[llvm-dev] debug_rnglists status

[Victor Leschuk via llvm-dev]

Hello Paul,

thanks a lot for the top. I will try to look into .debug_addr section 
and ask questions if any.


On 07/12/2018 08:32 PM, paul.robinson at sony.com wrote:
> Hi Victor,
>
> The work Wolfgang is doing should get us to the "minimum syntactically
> correct DWARF v5" stage, which we really wanted to have for LLVM 7.0.
> That is, once we have .debug_rnglists and .debug_loclists done, you can
> ask for DWARF 5 and get something that conforms to the spec.  However,
> it won't conform if you ask for type units (I'm working on that) or
> split DWARF.
>
> If your motivation is to help reduce the number of relocations needed,
> then working on the .debug_addr section is definitely the next step.
> This will reduce relocations in pretty much every other DWARF section.
>
> If you have other goals, let us know what they are.
> Thanks,
> --paulr
>
>
>> -----Original Message-----
>> From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of via
>> llvm-dev
>> Sent: Thursday, July 12, 2018 1:08 PM
>> To: vleschuk at accesssoftek.com; llvm-dev at lists.llvm.org
>> Subject: Re: [llvm-dev] debug_rnglists status
>>
>> Hi Victor!
>>
>> I am just about to commit https://reviews.llvm.org/D49214, the first
>> implementation of .debug_rnglists. As you can probably see from the review
>> it generates the v5 range list table with range list entries using
>> primarily the DW_RLE_start_length and DW_RLE_offset_pair entry kinds (and
>> DW_RLE_end_of_list and DW_RLE_base_address). So what is currently missing
>> is the following:
>>
>> - Support for split DWARF. I think this requires first support for
>> .debug_addr, because we need to generate at least DW_RLE_base_addressx
>> entries (or the CU needs to set its DW_AT_low_pc referencing the
>> .debug_addr section). If that's in place we can generate all the *x entry
>> kinds (DW_RLE_startx_endx etc.)
>>
>> - Generating the offset table and using DW_FORM_rnglistx with the
>> DW_AT_ranges attribute. This should cut down further on the relocations
>> the linker needs to perform.
>>
>> Also, I am currently working on a refactor of the .debug_rnglists dumper
>> (reader) part. The rationale is that the location list table in
>> .debug_loclists is identical in layout to the range list table, and so I
>> want to take advantage of that.
>>
>> Let me know if you have any more questions.
>>
>> Cheers,
>> Wolfgang
>>
>>> -----Original Message-----
>>> From: Victor Leschuk [mailto:vleschuk at accesssoftek.com]
>>> Sent: Thursday, July 12, 2018 2:24 AM
>>> To: Pieb, Wolfgang; LLVM Dev
>>> Cc: aprantl at apple.com; David Blaikie
>>> Subject: debug_rnglists status
>>>
>>> Hello Wolfgang and team,
>>>
>>> I see that you are working on support of .debug_rnglists, I am
>>> interested in the feature too, could you please point me out what else
>>> left to be done so that I could help you?
>>>
>>> --
>>> Best Regards,
>>>
>>> Victor Leschuk | Software Engineer | Access Softek
>>>
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-- 
Best Regards,

Victor Leschuk | Software Engineer | Access Softek