[Bug target/104117] [9,10 Regression] Darwin ppc64 uses invalid non-PIC address to access constants (in PIC code).

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104117

--- Comment #27 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Iain D Sandoe
<iains@gcc.gnu.org>:

https://gcc.gnu.org/g:cfad91385ae0f92eedda1fff5f6f4b23da9f1f1b

commit r10-10796-gcfad91385ae0f92eedda1fff5f6f4b23da9f1f1b
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Mon Feb 7 15:36:35 2022 +0000

    Darwin, rs6000: Amend lo_sum use for forced constants [PR104117].

    Two issues resulted in this PR, which manifests when we force a constant
into
    memory in LRA (in PIC code on Darwin).  The presence of such forced
constants
    is quite dependent on other RTL optimisations, and it is easy for the issue
to
    become latent for a specific case.

    First, in the Darwin-specific rs6000 backend code, we were not being
careful
    enough in rejecting invalid symbolic addresses.  Specifically, when
generating
    PIC code, we require a SYMBOL_REF to be wrapped in an
UNSPEC_MACHOPIC_OFFSET.

    We now split the Darwin high/low selectors into two:
     1. One that handles non-PIC addresses (kernel mode, mdynamic-no-pic).
     2. One that handles PIC addresses and rejects SYMBOL_REFs unless they are
        suitably wrapped in the MACHOPIC_OFFSET unspec.

    The second case is handled by providing a new predicate (macho_pic_address)
    that checks the requirements.

    Backported from 4c3792d448964f7bd99e7eac2c29c9eb7c2bfb84 and
    f1b3e3853329b58fb2e50c17487df2ecbc4a5608

    Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
    Co-authored-by: Vladimir Makarov <vmakarov@redhat.com>

            PR target/104117

    gcc/ChangeLog:

            * config/rs6000/rs6000.c (darwin_rs6000_legitimate_lo_sum_const_p):
            Check for UNSPEC_MACHOPIC_OFFSET wrappers on symbolic addresses
when
            emitting PIC code.
            (legitimate_lo_sum_address_p): Likewise.
            (rs6000_legitimize_address): Do not apply the TLS processing to
            Darwin.
            * config/rs6000/darwin.md (@machopic_high_<mode>): New.
            (@machopic_low_<mode>): New.
            * config/rs6000/predicates.md (macho_pic_address): New.