs arg_occ dc)
+ = do { args' <- argsToPats in_scope val_env (args `zip` conArgOccs arg_occ dc)
; return (True, mk_con_app dc (map snd args')) }
-- Check if the argument is a variable that
-- It's worth specialising on this if
-- (a) it's used in an interesting way in the body
-- (b) we know what its value is
-argToPat in_scope con_env (Var v) arg_occ
- | not (isLocalId v) || v `elemInScopeSet` in_scope,
- case arg_occ of { UnkOcc -> False; other -> True }, -- (a)
- isValueUnfolding (idUnfolding v) -- (b)
+argToPat in_scope val_env (Var v) arg_occ
+ | case arg_occ of { UnkOcc -> False; other -> True }, -- (a)
+ is_value -- (b)
= return (True, Var v)
+ where
+ is_value
+ | isLocalId v = v `elemInScopeSet` in_scope
+ && isJust (lookupVarEnv val_env v)
+ -- Local variables have values in val_env
+ | otherwise = isValueUnfolding (idUnfolding v)
+ -- Imports have unfoldings
-- I'm really not sure what this comment means
-- And by not wild-carding we tend to get forall'd
-- 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 con_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 con_env arg arg_occ
+argToPat in_scope val_env arg arg_occ
= wildCardPat (exprType arg)
wildCardPat :: Type -> UniqSM (Bool, CoreArg)
; let id = mkSysLocal FSLIT("sc") uniq ty
; return (False, Var id) }
-argsToPats :: InScopeSet -> ConstrEnv
+argsToPats :: InScopeSet -> ValueEnv
-> [(CoreArg, ArgOcc)]
-> UniqSM [(Bool, CoreArg)]
-argsToPats in_scope con_env args
+argsToPats in_scope val_env args
= mapUs do_one args
where
- do_one (arg,occ) = argToPat in_scope con_env arg occ
+ do_one (arg,occ) = argToPat in_scope val_env arg occ
\end{code}
\begin{code}
-isConApp :: ConstrEnv -> CoreExpr -> Maybe ConValue
-isConApp env (Lit lit)
- = Just (CV (LitAlt lit) [])
-
-isConApp env expr -- Maybe it's a constructor application
- | (Var fun, args) <- collectArgs expr,
- Just con <- isDataConWorkId_maybe fun,
- args `lengthAtLeast` dataConRepArity con
- -- Might be > because the arity excludes type args
- = Just (CV (DataAlt con) args)
-
-isConApp env (Var v)
+isValue :: ValueEnv -> CoreExpr -> Maybe Value
+isValue env (Lit lit)
+ = Just (ConVal (LitAlt lit) [])
+
+isValue env (Var v)
| Just stuff <- lookupVarEnv env v
= Just stuff -- You might think we could look in the idUnfolding here
-- but that doesn't take account of which branch of a
-- case we are in, which is the whole point
| not (isLocalId v) && isCheapUnfolding unf
- = isConApp env (unfoldingTemplate unf)
+ = isValue env (unfoldingTemplate unf)
where
unf = idUnfolding v
-- However we do want to consult the unfolding
-- as well, for let-bound constructors!
-isConApp env expr = Nothing
+isValue env (Lam b e)
+ | isTyVar b = isValue env e
+ | otherwise = Just LambdaVal
+
+isValue env expr -- Maybe it's a constructor application
+ | (Var fun, args) <- collectArgs expr
+ = case isDataConWorkId_maybe fun of
+
+ Just con | args `lengthAtLeast` dataConRepArity con
+ -- Check saturated; might be > because the
+ -- arity excludes type args
+ -> Just (ConVal (DataAlt con) args)
+
+ other | valArgCount args < idArity fun
+ -- Under-applied function
+ -> Just LambdaVal -- Partial application
+
+ other -> Nothing
+
+isValue env expr = Nothing
mk_con_app :: AltCon -> [CoreArg] -> CoreExpr
mk_con_app (LitAlt lit) [] = Lit lit
projects / ghc-hetmet.git / blobdiff