[Bug target/113295] [14 Regression] SPEC 2006 416.gamess miscompares on Aarch64 when built with -Ofast -mcpu=native since g:2f46e3578d45ff060a0a329cb39d4f52878f9d5a

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113295

--- Comment #8 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Richard Sandiford <rsandifo@gcc.gnu.org>:

https://gcc.gnu.org/g:9f105cfdc1bca6c9224384b3044c4ca5894e1e4c

commit r14-9156-g9f105cfdc1bca6c9224384b3044c4ca5894e1e4c
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Fri Feb 23 14:12:55 2024 +0000

    aarch64: Tighten early-ra chain test for wide registers [PR113295]

    Most code in early-ra used is_chain_candidate to check whether we
    should chain two allocnos.  This included both tests that matter
    for correctness and tests for certain heuristics.

    Once that test passes for one pair of allocnos, we test whether
    it's safe to chain the containing groups (which might contain
    multiple allocnos for x2, x3 and x4 modes).  This test used an
    inline test for correctness only, deliberately skipping the
    heuristics.  However, this instance of the test was missing
    some handling of equivalent allocnos.

    This patch fixes things by making is_chain_candidate take a
    strictness parameter: correctness only, or correctness + heuristics.
    It then makes the group-chaining test use the correctness version
    rather than trying to replicate it inline.

    gcc/
            PR target/113295
            * config/aarch64/aarch64-early-ra.cc
            (early_ra::test_strictness): New enum.
            (early_ra::is_chain_candidate): Add a strictness parameter to
            control whether only correctness matters, or whether both
correctness
            and heuristics should be used.  Handle multiple levels of
equivalence.
            (early_ra::find_related_start): Update call accordingly.
            (early_ra::strided_polarity_pref): Likewise.
            (early_ra::form_chains): Likewise.
            (early_ra::try_to_chain_allocnos): Use is_chain_candidate in
            correctness mode rather than trying to inline the test.

    gcc/testsuite/
            PR target/113295
            * gcc.target/aarch64/pr113295-2.c: New test.