[Bug tree-optimization/81884] [6 Regression] Invalid code generation with zero size arrays or flexible array members

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81884

--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Mon Aug 28 12:16:06 2017
New Revision: 251379

URL: https://gcc.gnu.org/viewcvs?rev=251379&root=gcc&view=rev
Log:
2017-08-28  Richard Biener  <rguenther@suse.de>

        Backport from mainline
        2017-08-21  Richard Biener  <rguenther@suse.de>

        PR middle-end/81884
        * tree-ssa-alias.c (stmt_kills_ref_p): Handle array accesses
        at struct end conservatively when comparing common bases.

        * g++.dg/torture/pr81884.C: New testcase.

        2017-05-04  Richard Biener  <rguenther@suse.de>

        * tree.c (array_at_struct_end_p): Handle arrays at struct
        end with flexarrays more conservatively.  Refactor and treat
        arrays of arrays or aggregates more strict.  Fix
        VIEW_CONVERT_EXPR handling.  Remove allow_compref argument.
        * tree.h (array_at_struct_end_p): Adjust prototype.
        * gimple-fold.c (get_range_strlen): Likewise.
        * tree-chkp.c (chkp_may_narrow_to_field): Likewise.

Added:
    branches/gcc-7-branch/gcc/testsuite/g++.dg/torture/pr81884.C
Modified:
    branches/gcc-7-branch/gcc/ChangeLog
    branches/gcc-7-branch/gcc/gimple-fold.c
    branches/gcc-7-branch/gcc/testsuite/ChangeLog
    branches/gcc-7-branch/gcc/tree-chkp.c
    branches/gcc-7-branch/gcc/tree-ssa-alias.c
    branches/gcc-7-branch/gcc/tree.c
    branches/gcc-7-branch/gcc/tree.h