From: Roland McGrath <roland@hack.frob.com>
To: Szabolcs Nagy <szabolcs.nagy@arm.com>
Cc: <nd@arm.com>, Renlin Li <renlin.li@foss.arm.com>,
<libc-alpha@sourceware.org>,
Marcus Shawcroft <Marcus.Shawcroft@arm.com>,
Richard Earnshaw <Richard.Earnshaw@arm.com>
Subject: Re: [GLIBC][AARCH64]Rewrite elf_machine_load_address using _DYNAMIC symbol
Date: Wed, 09 Nov 2016 22:02:00 -0000 [thread overview]
Message-ID: <20161109220242.C10FB2C3A24@topped-with-meat.com> (raw)
In-Reply-To: Szabolcs Nagy's message of Wednesday, 9 November 2016 14:48:21 +0000 <58233735.2050204@arm.com>
> On 08/11/16 21:28, Roland McGrath wrote:
> > Show me the code you have in mind using _DYNAMIC. The scheme using a
> > linker-defined symbol with value 0 is the only one I'm aware of that
> > reduces to the minimal number of assembly instructions, with none of them
> > being a load.
>
> well the current x86_64 code is already doing what i had in mind.
And it is more costly than using _BASE.
> i assumed GOT[0] is used elsewhere so it has to be computed anyway
> and then doing (_DYNAMIC-GOT[0]) should be the same as _BASE using
> an extra sub.
Of course all the methods that work get the same result!
The point is that the _BASE method does it the most efficiently.
next prev parent reply other threads:[~2016-11-09 22:02 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-04 9:42 Renlin Li
2016-11-04 21:24 ` Roland McGrath
2016-11-07 15:15 ` Szabolcs Nagy
2016-11-07 15:23 ` Szabolcs Nagy
2016-11-07 15:52 ` Szabolcs Nagy
2016-11-09 19:06 ` Maciej W. Rozycki
2016-11-08 21:28 ` Roland McGrath
2016-11-09 14:48 ` Szabolcs Nagy
2016-11-09 22:02 ` Roland McGrath [this message]
2017-10-17 15:41 ` Szabolcs Nagy
2017-10-17 16:28 ` Szabolcs Nagy
2017-10-18 10:32 ` Renlin Li
2017-10-18 16:12 ` Szabolcs Nagy
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20161109220242.C10FB2C3A24@topped-with-meat.com \
--to=roland@hack.frob.com \
--cc=Marcus.Shawcroft@arm.com \
--cc=Richard.Earnshaw@arm.com \
--cc=libc-alpha@sourceware.org \
--cc=nd@arm.com \
--cc=renlin.li@foss.arm.com \
--cc=szabolcs.nagy@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).