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Subject: [Bug c++/89074] valid pointer equality constexpr comparison rejected
Date: Sun, 06 Feb 2022 10:21:07 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D89074

--- Comment #18 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:f9e900ce9b17dc7d3a3809d0b0648ebe529a87c5

commit r12-7075-gf9e900ce9b17dc7d3a3809d0b0648ebe529a87c5
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Sun Feb 6 11:16:29 2022 +0100

    c++: Further address_compare fixes [PR89074]

    This patch introduces folding_cxx_constexpr, folding_initializer is used
    for both C and C++ initializer/constant expression folding and enables =
more
    optimizations over what we do normally at runtime, while
folding_cxx_constexpr
    is used only during C++ constant expression folding and disables some
optimizations.

    The patch improves STRING_CST vs. STRING_CST folding, for
folding_initializer
    FUNCTION_DECL vs. FUNCTION_DECL folding, disables some optimizations li=
ke
    is_global_var !=3D is_global_var or STRING_CST vs. DECL_P for
folding_cxx_constexpr
    etc.

    2022-02-06  Jakub Jelinek  <jakub@redhat.com>

            PR c++/89074
            PR c++/104033
            * fold-const.h (folding_initializer): Adjust comment.
            (folding_cxx_constexpr): Declare.
            * fold-const.cc (folding_initializer): Adjust comment.
            (folding_cxx_constexpr): New variable.
            (address_compare): Restrict the decl vs. STRING_CST
            or vice versa or STRING_CST vs. STRING_CST or
            is_global_var !=3D is_global_var optimizations to
!folding_cxx_constexpr.
            Punt for FUNCTION_DECLs with non-zero offsets.  If
folding_initializer,
            assume non-aliased functions have non-zero size and have differ=
ent
            addresses.  For folding_cxx_constexpr, punt on comparisons of s=
tart
            of some object and end of another one, regardless whether it is=
 a
decl
            or string literal.  Also punt for folding_cxx_constexpr on
            STRING_CST vs. STRING_CST comparisons if the two literals could=
 be
            overlapping.

            * constexpr.cc (cxx_eval_binary_expression): Temporarily set
            folding_cxx_constexpr.

            * g++.dg/cpp1y/constexpr-89074-3.C: New test.=