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From: Thiago Jung Bauermann <bauerman@br.ibm.com>
To: Nityananda <j.nityananda@gmail.com>
Cc: gdb@sourceware.org
Subject: Re: Help needed with browsing GDB code
Date: Fri, 06 Feb 2009 12:01:00 -0000	[thread overview]
Message-ID: <1233921666.14735.108.camel@localhost.localdomain> (raw)
In-Reply-To: <249DE25A-9555-4D36-8C59-56EF08F2E34A@gmail.com>

Hi Nityananda,

El jue, 05-02-2009 a las 18:26 -0800, Nityananda escribió:
> I am looking for how  
> GDB obtains the address of stack local variables. I am seeing some  
> code related to frame_info but do not know how it actually works.

Well, there are two situations: with debug information available, and
without. For the first case it's simple: the DWARF2 format includes the
frame base address as part of the unwind information, and addresses of
local variables in the debuginfo are relative to that base address.

When there's no debuginfo available, GDB uses its knowledge of the OS
ABI for the given architecture. For example, for ppc64-linux, the stack
frame layout is given here:

http://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html#STACK

And the code which uses that knowledge is in
rs6000-tdep.c:rs6000_frame_cache. It's kinda hairy...
-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center


  reply	other threads:[~2009-02-06 12:01 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-02-06  2:26 Nityananda
2009-02-06 12:01 ` Thiago Jung Bauermann [this message]
2009-02-06 20:22   ` Nityananda
2009-02-07 14:06     ` Ramana Radhakrishnan
     [not found]       ` <56d1e8cc0902070843o7e812b46l1897f8c9afd5b03e@mail.gmail.com>
2009-02-07 17:17         ` Ramana Radhakrishnan
2009-02-13 20:52           ` Nityananda
2009-02-19  5:17       ` Nityananda
2009-02-19  5:29         ` Nityananda

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