re PR tree-optimization/69719 (wrong code at -O3 on x86_64-linux-gnu)

2016-02-08  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/69719
	* tree-vect-data-refs.c (vect_prune_runtime_alias_test_list):
	Properly use absolute of the difference of the two offsets to
	compare or adjust the segment length.

	* gcc.dg/torture/pr69719.c: New testcase.

From-SVN: r233212

gcc/ChangeLog

 2016-02-08  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/69719
+	* tree-vect-data-refs.c (vect_prune_runtime_alias_test_list):
+	Properly use absolute of the difference of the two offsets to
+	compare or adjust the segment length.
+
+2016-02-08  Richard Biener  <rguenther@suse.de>
 	Jeff Law  <law@redhat.com>
 
 	PR target/68273

gcc/testsuite/ChangeLog

 2016-02-08  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/69719
+	* gcc.dg/torture/pr69719.c: New testcase.
+
+2016-02-08  Richard Biener  <rguenther@suse.de>
 	Jeff Law  <law@redhat.com>
 
 	PR target/68273

gcc/testsuite/gcc.dg/torture/pr69719.c

+/* { dg-do run } */
+
+int b, c = 1, e, f; 
+int a[6][5] = { {0, 0, 0, 0, 0}, {0, 0, 0, 0, 0}, {0, 1, 0, 0, 0} };
+
+void  __attribute__((noinline))
+fn1 ()
+{
+  int d;
+  for (b = 0; b < 5; b++)
+    for (d = 4; d; d--)
+      a[c + 1][b] = a[d + 1][d];
+}
+
+int
+main ()
+{
+  fn1 ();
+
+  if (a[2][1] != 0) 
+    __builtin_abort (); 
+
+  return 0; 
+}

gcc/tree-vect-data-refs.c

@@ -3081,8 +3081,9 @@ vect_prune_runtime_alias_test_list (loop_vec_info loop_vinfo)
 	      || !tree_fits_shwi_p (dr_a2->offset))
 	    continue;
 
-	  HOST_WIDE_INT diff = (tree_to_shwi (dr_a2->offset)
-				- tree_to_shwi (dr_a1->offset));
+	  unsigned HOST_WIDE_INT diff
+	    = absu_hwi (tree_to_shwi (dr_a2->offset)
+			- tree_to_shwi (dr_a1->offset));
 
 
 	  /* Now we check if the following condition is satisfied:
@@ -3101,13 +3102,14 @@ vect_prune_runtime_alias_test_list (loop_vec_info loop_vinfo)
 
 	     */
 
-	  HOST_WIDE_INT  min_seg_len_b = (tree_fits_shwi_p (dr_b1->seg_len)
-					  ? tree_to_shwi (dr_b1->seg_len)
-					  : vect_factor);
+	  unsigned HOST_WIDE_INT min_seg_len_b
+	    = (tree_fits_uhwi_p (dr_b1->seg_len)
+	       ? tree_to_uhwi (dr_b1->seg_len)
+	       : vect_factor);
 
 	  if (diff <= min_seg_len_b
-	      || (tree_fits_shwi_p (dr_a1->seg_len)
-		  && diff - tree_to_shwi (dr_a1->seg_len) < min_seg_len_b))
+	      || (tree_fits_uhwi_p (dr_a1->seg_len)
+		  && diff - tree_to_uhwi (dr_a1->seg_len) < min_seg_len_b))
 	    {
 	      if (dump_enabled_p ())
 		{