Re: [PATCH] x86_64: Remove unneeded static PIE check for undefined weak diagnostic

["H.J. Lu" <hjl.tools@gmail.com>]

On Thu, Jul 8, 2021 at 12:51 PM Fangrui Song via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> https://sourceware.org/bugzilla/show_bug.cgi?id=21782 dropped an ld
> diagnostic for R_X86_64_PC32 referencing an undefined weak symbol in
> -pie links.  Arguably keeping the diagnostic like other ports is more
> correct, since statically resolving movl foo(%rip), %eax to the
> link-time zero address produces a corrupted output.
>
> It turns out that --enable-static-pie builds do not depend on the ld
> behavior. GCC generates GOT indirection for weak declarations for
> -fPIE/-fPIC, so what ld does with the PC-relative relocation doesn't
> really matter. I confirmed the argument with a --enable-static-pie build
> with trunk LLD, whose -pie mode reports an error for `.weak foo; movl
> foo(%rip), %eax`
> (https://sourceware.org/bugzilla/show_bug.cgi?id=21782#c6

I agree that

https://sourceware.org/bugzilla/show_bug.cgi?id=21782

was a false alarm for static PIE.  This linker check isn't necessary.

The patch is OK.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

Thanks.

--
H.J.