Fix dependency information for RULES

[ghc-hetmet.git] / compiler / coreSyn / CoreFVs.lhs

diff --git a/compiler/coreSyn/CoreFVs.lhs b/compiler/coreSyn/CoreFVs.lhs
index bda9342..807b76c 100644 (file)
--- a/compiler/coreSyn/CoreFVs.lhs
+++ b/compiler/coreSyn/CoreFVs.lhs
@@ -14,7 +14,7 @@ module CoreFVs (
        exprFreeNames, exprsFreeNames,
 
        idRuleVars, idFreeVars, varTypeTyVars, 
-       ruleRhsFreeVars, rulesRhsFreeVars,
+       ruleRhsFreeVars, rulesFreeVars,
        ruleLhsFreeNames, ruleLhsFreeIds, 
 
        CoreExprWithFVs,        -- = AnnExpr Id VarSet
@@ -241,18 +241,18 @@ exprsFreeNames es = foldr (unionNameSets . exprFreeNames) emptyNameSet es
 ruleRhsFreeVars :: CoreRule -> VarSet
 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)
+  = delFromUFM fvs fn   -- Note [Rule free var hack]
   where
     fvs = addBndrs bndrs (expr_fvs rhs) isLocalVar emptyVarSet
 
-rulesRhsFreeVars :: [CoreRule] -> VarSet
-rulesRhsFreeVars rules
-  = foldr (unionVarSet . ruleRhsFreeVars) emptyVarSet rules
+ruleFreeVars :: CoreRule -> VarSet     -- All free variables, both left and right
+ruleFreeVars (Rule { ru_fn = fn, ru_bndrs = bndrs, ru_rhs = rhs, ru_args = args })
+  = delFromUFM fvs fn  -- Note [Rule free var hack]
+  where
+    fvs = addBndrs bndrs (exprs_fvs (rhs:args)) isLocalVar emptyVarSet
+
+rulesFreeVars :: [CoreRule] -> VarSet
+rulesFreeVars rules = foldr (unionVarSet . ruleFreeVars) emptyVarSet rules
 
 ruleLhsFreeIds :: CoreRule -> VarSet
 -- This finds all locally-defined free Ids on the LHS of the rule
@@ -261,6 +261,14 @@ ruleLhsFreeIds (Rule { ru_bndrs = bndrs, ru_args = args })
   = addBndrs bndrs (exprs_fvs args) isLocalId emptyVarSet
 \end{code}
 
+Note [Rule free var hack]
+~~~~~~~~~~~~~~~~~~~~~~~~~
+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)
+
+Also since rule_fn is a Name, not a Var, we have to use the grungy delUFM.
 
 %************************************************************************
 %*                                                                     *