release: 1.3.15

[lilypond.git] / lily / score-element.cc

diff --git a/lily/score-element.cc b/lily/score-element.cc
index 55f2b92c6f7834aee9cf11c39ea93745c5743920..6d3be5981c996fcc980d5185b1cc793823e18abd 100644 (file)
--- a/lily/score-element.cc
+++ b/lily/score-element.cc
@@ -367,6 +367,9 @@ Score_element::add_dependency (Score_element*e)
 SCM
 Score_element::handle_broken_smobs (SCM s, SCM criterion)
 {
+ again:
+
+  
   Score_element *sc = unsmob_element ( s);
   if (sc)
     {
@@ -402,16 +405,25 @@ Score_element::handle_broken_smobs (SCM s, SCM criterion)
       /*
        UGH! breaks on circular lists.
       */
-      gh_set_car_x (s, handle_broken_smobs (gh_car (s), criterion));
-      gh_set_cdr_x (s, handle_broken_smobs (gh_cdr (s), criterion));
-
-      SCM c = gh_cdr(s);
-
-      // gh_list_p () is linear, this is O(1)  
-      bool list = gh_pair_p (c) || c == SCM_EOL;
+      SCM car = handle_broken_smobs (gh_car (s), criterion);
+      SCM cdr = gh_cdr (s);
       
-      if (gh_car (s) == SCM_UNDEFINED && list)
-       return c;
+      if (car == SCM_UNDEFINED
+         && (gh_pair_p (cdr) || cdr == SCM_EOL))
+       {
+         /*
+           This is tail-recursion, ie. 
+           
+           return handle_broken_smobs (cdr, criterion);
+
+           We don't want to rely on the compiler to do this.  */
+         s =  cdr;     
+         goto again;
+       }
+
+      gh_set_car_x (s, car);
+      gh_set_cdr_x (s, handle_broken_smobs (cdr, criterion));
+      return s;
     }
   return s;
 }