[PATCH v3] elf: Handle .gnu.debuglto_.debug_* sections

[H.J. Lu]

On Thu, Mar 18, 2021 at 6:48 PM Alan Modra <amodra@gmail.com> wrote:
>
> On Thu, Mar 18, 2021 at 07:08:19AM -0700, H.J. Lu wrote:
> > On Thu, Mar 18, 2021 at 2:21 AM Alan Modra <amodra@gmail.com> wrote:
> > >
> > > On Wed, Mar 17, 2021 at 03:43:57PM -0700, H.J. Lu via Binutils wrote:
> > > > commit 994b25132814f4c2be93ce53a616a74139c4cf3c
> > > > Author: H.J. Lu <hjl.tools@gmail.com>
> > > > Date:   Sun Jan 17 20:01:16 2021 -0800
> > > >
> > > >     ld/elf: Ignore section symbols when matching linkonce with comdat
> > > >
> > > > ignored section symbols when comparing symbols in 2 sections.  Since all
> > > > references to debugging sections are done with section symbols, symbols
> > > > in debugging sections are ignored and we fail to match symbols in comdat
> > > > debugging sections.  Also .gnu.debuglto_.debug_* sections aren't treated
> > > > as debugging sections.
> > > >
> > > > 1. Treate .gnu.debuglto_.debug_ section as debugging section unless it
> > > > is marked with SHF_EXCLUDE.
> > >
> > > This part is OK.
> > >
> > > > 2. Ignore section symbols only when matching non-debugging sections or
> > > > linkonce section with comdat section.
> > >
> > > This part has a problem.  elf_create_symbuf stashes away symbols of
> > > interest for an object file, and that set of symbols might be used for
> > > multiple invocations of bfd_elf_match_symbols_in_sections.  You can't
> > > vary the set of symbols stashed based on section, since that would
> > > give the right answer for the first section but possibly wrong answers
> > > for subsequent sections.  Any per-section logic must go in
> > > bfd_elf_match_symbols_in_sections.
> >
> > Here is the v2 patch to revert commit 994b2513281 in elf_create_symbuf
> > and put per-section logic in bfd_elf_match_symbols_in_sections.
> >
> > OK for master?
>
> Did you test with --reduce-memory-overheads?  I don't see any changes
> to bfd_elf_match_symbols_in_sections in code handling that case..

Good point.  Here is the v3 patch with a testcase for
--reduce-memory-overheads.  OK for master?

Thanks.

-- 
H.J.
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