Hello,
Wanted to follow up on the CTF/BTF debug info + LTO workings.
To summarize, the current status/workflow on trunk is:
- The CTF container is written out in the ctfout.c or btfout.c via the
ctf_debug_finalize () API.
- At this time, the ctf_debug_finalize () itself is called once in
dwarf2out_early_finish ().
- Until this time, the requirements of CTF and BTF are simple.
- The generated .ctf/.BTF sections needs no demarcation of
"early"/"late" debug. All of it can be generated "early".
- The generated .ctf/.BTF information does not need to be different
for the final assembly and the fat LTO IR.
- The BPF CO-RE is not yet implemented on trunk.
Writing out the CTF/BTF at dwarf2out_early_finish seems to work - there
will always be a .ctf/.BTF section whether it's fat or slim LTO objects
(because the emission is still in dwarf2out_early_finish on the trunk).
And we have functionality to copy over the .ctf/.BTF debug sections in
handle_lto_debug_sections (). However, reading through some of the past
emails on the CTF/BTF patch series, it seems that you have been pointing
to the CTF/BTF debug info generation being broken when used with LTO. If
true, I am most certainly missing some key point here.
So, before we move to the next steps of supporting additional
requirements of BPF CO-RE etc., I would like to make sure that my
current understanding is OK and that the current state of CTF/BTF on
trunk is functional -with LTO-. I have tested some bits (with and
without fat objects on x86_64) and have not run into issues.
Can you please confirm what you see amiss in the current workings of
CTF/BTF with LTO on trunk ?
Thanks
Indu
