[Bug debug/113566] btf: incorrect BTF_KIND_DATASEC entries for variables which are optimized out

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113566

--- Comment #1 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by David Faust <dfaust@gcc.gnu.org>:

https://gcc.gnu.org/g:8075477f81ae8d0abf64b80dfbd179151f91b417

commit r14-9876-g8075477f81ae8d0abf64b80dfbd179151f91b417
Author: David Faust <david.faust@oracle.com>
Date:   Mon Apr 8 11:10:41 2024 -0700

    btf: emit symbol refs in DATASEC entries only for BPF [PR114608]

    The behavior introduced in
      fa60ac54964 btf: Emit labels in DATASEC bts_offset entries.

    is only fully correct when compiling for the BPF target with BPF CO-RE
    enabled.  In other cases, depending on optimizations, it can result in
    an incorrect symbol reference in the entry bts_offset field for a symbol
    which may not be emitted at all, causing link-time undefined symbol
    reference errors like in PR114608.

    The offending bts_offset field of BTF_KIND_DATASEC entries is in reality
    only currently useful to consumers of BTF information for BPF programs
    anyway.  Correct the regression by only emitting symbol references in
    these entries when compiling for the BPF target.  For other targets, the
    behavior returns to that prior to fa60ac54964.

    The underlying cause is related to PR 113566 "btf: incorrect
    BTF_KIND_DATASEC entries for variables which are optimized out." A
    complete fix for 113566 is more involved and unsuitable for stage 4,
    but will be addressed in the near future.

    gcc/
            PR debug/114608
            * btfout.cc (btf_asm_datasec_entry): Only emit a symbol reference
when
            generating BTF for BPF CO-RE target.

    gcc/testsuite/
            PR debug/114608
            * gcc.dg/debug/btf/btf-datasec-1.c: Check bts_offset symbol
references
            only for BPF target.
            * gcc.dg/debug/btf/btf-datasec-2.c: Likewise.
            * gcc.dg/debug/btf/btf-pr106773.c: Likewise.