* alloc.c (mark_object_loop_halt, mark_object): Use size_t, not int.

Otherwise, GCC 4.6.0 optimizes the loop check away since the check
can always succeed if overflow has undefined behavior.

src/ChangeLog

@@ -1,5 +1,9 @@
 2011-04-03  Paul Eggert  <eggert@cs.ucla.edu>
 
+	* alloc.c (mark_object_loop_halt, mark_object): Use size_t, not int.
+	Otherwise, GCC 4.6.0 optimizes the loop check away since the check
+	can always succeed if overflow has undefined behavior.
+
 	* search.c (boyer_moore, wordify): Remove vars set but not used.
 	(wordify): Omit three unnecessary tests.
 

src/alloc.c

@@ -5221,7 +5221,7 @@ int last_marked_index;
    links of a list, in mark_object.  In debugging,
    the call to abort will hit a breakpoint.
    Normally this is zero and the check never goes off.  */
-static int mark_object_loop_halt;
+static size_t mark_object_loop_halt;
 
 static void
 mark_vectorlike (struct Lisp_Vector *ptr)
@@ -5278,7 +5278,7 @@ mark_object (Lisp_Object arg)
   void *po;
   struct mem_node *m;
 #endif
-  int cdr_count = 0;
+  size_t cdr_count = 0;
 
  loop: