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Re: [PATCH] PR gold/17640
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Cary Coutant <ccoutant at google dot com>
- Cc: Ilya Tocar <tocarip dot intel at gmail dot com>, Binutils <binutils at sourceware dot org>
- Date: Thu, 12 Mar 2015 16:37:04 -0700
- Subject: Re: [PATCH] PR gold/17640
- Authentication-results: sourceware.org; auth=none
- References: <CAHACq4ojyujhxYSsMaF_jSVWUg0=YgNawR6=6XYdZie1PMhXYQ at mail dot gmail dot com> <20150227142003 dot GA122934 at msticlxl7 dot ims dot intel dot com> <CAMe9rOrzXOu+CkT_A7XZLJ1MK_nqnMk69LjgXUSQ-FnS1fKsEQ at mail dot gmail dot com> <CAMe9rOq-uSd64h6eeogR3SywtQipMupN9Ng9-EvPLF+3bp7Exw at mail dot gmail dot com> <20150305104052 dot GA16361 at msticlxl7 dot ims dot intel dot com> <CAMe9rOqRQ+HMS12+hn9Nz0pnb95tUDmbAU2QjK9G1Rc-q=woCA at mail dot gmail dot com> <20150310112745 dot GA104717 at msticlxl7 dot ims dot intel dot com> <CAMe9rOoG6NOVLYxZBJ5KRuS9_47=ptsd=Ft9iA9HfN2Asw0UeQ at mail dot gmail dot com> <20150312143236 dot GA95320 at msticlxl7 dot ims dot intel dot com> <CAMe9rOpn0uGDm1qbwgL-7CiYKjQeSHMHX6WzsnZ6eyfcp2MBAw at mail dot gmail dot com> <20150312145732 dot GB95320 at msticlxl7 dot ims dot intel dot com> <CAHACq4qF26jr8QYR_V55oVewLyHpgD2g7TrxDmgye0_S4pdroQ at mail dot gmail dot com>
On Thu, Mar 12, 2015 at 3:08 PM, Cary Coutant <ccoutant@google.com> wrote:
> + // If we convert this from
> + // mov foo@GOT(%reg), %reg
> + // to
> + // lea foo@GOTOFF(%reg), %reg
> + // in Relocate::relocate, then there is nothing to do here.
> + // Avoid converting _DYNAMIC, because its address may be used.
>
> I'm sorry, but I still don't understand the rationale for treating
> _DYNAMIC specially. If you convert all of the references to @GOTOFF,
> what's the point of having the GOT entry? If the loader is going to
> use it, how does it find it?
It is related to
https://sourceware.org/bugzilla/show_bug.cgi?id=14538
With the old x86-64 elf_machine_dynamic, we generate
addq _DYNAMIC@GOTPCREL(%rip), %rdx
We need to keep _DYNAMIC GOT entry.
--
H.J.