Re: [glibc/release/2.34/master] elf: Drop elf/tls-macros.h in favor of __thread and tls_model attributes [BZ #28152] [BZ #28205]

[Florian Weimer <fweimer@redhat.com>]

* Florian Weimer via Glibc-cvs:

> https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=bbe4bbb6e8997b5ff9843bd3f32ac77dbaec7284
>
> commit bbe4bbb6e8997b5ff9843bd3f32ac77dbaec7284
> Author: Fangrui Song <maskray@google.com>
> Date:   Mon Aug 16 09:59:30 2021 -0700
>
>     elf: Drop elf/tls-macros.h in favor of __thread and tls_model attributes [BZ #28152] [BZ #28205]
>     
>     elf/tls-macros.h was added for TLS testing when GCC did not support
>     __thread. __thread and tls_model attributes are mature now and have been
>     used by many newer tests.
>     
>     Also delete tst-tls2.c which tests .tls_common (unused by modern GCC and
>     unsupported by Clang/LLD). .tls_common and .tbss definition are almost
>     identical after linking, so the runtime test doesn't add additional
>     coverage.  Assembler and linker tests should be on the binutils side.
>     
>     When LLD 13.0.0 is allowed in configure.ac
>     (https://sourceware.org/pipermail/libc-alpha/2021-August/129866.html),
>     `make check` result is on par with glibc built with GNU ld on aarch64
>     and x86_64.
>     
>     As a future clean-up, TLS_GD/TLS_LD/TLS_IE/TLS_IE macros can be removed from
>     sysdeps/*/tls-macros.h. We can add optional -mtls-dialect={gnu2,trad}
>     tests to ensure coverage.
>     
>     Tested on aarch64-linux-gnu, powerpc64le-linux-gnu, and x86_64-linux-gnu.
>     
>     Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
>     (cherry picked from commit 33c50ef42878b07ee6ead8b3f1a81d8c2c74697c)

I backported this because it fixes many TLS test failures when building
powerpc64le-linux-gnu with with -mcpu=power10.  Together with:

commit d0e2ac0c5902bd0e671863cc6cb14024d0365e67
Author: Alan Modra <amodra@gmail.com>
Date:   Sat Nov 12 11:20:31 2022 +1030

    elf/tst-tlsopt-powerpc fails when compiled with -mcpu=power10 (BZ# 29776)
    
    Supports pcrel addressing of TLS GOT entry.  Also tweak the non-pcrel
    asm constraint to better reflect how the reg is used.
    
    (cherry picked from commit 94628de77888c3292fc103840731ff85f283368e)

the test suite is now clean.

Thanks,
Florian