dwarf2 & DW_FORM_ref_addr

dwarf2 & DW_FORM_ref_addr

[Stanley Gambarin]

Hello,
  i'm working with the compiler that makes use
of DW_FORM_ref_addr to generate 'type' attributes
(DW_AT_type) that span multiple dwarf2 compilation
units within a single source file (multiple 
compilation units are produced for template
functions and are eliminated by linker via
.gnu.linkonce sections).  When trying to debug 
executable with GDB, i get the following message:

Dwarf Error: Cannot find referent at offset 3716.

Digging into it a bit further, I find that dies 
are stored in the die_ref_table (hash) for each
dwarf2 compilation unit.  At the beginning of 
read_comp_unit() there is a call to clear the
hash table, so that later lookup for my type
in die_type() function will fail !!!  According to
dwarf2 spec (page 69 of 2.0.0 revision):
...
The second type of reference is the address of any
debugging information entry within the same executable
or shared object; it may refer to an entry in a 
different compilation unit from the unit containing
the reference.  This type of reference 
(DW_FORM_ref_addr) ...

I guess that GCC is not generating it, but I wonder
if GDB should support it ?

-- stanley


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Re: dwarf2 & DW_FORM_ref_addr

[Kevin Buettner]

On Mar 27,  7:21pm, Stanley Gambarin wrote:

> I guess that GCC is not generating it, but I wonder
> if GDB should support it ?

Definitely.

Kevin

Re: dwarf2 & DW_FORM_ref_addr

[Daniel Berlin]

On Friday, March 28, 2003, at 12:08  AM, Kevin Buettner wrote:

> On Mar 27,  7:21pm, Stanley Gambarin wrote:
>
>> I guess that GCC is not generating it, but I wonder
>> if GDB should support it ?
>
> Definitely.
>

Particularly because the reason GCC doesn't generate it is *because* 
gdb doesn't support it.

> Kevin

Re: dwarf2 & DW_FORM_ref_addr

[Daniel Jacobowitz]

On Thu, Mar 27, 2003 at 07:21:24PM -0800, Stanley Gambarin wrote:
> Hello,
>   i'm working with the compiler that makes use
> of DW_FORM_ref_addr to generate 'type' attributes
> (DW_AT_type) that span multiple dwarf2 compilation
> units within a single source file (multiple 
> compilation units are produced for template
> functions and are eliminated by linker via
> .gnu.linkonce sections).  When trying to debug 
> executable with GDB, i get the following message:
> 
> Dwarf Error: Cannot find referent at offset 3716.
> 
> Digging into it a bit further, I find that dies 
> are stored in the die_ref_table (hash) for each
> dwarf2 compilation unit.  At the beginning of 
> read_comp_unit() there is a call to clear the
> hash table, so that later lookup for my type
> in die_type() function will fail !!!  According to
> dwarf2 spec (page 69 of 2.0.0 revision):
> ...
> The second type of reference is the address of any
> debugging information entry within the same executable
> or shared object; it may refer to an entry in a 
> different compilation unit from the unit containing
> the reference.  This type of reference 
> (DW_FORM_ref_addr) ...
> 
> I guess that GCC is not generating it, but I wonder
> if GDB should support it ?

It should support it and doesn't currently.  It's come up a couple
times if you search the list archives.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer