[PR tree-optimization/68599] Avoid over-zealous optimization with -funsafe-loop-optimizations

	PR tree-optimization/68599
	* loop-init.c (rtl_loop_init): Set LOOPS_HAVE_RECORDED_EXITS
	in call to loop_optimizer_init.
	* loop-iv.c (get_simple_loop_desc): Only allow unsafe loop
	optimization to drop the assumptions/infinite notations if
	the loop has a single exit.

From-SVN: r231231

gcc/ChangeLog

+2015-12-03  Jeff Law  <law@redhat.com>
+
+	PR tree-optimization/68599
+	* loop-init.c (rtl_loop_init): Set LOOPS_HAVE_RECORDED_EXITS
+	in call to loop_optimizer_init.
+	* loop-iv.c (get_simple_loop_desc): Only allow unsafe loop
+	optimization to drop the assumptions/infinite notations if
+	the loop has a single exit.
+
 2015-12-03  Richard Sandiford  <richard.sandiford@arm.com>
 
 	* doc/md.texi (vec_load_lanes@var{m}@var{n}): Document that

gcc/loop-init.c

@@ -395,7 +395,7 @@ rtl_loop_init (void)
       dump_flow_info (dump_file, dump_flags);
     }
 
-  loop_optimizer_init (LOOPS_NORMAL);
+  loop_optimizer_init (LOOPS_NORMAL | LOOPS_HAVE_RECORDED_EXITS);
   return 0;
 }
 

gcc/loop-iv.c

@@ -3054,7 +3054,7 @@ get_simple_loop_desc (struct loop *loop)
 	    }
 	}
 
-      if (flag_unsafe_loop_optimizations)
+      if (flag_unsafe_loop_optimizations && single_exit (loop))
 	{
 	  desc->assumptions = NULL_RTX;
 	  desc->infinite = NULL_RTX;