llvm dev - Jun 2010 - [LLVMdev] [patch] DwarfDebug problem with line section

Hi all,
While implementing debug info for our backend, we've noticed a problem with
debug_line section. We believe that the following code is wrong:

// DW_AT_stmt_list is a offset of line number information for this
// compile unit in debug_line section. It is always zero when only one
// compile unit is emitted in one object file.
addUInt(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4, 0);

After compiling several files and linking them together (not only using our
backend, but also x86) debug information was incorrect.
I'm not 100% sure if this fix is correct, but patch attached.

Artur
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20100629/80c941e9/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: section_line_debug.patch
Type: text/x-patch
Size: 1275 bytes
Desc: not available
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20100629/80c941e9/attachment.bin>

DW_AT_stmt_list attribute's value is a section offset to the line no
info for current compilation unit. If there is only one  compilation
unit generated per .o file then it is always zero. What kind of errors
are you seeing ?

-
Devang

On Tue, Jun 29, 2010 at 9:02 AM, Artur Pietrek <pietreka at gmail.com>
wrote:
> Hi all,
> While implementing debug info for our backend, we've noticed a problem
with
> debug_line section. We believe that the following code is wrong:
> // DW_AT_stmt_list is a offset of line number information for this
> // compile unit in debug_line section. It is always zero when only one
> // compile unit is emitted in one object file.
> addUInt(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4, 0);
> After compiling several files and linking them together (not only using our
> backend, but also x86) debug information was incorrect.
> I'm not 100% sure if this fix is correct, but patch attached.
> Artur
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>


-- 
-
Devang

I updated DwarfDebug to use section offset, instead of hard coding 0,
to handle LTO properly.
r107202.

Thanks for brining this up.
-
Devang

On Tue, Jun 29, 2010 at 11:27 AM, Devang Patel <devang.patel at gmail.com>
wrote:
> DW_AT_stmt_list attribute's value is a section offset to the line no
> info for current compilation unit. If there is only one  compilation
> unit generated per .o file then it is always zero. What kind of errors
> are you seeing ?
>
> -
> Devang
>
> On Tue, Jun 29, 2010 at 9:02 AM, Artur Pietrek <pietreka at
gmail.com> wrote:
>> Hi all,
>> While implementing debug info for our backend, we've noticed a
problem with
>> debug_line section. We believe that the following code is wrong:
>> // DW_AT_stmt_list is a offset of line number information for this
>> // compile unit in debug_line section. It is always zero when only one
>> // compile unit is emitted in one object file.
>> addUInt(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4, 0);
>> After compiling several files and linking them together (not only using
our
>> backend, but also x86) debug information was incorrect.
>> I'm not 100% sure if this fix is correct, but patch attached.
>> Artur
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>>
>
>
>
> --
> -
> Devang
>


-- 
-
Devang