import Type ( isUnLiftedType, Type )
import BasicTypes ( TopLevelFlag(..), Arity )
import UniqSupply
-import Util ( sortLe, isSingleton, count )
+import Util
import Outputable
import FastString
\end{code}
\begin{code}
lvlBind top_lvl ctxt_lvl env (AnnRec pairs)
- | null abs_vars
+ | null abs_vars
= do (new_env, new_bndrs) <- cloneRecVars top_lvl env bndrs ctxt_lvl dest_lvl
new_rhss <- mapM (lvlExpr ctxt_lvl new_env) rhss
return (Rec ([TB b dest_lvl | b <- new_bndrs] `zip` new_rhss), new_env)
+-- ToDo: when enabling the floatLambda stuff,
+-- I think we want to stop doing this
| isSingleton pairs && count isId abs_vars > 1
= do -- Special case for self recursion where there are
-- several variables carried around: build a local loop:
destLevel env fvs is_function mb_bot
| Just {} <- mb_bot = tOP_LEVEL -- Send bottoming bindings to the top
-- regardless; see Note [Bottoming floats]
- | floatLams env
- && is_function = tOP_LEVEL -- Send functions to top level; see
+ | Just n_args <- floatLams env
+ , n_args > 0 -- n=0 case handled uniformly by the 'otherwise' case
+ , is_function
+ , countFreeIds fvs <= n_args
+ = tOP_LEVEL -- Send functions to top level; see
-- the comments with isFunction
| otherwise = maxIdLevel env fvs
| otherwise = isFunction e
isFunction (_, AnnNote _ e) = isFunction e
isFunction _ = False
+
+countFreeIds :: VarSet -> Int
+countFreeIds = foldVarSet add 0
+ where
+ add :: Var -> Int -> Int
+ add v n | isId v = n+1
+ | otherwise = n
\end{code}
%************************************************************************
\begin{code}
-type LevelEnv = (FloatOutSwitches,
- VarEnv Level, -- Domain is *post-cloned* TyVars and Ids
- Subst, -- Domain is pre-cloned Ids; tracks the in-scope set
- -- so that subtitution is capture-avoiding
- IdEnv ([Var], LevelledExpr)) -- Domain is pre-cloned Ids
+data LevelEnv
+ = LE { le_switches :: FloatOutSwitches
+ , le_lvl_env :: VarEnv Level -- Domain is *post-cloned* TyVars and Ids
+ , le_subst :: Subst -- Domain is pre-cloned Ids; tracks the in-scope set
+ -- so that subtitution is capture-avoiding
+ , le_env :: IdEnv ([Var], LevelledExpr) -- Domain is pre-cloned Ids
+ }
-- We clone let-bound variables so that they are still
- -- distinct when floated out; hence the SubstEnv/IdEnv.
+ -- distinct when floated out; hence the le_subst/le_env.
-- (see point 3 of the module overview comment).
-- We also use these envs when making a variable polymorphic
-- because we want to float it out past a big lambda.
--
- -- The Subst and IdEnv always implement the same mapping, but the
- -- Subst maps to CoreExpr and the IdEnv to LevelledExpr
+ -- The le_subst and le_env always implement the same mapping, but the
+ -- le_subst maps to CoreExpr and the le_env to LevelledExpr
-- Since the range is always a variable or type application,
-- there is never any difference between the two, but sadly
- -- the types differ. The SubstEnv is used when substituting in
- -- a variable's IdInfo; the IdEnv when we find a Var.
+ -- the types differ. The le_subst is used when substituting in
+ -- a variable's IdInfo; the le_env when we find a Var.
--
- -- In addition the IdEnv records a list of tyvars free in the
+ -- In addition the le_env records a list of tyvars free in the
-- type application, just so we don't have to call freeVars on
-- the type application repeatedly.
--
-- The domain of the both envs is *pre-cloned* Ids, though
--
- -- The domain of the VarEnv Level is the *post-cloned* Ids
+ -- The domain of the le_lvl_env is the *post-cloned* Ids
initialEnv :: FloatOutSwitches -> LevelEnv
-initialEnv float_lams = (float_lams, emptyVarEnv, emptySubst, emptyVarEnv)
+initialEnv float_lams
+ = LE { le_switches = float_lams, le_lvl_env = emptyVarEnv
+ , le_subst = emptySubst, le_env = emptyVarEnv }
-floatLams :: LevelEnv -> Bool
-floatLams (fos, _, _, _) = floatOutLambdas fos
+floatLams :: LevelEnv -> Maybe Int
+floatLams le = floatOutLambdas (le_switches le)
floatConsts :: LevelEnv -> Bool
-floatConsts (fos, _, _, _) = floatOutConstants fos
+floatConsts le = floatOutConstants (le_switches le)
floatPAPs :: LevelEnv -> Bool
-floatPAPs (fos, _, _, _) = floatOutPartialApplications fos
+floatPAPs le = floatOutPartialApplications (le_switches le)
extendLvlEnv :: LevelEnv -> [TaggedBndr Level] -> LevelEnv
-- Used when *not* cloning
-extendLvlEnv (float_lams, lvl_env, subst, id_env) prs
- = (float_lams,
- foldl add_lvl lvl_env prs,
- foldl del_subst subst prs,
- foldl del_id id_env prs)
+extendLvlEnv le@(LE { le_lvl_env = lvl_env, le_subst = subst, le_env = id_env })
+ prs
+ = le { le_lvl_env = foldl add_lvl lvl_env prs
+ , le_subst = foldl del_subst subst prs
+ , le_env = foldl del_id id_env prs }
where
add_lvl env (TB v l) = extendVarEnv env v l
del_subst env (TB v _) = extendInScope env v
-- KSW 2000-07.
extendInScopeEnv :: LevelEnv -> Var -> LevelEnv
-extendInScopeEnv (fl, le, subst, ids) v = (fl, le, extendInScope subst v, ids)
+extendInScopeEnv le@(LE { le_subst = subst }) v
+ = le { le_subst = extendInScope subst v }
extendInScopeEnvList :: LevelEnv -> [Var] -> LevelEnv
-extendInScopeEnvList (fl, le, subst, ids) vs = (fl, le, extendInScopeList subst vs, ids)
+extendInScopeEnvList le@(LE { le_subst = subst }) vs
+ = le { le_subst = extendInScopeList subst vs }
-- extendCaseBndrLvlEnv adds the mapping case-bndr->scrut-var if it can
-- (see point 4 of the module overview comment)
extendCaseBndrLvlEnv :: LevelEnv -> Expr (TaggedBndr Level) -> Var -> Level
-> LevelEnv
-extendCaseBndrLvlEnv (float_lams, lvl_env, subst, id_env) (Var scrut_var) case_bndr lvl
- = (float_lams,
- extendVarEnv lvl_env case_bndr lvl,
- extendIdSubst subst case_bndr (Var scrut_var),
- extendVarEnv id_env case_bndr ([scrut_var], Var scrut_var))
+extendCaseBndrLvlEnv le@(LE { le_lvl_env = lvl_env, le_subst = subst, le_env = id_env })
+ (Var scrut_var) case_bndr lvl
+ = le { le_lvl_env = extendVarEnv lvl_env case_bndr lvl
+ , le_subst = extendIdSubst subst case_bndr (Var scrut_var)
+ , le_env = extendVarEnv id_env case_bndr ([scrut_var], Var scrut_var) }
extendCaseBndrLvlEnv env _scrut case_bndr lvl
- = extendLvlEnv env [TB case_bndr lvl]
+ = extendLvlEnv env [TB case_bndr lvl]
extendPolyLvlEnv :: Level -> LevelEnv -> [Var] -> [(Var, Var)] -> LevelEnv
-extendPolyLvlEnv dest_lvl (float_lams, lvl_env, subst, id_env) abs_vars bndr_pairs
- = (float_lams,
- foldl add_lvl lvl_env bndr_pairs,
- foldl add_subst subst bndr_pairs,
- foldl add_id id_env bndr_pairs)
+extendPolyLvlEnv dest_lvl
+ le@(LE { le_lvl_env = lvl_env, le_subst = subst, le_env = id_env })
+ abs_vars bndr_pairs
+ = le { le_lvl_env = foldl add_lvl lvl_env bndr_pairs
+ , le_subst = foldl add_subst subst bndr_pairs
+ , le_env = foldl add_id id_env bndr_pairs }
where
add_lvl env (_, v') = extendVarEnv env v' dest_lvl
add_subst env (v, v') = extendIdSubst env v (mkVarApps (Var v') abs_vars)
add_id env (v, v') = extendVarEnv env v ((v':abs_vars), mkVarApps (Var v') abs_vars)
extendCloneLvlEnv :: Level -> LevelEnv -> Subst -> [(Var, Var)] -> LevelEnv
-extendCloneLvlEnv lvl (float_lams, lvl_env, _, id_env) new_subst bndr_pairs
- = (float_lams,
- foldl add_lvl lvl_env bndr_pairs,
- new_subst,
- foldl add_id id_env bndr_pairs)
+extendCloneLvlEnv lvl le@(LE { le_lvl_env = lvl_env, le_env = id_env })
+ new_subst bndr_pairs
+ = le { le_lvl_env = foldl add_lvl lvl_env bndr_pairs
+ , le_subst = new_subst
+ , le_env = foldl add_id id_env bndr_pairs }
where
add_lvl env (_, v') = extendVarEnv env v' lvl
add_id env (v, v') = extendVarEnv env v ([v'], Var v')
-
maxIdLevel :: LevelEnv -> VarSet -> Level
-maxIdLevel (_, lvl_env,_,id_env) var_set
+maxIdLevel (LE { le_lvl_env = lvl_env, le_env = id_env }) var_set
= foldVarSet max_in tOP_LEVEL var_set
where
max_in in_var lvl = foldr max_out lvl (case lookupVarEnv id_env in_var of
| otherwise = lvl -- Ignore tyvars in *maxIdLevel*
lookupVar :: LevelEnv -> Id -> LevelledExpr
-lookupVar (_, _, _, id_env) v = case lookupVarEnv id_env v of
- Just (_, expr) -> expr
- _ -> Var v
+lookupVar le v = case lookupVarEnv (le_env le) v of
+ Just (_, expr) -> expr
+ _ -> Var v
abstractVars :: Level -> LevelEnv -> VarSet -> [Var]
-- Find the variables in fvs, free vars of the target expresion,
-- whose level is greater than the destination level
-- These are the ones we are going to abstract out
-abstractVars dest_lvl (_, lvl_env, _, id_env) fvs
+abstractVars dest_lvl (LE { le_lvl_env = lvl_env, le_env = id_env }) fvs
= map zap $ uniq $ sortLe le
[var | fv <- varSetElems fvs
, var <- absVarsOf id_env fv
= return (extendInScopeEnv env v, v) -- Don't clone top level things
-- But do extend the in-scope env, to satisfy the in-scope invariant
-cloneVar NotTopLevel env@(_,_,subst,_) v ctxt_lvl dest_lvl
+cloneVar NotTopLevel env v ctxt_lvl dest_lvl
= ASSERT( isId v ) do
us <- getUniqueSupplyM
let
- (subst', v1) = cloneIdBndr subst us v
+ (subst', v1) = cloneIdBndr (le_subst env) us v
v2 = zap_demand ctxt_lvl dest_lvl v1
env' = extendCloneLvlEnv dest_lvl env subst' [(v,v2)]
return (env', v2)
cloneRecVars :: TopLevelFlag -> LevelEnv -> [Id] -> Level -> Level -> LvlM (LevelEnv, [Id])
cloneRecVars TopLevel env vs _ _
= return (extendInScopeEnvList env vs, vs) -- Don't clone top level things
-cloneRecVars NotTopLevel env@(_,_,subst,_) vs ctxt_lvl dest_lvl
+cloneRecVars NotTopLevel env vs ctxt_lvl dest_lvl
= ASSERT( all isId vs ) do
us <- getUniqueSupplyM
let
- (subst', vs1) = cloneRecIdBndrs subst us vs
+ (subst', vs1) = cloneRecIdBndrs (le_subst env) us vs
vs2 = map (zap_demand ctxt_lvl dest_lvl) vs1
env' = extendCloneLvlEnv dest_lvl env subst' (vs `zip` vs2)
return (env', vs2)
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