X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FsimplCore%2FSetLevels.lhs;h=0797ad7727eb1fd5a37d22e7a9be2970f8c74def;hp=270ce170950160db4b9aae9944277cf5e49c66ce;hb=703ca1542c8e0983cc9d8eebce6e9f3dd3fd71e2;hpb=9bcd95bad83ee937c178970e8b729732e680fe1e diff --git a/compiler/simplCore/SetLevels.lhs b/compiler/simplCore/SetLevels.lhs index 270ce17..0797ad7 100644 --- a/compiler/simplCore/SetLevels.lhs +++ b/compiler/simplCore/SetLevels.lhs @@ -60,7 +60,7 @@ import CoreUtils ( exprType, exprIsTrivial, mkPiTypes ) import CoreFVs -- all of it import CoreSubst ( Subst, emptySubst, extendInScope, extendIdSubst, cloneIdBndr, cloneRecIdBndrs ) -import Id ( Id, idType, mkSysLocal, isOneShotLambda, +import Id ( idType, mkSysLocal, isOneShotLambda, zapDemandIdInfo, transferPolyIdInfo, idSpecialisation, idWorkerInfo, setIdInfo ) @@ -366,6 +366,14 @@ For example: where h :: Int -> Int# is expensive. We'd like to float the (h y) outside the \x, but we don't because it's unboxed. Possible solution: box it. +Note [Case MFEs] +~~~~~~~~~~~~~~~~ +We don't float a case expression as an MFE from a strict context. Why not? +Because in doing so we share a tiny bit of computation (the switch) but +in exchange we build a thunk, which is bad. This case reduces allocation +by 7% in spectral/puzzle (a rather strange benchmark) and 1.2% in real/fem. +Doesn't change any other allocation at all. + \begin{code} lvlMFE :: Bool -- True <=> strict context [body of case or let] -> Level -- Level of innermost enclosing lambda/tylam @@ -384,6 +392,10 @@ lvlMFE strict_ctxt ctxt_lvl env (_, AnnCast e co) = do { expr' <- lvlMFE strict_ctxt ctxt_lvl env e ; return (Cast expr' co) } +-- Note [Case MFEs] +lvlMFE True ctxt_lvl env e@(_, AnnCase {}) + = lvlExpr ctxt_lvl env e -- Don't share cases + lvlMFE strict_ctxt ctxt_lvl env ann_expr@(fvs, _) | isUnLiftedType ty -- Can't let-bind it; see Note [Unlifted MFEs] || isInlineCtxt ctxt_lvl -- Don't float out of an __inline__ context @@ -525,7 +537,7 @@ lvlBind top_lvl ctxt_lvl env (AnnRec pairs) new_rhss <- mapM (lvlExpr ctxt_lvl new_env) rhss return (Rec ([TB b dest_lvl | b <- new_bndrs] `zip` new_rhss), new_env) - | isSingleton pairs && count isIdVar abs_vars > 1 + | isSingleton pairs && count isId abs_vars > 1 = do -- Special case for self recursion where there are -- several variables carried around: build a local loop: -- poly_f = \abs_vars. \lam_vars . letrec f = \lam_vars. rhs in f lam_vars @@ -605,7 +617,7 @@ lvlLamBndrs lvl bndrs [] bndrs where go old_lvl bumped_major rev_lvld_bndrs (bndr:bndrs) - | isIdVar bndr && -- Go to the next major level if this is a value binder, + | isId bndr && -- Go to the next major level if this is a value binder, not bumped_major && -- and we havn't already gone to the next level (one jump per group) not (isOneShotLambda bndr) -- and it isn't a one-shot lambda = go new_lvl True (TB bndr new_lvl : rev_lvld_bndrs) bndrs @@ -647,7 +659,7 @@ isFunction :: CoreExprWithFVs -> Bool -- We may only want to do this if there are sufficiently few free -- variables. We certainly only want to do it for values, and not for -- constructors. So the simple thing is just to look for lambdas -isFunction (_, AnnLam b e) | isIdVar b = True +isFunction (_, AnnLam b e) | isId b = True | otherwise = isFunction e isFunction (_, AnnNote _ e) = isFunction e isFunction _ = False @@ -765,10 +777,10 @@ maxIdLevel (_, lvl_env,_,id_env) var_set Nothing -> [in_var]) max_out out_var lvl - | isIdVar out_var = case lookupVarEnv lvl_env out_var of + | isId out_var = case lookupVarEnv lvl_env out_var of Just lvl' -> maxLvl lvl' lvl Nothing -> lvl - | otherwise = lvl -- Ignore tyvars in *maxIdLevel* + | otherwise = lvl -- Ignore tyvars in *maxIdLevel* lookupVar :: LevelEnv -> Id -> LevelledExpr lookupVar (_, _, _, id_env) v = case lookupVarEnv id_env v of @@ -808,7 +820,7 @@ abstractVars dest_lvl (_, lvl_env, _, id_env) fvs -- We are going to lambda-abstract, so nuke any IdInfo, -- and add the tyvars of the Id (if necessary) - zap v | isIdVar v = WARN( workerExists (idWorkerInfo v) || + zap v | isId v = WARN( workerExists (idWorkerInfo v) || not (isEmptySpecInfo (idSpecialisation v)), text "absVarsOf: discarding info on" <+> ppr v ) setIdInfo v vanillaIdInfo @@ -823,7 +835,7 @@ absVarsOf :: IdEnv ([Var], LevelledExpr) -> Var -> [Var] -- we must look in x's type -- And similarly if x is a coercion variable. absVarsOf id_env v - | isIdVar v = [av2 | av1 <- lookup_avs v + | isId v = [av2 | av1 <- lookup_avs v , av2 <- add_tyvars av1] | isCoVar v = add_tyvars v | otherwise = [v] @@ -851,7 +863,7 @@ newPolyBndrs dest_lvl env abs_vars bndrs = do let new_bndrs = zipWith mk_poly_bndr bndrs uniqs return (extendPolyLvlEnv dest_lvl env abs_vars (bndrs `zip` new_bndrs), new_bndrs) where - mk_poly_bndr bndr uniq = transferPolyIdInfo bndr $ -- Note [transferPolyIdInfo] in Id.lhs + mk_poly_bndr bndr uniq = transferPolyIdInfo bndr abs_vars $ -- Note [transferPolyIdInfo] in Id.lhs mkSysLocal (mkFastString str) uniq poly_ty where str = "poly_" ++ occNameString (getOccName bndr) @@ -871,7 +883,7 @@ cloneVar :: TopLevelFlag -> LevelEnv -> Id -> Level -> Level -> LvlM (LevelEnv, cloneVar TopLevel env v _ _ = return (env, v) -- Don't clone top level things cloneVar NotTopLevel env@(_,_,subst,_) v ctxt_lvl dest_lvl - = ASSERT( isIdVar v ) do + = ASSERT( isId v ) do us <- getUniqueSupplyM let (subst', v1) = cloneIdBndr subst us v @@ -883,7 +895,7 @@ cloneRecVars :: TopLevelFlag -> LevelEnv -> [Id] -> Level -> Level -> LvlM (Leve cloneRecVars TopLevel env vs _ _ = return (env, vs) -- Don't clone top level things cloneRecVars NotTopLevel env@(_,_,subst,_) vs ctxt_lvl dest_lvl - = ASSERT( all isIdVar vs ) do + = ASSERT( all isId vs ) do us <- getUniqueSupplyM let (subst', vs1) = cloneRecIdBndrs subst us vs