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

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

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

--- Comment #12 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Thu Jan 26 08:16:37 2017
New Revision: 244918

URL: https://gcc.gnu.org/viewcvs?rev=244918&root=gcc&view=rev
Log:
2017-01-26  Richard Biener  <rguenther@suse.de>

        Backport from mainline
        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.

        2016-09-29  Richard Biener  <rguenther@suse.de>

        PR tree-optimization/77768
        * tree-ssa-sccvn.c (visit_reference_op_store): Properly deal
        with stores to a place we know has a constant value.
        * tree-vrp.c (set_defs_to_varying): New helper avoiding
        writing to vr_const_varying.
        (vrp_initialize): Call it.
        (vrp_visit_stmt): Likewise.
        (evrp_dom_walker::before_dom_children): Likewise.
        * tree-ssa-pre.c (eliminate_dom_walker::before_dom_children):
        Handle stores to readonly memory when removing redundant stores.

        * gcc.dg/torture/pr77768.c: New testcase.

Added:
    branches/gcc-5-branch/gcc/testsuite/g++.dg/torture/pr77745.C
    branches/gcc-5-branch/gcc/testsuite/gcc.dg/torture/pr77768.c
Modified:
    branches/gcc-5-branch/gcc/ChangeLog
    branches/gcc-5-branch/gcc/testsuite/ChangeLog
    branches/gcc-5-branch/gcc/tree-ssa-pre.c
    branches/gcc-5-branch/gcc/tree-ssa-sccvn.c
    branches/gcc-5-branch/gcc/tree-vrp.c