[Bug middle-end/37491] [4.4 Regression] Revision 140257 causes vectorizer tests failures

["rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #17 from rguenther at suse dot de  2008-09-22 11:14 -------
Subject: Re:  [4.4 Regression] Revision 140257 causes
 vectorizer tests failures

On Mon, 22 Sep 2008, irar at il dot ibm dot com wrote:

> ------- Comment #16 from irar at il dot ibm dot com  2008-09-22 10:33 -------
> (In reply to comment #15)
> > This is because the original access is through a restricted pointer, so the
> > check is conservatively correct at this point.  We can move it to the
> > point where the vector pointer is created 
> 
> But this way we move the check to the transformation and we don't have a
> mechanism to stop in the middle of transformation.

Right, but if we correctly base the vectorized access on the scalar
one we never should fail this test (so I made it an assert - though
logically inverted :().

WRT vect_create_data_ref_ptr not only we have to build a correctly
restrict qualified type but also the decl (vect_get_new_vect_var)
needs to have its DECL_POINTER_ALIAS_SET set correctly.

So, like the following (which seems to work on x86_64, but it looks
like all the testcases with restricted pointers are not supported on 
x86_64).

Index: gcc/tree-vect-transform.c
===================================================================
*** gcc/tree-vect-transform.c   (revision 140544)
--- gcc/tree-vect-transform.c   (working copy)
*************** vect_create_data_ref_ptr (gimple stmt, s
*** 1077,1084 ****
--- 1077,1095 ----
    else
      vect_ptr_type = build_pointer_type (vectype);

+   if (TREE_CODE (DR_BASE_ADDRESS (dr)) == SSA_NAME
+       && TYPE_RESTRICT (TREE_TYPE (DR_BASE_ADDRESS (dr))))
+     vect_ptr_type = build_qualified_type (vect_ptr_type, TYPE_QUAL_RESTRICT);
    vect_ptr = vect_get_new_vect_var (vect_ptr_type, vect_pointer_var,
                                      get_name (base_name));
+   if (TREE_CODE (DR_BASE_ADDRESS (dr)) == SSA_NAME
+       && TYPE_RESTRICT (TREE_TYPE (DR_BASE_ADDRESS (dr))))
+     {
+       get_alias_set (base_name);
+       DECL_POINTER_ALIAS_SET (vect_ptr)
+       = DECL_POINTER_ALIAS_SET (SSA_NAME_VAR (DR_BASE_ADDRESS (dr)));
+     }
+ 
    add_referenced_var (vect_ptr);

    /** (2) Add aliasing information to the new vector-pointer:
*************** vectorizable_load (gimple stmt, gimple_s
*** 6388,6404 ****
        return false;
      }

-   /* If accesses through a pointer to vectype do not alias the original
-      memory reference we have a problem.  This should never happen.  */
-   if (get_alias_set (vectype) != get_alias_set (gimple_assign_rhs1 (stmt))
-       && !alias_set_subset_of (get_alias_set (vectype),
-                                get_alias_set (gimple_assign_rhs1 (stmt))))
-     {
-       if (vect_print_dump_info (REPORT_DETAILS))
-         fprintf (vect_dump, "???  vector type does not alias scalar type");
-       return false;
-     }
- 
    /* The vector component type needs to be trivially convertible to the
       scalar lhs.  This should always be the case.  */
    if (!useless_type_conversion_p (TREE_TYPE (scalar_dest), TREE_TYPE
(vectype)))
--- 6399,6404 ----
*************** vectorizable_load (gimple stmt, gimple_s
*** 6662,6667 ****
--- 6662,6672 ----
            default:
              gcc_unreachable ();
            }
+         /* If accesses through a pointer to vectype do not alias the original
+            memory reference we have a problem.  This should never happen.  */
+         gcc_assert (get_alias_set (data_ref) == get_alias_set
(gimple_assign_rhs1 (stmt))
+                     || alias_set_subset_of (get_alias_set (data_ref),
+                                             get_alias_set (gimple_assign_rhs1
(stmt))));
          vec_dest = vect_create_destination_var (scalar_dest, vectype);
          new_stmt = gimple_build_assign (vec_dest, data_ref);
          new_temp = make_ssa_name (vec_dest, new_stmt);


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37491