On Wed, Mar 31, 2021 at 7:58 PM Yonghong Song <yhs@xxxxxx> wrote:
>
> Function cus__merging_cu() is introduced in Commit 39227909db3c
> ("dwarf_loader: Permit merging all DWARF CU's for clang LTO built
> binary") to test whether cross-cu references may happen.
> The original implementation anticipates compilation flags
> in dwarf, but later some concerns about binary size surfaced
> and the decision is to scan .debug_abbrev as a faster way
> to check cross-cu references. Also putting a note in vmlinux
> to indicate whether lto is enabled for built or not can
> provide a much faster way.
>
> This patch set implemented this two approaches, first
> checking the note (in Patch #2), if not found, then
> check .debug_abbrev (in Patch #1).
For the series:
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Tested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
(Noting for others on our mailing list:
https://lore.kernel.org/linux-kbuild/20210401012406.1800957-1-yhs@xxxxxx/
is a series of kernel patches required to test this. I had feedback on
the kernel patches, but this approach in pahole LGTM since I think
using simple notes in ELF is a good approach).
>
> Yonghong Song (2):
> dwarf_loader: check .debug_abbrev for cross-cu references
> dwarf_loader: check .notes section for lto build info
>
> dwarf_loader.c | 76 ++++++++++++++++++++++++++++++++++++--------------
> 1 file changed, 55 insertions(+), 21 deletions(-)
>
> --
> 2.30.2
>
--
Thanks,
~Nick Desaulniers
