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Subject: [Bug middle-end/95757] [11 regression] missing warning in
 gcc.dg/Wstringop-overflow-25.c since r11-1517
Date: Tue, 02 Mar 2021 10:49:59 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95757

--- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:ff92ede8d269375f800e1b347a48f4698874b4a3

commit r11-7448-gff92ede8d269375f800e1b347a48f4698874b4a3
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue Mar 2 11:49:12 2021 +0100

    vrp: Improve register_edge_assert_for [PR95757]

    The Wstringop-overflow-25.c testcase doesn't emit one of the expected
    warnings on targets that don't do short curcuiting due to target costs
    (or e.g. with --param=3Dlogical-op-non-short-circuit=3D0 on all targets=
).

    The problem is that only reassoc2 optimizes:
      _49 =3D{v} unsigned_value_source;
      if (_49 =3D=3D 0)
        goto <bb 7>; [50.00%]
      else
        goto <bb 5>; [50.00%]

      <bb 5> [local count: 536870913]:
      if (_49 > 2)
        goto <bb 7>; [50.00%]
      else
        goto <bb 6>; [50.00%]

      <bb 6> [local count: 268435457]:
      _53 =3D _49 + 1;
    into:
      _49 =3D{v} unsigned_value_source;
      _48 =3D _49 + 18446744073709551615;
      _1 =3D _48 > 1;
      if (_1 !=3D 0)
        goto <bb 6>; [50.00%]
      else
        goto <bb 5>; [50.00%]

      <bb 5> [local count: 268435457]:
      _53 =3D _49 + 1;
    (but, note the _1 =3D _48 > 1; if (_1 !=3D 0)),
    then dom3 is run and because of that if (_1 !=3D 0) vs. if (_48 > 1) do=
esn't
    register edge asserts for _48 and _49) and so we don't get
    SSA_NAME_RANGE_INFO for _53 (and ditto for vrp2) and only afterwards co=
mes
    forwprop4 that canonicalizes it to if (_48 > 1).  While with
    --param=3Dlogical-op-non-short-circuit=3D1 it is already reassoc1 that
optimizes
    it and forwprop3 that propagates it, so we have on the SSA_NAME
    corresponding to _53 above SSA_NAME_RANGE_INFO and during expansion we
warn.

    The following patch fixes it by handling those not yet propagated
    comparisons into GIMPLE_COND in register_edge_assert_for.  We already
    have all the infrastructure there to handle the
--param=3Dlogical-op-non-short-circuit=3D1
    | and &s.

    2021-03-02  Jakub Jelinek  <jakub@redhat.com>

            PR middle-end/95757
            * tree-vrp.c (register_edge_assert_for): Remove superfluous ()s
around
            condition.  Call register_edge_assert_for_1 for =3D=3D 0, !=3D =
0, =3D=3D 1
and
            !=3D 1 comparisons if name is lhs of a comparison.=