Re: [RFC PATCH] x86: enable dead code and data elimination (LTO)

[Masahiro Yamada]

Hi.

2017-07-09 18:05 GMT+09:00 Ingo Molnar <mingo@xxxxxxxxxx>:
>
> * Nicholas Piggin <npiggin@xxxxxxxxx> wrote:
>
>> FYI, easiest way to check if you forgot to KEEP a linker table is
>> to look at `readelf -S vmlinux` differences, and to see what is
>> being trimmed, look at nm differences or use --print-gc-sections
>> LD option to see what symbols you're trimming. Linker tables,
>> boot entry, and exception entry tends to require anchoring.
>
> Could you please add a debug build target to display all discarded
> symbols/sections? Something like:
>
>         make lto-check
>
> ... or so?
>
> Thanks,
>
>         Ingo


Actually, LTO activity existed some years ago
(but not pulled in).

http://www.spinics.net/lists/linux-kbuild/msg09242.html


IIUC, this patch enables "dead code elimination",
(or "garbage collection"?),
but I think it is different from what is called LTO.


-- 
Best Regards
Masahiro Yamada