Wibble to the OccurAnal fix for RULEs and loop-breakers

diff --git a/compiler/simplCore/OccurAnal.lhs b/compiler/simplCore/OccurAnal.lhs
index e489614..a9518d7 100644 (file)
--- a/compiler/simplCore/OccurAnal.lhs
+++ b/compiler/simplCore/OccurAnal.lhs
@@ -221,7 +221,7 @@ However things are made quite a bit more complicated by RULES.  Remember
     Remmber that we simplify the RULES before any RHS (see Note
     [Rules are visible in their own rec group] above).
 
-    So we must *not* postInlineUnconditinoally 'g', even though
+    So we must *not* postInlineUnconditionally 'g', even though
     its RHS turns out to be trivial.  (I'm assuming that 'g' is
     not choosen as a loop breaker.)
 
@@ -235,7 +235,7 @@ However things are made quite a bit more complicated by RULES.  Remember
        other                   yes     yes
 
     The **sole** reason for this kind of loop breaker is so that
-    postInlineUnconditioanlly does not fire.  Ugh.
+    postInlineUnconditionally does not fire.  Ugh.
 
   * Note [Rule dependency info]
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -307,10 +307,14 @@ occAnalBind env (Rec pairs) body_usage
        = body_usage +++ addRuleUsage rhs_usage bndr
 
     (final_usage, tagged_bndrs) = tagBinders total_usage bndrs
-    final_bndrs | no_rules  = tagged_bndrs
+    final_bndrs | isEmptyVarSet all_rule_fvs = tagged_bndrs
                | otherwise = map tag_rule_var tagged_bndrs
+               
     tag_rule_var bndr | bndr `elemVarSet` all_rule_fvs = makeLoopBreaker True bndr
                      | otherwise                      = bndr
+    all_rule_fvs = bndr_set `intersectVarSet` foldr (unionVarSet . idRuleVars) emptyVarSet bndrs
+       -- Mark the binder with OccInfo saying "no preInlineUnconditionally" if
+       -- it is used in any rule (lhs or rhs) of the recursive group
 
     ---- stuff for dependency analysis of binds -------------------------------
     sccs :: [SCC (Node Details)]
@@ -353,7 +357,6 @@ occAnalBind env (Rec pairs) body_usage
     rule_fv_env = rule_loop init_rule_fvs
 
     no_rules      = null init_rule_fvs
-    all_rule_fvs  = foldr (unionVarSet . snd) emptyVarSet init_rule_fvs
     init_rule_fvs = [(b, rule_fvs)
                    | b <- bndrs 
                    , let rule_fvs = idRuleRhsVars b `intersectVarSet` bndr_set