[Bug tree-optimization/77745] [5/6 Regression] Inconsistent application of aliasing rules

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77745

--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Tue Sep 27 12:56:38 2016
New Revision: 240534

URL: https://gcc.gnu.org/viewcvs?rev=240534&root=gcc&view=rev
Log:
2016-09-27  Richard Biener  <rguenther@suse.de>

        PR tree-optimization/77745
        * tree-ssa-pre.c (eliminate_dom_walker::before_dom_children):
        When removing redundant stores make sure to check compatibility
        of the TBAA state for downstream accesses.
        * tree-ssa-sccvn.c (visit_reference_op_store): Likewise for when
        value-numbering virtual operands for store matches.

        * g++.dg/torture/pr77745.C: New testcase.

Added:
    trunk/gcc/testsuite/g++.dg/torture/pr77745.C
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-pre.c
    trunk/gcc/tree-ssa-sccvn.c