[Bug tree-optimization/52406] [4.7/4.8 Regression] likely wrong code bug

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52406

--- Comment #8 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-03-02 14:59:01 UTC ---
Author: rguenth
Date: Fri Mar  2 14:58:55 2012
New Revision: 184789

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=184789
Log:
2012-03-02  Richard Guenther  <rguenther@suse.de>

    PR tree-optimization/52406
    * tree-data-ref.h: Update documentation about DR_BASE_OBJECT.
    (struct indices): Add unconstrained_base member.
    (struct dr_alias): Remove unused vops member.
    (DR_UNCONSTRAINED_BASE): New define.
    * tree-data-ref.c (dr_analyze_indices): For COMPONENT_REFs
    add indices to allow their disambiguation.  Make DR_BASE_OBJECT
    be an artificial access that covers the whole indexed object,
    or mark it with DR_UNCONSTRAINED_BASE if we cannot do so.  Canonicalize
    plain decl base-objects to their MEM_REF variant.
    (dr_may_alias_p): When the base-object of either data reference
    has unknown size use only points-to information.
    (compute_affine_dependence): Make dumps easier to read and
    more verbose.
    * tree-vect-data-ref.c (vector_alignment_reachable_p): Use
    DR_REF when looking for packed references.
    (vect_supportable_dr_alignment): Likewise.

    * gcc.dg/torture/pr52406.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/torture/pr52406.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-data-ref.c
    trunk/gcc/tree-data-ref.h
    trunk/gcc/tree-vect-data-refs.c