From: Suprateeka R Hegde <hegdesmailbox@gmail.com>
To: David Edelsohn <dje.gcc@gmail.com>,
Rafael Avila de Espindola <rafael.espindola@gmail.com>
Cc: Binutils Development <binutils@sourceware.org>,
Alan Modra <amodra@gmail.com>,
Florian Weimer <fweimer@redhat.com>,
Cary Coutant <ccoutant@gmail.com>,
Sriraman Tallam <tmsriram@google.com>,
gnu-gabi@sourceware.org, Xinliang David Li <davidxl@google.com>,
Sterling Augustine <saugustine@google.com>,
Paul Pluzhnikov <ppluzhnikov@google.com>,
Ian Lance Taylor <iant@google.com>,
"H.J. Lu" <hjl.tools@gmail.com>,
Rahul Chaudhry <rahulchaudhry@google.com>,
Luis Lozano <llozano@google.com>,
Peter Collingbourne <pcc@google.com>,
Rui Ueyama <ruiu@google.com>
Subject: Re: Reducing code size of Position Independent Executables (PIE) by shrinking the size of dynamic relocations section
Date: Sun, 01 Jan 2017 00:00:00 -0000 [thread overview]
Message-ID: <a3e5c76c-8cb9-fc53-a30a-96b2c85079e1@gmail.com> (raw)
In-Reply-To: <CAGWvnynEe3QkhDMGc=Tx8Vr44egtv3xLuh1yiVcAhv+e3GLtZg@mail.gmail.com>
Is the AIX available on x86-64? Otherwise it may not be much useful to
refer the linker design. And it is just not linker when it comes to
relocs, it indeed involves entire runtime architecture and ISA of the
platform.
HP-UX on Itanium also uses PIC by default and we have never faced any
such exponential difference between relative and non-relative relocs,
and its been almost 2 decades now.
I just did some numbers. On a Ubuntu 16.10, I just took the ratio of
RELATIVE vs non-RELATIVE on x86-64. I apologize if this number is
already discussed.
readelf -Wr /usr/bin/* 2>&1 | grep RELATIVE | wc -l
1238652
readelf -Wr /usr/bin/* 2>&1 | grep -v RELATIVE | wc -l
51551
So the ratio shows ~96% is RELATIVE reloc. And only ~4% others. This is
not the case on HP-UX/Itanium. But as I said, this comparison does not
make sense as the runtime architecture and ISA are totally different.
At this point, I would say the combination of original ideas proposed
and some work already done in this direction is the way to go. On HP-UX,
our tool chain greatly reduces dyn relocs with IPO kind of options too.
--
Supra
On 01-May-2017 07:43 PM, David Edelsohn wrote:
> GNU ld supports earlier versions of AIX XCOFF, so one can look at that code.
>
> The current documentation for XCOFF is
>
> https://www.ibm.com/support/knowledgecenter/ssw_aix_72/com.ibm.aix.files/XCOFF.htm
>
> - David
>
>
> On Mon, May 1, 2017 at 9:31 AM, Rafael Avila de Espindola
> <rafael.espindola@gmail.com> wrote:
>> Where is it documented?
>>
>> Thanks,
>> Rafael
>>
>> David Edelsohn <dje.gcc@gmail.com> writes:
>>
>>> AIX uses relative relocations and generates position independent
>>> executables by default. The design of the AIX linker might provide
>>> some additional inspiration.
>>>
>>> Thanks, David
next prev parent reply other threads:[~2017-05-01 18:28 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAGWvnynFwXFGLj3tAVgDatn0zmuHcWHyRNuDvR+wRZCXLnar_A@mail.gmail.com>
2017-01-01 0:00 ` Rafael Avila de Espindola
2017-01-01 0:00 ` David Edelsohn
2017-01-01 0:00 ` Suprateeka R Hegde [this message]
2017-01-01 0:00 ` Florian Weimer
2017-01-01 0:00 ` Suprateeka R Hegde
2017-01-01 0:00 ` Sriraman Tallam via gnu-gabi
2017-01-01 0:00 ` Rahul Chaudhry via gnu-gabi
2017-01-01 0:00 ` Cary Coutant
2017-01-01 0:00 ` Rahul Chaudhry via gnu-gabi
2017-01-01 0:00 ` Rahul Chaudhry via gnu-gabi
2017-01-01 0:00 ` Florian Weimer
2017-01-01 0:00 ` Sriraman Tallam via gnu-gabi
2017-01-01 0:00 ` Rahul Chaudhry via gnu-gabi
[not found] ` <CAORpzuMftCGpXUObOyoFY0=jorMBDWEDbQJ23DifTNW3v-WA6Q@mail.gmail.com>
2017-01-01 0:00 ` Rahul Chaudhry via gnu-gabi
2017-01-01 0:00 ` Cary Coutant
2017-01-01 0:00 ` Rahul Chaudhry via gnu-gabi
[not found] ` <CAORpzuPYsSBJtypm3NDcfcgRzos3WO4JjkvgiqpyBYBhoqLVFA@mail.gmail.com>
2018-01-01 0:00 ` Florian Weimer
2017-01-01 0:00 ` Ian Lance Taylor via gnu-gabi
2017-01-01 0:00 Sriraman Tallam
2017-01-01 0:00 ` Cary Coutant
2017-01-01 0:00 ` Markus Trippelsdorf
2017-01-01 0:00 ` Florian Weimer
2017-01-01 0:00 ` Alan Modra
2017-01-01 0:00 ` H.J. Lu
2017-01-01 0:00 ` Sriraman Tallam
2017-01-01 0:00 ` Rafael Espíndola
2017-01-01 0:00 ` Sriraman Tallam
2017-01-01 0:00 ` H.J. Lu
2017-01-01 0:00 ` Sriraman Tallam
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