flow.c (split_edge): Don't allocate global_live_at_start for the new block unless...

        * flow.c (split_edge): Don't allocate global_live_at_start for
        the new block unless the old blocks had them as well.

From-SVN: r33735

gcc/ChangeLog

+2000-05-06  Richard Henderson  <rth@cygnus.com>
+
+	* flow.c (split_edge): Don't allocate global_live_at_start for
+	the new block unless the old blocks had them as well.
+
 2000-05-06  Zack Weinberg  <zack@wolery.cumb.org>
 
  	* cpphash.h: Remove conditional #define of __extension__.

gcc/flow.c

@@ -1349,20 +1349,15 @@ split_edge (edge_in)
   n_edges++;
 
   memset (bb, 0, sizeof (*bb));
-  bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (function_obstack);
-  bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (function_obstack);
 
   /* ??? This info is likely going to be out of date very soon.  */
   if (old_succ->global_live_at_start)
     {
+      bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (function_obstack);
+      bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (function_obstack);
       COPY_REG_SET (bb->global_live_at_start, old_succ->global_live_at_start);
       COPY_REG_SET (bb->global_live_at_end, old_succ->global_live_at_start);
     }
-  else
-    {
-      CLEAR_REG_SET (bb->global_live_at_start);
-      CLEAR_REG_SET (bb->global_live_at_end);
-    }
 
   /* Wire them up.  */
   bb->pred = edge_in;