[Bug tree-optimization/106064] Wrong code comparing two global zero-sized arrays

[acoplan at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106064

Alex Coplan <acoplan at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |jakub at gcc dot gnu.org

--- Comment #5 from Alex Coplan <acoplan at gcc dot gnu.org> ---
Bisection shows this changed with
r9-5411-g93aa3c4aca3647645cd5bce724f9d2126de4b5ea on AArch64:

commit 93aa3c4aca3647645cd5bce724f9d2126de4b5ea (refs/bisect/bad)
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue Jan 15 09:11:00 2019 +0100

    re PR tree-optimization/88775 (Optimize std::string assignment)

            PR tree-optimization/88775
            * match.pd (cmp (convert1?@2 addr@0) (convert2? addr@1)): Optimize
            equal == 0 equality pointer comparisons some more if compared in
            integral types and either one points to an automatic var and the
            other to a global, or we can prove at least one points to the
middle
            or both point to start or both point to end.

            * gcc.dg/tree-ssa/pr88775-1.c: New test.
            * gcc.dg/tree-ssa/pr88775-2.c: New test.