re PR middle-end/38474 (compile time explosion in dataflow_set_preserve_mem_locs at -O3)

	PR middle-end/38474
	* function.c (free_temp_slots): Only walk the temp slot
	addresses and combine slots if we actually changes something.
	(pop_temp_slots): Ditto.

From-SVN: r155087

gcc/ChangeLog

+2009-12-08  Michael Matz  <matz@suse.de>
+
+	PR middle-end/38474
+	* function.c (free_temp_slots): Only walk the temp slot
+	addresses and combine slots if we actually changes something.
+	(pop_temp_slots): Ditto.
+
 2009-12-08  Olga Golovanevsky  <olga@il.ibm.com>
 
 	PR middle-end/41843

gcc/function.c

@@ -1164,17 +1164,24 @@ void
 free_temp_slots (void)
 {
   struct temp_slot *p, *next;
+  bool some_available = false;
 
   for (p = *temp_slots_at_level (temp_slot_level); p; p = next)
     {
       next = p->next;
 
       if (!p->keep)
+	{
 	  make_slot_available (p);
+	  some_available = true;
+	}
     }
 
+  if (some_available)
+    {
       remove_unused_temp_slot_addresses ();
       combine_temp_slots ();
+    }
 }
 
 /* Push deeper into the nesting level for stack temporaries.  */
@@ -1192,15 +1199,20 @@ void
 pop_temp_slots (void)
 {
   struct temp_slot *p, *next;
+  bool some_available = false;
 
   for (p = *temp_slots_at_level (temp_slot_level); p; p = next)
     {
       next = p->next;
       make_slot_available (p);
+      some_available = true;
     }
 
+  if (some_available)
+    {
       remove_unused_temp_slot_addresses ();
       combine_temp_slots ();
+    }
 
   temp_slot_level--;
 }