From: Michael Haupt <michael.haupt@oracle.com>
To: "java@gcc.gnu.org" <java@gcc.gnu.org>
Subject: Re: gcj and debugging
Date: Mon, 11 Feb 2013 16:26:00 -0000 [thread overview]
Message-ID: <C4784CAC-C72D-4FA5-9FCD-C89B20F1C192@oracle.com> (raw)
In-Reply-To: <87y5f0ufko.fsf@fleche.redhat.com>
Tom,
thank you very much for your reply.
Am 07.02.2013 um 19:47 schrieb Tom Tromey <tromey@redhat.com>:
> Michael> in a research project, I'm generating DWARF debugging info for machine
> Michael> code generated from Java. I looked at some of the DWARF debug info
> Michael> generated by gcj (including that contained in libgcj.so).
>
> I think the first thing to realize is that the gdb support for Java was
> all written to target gcj specifically, and also written long ago and
> then barely updated.
>
> It isn't very general or done the way it would be done now.
> It was never updated for the gcj binary compatibility ABI.
Would you suggest to generate DWARF info with the language set to C89 then, to avoid misleading gdb?
> I thought things like "print array[0]" used to work, but even that seems
> to fail for me now. There is definitely some code for this in gdb, see
> jv-valprint.c:java_value_print. It seems to know a bit about array
> layout and then goes from there (though the code looks somewhat bogus to
> me...). See also jv-lang.c:evaluate_subexp_java for the code that tries
> to do array subscripting.
If gdb's Java language support is really tailored to gcj, it surely assumes internal layout details about arrays. I cannot guarantee that "my" arrays have the same internal representation. :-)
> gdb has special code for this. It looks for a type named
> "java.lang.String" and then knows what fields it has.
>
> Yucky.
Indeed.
Thanks again,
Michael
--
Dr. Michael Haupt
Principal Member of Technical Staff
Phone: +49 331 200 7277, Fax: +49 331 200 7561
Oracle Labs
Oracle Deutschland B.V. & Co. KG, Schiffbauergasse 14, 14467 Potsdam, Germany
next prev parent reply other threads:[~2013-02-11 16:26 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-01 15:10 Michael Haupt
2013-02-01 17:26 ` Andrew Haley
2013-02-07 18:47 ` Tom Tromey
2013-02-09 0:38 ` David Daney
2013-02-11 16:26 ` Michael Haupt [this message]
2013-02-11 16:32 ` Andrew Haley
2013-02-11 16:47 ` Michael Haupt
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=C4784CAC-C72D-4FA5-9FCD-C89B20F1C192@oracle.com \
--to=michael.haupt@oracle.com \
--cc=java@gcc.gnu.org \
/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).