Re: [PATCH v2 3/3] configure: Allow LD to be LLD 13.0.0 or above [BZ #26558]

[Fangrui Song via Libc-alpha <libc-alpha@sourceware.org>]

On 2021-08-05, Fangrui Song wrote:
>When using LLD (LLVM linker) as the linker, configure prints a confusing
>message.
>
>    *** These critical programs are missing or too old: GNU ld
>
>LLD>=13.0.0 can build glibc --enable-static-pie. (8.0.0 needs one
>workaround for -Wl,-defsym=_begin=0. 9.0.0 works with
>--disable-static-pie).
>
>With BZ #28153 (glibc bug exposed by testing with LLD) fixed,
>`make check` only has 2 more failures with LLD than with GNU ld:
>BZ #28154 (LLD follows the PowerPC port of GNU ld for ifunc by
>placing IRELATIVE relocations in .rela.dyn).
>The set of dynamic symbols is the same with GNU ld and LLD,
>modulo unused SHN_ABS version node symbols.
>
>For comparison, gold does not support --enable-static-pie
>yet (--no-dynamic-linker is unsupported BZ #22221), yet
>has 6 failures more than LLD. gold linked libc.so has
>larger .dynsym differences with GNU ld and LLD
>(ISTM non-default version symbols are changed to default versions
>by a version script).
>
>---
>
>I identified the lack of support of
>
>* version script on non-default version symbols
>* copy relocations on non-default version symbols
>
>in an earlier snapshot of LLD 13.0.0 and fixed them.
>The functionality of the LLD linked libc.so and ld.so looks pretty good.
>---
> configure    | 77 +++++++++++++++++++++++++++++++++++++++++++++++++---
> configure.ac | 20 ++++++++++----
> 2 files changed, 88 insertions(+), 9 deletions(-)

Ping:)

(The code/test hasn't been changed since v1.
  v2 just added BZ numbers.)

x86-64 only 2 more ifunc FAIL which tickle some weak point of ifunc implementation.

aarch64 `make-check` is fully on par with GNU ld.
   (https://sourceware.org/pipermail/libc-alpha/2021-August/130040.html)