llvm dev - Sep 2019 - [DebugInfo] emission of loclists.dwo

Hi Folks,

While working on dwarf5 features in clang, I noticed some subtleties wrt
locationlists--

In split-dwarf  + dwarf5 mode -
debug_loclists.dwo section is not generated, instead debug_loc.dwo is
getting populated in dwo file. + Hexdump shows that pre-standardized
encoding used while encoding.

This is causing problems for llvm-dwarfdump in dumping location list.
I'm guessing, llvm-dwarfdump is assuming it should be accessed according to
dwarf5, hence failing{not reporting}  ???

In, split-mode +dwarf-4{default} mode -- everything is fine. section
generation and llvm-dwarfdump.

+ While fixing this issue, I've been trying to bring this section
debug_loclists.dwo from ground up -- creating LoclistsDWOSection and so
forth.

Can anybody faced  with these issues earlier, validate these findings?,
work in progress if it's their any?, approach / solution taken to fix these
???

Thanks !
-- Sourabh Singh Tomar
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Yep, I've been looking at making some improvements to location list
emission (using base address specifiers, etc) & came across this hole as
well.

Don't have any immediate fix myself - but I'm pretty sure we don't
ever
want to use the direct address forms (LLE_base_address, LLE_start_length,
etc) even in non-Split DWARF (sticking to the address pool forms -
base_addressx, startx_length, etc) - so it should be fine to use exactly
the same code for debug_loclists and debug_loclists.dwo

On Sat, Sep 28, 2019 at 9:54 AM Sourabh Singh Tomar via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hi Folks,
>
> While working on dwarf5 features in clang, I noticed some subtleties wrt
> locationlists--
>
> In split-dwarf  + dwarf5 mode -
> debug_loclists.dwo section is not generated, instead debug_loc.dwo is
> getting populated in dwo file. + Hexdump shows that pre-standardized
> encoding used while encoding.
>
> This is causing problems for llvm-dwarfdump in dumping location list.
> I'm guessing, llvm-dwarfdump is assuming it should be accessed
according
> to dwarf5, hence failing{not reporting}  ???
>
> In, split-mode +dwarf-4{default} mode -- everything is fine. section
> generation and llvm-dwarfdump.
>
> + While fixing this issue, I've been trying to bring this section
> debug_loclists.dwo from ground up -- creating LoclistsDWOSection and so
> forth.
>
> Can anybody faced  with these issues earlier, validate these findings?,
> work in progress if it's their any?, approach / solution taken to fix
these
> ???
>
> Thanks !
> -- Sourabh Singh Tomar
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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