mode-switching.c (optimize_mode_switching): Fix bug in MODE_AFTER handling.

        * mode-switching.c (optimize_mode_switching): Fix bug in MODE_AFTER
        handling.

From-SVN: r177068

gcc/ChangeLog

+2011-08-01  Joern Rennecke  <joern.rennecke@embecosm.com>
+
+	* mode-switching.c (optimize_mode_switching): Fix bug in MODE_AFTER
+	handling.
+
 2011-08-01  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR target/47766

gcc/mode-switching.c

@@ -499,6 +499,7 @@ optimize_mode_switching (void)
 	{
 	  struct seginfo *ptr;
 	  int last_mode = no_mode;
+	  bool any_set_required = false;
 	  HARD_REG_SET live_now;
 
 	  REG_SET_TO_HARD_REG_SET (live_now, df_get_live_in (bb));
@@ -527,6 +528,7 @@ optimize_mode_switching (void)
 
 		  if (mode != no_mode && mode != last_mode)
 		    {
+		      any_set_required = true;
 		      last_mode = mode;
 		      ptr = new_seginfo (mode, insn, bb->index, live_now);
 		      add_seginfo (info + bb->index, ptr);
@@ -548,8 +550,10 @@ optimize_mode_switching (void)
 	    }
 
 	  info[bb->index].computing = last_mode;
-	  /* Check for blocks without ANY mode requirements.  */
-	  if (last_mode == no_mode)
+	  /* Check for blocks without ANY mode requirements.
+	     N.B. because of MODE_AFTER, last_mode might still be different
+	     from no_mode.  */
+	  if (!any_set_required)
 	    {
 	      ptr = new_seginfo (no_mode, BB_END (bb), bb->index, live_now);
 	      add_seginfo (info + bb->index, ptr);