[Bug tree-optimization/69776] [4.9/5/6 Regression] Wrong optimization with aliasing

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69776

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Mon Feb 15 08:42:38 2016
New Revision: 233418

URL: https://gcc.gnu.org/viewcvs?rev=233418&root=gcc&view=rev
Log:
2016-02-15  Richard Biener  <rguenther@suse.de>

        PR tree-optimization/69776
        * tree-ssa-sccvn.h (vn_reference_lookup): Adjust prototype.
        * tree-ssa-sccvn.c (vn_reference_lookup): Add parameter to
        indicate whether we can use TBAA to disambiguate against stores.
        Use alias-set zero if not.
        (visit_reference_op_store): Do not use TBAA when looking up
        redundant stores.
        * tree-ssa-pre.c (compute_avail): Use TBAA here.
        (eliminate_dom_walker::before_dom_children): But not when looking
        up redundant stores.

        * gcc.dg/torture/pr69776.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.dg/torture/pr69776.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-pre.c
    trunk/gcc/tree-ssa-sccvn.c
    trunk/gcc/tree-ssa-sccvn.h