[patch] Fix PR tree-optimization/49093

[Ira Rosen]

Hi,

This patch fails vectorization for volatile data references.

Bootstrapped on powerpc64-suse-linux and tested on
powerpc64-suse-linux and x86_64-suse-linux.
Applied to trunk.
OK for 4.6 after testing?

Thanks,
Ira

ChangeLog:

        PR tree-optimization/49093
        * tree-vect-data-refs.c (vect_analyze_data_refs): Fail for volatile
        data references.

testsuite/ChangeLog:

        PR tree-optimization/49093
        * gcc.dg/vect/pr49093.c: New test.

Index: testsuite/gcc.dg/vect/pr49093.c
===================================================================
--- testsuite/gcc.dg/vect/pr49093.c     (revision 0)
+++ testsuite/gcc.dg/vect/pr49093.c     (revision 0)
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -ftree-vectorize -fdump-tree-vect-details
-fno-tree-fre" } */
+
+volatile unsigned char g_324[4] = {0, 1, 0, 1};
+void foo (int);
+int x, y;
+void func_81(void)
+{
+    int l_466, l_439[7] = {0}, g_97;
+lbl_473:
+    if (x) {
+        for (g_97 = 0; (g_97 < 4); ++g_97) {
+            if (y)
+              goto lbl_473;
+            g_324[g_97];
+            l_466 = l_439[g_97];
+        }
+        foo(l_466);
+    }
+}
+
+/* { dg-final { cleanup-tree-dump "vect" } } */
Index: tree-vect-data-refs.c
===================================================================
--- tree-vect-data-refs.c       (revision 174471)
+++ tree-vect-data-refs.c       (working copy)
@@ -2584,6 +2584,16 @@ vect_analyze_data_refs (loop_vec_info loop_vinfo,
             return false;
         }

+      if (TREE_THIS_VOLATILE (DR_REF (dr)))
+        {
+          if (vect_print_dump_info (REPORT_UNVECTORIZED_LOCATIONS))
+            {
+              fprintf (vect_dump, "not vectorized: volatile type ");
+              print_gimple_stmt (vect_dump, stmt, 0, TDF_SLIM);
+            }
+          return false;
+        }
+
       base = unshare_expr (DR_BASE_ADDRESS (dr));
       offset = unshare_expr (DR_OFFSET (dr));
       init = unshare_expr (DR_INIT (dr));