re PR rtl-optimization/40209 (ICE in iv_analyze_def caused by stale REG_UNUSED note)

	PR rtl-optimization/40209
	* loop-iv.c (iv_analysis_loop_init): Call df_note_add_problem.

From-SVN: r150038

gcc/ChangeLog

+2009-07-23  Neil Vachharajani  <nvachhar@google.com>
+
+	PR rtl-optimization/40209
+	* loop-iv.c (iv_analysis_loop_init): Call df_note_add_problem.
+
 2009-07-23  Uros Bizjak  <ubizjak@gmail.com>
 
 	* config/i386/i386.c: Use ASM_LONG instead of .long.  Concatenate

gcc/loop-iv.c

@@ -278,6 +278,7 @@ iv_analysis_loop_init (struct loop *loop)
   df_remove_problem (df_chain);
   df_process_deferred_rescans ();
   df_chain_add_problem (DF_UD_CHAIN);
+  df_note_add_problem ();
   df_set_blocks (blocks);
   df_analyze ();
   if (dump_file)