[llvm-dev] debug_rnglists status

[David Blaikie via llvm-dev]

Note that debug_addr support is already present for pre-DWARFv5
fission/split-dwarf support. I imagine the thing to do for DWARFv5 support
is to generalize this for non-split-DWARF cases, etc.

Happy to help, code review, etc. This stuff as I've dabbled a fair bit with
the original split DWARF support over the years. (though echristo
originally implemented most of it)

On Fri, Jul 13, 2018 at 7:39 AM Victor Leschuk via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> 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
> >>>
> >> _______________________________________________
> >> LLVM Developers mailing list
> >> llvm-dev at lists.llvm.org
> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
> --
> Best Regards,
>
> Victor Leschuk | Software Engineer | Access Softek
>
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