re PR tree-optimization/72517 (436.cactusADM: More than 40% regression in O3 and…

re PR tree-optimization/72517 (436.cactusADM: More than 40% regression in O3 and Ofast on AMD bdver4 m/c.)

2016-07-27  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/72517
	* tree-vect-data-refs.c (vect_analyze_data_ref_dependences):
	Revert change to not compute read-read dependences.

From-SVN: r238783

gcc/ChangeLog

 2016-07-27  Richard Biener  <rguenther@suse.de>
 
+	PR tree-optimization/72517
+	* tree-vect-data-refs.c (vect_analyze_data_ref_dependences):
+	Revert change to not compute read-read dependences.
+
+2016-07-27  Richard Biener  <rguenther@suse.de>
+
 	* predict.c (set_even_probabilities): Make nedges unsigned.
 
 2016-07-27  Martin Liska  <mliska@suse.cz>

gcc/tree-vect-data-refs.c

@@ -473,9 +473,10 @@ vect_analyze_data_ref_dependences (loop_vec_info loop_vinfo, int *max_vf)
     .create (LOOP_VINFO_DATAREFS (loop_vinfo).length ()
 	     * LOOP_VINFO_DATAREFS (loop_vinfo).length ());
   LOOP_VINFO_NO_DATA_DEPENDENCIES (loop_vinfo) = true;
+  /* We need read-read dependences to compute STMT_VINFO_SAME_ALIGN_REFS.  */
   if (!compute_all_dependences (LOOP_VINFO_DATAREFS (loop_vinfo),
 				&LOOP_VINFO_DDRS (loop_vinfo),
-				LOOP_VINFO_LOOP_NEST (loop_vinfo), false))
+				LOOP_VINFO_LOOP_NEST (loop_vinfo), true))
     return false;
 
   FOR_EACH_VEC_ELT (LOOP_VINFO_DDRS (loop_vinfo), i, ddr)