[Bug rtl-optimization/114924] [11/12/13/14/15 Regression] Wrong update of MEM_EXPR by RTL loop unrolling since r11-2963-gd6a05b494b4b71

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114924

--- Comment #1 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Alex Coplan <acoplan@gcc.gnu.org>:

https://gcc.gnu.org/g:fe40d525619eee9c2821126390df75068df4773a

commit r15-126-gfe40d525619eee9c2821126390df75068df4773a
Author: Alex Coplan <alex.coplan@arm.com>
Date:   Fri May 3 09:23:59 2024 +0100

    cfgrtl: Fix MEM_EXPR update in duplicate_insn_chain [PR114924]

    The PR shows that when cfgrtl.cc:duplicate_insn_chain attempts to
    update the MR_DEPENDENCE_CLIQUE information for a MEM_EXPR we can end up
    accidentally dropping (e.g.) an ARRAY_REF from the MEM_EXPR and end up
    replacing it with the underlying MEM_REF.  This leads to an
    inconsistency in the MEM_EXPR information, and could lead to wrong code.

    While the walk down to the MEM_REF is necessary to update
    MR_DEPENDENCE_CLIQUE, we should use the outer tree expression for the
    MEM_EXPR.  This patch does that.

    gcc/ChangeLog:

            PR rtl-optimization/114924
            * cfgrtl.cc (duplicate_insn_chain): When updating MEM_EXPRs,
            don't strip (e.g.) ARRAY_REFs from the final MEM_EXPR.