re PR middle-end/56525 (Access to ggc_freed memory in flow_loops_find)

2013-03-05  Richard Biener  <rguenther@suse.de>

	PR middle-end/56525
	* loop-init.c (fix_loop_structure): Remove loops in two stages,
	not freeing them until the end.

From-SVN: r196462

gcc/ChangeLog

+2013-03-05  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/56525
+	* loop-init.c (fix_loop_structure): Remove loops in two stages,
+	not freeing them until the end.
+
 2013-03-05  Andreas Krebbel  <Andreas.Krebbel@de.ibm.com>
 
 	* config/s390/s390.h: Define DWARF2_ASM_LINE_DEBUG_INFO.

gcc/loop-init.c

@@ -186,7 +186,7 @@ fix_loop_structure (bitmap changed_bbs)
   int record_exits = 0;
   loop_iterator li;
   struct loop *loop;
-  unsigned old_nloops;
+  unsigned old_nloops, i;
 
   timevar_push (TV_LOOP_INIT);
 
@@ -230,8 +230,9 @@ fix_loop_structure (bitmap changed_bbs)
 	  flow_loop_tree_node_add (loop_outer (loop), ploop);
 	}
 
-      /* Remove the loop and free its data.  */
-      delete_loop (loop);
+      /* Remove the loop.  */
+      loop->header = NULL;
+      flow_loop_tree_node_remove (loop);
     }
 
   /* Remember the number of loops so we can return how many new loops
@@ -253,6 +254,14 @@ fix_loop_structure (bitmap changed_bbs)
 	}
     }
 
+  /* Finally free deleted loops.  */
+  FOR_EACH_VEC_ELT (*get_loops (), i, loop)
+    if (loop && loop->header == NULL)
+      {
+	(*get_loops ())[i] = NULL;
+	flow_loop_free (loop);
+      }
+
   loops_state_clear (LOOPS_NEED_FIXUP);
 
   /* Apply flags to loops.  */