--- var-tracking.c.xx	2013-01-11 09:03:01.000000000 +0100
+++ var-tracking.c	2013-01-16 15:00:39.012478547 +0100
@@ -2172,11 +2172,14 @@ drop_overlapping_mem_locs (void **slot,
 
 /* Remove from SET all VALUE bindings to MEMs that overlap with LOC.  */
 
+static bool vt_initialize_p;
+
 static void
 clobber_overlapping_mems (dataflow_set *set, rtx loc)
 {
   struct overlapping_mems coms;
 
+gcc_assert (!vt_initialize_p);
   coms.set = set;
   coms.loc = canon_rtx (loc);
   coms.addr = vt_canonicalize_addr (set, XEXP (loc, 0));
@@ -9604,6 +9607,8 @@ vt_initialize (void)
       VTI (bb)->permp = NULL;
     }
 
+vt_initialize_p = true;
+
   if (MAY_HAVE_DEBUG_INSNS)
     {
       cselib_init (CSELIB_RECORD_MEMORY | CSELIB_PRESERVE_CONSTANTS);
@@ -9861,6 +9866,7 @@ vt_initialize (void)
 	}
     }
 
+vt_initialize_p = false;
   hard_frame_pointer_adjustment = -1;
   VTI (ENTRY_BLOCK_PTR)->flooded = true;
   cfa_base_rtx = NULL_RTX;