[llvm-dev] Collecting address ranges in DWARFUnit::collectAddressRanges.

[David Blaikie via llvm-dev]

Totally fair call, sorry it took me a while to come back around to this -
added in r324702

On Thu, Nov 16, 2017 at 3:47 PM Rafael Avila de Espindola <
rafael.espindola at gmail.com> wrote:

> David Blaikie via llvm-dev <llvm-dev at lists.llvm.org> writes:
>
> > On Thu, Nov 16, 2017 at 11:44 AM Robinson, Paul <paul.robinson at sony.com>
> > wrote:
> >
> >> There's no requirement that DW_AT_ranges (or high/low_pc) appear on the
> >> skeleton CU rather than the DWO CU. So it's quite possible that to get
> the
> >> address ranges covered by the CU one would need to look in the DWO, I
> think?
> >>
> >> Is that not correct/have I misunderstood something there?
> >>
> >> The DWO isn't supposed to contain addresses (because it isn't supposed
> to
> >> contain relocations).  In DWARF 5 the DWO can have FORM_addrx
> references to
> >> the .debug_addr section in the main .o file, which allows the DWO to
> >> contain DIEs/attributes that should have address values, because the
> actual
> >> address values are still in the .o file; but before that anything
> that's an
> >> address really can't go into the DWO.
> >>
> >
> > DWOs didn't exist (in a standard form) before DWARF 5, right? Insofar as
> > they did exist (in a non-standard form) they have always supported
> > FORM_addr_index to reference addresses in .debug_addr in the main .o.
> >
> > But the low_pc/high_pc/ranges attributes would appear in the .dwo, using
> a
> > FORM_addr_index/FORM_addrx - so if you want to collect the address range
> of
> > a CU you might need to load the .dwo to do so. That's the crux of what I
> > was getting at: To get the address range a CU covers, you may need to
> read
> > the .dwo.
>
> Is it possible to add a test for that? I can confirm that the attached
> patch causes not failures on llvm, clang or lld tests.
>
> Cheers,
> Rafael
>
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