cfgcleanup: Bugfix in try_simplify_condjump

If the jump_block here contains just a return, we will crash later
in invert_jump.  Don't allow that case.


	* cfgcleanup.c (try_simplify_condjump): Don't try to simplify a
	branch to a return.

From-SVN: r235903

gcc/ChangeLog

+2016-05-04  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	* cfgcleanup.c (try_simplify_condjump): Don't try to simplify a
+	branch to a return.
+
 2016-05-04  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/70906

gcc/cfgcleanup.c

@@ -156,6 +156,7 @@ try_simplify_condjump (basic_block cbranch_block)
   cbranch_dest_block = cbranch_jump_edge->dest;
 
   if (cbranch_dest_block == EXIT_BLOCK_PTR_FOR_FN (cfun)
+      || jump_dest_block == EXIT_BLOCK_PTR_FOR_FN (cfun)
       || !can_fallthru (jump_block, cbranch_dest_block))
     return false;