X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FcoreSyn%2FCoreFVs.lhs;h=fb6017eabff03ab1357d933643f4fa518ee4916d;hb=28a464a75e14cece5db40f2765a29348273ff2d2;hp=4729b203f7b47076a3a118ca30b783cfc53d6700;hpb=51a571c0f5b0201ea53bec60fcaafb78c01c017e;p=ghc-hetmet.git diff --git a/ghc/compiler/coreSyn/CoreFVs.lhs b/ghc/compiler/coreSyn/CoreFVs.lhs index 4729b20..fb6017e 100644 --- a/ghc/compiler/coreSyn/CoreFVs.lhs +++ b/ghc/compiler/coreSyn/CoreFVs.lhs @@ -9,9 +9,11 @@ module CoreFVs ( exprsFreeVars, -- [CoreExpr] -> VarSet exprSomeFreeVars, exprsSomeFreeVars, + exprFreeNames, exprsFreeNames, - idRuleVars, idFreeVars, idFreeTyVars, - ruleSomeFreeVars, ruleSomeLhsFreeVars, ruleRhsFreeVars, + idRuleVars, idFreeVars, idFreeTyVars, + ruleRhsFreeVars, rulesRhsFreeVars, + ruleLhsFreeNames, ruleLhsFreeIds, CoreExprWithFVs, -- = AnnExpr Id VarSet CoreBindWithFVs, -- = AnnBind Id VarSet @@ -22,10 +24,15 @@ module CoreFVs ( #include "HsVersions.h" import CoreSyn -import Id ( Id, idType, isLocalId, hasNoBinding, idSpecialisation ) +import Id ( Id, idType, idSpecialisation, isLocalId ) +import IdInfo ( specInfoFreeVars ) +import NameSet +import UniqFM ( delFromUFM ) +import Name ( isExternalName ) import VarSet -import Var ( Var, isId, isLocalVar ) +import Var ( Var, isId, isLocalVar, varName ) import Type ( tyVarsOfType ) +import TcType ( tyClsNamesOfType ) import Util ( mapAndUnzip ) import Outputable \end{code} @@ -68,8 +75,8 @@ type InterestingVarFun = Var -> Bool -- True <=> interesting \begin{code} type FV = InterestingVarFun - -> VarSet -- In scope - -> VarSet -- Free vars + -> VarSet -- In scope + -> VarSet -- Free vars union :: FV -> FV -> FV union fv1 fv2 fv_cand in_scope = fv1 fv_cand in_scope `unionVarSet` fv2 fv_cand in_scope @@ -77,21 +84,40 @@ union fv1 fv2 fv_cand in_scope = fv1 fv_cand in_scope `unionVarSet` fv2 fv_cand noVars :: FV noVars fv_cand in_scope = emptyVarSet --- At a variable occurrence, add in any free variables of its rule rhss --- Curiously, we gather the Id's free *type* variables from its binding --- site, but its free *rule-rhs* variables from its usage sites. This --- is a little weird. The reason is that the former is more efficient, --- but the latter is more fine grained, and a makes a difference when --- a variable mentions itself one of its own rule RHSs +-- Comment about obselete code +-- We used to gather the free variables the RULES at a variable occurrence +-- with the following cryptic comment: +-- "At a variable occurrence, add in any free variables of its rule rhss +-- Curiously, we gather the Id's free *type* variables from its binding +-- site, but its free *rule-rhs* variables from its usage sites. This +-- is a little weird. The reason is that the former is more efficient, +-- but the latter is more fine grained, and a makes a difference when +-- a variable mentions itself one of its own rule RHSs" +-- Not only is this "weird", but it's also pretty bad because it can make +-- a function seem more recursive than it is. Suppose +-- f = ...g... +-- g = ... +-- RULE g x = ...f... +-- Then f is not mentioned in its own RHS, and needn't be a loop breaker +-- (though g may be). But if we collect the rule fvs from g's occurrence, +-- it looks as if f mentions itself. (This bites in the eftInt/eftIntFB +-- code in GHC.Enum.) +-- +-- Anyway, it seems plain wrong. The RULE is like an extra RHS for the +-- function, so its free variables belong at the definition site. +-- +-- Deleted code looked like +-- foldVarSet add_rule_var var_itself_set (idRuleVars var) +-- add_rule_var var set | keep_it fv_cand in_scope var = extendVarSet set var +-- | otherwise = set +-- SLPJ Feb06 + oneVar :: Id -> FV oneVar var fv_cand in_scope = ASSERT( isId var ) - foldVarSet add_rule_var var_itself_set (idRuleVars var) - where - var_itself_set | keep_it fv_cand in_scope var = unitVarSet var - | otherwise = emptyVarSet - add_rule_var var set | keep_it fv_cand in_scope var = extendVarSet set var - | otherwise = set + if keep_it fv_cand in_scope var + then unitVarSet var + else emptyVarSet someVars :: VarSet -> FV someVars vars fv_cand in_scope @@ -125,46 +151,105 @@ expr_fvs (Note _ expr) = expr_fvs expr expr_fvs (App fun arg) = expr_fvs fun `union` expr_fvs arg expr_fvs (Lam bndr body) = addBndr bndr (expr_fvs body) -expr_fvs (Case scrut bndr alts) - = expr_fvs scrut `union` addBndr bndr (foldr (union . alt_fvs) noVars alts) +expr_fvs (Case scrut bndr ty alts) + = expr_fvs scrut `union` someVars (tyVarsOfType ty) `union` addBndr bndr + (foldr (union . alt_fvs) noVars alts) where alt_fvs (con, bndrs, rhs) = addBndrs bndrs (expr_fvs rhs) expr_fvs (Let (NonRec bndr rhs) body) - = expr_fvs rhs `union` addBndr bndr (expr_fvs body) + = rhs_fvs (bndr, rhs) `union` addBndr bndr (expr_fvs body) expr_fvs (Let (Rec pairs) body) - = addBndrs bndrs (foldr (union . expr_fvs) (expr_fvs body) rhss) - where - (bndrs,rhss) = unzip pairs + = addBndrs (map fst pairs) + (foldr (union . rhs_fvs) (expr_fvs body) pairs) + +--------- +rhs_fvs (bndr, rhs) = expr_fvs rhs `union` someVars (idRuleVars bndr) + -- Treat any RULES as extra RHSs of the binding + +--------- +exprs_fvs exprs = foldr (union . expr_fvs) noVars exprs \end{code} +%************************************************************************ +%* * +\section{Free names} +%* * +%************************************************************************ + +exprFreeNames finds the free *external* *names* of an expression, notably +including the names of type constructors (which of course do not show +up in exprFreeVars). Similarly ruleLhsFreeNames. The latter is used +when deciding whether a rule is an orphan. In particular, suppose that +T is defined in this module; we want to avoid declaring that a rule like + fromIntegral T = fromIntegral_T +is an orphan. Of course it isn't, an declaring it an orphan would +make the whole module an orphan module, which is bad. + +There's no need to delete local binders, because they will all +be *internal* names. \begin{code} -rulesSomeFreeVars :: InterestingVarFun -> CoreRules -> VarSet -rulesSomeFreeVars interesting (Rules rules _) - = foldr (unionVarSet . ruleSomeFreeVars interesting) emptyVarSet rules +ruleLhsFreeNames :: CoreRule -> NameSet +ruleLhsFreeNames (BuiltinRule { ru_fn = fn }) = unitNameSet fn +ruleLhsFreeNames (Rule { ru_fn = fn, ru_bndrs = tpl_vars, ru_args = tpl_args }) + = addOneToNameSet (exprsFreeNames tpl_args) fn + +exprFreeNames :: CoreExpr -> NameSet +-- Find the free *external* names of an expression +exprFreeNames e + = go e + where + go (Var v) + | isExternalName n = unitNameSet n + | otherwise = emptyNameSet + where n = varName v + go (Lit _) = emptyNameSet + go (Type ty) = tyClsNamesOfType ty -- Don't need free tyvars + go (App e1 e2) = go e1 `unionNameSets` go e2 + go (Lam v e) = go e `delFromNameSet` varName v + go (Note n e) = go e + go (Let (NonRec b r) e) = go e `unionNameSets` go r + go (Let (Rec prs) e) = exprsFreeNames (map snd prs) `unionNameSets` go e + go (Case e b ty as) = go e `unionNameSets` tyClsNamesOfType ty + `unionNameSets` unionManyNameSets (map go_alt as) + + go_alt (_,_,r) = go r + +exprsFreeNames es = foldr (unionNameSets . exprFreeNames) emptyNameSet es +\end{code} +%************************************************************************ +%* * +\section[freevars-everywhere]{Attaching free variables to every sub-expression} +%* * +%************************************************************************ + + +\begin{code} ruleRhsFreeVars :: CoreRule -> VarSet -ruleRhsFreeVars (BuiltinRule _) = noFVs -ruleRhsFreeVars (Rule str tpl_vars tpl_args rhs) - = rule_fvs isLocalVar emptyVarSet +ruleRhsFreeVars (BuiltinRule {}) = noFVs +ruleRhsFreeVars (Rule { ru_fn = fn, ru_bndrs = bndrs, ru_rhs = rhs }) + = delFromUFM fvs fn + -- Hack alert! + -- Don't include the Id in its own rhs free-var set. + -- Otherwise the occurrence analyser makes bindings recursive + -- that shoudn't be. E.g. + -- RULE: f (f x y) z ==> f x (f y z) where - rule_fvs = addBndrs tpl_vars (expr_fvs rhs) + fvs = addBndrs bndrs (expr_fvs rhs) isLocalVar emptyVarSet -ruleSomeFreeVars :: InterestingVarFun -> CoreRule -> VarSet -ruleSomeFreeVars interesting (BuiltinRule _) = noFVs -ruleSomeFreeVars interesting (Rule _ tpl_vars tpl_args rhs) - = rule_fvs interesting emptyVarSet - where - rule_fvs = addBndrs tpl_vars $ - foldr (union . expr_fvs) (expr_fvs rhs) tpl_args +rulesRhsFreeVars :: [CoreRule] -> VarSet +rulesRhsFreeVars rules + = foldr (unionVarSet . ruleRhsFreeVars) emptyVarSet rules -ruleSomeLhsFreeVars :: InterestingVarFun -> CoreRule -> VarSet -ruleSomeLhsFreeVars fn (BuiltinRule _) = noFVs -ruleSomeLhsFreeVars fn (Rule _ tpl_vars tpl_args rhs) - = foldl delVarSet (exprsSomeFreeVars fn tpl_args) tpl_vars +ruleLhsFreeIds :: CoreRule -> VarSet +-- This finds all locally-defined free Ids on the LHS of the rule +ruleLhsFreeIds (BuiltinRule {}) = noFVs +ruleLhsFreeIds (Rule { ru_bndrs = bndrs, ru_args = args }) + = addBndrs bndrs (exprs_fvs args) isLocalId emptyVarSet \end{code} @@ -234,11 +319,11 @@ idFreeTyVars :: Id -> TyVarSet -- Only local Ids conjured up locally, can have free type variables. -- (During type checking top-level Ids can have free tyvars) idFreeTyVars id = tyVarsOfType (idType id) --- | isLocalId id = tyVarsOfType (idType id) --- | otherwise = emptyVarSet +-- | isLocalId id = tyVarsOfType (idType id) +-- | otherwise = emptyVarSet idRuleVars ::Id -> VarSet -idRuleVars id = ASSERT( isId id) rulesRhsFreeVars (idSpecialisation id) +idRuleVars id = ASSERT( isId id) specInfoFreeVars (idSpecialisation id) \end{code} @@ -274,9 +359,10 @@ freeVars (App fun arg) fun2 = freeVars fun arg2 = freeVars arg -freeVars (Case scrut bndr alts) - = ((bndr `delBinderFV` alts_fvs) `unionFVs` freeVarsOf scrut2, - AnnCase scrut2 bndr alts2) +freeVars (Case scrut bndr ty alts) +-- gaw 2004 + = ((bndr `delBinderFV` alts_fvs) `unionFVs` freeVarsOf scrut2 `unionFVs` tyVarsOfType ty, + AnnCase scrut2 bndr ty alts2) where scrut2 = freeVars scrut