[PATCH] Fix PR68951

[Richard Biener]

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2015-12-17  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/68951
        * tree-vect-data-refs.c (vect_peeling_hash_get_lowest_cost):
        Ignore strided non-group accesses.

        * gcc.dg/torture/pr68951.c: New testcase.

Index: gcc/tree-vect-data-refs.c
===================================================================
--- gcc/tree-vect-data-refs.c   (revision 231745)
+++ gcc/tree-vect-data-refs.c   (working copy)
@@ -1215,6 +1215,12 @@ vect_peeling_hash_get_lowest_cost (_vect
           && GROUP_FIRST_ELEMENT (stmt_info) != stmt)
         continue;
 
+      /* Strided accesses perform only component accesses, alignment is
+         irrelevant for them.  */
+      if (STMT_VINFO_STRIDED_P (stmt_info)
+         && !STMT_VINFO_GROUPED_ACCESS (stmt_info))
+       continue;
+
       save_misalignment = DR_MISALIGNMENT (dr);
       vect_update_misalignment_for_peel (dr, elem->dr, elem->npeel);
       vect_get_data_access_cost (dr, &inside_cost, &outside_cost,
Index: gcc/testsuite/gcc.dg/torture/pr68951.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr68951.c      (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr68951.c      (working copy)
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-w" } */
+
+static int g_534[1][1];
+int fn1()
+{
+  int i;
+  for (i = 0; i < 4; i++)
+    g_534[i + 2][i] ^= 3;
+  for (;;)
+    ;
+}