[Bug middle-end/118939] [14/15/16 Regression] ada: executable segfaults on arm-linux-gnueabi when assigning an access to controlled type since r14-2653-g2971ff7b1d564a

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118939

--- Comment #25 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Alexandre Oliva <aoliva@gcc.gnu.org>:

https://gcc.gnu.org/g:2edb50a310896da72710dba7724a3b4a541a1cbb

commit r16-1065-g2edb50a310896da72710dba7724a3b4a541a1cbb
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Mon Jun 2 20:21:45 2025 -0300

    [lra] force reg update after spilling to memory [PR120424]

    In the added C++ testcase, a stack slot at a negative sp offset is
    used to hold a value across a call.

    There are a couple of causes that directly lead to this outcome:

    - the -fstack-clash-protection and -fnon-call-exception options, that
    cause arm_frame_pointer_required to flip from false to true when the
    first pseudo gets spilled to memory;

    - when the affected pseudo is spilled to memory, we fail to update lra
    regno info, because the insns that reference it are already on the
    lra_constraint_insn_stack;

    There is another potentially-related issue:

    - when we notice that the frame pointer can no longer be eliminated to
    the stack pointer, we immediately clear can_eliminate, and also
    prev_can_eliminate, but update_reg_eliminate relied on the latter to
    tell that it needs to propagate a previous_offset to the
    newly-selected elimination, or restore the original offsets.

    This patch ensures that we update insn register info after spilling a
    pseudo to memory, and enables update_reg_eliminate to recognize the
    case in which a previously-preferred elimination is disabled
    regardless of prev_can_eliminate.


    for  gcc/ChangeLog

            PR rtl-optimization/120424
            PR middle-end/118939
            * lra-spills.cc (spill_pseudos): Update insn regno info.
            * lra-eliminations.cc (update_reg_eliminate): Recognize
            disabling of active elimination regardless of
            prev_can_eliminate.

    for  gcc/testsuite/ChangeLog

            PR rtl-optimization/120424
            PR middle-end/118939
            * g++.target/arm/pr120424.C: New.
            * gnat.dg/controlled9.adb: New.
            * gnat.dg/controlled9_pkg.ads: New.