[PATCH] bfd/dwarf2: break equal-range function ties by DIE offset, not pointer

[Jan Beulich]

On 18.08.2026 04:11, Sam Price wrote:
> lookup_address_in_function_table picks the function with the smallest range
> containing the address.  When two candidates have the same range -- an inlined
> subroutine covering its containing subprogram exactly -- the tie was broken by
> comparing the two funcinfo pointers.  Those come from bfd_zalloc, so the winner
> tracked heap layout (a new objalloc chunk can land below the old one), and
> addr2line named a different function from run to run on the same binary; only
> the function and its inlined frames varied, never file and line.
> 
> Order by unit_offset instead.  It does not move with the heap, and it restores
> the pre-089e3718bd8 result: that algorithm walked the prepend-built
> function_table and kept the last-parsed among equals, i.e. the greater DW_AT
> offset.  An inlined subroutine's DIE is a child of its subprogram's, so it has
> the greater offset and now wins every time -- the innermost routine, as
> intended.  The offsets are unique within the one comp_unit these candidates
> share.
> 
> This only changes output that was already unstable: funcinfos are allocated in
> increasing-offset scan order, so within a single chunk pointer order and offset
> order agree and both rules pick the same function -- verified byte-identical
> over 164k addresses across ten inlined binaries.  Forcing the divergence needs
> a chunk placed below its predecessor, which test input cannot, so the added
> dw2-inline-tie test is a regression pin (inverting the compare to < fails it),
> not a trigger.
> 
> bfd/
> 	* dwarf2.c (lookup_address_in_function_table): Break equal
> 	best_fit_len ties on funcinfo->unit_offset rather than on the
> 	funcinfo pointer.
> 
> Signed-off-by: Samuel Price <thesamprice@gmail.com>
> Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
> ---
>  bfd/dwarf2.c                                     |   11 +
>  binutils/testsuite/binutils-all/addr2line.exp    |    7 +
>  binutils/testsuite/binutils-all/dw2-inline-tie.S |  186 ++++++++++++++++++++++
>  binutils/testsuite/binutils-all/dw2-inline-tie.d |   12 +
>  4 files changed, 214 insertions(+), 2 deletions(-)

This all looks good to me, if there wasn't the Co-Authored-By:. That, to me,
suggests that part of the patch was AI-generated, which would be in conflict
with [1].

Nick - if Sam came back saying the patch itself wasn't co-authored by Claude,
i.e. if this was more like an Assisted-by: tag, would that then be okay to
accept without asking further questions? Further, had the tag been absent, I
likely wouldn't have recognized any possible AI origin. Which puts under
question how to actually put the policy into practical effect.

Jan

[1] https://sourceware.org/binutils/wiki/LLM_Generated_Content