re PR tree-optimization/81303 (410.bwaves regression caused by r249919)

2017-07-25  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/81303
	* tree-vect-loop-manip.c (vect_loop_versioning): Build
	profitability check against LOOP_VINFO_NITERSM1.

From-SVN: r250503

gcc/ChangeLog

+2017-07-25  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/81303
+	* tree-vect-loop-manip.c (vect_loop_versioning): Build
+	profitability check against LOOP_VINFO_NITERSM1.
+
 2017-07-25  Alexander Monakov  <amonakov@ispras.ru>
 
 	* domwalk.c (cmp_bb_postorder): Simplify.

gcc/tree-vect-loop-manip.c

@@ -2136,7 +2136,7 @@ vect_loop_versioning (loop_vec_info loop_vinfo,
   tree arg;
   profile_probability prob = profile_probability::likely ();
   gimple_seq gimplify_stmt_list = NULL;
-  tree scalar_loop_iters = LOOP_VINFO_NITERS (loop_vinfo);
+  tree scalar_loop_iters = LOOP_VINFO_NITERSM1 (loop_vinfo);
   bool version_align = LOOP_REQUIRES_VERSIONING_FOR_ALIGNMENT (loop_vinfo);
   bool version_alias = LOOP_REQUIRES_VERSIONING_FOR_ALIAS (loop_vinfo);
   bool version_niter = LOOP_REQUIRES_VERSIONING_FOR_NITERS (loop_vinfo);
@@ -2144,7 +2144,7 @@ vect_loop_versioning (loop_vec_info loop_vinfo,
   if (check_profitability)
     cond_expr = fold_build2 (GE_EXPR, boolean_type_node, scalar_loop_iters,
 			     build_int_cst (TREE_TYPE (scalar_loop_iters),
-						       th));
+					    th - 1));
 
   if (version_niter)
     vect_create_cond_for_niters_checks (loop_vinfo, &cond_expr);